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Lakis Amarantithis
08-17-2014, 06:53 PM
Can someone maybe from Red take some shots at night in various situations with some nice fast lenses without the olpf and post some r3d's here?

Thanks!

Roger Viloria
08-17-2014, 07:02 PM
Yeah, I like that request!

Will Keir
08-17-2014, 07:24 PM
Yeah, I like that too. Might just be crazy enough to try it... Will that effect the warranty?

Brian Merlen
08-17-2014, 07:55 PM
my dp just made a pinhole lens out of a beer can, shoot rugged brah

John Marchant
08-18-2014, 08:46 AM
You won't see the clean image you're hoping for (like a V1 olpf) with a V2 calibrated cam and the OLPF removed - there's calibration to consider, and I imagine Red will be providing for that in firmware once alternate OLPFs hit the street.

Best case your ISO will be lying to you, but even then I believe the per-channel calibrations are different too.

For clarity - a lens cap shot on V1 is cleaner than on V2. Clearly that has nothing to do with optics, and everything to do with how the camera is calibrated to work in conjunction with its optics.

Will Keir
08-18-2014, 09:16 AM
How do you know? Until you've tried it, it sounds like a guess.


You won't see the clean image you're hoping for (like a V1 olpf) with a V2 calibrated cam and the OLPF removed - there's calibration to consider

Jason Diamond
08-18-2014, 09:21 AM
How do you know? Until you've tried it, it sounds like a guess.
I wouldn't doubt John's comments, he definitely knows what he's talking about. :)

John Marchant
08-18-2014, 09:50 AM
Definitely not a guess hehe. Appreciate that for many it would be of course :) The lens cap test is the proof though, even if it were a guess.

Lakis Amarantithis
08-18-2014, 11:05 AM
I have seen footage with the Epic someone posted here with no OLPF and (for the kind of that particular shot - poor families in far East dumps) looked awesome to me. Extremely sharp also!
I experiment with the Epic and no OLPF and it's awesome for particular shots only.

I think Dragon will have some commonalities with the Epic on that.

I don't mind the ISO lying, the monitor says everything to me.

I hope the great people in Red are working hard to make these OLPF's availabe Fast!

They will make a huge difference.

I wish they could put them in the Motion Mount or do something else so we could change them on the fly.

Maybe they can do that and then we all have to gladly send the Dragons back for The modification?...

Will Keir
08-18-2014, 11:11 AM
So you have done tests with the OLPF removed John?


Definitely not a guess hehe. Appreciate that for many it would be of course :) The lens cap test is the proof though, even if it were a guess.

Sounds like a guess...


I wouldn't doubt John's comments, he definitely knows what he's talking about. :)

Understood, it's not a guess then... So can you share what test you did with the OLPF removed?


Definitely not a guess hehe.

Prove it.

Les Dittert
08-18-2014, 11:25 AM
Will, what are you hoping to gain ?
BTW, shooting without low pass and using current Red processing is not going to make an optimal picture. It was not made for that.

Gavin Greenwalt
08-18-2014, 07:46 PM
For the people whose OLPFs were installed upside down, RED let them flip it with a kit if I remember correctly without returning it to RED. I imagine some people took that opportunity to take it off without voiding warranty to shoot some footage. ;)

Will Keir
08-18-2014, 08:05 PM
Hoping to gain another stop or so of light in the lows.

OLPF's are like sunglasses, the new OLPF is just a heavier shady. So so brightness goes up when you take em all off? Ya.

Will, what are you hoping to gain ?
BTW, shooting without low pass and using current Red processing is not going to make an optimal picture. It was not made for that.

Gavin Greenwalt
08-18-2014, 10:32 PM
Hoping to gain another stop or so of light in the lows.

OLPF's are like sunglasses, the new OLPF is just a heavier shady. So so brightness goes up when you take em all off? Ya.

No. OLPFs are like very very weak diffusion filters and an IR hot mirror plus a slight color filter. The actual loss of light is probably pretty small. Most of the light loss is in the OLPF color filters. At best you'll probably get 1/4 of a stop without an OLPF. The biggest difference is shaprness, you trade off resolution for aliasing and possible moire. You would also have substantially more IR sensitivity and would have to use a hot mirror in front of the lens (and lose at least 1/4 of a stop anyway) and the debayer color science would be off since it would be purely neutral.

The new OLPF added extra red filtration to cut out near IR flaring. Without it the red channel would be cleaner since it would be less underexposed but it will be too bright unless RED changes your color science to not apply the corrective digital gain.

John Marchant
08-18-2014, 10:39 PM
Some example OLPF / sensor filters from my stash. You can see more easily like this how the filters are more complex than just an ND. You can also see how the later Dragon OLPF cuts a lot of red light.

http://kippertie.com/red/glass.jpg

Gavin Greenwalt
08-18-2014, 10:44 PM
Whoa, that is a pretty intense red cut. I would have expected it to be closer to the MX sensor or even less for the V1 since they were starting from a fresh sensor design.

John Marchant
08-18-2014, 10:55 PM
I don't have a loose V1 OLPF around to photograph... Its closer visually to the MX than the V2 above, but there's more going on than that of course.

Gunleik Groven
08-18-2014, 11:29 PM
Some example OLPF / sensor filters from my stash. You can see more easily like this how the filters are more complex than just an ND. You can also see how the later Dragon OLPF cuts a lot of red light.

http://kippertie.com/red/glass.jpg

That was an interesting lineup.

THX

Will Keir
08-18-2014, 11:51 PM
Gavin. I thought your views on 4k were enlightening and appreciate your challenge of Michael Cioni's post for the Expendables 4k workflow.

Now how do you come up with the number 1/4 of a stop of light from the New OLPF to none? A guess?

The New OLPF is less sensitive in lowlight than the old. Has anyone actually measured the difference? It's dramatic enough for RED to consider the old OLPF to be the "lowlight" option in their modular OLPF design. I'm just looking for some numbers here man, it seems obvious the image will suffer. Diffusion filters lower measured light levels correct? So do sunglasses.


No. OLPFs are like very very weak diffusion filters and an IR hot mirror plus a slight color filter. The actual loss of light is probably pretty small. Most of the light loss is in the OLPF color filters. At best you'll probably get 1/4 of a stop without an OLPF. The biggest difference is shaprness, you trade off resolution for aliasing and possible moire. You would also have substantially more IR sensitivity and would have to use a hot mirror in front of the lens (and lose at least 1/4 of a stop anyway) and the debayer color science would be off since it would be purely neutral.

The new OLPF added extra red filtration to cut out near IR flaring. Without it the red channel would be cleaner since it would be less underexposed but it will be too bright unless RED changes your color science to not apply the corrective digital gain.

Will Keir
08-18-2014, 11:55 PM
Looks like four difference pairs of sunglasses, with one missing. Why don't we add the Dragon V2 filter as a Mattebox filter? It's like having another filter on the mattebox except this one get's a little more personal.

I've never seen the OLPF lineup, thank you sincerely for taking the time to share this.


Some example OLPF / sensor filters from my stash. You can see more easily like this how the filters are more complex than just an ND. You can also see how the later Dragon OLPF cuts a lot of red light.

http://kippertie.com/red/glass.jpg

Gunleik Groven
08-18-2014, 11:56 PM
Gavin. I thought your views on 4k were enlightening and appreciate your challenge of Michael Cioni's post for the Expendables 4k workflow.

Now how do you come up with the number 1/4 of a stop of light from the New OLPF to none? A guess?

The New OLPF is less sensitive in lowlight than the old. Has anyone actually measured the difference? It's dramatic enough for RED to consider the old OLPF to be the "lowlight" option in their modular OLPF design. I'm just looking for some numbers here man, it seems obvious the image will suffer. Diffusion filters lower measured light levels correct? So do sunglasses.

You should re-read Gawins post...

Will Keir
08-18-2014, 11:56 PM
Who is Gawins? Which line specifically of Gavins post do you feel I need to reread? In your estimation, what am I not getting?


You should re-read Gawins post...

This one?


I'm going to be the voice of dissent here and say that while I agree uprezzing in software is superior to uprezzing in the projector, let's not lose sight of the fact that we're still talking about up-rezzed content.

The two options you're proposing Michael are essentially:

1) Shoot 4k -> Scale 200% in Software -> Project 4k.
2) Shoot 4k -> Crop to 2k (no scale) -> Scale in Projector 200% -> Project 4k.

Yes the software option can be a slightly better choice since you can employ more sophisticated algorithms but that's not a universal true statement. There are some superb hardware solutions these days at uprezzing content to 4k. And there are some superb software solutions to uprezzing content. I wouldn't say "Software uprezzing looks better" what I would say is that "If you deliver a 2k master in 2k then you have no idea what algorithm will be employed to uprez it for 4k, if you uprez your movie yourself it will have full control over what algorithm is employed."

However, if you just use something like a vanilla bicubic then your projector and your software will probably look identical pixel for pixel since they're literally doing the exact same thing to your footage.

Ultimately I agree with the sentiment. I've done 720p YouTube spots in 5k and ran out of resolution. But since it was a 720p delivery I didn't scale the entire project up to 4k. One nearly universal truth is that if you can't deliver a 4k display it's better not to do what you just described and simply crop? Why? Number of processes.

Let's say you are delivering 1080p for TV. In this case you're going to do one of the following:

1) Capture 5k -> Crop 50% -> Delivery 1080p Master
2) Capture 5k -> Scale 266% -> Scale 37% -> Delivery 1080p Master


Option 1 is going to look WAY BETTER. One of the really important things when manipulating images in VFX is that you concatenate your operations wherever possible, so if you transform, skew and scale an image you have to be very very careful to ensure that you don't perform multiple transform operations out of sync. The problem with scaling up to 266% and then scaling back down for a 1080p delivery is that both are destructive operations. Stacking multiple destructive operations on top of each other and lose quality at each step. MOAR PIXELS isn't always true. I'm glad it worked well for a film where you were confident most of your projectors could display a 4k master and of course if you're going 4k because 50% of your shots are 4k then you'll be better off, but this advice does not carry over to TV where 0% of your displays will be in 4k and 0% of your shots will end up in 4k.

http://i111.photobucket.com/albums/n134/im_thatoneguy/rescaling_zps34ea59ab.png (http://s111.photobucket.com/user/im_thatoneguy/media/rescaling_zps34ea59ab.png.html)

In this example I started with a 0.25k image, scaled it up to 200%, then scaled it back down by 50%. As you can see you've lost substantial sharpness by running it through 2 scaling algorithms as opposed to no scaling at all.

Similarly if you are able and have time your 2k masters should not be from a 4k timeline for this reason other wise you are doing:

1) 4k Master -> 200% Scale to 4k zoom -> 50% to 2k DCP -> 200% scale to ?4k projector?
vs
2) 4k Master -> Crop to 2k DCP -> 200% Scale to 4k projection.

You've eliminated one scale operation and your image will look way sharper than a 2k master from a 4k master.

Or this one?


No. OLPFs are like very very weak diffusion filters and an IR hot mirror plus a slight color filter. The actual loss of light is probably pretty small. Most of the light loss is in the OLPF color filters. At best you'll probably get 1/4 of a stop without an OLPF. The biggest difference is shaprness, you trade off resolution for aliasing and possible moire. You would also have substantially more IR sensitivity and would have to use a hot mirror in front of the lens (and lose at least 1/4 of a stop anyway) and the debayer color science would be off since it would be purely neutral.

The new OLPF added extra red filtration to cut out near IR flaring. Without it the red channel would be cleaner since it would be less underexposed but it will be too bright unless RED changes your color science to not apply the corrective digital gain.

Gunleik Groven
08-18-2014, 11:58 PM
hahahaha
The post of Gavin...

He says:
IF you remove the OLPF, you'll need to IR cut and the IR cut will lose you 1/4 stop.
Has nothing to do with the rest of the chain... :)

Will Keir
08-19-2014, 12:00 AM
My question is how is this measurement quantified? Why 1/4th, how did he come up with this number? Or is it a theory... a guess based on his experience and intelligence?


hahahaha
The post of Gavin...

He says:
IF you remove the OLPF, you'll need to IR cut and the IR cut will lose you 1/4 stop.
Has nothing to do with the rest of the chain... :)

Gunleik Groven
08-19-2014, 12:11 AM
If you set in a hot mirror/IR cut, the filtermaker will usually inform you of the lightloss. 1/4 to me seems conservative... :)

Will Keir
08-19-2014, 12:15 AM
Who makes IR Cut OLPF filters?




If you set in a hot mirror/IR cut, the filtermaker will usually inform you of the lightloss. 1/4 to me seems conservative... :)

Matt Ryan
08-19-2014, 12:33 AM
Will, remember the olpf is only part of the chain. The accompanying calibration is the second part of the chain. The old calibration was more favorable to the low end whereas the new olpf/calibration favors a shift towards the high lights. That's where we get the 1.3 less latitude in the low end in favor of swapping it up top.

Gunleik Groven
08-19-2014, 12:40 AM
What Matt said.

Dunno if I am particularly unclear, but I'll try again...

In an OLPF like Dragons it's baked in.

If you REMOVE the OLPF, you need to fit an IR cut in front of the lens.

THAT will according to Gavin take 1/ of a stop light.
I commented that I think that might be a conservative number, depending on which IR-cut you apply.

John Marchant
08-19-2014, 02:23 AM
Who makes IR Cut OLPF filters?

Low volume

http://goochandhousego.com/
http://www.uqgoptics.com/
https://www.knightoptical.com/
http://www.kingsviewoptical.com/

High volume

http://www.moe.com.tw/
http://www.tradekorea.com/product/detail/P399869/Sell-OLPF-filter.html
http://www.isuzuglass.com/


And many many more with varying costs, capabilities and standards.

Will Keir
08-19-2014, 08:15 AM
Looks like you got an edge on the custom OLPF market. Wonder if RED would let it go 3rd party which would probably produce some really cool custom results. Very similar to filters, like the popular promist 1/8th, I'd bet. But this all voids the warranty according to my Bomb Squad Rep Clark McClanathan.

"Hello Will,

At this point, removing the tamper stickers and changing out the OLPF will void your warranty on the sensor and the OLPF itself. It could possibly void warranty on the camera completely as well, if anything went wrong, which would be determined by a RED technician during an evaluation.

If you would like to have any OLPF changes made, I would highly suggest sending in your camera.

There has been no date or timeline set for the INTERCHANGEABLE OLPF. Once any information is made available I can let you know. I would keep checking REDuser.net though, as a lot of times Jarred/other RED employees will post information there before we get in for the next work day and are notified of changes or updates.

Regards,"

So take out the OLPF and put a 1/4th IR filter on your mattbox, you gain some low light sensitivity?

What is the low light sensitivity of the OLD OLPF vs the New?

Matt. 1.3 Stops of light was the measurement by Phill Holland on Epic vs Dragon.

Low volume

http://goochandhousego.com/
http://www.uqgoptics.com/
https://www.knightoptical.com/
http://www.kingsviewoptical.com/

High volume

http://www.moe.com.tw/
http://www.tradekorea.com/product/detail/P399869/Sell-OLPF-filter.html
http://www.isuzuglass.com/


And many many more with varying costs, capabilities and standards.

Gavin Greenwalt
08-19-2014, 08:31 AM
My question is how is this measurement quantified? Why 1/4th, how did he come up with this number? Or is it a theory... a guess based on his experience and intelligence?

Educated guess on most of the OLPFs I have seen. Apparently I was off though by a good margin for Dragon which has a super intense color filter now. Still my point is when you say "sunglasses" I think Neutral Density. OLPFs aren't just bringing down the exposure they're optically calibrating the image chain to balance out negative

As to the Hotmirror being 1/4 there are IR coatings out there which will mostly eliminate IR with only a 15% transmission loss in the visible range but they don't handle the full IR range so I figured doubling it would be safe. ;)

JanneJansson
08-19-2014, 10:08 AM
Some example OLPF / sensor filters from my stash. You can see more easily like this how the filters are more complex than just an ND. You can also see how the later Dragon OLPF cuts a lot of red light.

http://kippertie.com/red/glass.jpg


Great post! Thank you!

John Marchant
08-19-2014, 10:22 AM
I have a bunch more options too, but they're a real rogue's gallery hehe!

Lakis Amarantithis
08-19-2014, 11:11 AM
Too much talk and no r3d's. Talk is talk r3d's are r3d's! I just asked for r3d's. Let them talk. Then everybody can make his/her mind.

Matt Ryan
08-19-2014, 11:53 AM
Too much talk and no r3d's. Talk is talk r3d's are r3d's! I just asked for r3d's. Let them talk. Then everybody can make his/her mind.

Agreed. This site has become a lot of talk and very little R3D's to back it up. Usually processed jpegs with NR and sharpening are the norm. Let's see the R3D's...

Gunleik Groven
08-19-2014, 12:04 PM
As one who have shared a few...

There are issues with sharing RAW files.... :)
Unless they are specifically made for sharing.

Matt Ryan
08-19-2014, 12:18 PM
As one who have shared a few...

There are issues with sharing RAW files.... :)
Unless they are specifically made for sharing.

OLPF tests hardly seem like an NDA issue ;)

Gunleik Groven
08-19-2014, 12:23 PM
OLPF tests hardly seem like an NDA issue ;)

That depends on the context of the test.

Tests like the one we did in Bristol are done all the time (with relevant cameras), but mostly they are not publishable as they belong to productions which pay for them.

I don't really see many popping out their OLPFs just out of curiosity. I won't... :)

Mark van Coller
08-19-2014, 12:41 PM
Coming from an underwater shooting background it looks like the Dragon V2 filter blocks out a lot of the red light wavelength. This is exactly what we do NOT want for underwater shooting. I do realize that underwater shooting is a very small market.

Matt Ryan
08-19-2014, 12:49 PM
Coming from an underwater shooting background it looks like the Dragon V2 filter blocks out a lot of the red light wavelength. This is exactly what we do NOT want for underwater shooting. I do realize that underwater shooting is a very small market.

That would explain the red noise issue as well...

John Marchant
08-19-2014, 12:57 PM
I try and share what I can on this forum. An informed user base is good for me commercially, plus I just like to share.

I'll post some R3Ds on this subject when I have time, but right this moment I'm prepping to spend a day covering exactly this kind of stuff for some of my trusted paying clients. They value my input, but you're under no obligation to do likewise.

That said, who actually wants to bet against my opinion on this?

Gunleik Groven
08-19-2014, 01:02 PM
#notme

Matt Ryan
08-19-2014, 01:04 PM
I don't think anyone does, we just want to see with our own eyes ;)

Nobody I know would pop off an OLPF right now and test other ones...

John Marchant
08-19-2014, 01:05 PM
That post is about as grumpy as I get btw. So sit tight and christmas will come.

Jeremy Hildebrant
08-19-2014, 03:06 PM
That would explain the red noise issue as well...

This also may explain why Dragon is doing better under tungsten light than the MX did...

Matt Ryan
08-19-2014, 03:35 PM
This also may explain why Dragon is doing better under tungsten light than the MX did...

exactly

Will Keir
08-19-2014, 05:34 PM
I have no trouble sharing R3Ds but first I gotta know what I'm talking about. :)


Agreed. This site has become a lot of talk and very little R3D's to back it up. Usually processed jpegs with NR and sharpening are the norm. Let's see the R3D's...

Will Keir
08-19-2014, 05:35 PM
But still am important one.


I do realize that underwater shooting is a very small market.

Will Keir
08-19-2014, 05:36 PM
What's the bet? :)


I try and share what I can on this forum. An informed user base is good for me commercially, plus I just like to share.

I'll post some R3Ds on this subject when I have time, but right this moment I'm prepping to spend a day covering exactly this kind of stuff for some of my trusted paying clients. They value my input, but you're under no obligation to do likewise.

That said, who actually wants to bet against my opinion on this?

Elan Gunos
08-20-2014, 12:38 AM
Doesn't that guy on here, Les Dittert, shoot without one but for his Scarlet? Perhaps the best Scarlet footage around actually, especially the stuff he shot in India. Can the same be applied to the Dragon?

http://www.reduser.net/forum/showthread.php?89556-Got-6K-(-link-to-my-LA-vista-shoot-test-)

Les Dittert
08-20-2014, 12:50 AM
Doesn't that guy on here, Les Dittert, shoot without one but for his Scarlet? Perhaps the best Scarlet footage around actually, especially the stuff he shot in India. Can the same be applied to the Dragon?

http://www.reduser.net/forum/showthread.php?89556-Got-6K-(-link-to-my-LA-vista-shoot-test-)

Sure can, but RED is going to cover the Dragon OLPF kit needs for you guys, you just have to wait a bit more for Red's kit.
I continue to enjoy my Epic with the extra sharpness, which is sharper than a Dragon 6K with OLPF. It does alias sometimes, so be aware that it is like driving without seat belts ;)

I have messaged John in hoping to get a Dragon r3d to look at as well. I think it will be interesting.

Elan Gunos
08-20-2014, 01:01 AM
Oh wow, you switched to an Epic? How is that stuff looking? Shit, I need to go on here more.


Sure can, but RED is going to cover the Dragon OLPF kit needs for you guys, you just have to wait a bit more for Red's kit.
I continue to enjoy my Epic with the extra sharpness, which is sharper than a Dragon 6K with OLPF. It does alias sometimes, so be aware that it is like driving without seat belts ;)

I have messaged John in hoping to get a Dragon r3d to look at as well. I think it will be interesting.

Les Dittert
08-20-2014, 01:07 AM
Like this,

http://www.pixelharvest.com/Tondo2014.html


Oh wow, you switched to an Epic? How is that stuff looking? Shit, I need to go on here more.

Elan Gunos
08-20-2014, 01:10 AM
Holy crap amazing. You still need to run it with that special process of yours? How long did that movie take to process/render?


Like this,

http://www.pixelharvest.com/Tondo2014.html

Les Dittert
08-20-2014, 01:15 AM
Holy crap amazing. You still need to run it with that special process of yours? How long did that movie take to process/render?

Thanks. I was lazy on that edit and processed the r3d's with ordinary RCX . You can see the aliasing on the fence and some water. It looks sharper in 4K when I do special processing.

Lakis Amarantithis
08-24-2014, 11:33 AM
Thanks. I was lazy on that edit and processed the r3d's with ordinary RCX . You can see the aliasing on the fence and some water. It looks sharper in 4K when I do special processing.

That's one of the best uses of a camera I've seen let alone a Red.

Finally someone who uses the camera as it should be used including the subject matter! Finally!

However... I think Dragon is hugely under estimated. When the new OLPF's come it'll change everyone's perception about the Dragon. I'm sure and anxious to see that.

I also wish if Mr. Toia reads this to share some of the r3d's from the very first Dragons he had the chance to shoot. Many of those shots at 2000 iso look fantastic.

Peter Strietmann
08-24-2014, 12:28 PM
Like this,

http://www.pixelharvest.com/Tondo2014.html

I am speechless. Thank you for sharing this.

Brandon J.F.
08-24-2014, 12:56 PM
Like this,

http://www.pixelharvest.com/Tondo2014.html

That was utterly compelling. You captured some amazing moments. Well done.

Brice Ansel
08-24-2014, 04:26 PM
Like this,

http://www.pixelharvest.com/Tondo2014.html

Wow!
What a strong 7mn movie, really well done Les Ditert.
B.

Mark George
08-24-2014, 09:43 PM
Like this,

http://www.pixelharvest.com/Tondo2014.html


Les, that was incredibly powerful.

Les Dittert
08-24-2014, 11:01 PM
Thank you for all the kind comments on my short piece, shot on Epic.

As I gain more experience I am learning that the camera capabilities are important but the locations and subjects are even more so.
If you want to see some incredible cinematography take a look at "These Birds Walk" ( on netflix instant now ) , a documentary shot in Pakistan by two new filmmakers. They used a rather striped Canon 5dmkII . There are aliasing artifacts and other tech issues, but my god, the beauty of the shots is jaw dropping and frankly the nit picking tech details are quickly forgotten. I want to shoot more like those guys in the future.

Michel Hafner
08-25-2014, 04:47 AM
Like this,

http://www.pixelharvest.com/Tondo2014.html

Katsi trilogy, Baraka, Samsara...

Sidney L. Plaut
08-25-2014, 06:12 AM
amazing footage. incredible to see them smile, when they live like this. 2014 no one should be allowed to live on garbage.

Björn Benckert
08-25-2014, 06:47 AM
Thank you for all the kind comments on my short piece, shot on Epic.

As I gain more experience I am learning that the camera capabilities are important but the locations and subjects are even more so.
If you want to see some incredible cinematography take a look at "These Birds Walk" ( on netflix instant now ) , a documentary shot in Pakistan by two new filmmakers. They used a rather striped Canon 5dmkII . There are aliasing artifacts and other tech issues, but my god, the beauty of the shots is jaw dropping and frankly the nit picking tech details are quickly forgotten. I want to shoot more like those guys in the future.

I really like your film Les. But ofcourse difficult to see or judge the detials on a vimeo link. would low to see a r3d snap from it just to see how it actually looks.

Les Dittert
08-26-2014, 01:03 PM
I really like your film Les. But ofcourse difficult to see or judge the detials on a vimeo link. would low to see a r3d snap from it just to see how it actually looks.

Björn, here are some stills from those or similar shots. I sized these to 4096x2160. Worst case thin wire 'color error' situations on a couple of them.

https://dl.dropboxusercontent.com/u/61349012/misc-RED-test/Tondo_4k_stills/63__2.jpg
https://dl.dropboxusercontent.com/u/61349012/misc-RED-test/Tondo_4k_stills/63__7.jpg
https://dl.dropboxusercontent.com/u/61349012/misc-RED-test/Tondo_4k_stills/100__0.jpg
https://dl.dropboxusercontent.com/u/61349012/misc-RED-test/Tondo_4k_stills/105__00.jpg

Lakis Amarantithis
08-26-2014, 03:14 PM
Thanks Les!

If taking off the olpf in Dragon can make a comparable difference then we will be talking about a new game here. And I think we will.

I still like the r3d's better because someone can do so much with those but I thank you for sharing these exceptional images.

Juergen Schloss
08-27-2014, 04:35 AM
This is my first post here, hello to everybody! I am a beginner in using RED cameras and I am from Germany.

I want to get high quality 4k footage for demo purposes.

I planned to buy a scarlet. So I rent one first to gain some experience. But I was really disappointed seeing the first results. My expectations were to get a picture quality like a DSLR with the REd cam.
Then I found the postings an picture examples of Les Dittert. This was exactly what I was looking for.

Now what should I do? I do not find here an explanation how to get these results. Does anybody know whether RED will come out with some new components that allow us to shoot on that quality level?

My results btw were not better than what I saw for example from a panasonic GH4 in terms of sharpness.

Brice Ansel
08-27-2014, 05:28 AM
This is my first post here, hello to everybody! I am a beginner in using RED cameras.
I want to get high quality 4k footage for demo purposes.
I planned to buy a scarlet. So I rent one first to gain some experience.
My results btw were not better than what I saw for example from a panasonic GH4 in terms of sharpness.
Really?
Interesting first post.
My advise go and get a GH4 then.
Edit: Or check this thread http://www.reduser.net/forum/showthread.php?112235-shut-up-and-shoot-that-Scarlet
Good luck and happy shooting. ;)

Lakis Amarantithis
08-27-2014, 07:16 AM
>>Now what should I do? I do not find here an explanation how to get these results. Does anybody know whether RED will come out with some new components that allow us to shoot on that quality level?

There's no doubt about it in my opinion. But also you could have gotten these results yrs ago if you have followed the same olpf procedure Les did.

I think your judgement has not taken in consideration the complete picture. Maybe is a good idea to rent the Scarlet again and learn it better. Also use the rcx and read the manual before using it and while using it.

Les Dittert
08-27-2014, 09:12 AM
I recently got a GH4 to try. So far I am pleased with it. I resolves more detail than a factory MX camera. It shoots 4096 x 2160.
I held off getting one because it was only 100 megabits data rate but when I saw some 4k Youtube videos doing side by side comparisons with the Red I decided to give it a look.
The response curves in it are very adjustable letting you get about 10 or 11 stops dynamic range. The video from it is more color correctable than I would have guessed.
My damaged back is telling me to use it, but I like the high frame rates of the Red. For my developing world shooting projects the light weight and insane battery life make it very seductive. The camera weighs 600 grams, about the same as one of my v-lock batteries for my Epic. Getting shallow focus shots is a challenge. I have an f 0.95 lens for that, but it's optical performance wide open is not that great.

Lakis Amarantithis
08-27-2014, 01:15 PM
I can say and debate about the GH4... Let's not forget what the ORIGINAL QUESTION here was.

Mike Finegan
08-27-2014, 02:05 PM
If it was intentional then expert
But if he just forgot the lens cap was on...

Definitely not a guess hehe. Appreciate that for many it would be of course :) The lens cap test is the proof though, even if it were a guess.

Juergen Schloss
08-27-2014, 03:25 PM
Les, I fully understand your position to not explain in detail your procedure to achive these really amazing results in image resolution. I am totally enthusiastic about it.
Anyhow please allow me to ask a question. When I look only to the aliasing aspect and not to the IR and other color requirements then I do not understand why the resolution in 4k is so much influenced by the OLPF in a system that is able to resolve 5k or 6k. The cut off spatial frequency of that OLPF should fit to the 5k or 6k anti aliasing requirements and therefore it's influence on 4k should be neglibigle when 4k is not a crop but a downscaling. Am I wrong?

If this discussion does not fit to this thread, then please ignore my post.

Les Dittert
08-27-2014, 04:53 PM
Since this is kind-of an OLPF thread, let me answer:

The OLPF causes the light going through it to get directed in four different directions by a small amount. This amount is determined by design. The reason for this need to spread the image around is the color filter array on the sensor and the subsequent debayer software can get tricked by very thin details in the image, such as thin wires and hair strands. By spreading the image around to the neighboring color filtered pixels the debayer software can be more confident that the color for the final color pixel the user sees is more true to the real image before the camera. A side effect is that those very same tiny details will appear to be softer, again because the detail information has been more spread around.
Because this is a movie camera the issue is of more concern because on details that move across the screen the errors can come and go, making the errors more visible than just looking at a motionless still image.
It's by belief that the OLPF spread of the MX was chosen to be ultra conservative and will never make debayer color mistakes. This is why people looking at DSLR raw images against the MX images are seeing less detail.
On Dragon I have ( with V2 OLPF) been able to get it to make small visible color rainbow errors on a black and white test charts. It seems tighter.
I have learned that advanced debayers can minimize these problems as you move towards less and less spread from the OLPF.


Les, I fully understand your position to not explain in detail your procedure to achive these really amazing results in image resolution. I am totally enthusiastic about it.
Anyhow please allow me to ask a question. When I look only to the aliasing aspect and not to the IR and other color requirements then I do not understand why the resolution in 4k is so much influenced by the OLPF in a system that is able to resolve 5k or 6k. The cut off spatial frequency of that OLPF should fit to the 5k or 6k anti aliasing requirements and therefore it's influence on 4k should be neglibigle when 4k is not a crop but a downscaling. Am I wrong?

If this discussion does not fit to this thread, then please ignore my post.

Jarek Zabczynski
08-27-2014, 05:48 PM
Like this,

http://www.pixelharvest.com/Tondo2014.html

Amazing!

Lakis Amarantithis
08-27-2014, 06:17 PM
Since this is kind-of an OLPF thread, let me answer:

The OLPF causes the light going through it to get directed in four different directions by a small amount. This amount is determined by design. The reason for this need to spread the image around is the color filter array on the sensor and the subsequent debayer software can get tricked by very thin details in the image, such as thin wires and hair strands. By spreading the image around to the neighboring color filtered pixels the debayer software can be more confident that the color for the final color pixel the user sees is more true to the real image before the camera. A side effect is that those very same tiny details will appear to be softer, again because the detail information has been more spread around.
Because this is a movie camera the issue is of more concern because on details that move across the screen the errors can come and go, making the errors more visible than just looking at a motionless still image.
It's by belief that the OLPF spread of the MX was chosen to be ultra conservative and will never make debayer color mistakes. This is why people looking at DSLR raw images against the MX images are seeing less detail.
On Dragon I have ( with V2 OLPF) been able to get it to make small visible color rainbow errors on a black and white test charts. It seems tighter.
I have learned that advanced debayers can minimize these problems as you move towards less and less spread from the OLPF.

Thank you Juergen for this great question and Les for an even greater answer.

It appears that if I want to film black and white shooting night or late hours it'll be extremely beneficial to take the olpf off. The pic will be sharper and get more iso?

The problem with changing olpf's or taking it completely off is also dust. I think once people start changing it often we'll see lots of problems with dust.

Les Dittert
08-27-2014, 07:25 PM
Two quick things:

1> The camera needs some glass in there in place of the OLPF to maintain backfocus. It is so far off without it that you can't focus on much at all.

2> The ISO stuff is really more effected by the IR cut filter that is sandwiched with the OLPF filter. To cut the IR out even better, the V2 IR filter eats into the red spectrum just a little more with a sharper cutoff slope , and it also passes the remaining useful color spectrum a little less as a side effect. This is why the older filter is prefered for low light, as far as I can tell. That combined with a different characteristic sensor curve that allows the more film like bright roll-off by underexposing the rest of the range, or as some call it, highlight protection. It will be interesting to see what the new firmware does to change OLPF metadata settings without actually changing the actual filter !


You don't get very sharp pictures shooting no IR cut because the IR that is then allowed through focuses at a different image plane and will be out of focus compared to the color part of the image. This can look like a bit of blurriness and fogginess to your image, with awful color as well.


Thank you Juergen for this great question and Les for an even greater answer.

It appears that if I want to film black and white shooting night or late hours it'll be extremely beneficial to take the olpf off. The pic will be sharper and get more iso?

The problem with changing olpf's or taking it completely off is also dust. I think once people start changing it often we'll see lots of problems with dust.

Lakis Amarantithis
08-27-2014, 09:02 PM
Les,

I played tonight with several lenses at high iso with the new v2 and v5.2.28 and I see a much better much less noisier pic.

Les,
I understand what you say exactly and all makes sense.

What I don't understand is how you managed to take That footage without olpf and look so good! I understand the need to put some glass instead of the olpf to maintain backfocus.

I took the olpf out of one Epic and shot some test a yr ago and all was bluish and unacceptable to put it kindly. No matter what I tried in rcx was still unacceptable so after a quick and unsuccessful shot I put it back disappointed...

Your footage looks fantastic and very sharp especially as the lenses you used I own and they are not that sharp in my Epics or Dragons.

Probably I miss something? Is it possible to put some r3d's?

Very repectfully
Lakis

Les Dittert
08-27-2014, 10:24 PM
When you shot your Epic test with no OLPF, what were you cutting the IR with ?



I took the olpf out of one Epic and shot some test a yr ago and all was bluish and unacceptable to put it kindly. No matter what I tried in rcx was still unacceptable so after a quick and unsuccessful shot I put it back disappointed...

Your footage looks fantastic and very sharp especially as the lenses you used I own and they are not that sharp in my Epics or Dragons.

Probably I miss something? Is it possible to put some r3d's?

Very repectfully
Lakis

Matthew Scott
08-27-2014, 10:24 PM
Les, you're amazing. Thanks for the breakdown :)

Brett Harrison
08-28-2014, 07:59 AM
Good to hear someone talk about the characteristic curve the V2 entails. Thanks for the great thread.

Juergen Schloss
08-28-2014, 10:57 AM
Since this is kind-of an OLPF thread, let me answer:
...
It's by belief that the OLPF spread of the MX was chosen to be ultra conservative and will never make debayer color mistakes ...

Thanks for your comprehensible and competent explanation. I learn a lot out of this discussion. What I understood is that the OLPF blurres the image on the sensor such that even the smallest objects by shure cover all 3 colors of the Bayer matrix. The result would then be a reduction of the resolution by a factor of 2 (times2) . This would totally explain my experiences. Even when the debayering algorithm can reconstruct a more or less small amount of resolution.

Btw I got inspired by this discussion to my avatar :smile5:

Lakis Amarantithis
08-28-2014, 12:52 PM
When you shot your Epic test with no OLPF, what were you cutting the IR with ?

Nothing. Just took the olpf off and shot. So probably I had to use an IR filter!? Makes sense. Especially as the shots were under the bright Florida sun. Did you had an IR filter? that must had cut some good amount of light but it does not look like.

Phil said in a previous tread that the Dragon does not need an IR filter any more. Is it perhaps because the olpf takes care of that or some other factor. If it's some other factor then a non olpf Dragon will work fine theoretically.

Les Dittert
08-28-2014, 01:49 PM
My post #77 mentioned the IR filter and what happens if you don't use one.


Nothing. Just took the olpf off and shot. So probably I had to use an IR filter!? Makes sense. Especially as the shots were under the bright Florida sun. Did you had an IR filter? that must had cut some good amount of light but it does not look like.

Phil said in a previous tread that the Dragon does not need an IR filter any more. Is it perhaps because the olpf takes care of that or some other factor. If it's some other factor then a non olpf Dragon will work fine theoretically.

Lakis Amarantithis
08-28-2014, 03:56 PM
My post #77 mentioned the IR filter and what happens if you don't use one.

Yes, you right. Is that IR filter that is needed something like this? http://www.bhphotovideo.com/c/product/751599-REG/Formatt_BF_105IR680_105mm_Hot_Mirror_Filter.html

Thanks!

Les Dittert
08-28-2014, 04:44 PM
Yes, you right. Is that IR filter that is needed something like this? http://www.bhphotovideo.com/c/product/751599-REG/Formatt_BF_105IR680_105mm_Hot_Mirror_Filter.html

Thanks!

Use a $30 one from ebay.
Screw on.

Juergen Schloss
08-29-2014, 12:58 AM
Lakis, I am so curious to see first results when you try out your cam without OLPF and with IR filter.

Juergen Schloss
08-29-2014, 01:48 AM
I just found an information from NIKON. They use the software Capture NX2 with a moiré-reduction tool for their D800E which has no OLPF Function in front of the sensor. I wonder what this tool is doing.

Lakis Amarantithis
08-29-2014, 10:05 AM
Lakis, I am so curious to see first results when you try out your cam without OLPF and with IR filter.

Of course, I'll be happy to share Juergen IF I decide to take off the olpf, I like better someone else or someone from the RED to do that instead and post some samples here. My main concern is dust in the processor. I had problems with other cameras and lenses and is a pain to clean it. Ebay is great by the way to buy tiffen ir's with a 70% discount! Thanks Les!

I think in the future when people start changing to other olpf's often this might be a big one.

My only concern now is how to address this issue:

(from post #77 of Les)
>>1> The camera needs some glass in there in place of the OLPF to maintain backfocus. It is so far off without it that you can't focus on much at all.

I have no idea what else can be put there.

Roy Heisler
09-12-2014, 03:49 PM
Like this,

http://www.pixelharvest.com/Tondo2014.html

All handheld??

Blair S. Paulsen
09-12-2014, 04:49 PM
This topic was mentioned briefly in the swappable OLPF thread. Both John Marchant and I believe that in order to maintain proper focus response you would need a piece of glass (optical flat perhaps) rather than air in that position in the optical path. He also noted that an anti-reflectivity coating might be needed to avoid internal reflection problems, which makes sense to me. Perhaps RED can be convinced to make a swappable OLPF that's really just a bit of clear glass with an anti-reflective coating as an option.

Hope this isn't a threadjack, just sharing info.

Cheers - #19

Matt Ryan
09-12-2014, 04:52 PM
This topic was mentioned briefly in the swappable OLPF thread. Both John Marchant and I believe that in order to maintain proper focus response you would need a piece of glass (optical flat perhaps) rather than air in that position in the optical path. He also noted that an anti-reflectivity coating might be needed to avoid internal reflection problems, which makes sense to me. Perhaps RED can be convinced to make a swappable OLPF that's really just a bit of clear glass with an anti-reflective coating as an option.

Hope this isn't a threadjack, just sharing info.

Cheers - #19

Jarred has already said they will be making a clear olpf as well...

Blair S. Paulsen
09-12-2014, 04:59 PM
I saw some IR pass versions for color and monochrome, but not IR cut with no low pass filtering or clear - must have missed that. Thanks for the update Matt.

Cheers - #19

Lakis Amarantithis
09-12-2014, 05:30 PM
Yes, I did not noticed any clear as well.

I would love to see a simple plain one.

From some tests I've done I think it would be Fantastic.

I would buy all of them x2 but I also like to have the freedom to put the IR filters that I want (like these just to use an example: http://www.ebay.com/itm/77mm-Zomei-super-Slim-680nm-720nm-760nm-850nm-950nm-Infrared-IR-Filter-/121314857927?ssPageName=ADME:L:OU:US:1120 ) and control the picture as I specifically want it. Another reason is Fantastic light sensitivity. I'm talking an 800mm lens with Noctilux abilities from what I tested. It's shocking. Imagine using Noctilux with 1 candle and have to put ND...
But the benefits are a lot more.

Matt Ryan
09-12-2014, 05:44 PM
I saw some IR pass versions for color and monochrome, but not IR cut with no low pass filtering or clear - must have missed that. Thanks for the update Matt.

Cheers - #19


Yes, I did not noticed any clear as well.

I would love to see a simple plain one.

From some tests I've done I think it would be Fantastic.

I would buy all of them x2 but I also like to have the freedom to put the IR filters that I want (like these just to use an example: http://www.ebay.com/itm/77mm-Zomei-super-Slim-680nm-720nm-760nm-850nm-950nm-Infrared-IR-Filter-/121314857927?ssPageName=ADME:L:OU:US:1120 ) and control the picture as I specifically want it. Another reason is Fantastic light sensitivity. I'm talking an 800mm lens with Noctilux abilities from what I tested. It's shocking. Imagine using Noctilux with 1 candle and have to put ND...
But the benefits are a lot more.

From Jarred in an earlier thread (The last line states there will be a Clear olpf):

Just thought I would give people a sneak peek on the Modular OLPF thats going to be available for Dragon soon.

There still people that prefer the old OLPF because even though skintones and highlight protection isn't as good as the new OLPF, they want a noise free image at higher ISOs that the old OLPF gives you by letting in more light. We of course will put whichever OLPF you want in your camera now... but the new OLPF module will make things alot easier to change.

The freedom and flexibility to make that kind of decision in different environments should be beneficial to everyone.. even if they only make the choice once and never change it again.

The Module install is pretty straight forward... we can do it or you can do it. Getting the old stuff out is the hardest part. The new "module" goes in easy and 4 little bolts and you are done. You dont need to touch any glass and you dont need to worry about putting it upside down or right side left. The front of the module is marked so you can see which one it is by just looking at the sensor so rental customers can quickly see which one is in camera.

At any rate... we are testing prototypes now and I expect these to be ready in 6-8 weeks after we get out of tooling. The OLPF Modules will be for sale in the store so you can choose whichever one you want or all of them and change at will. If you want to keep whatever OLPF you have in your camera right now you can still send us your camera and we can transfer your OLPF into a new module and send it back to you.

There will be 2 modules available out of the gate obviously ( The new OLPF and the OLD OLPF ) and IR PASS, ND, Clear and a few specialty ones will come after.

http://www.redgrabs.com/up/1406205543.jpg

Lakis Amarantithis
09-12-2014, 06:24 PM
Thanks Matt, my omission. So excited can't read fast enough and clear enough like Tuco in the graveyard.

stewart addison
09-13-2014, 03:38 PM
Hmm, interesting! I might try our Dragon without the OLPF!

Matt Ryan
09-13-2014, 03:56 PM
Hmm, interesting! I might try our Dragon without the OLPF!

It will not work... You need glass in there or your backfocus will be way off and unable to achieve infinity focus...

Juergen Schloss
09-14-2014, 10:46 AM
May be I am wrong with my impression about RED's new strategy with OLPF, which is really great in my opinion. But I understand it does not help us getting high res footage with the first set of OLPFs that were announced by Jarred.

Or can the "Monochrome: Standard Monochrome OLPF" help us? (or is it a silly idea?) My thought is: it is optimized for the higher resolution of the Monochrome dragon and eventually it can also be used for the Bayer Dragon (with reduced anti aliasing).

Gavin Greenwalt
09-15-2014, 10:49 AM
It will not work... You need glass in there or your backfocus will be way off and unable to achieve infinity focus...

Why? Neither Film nor still cameras have OLPFs. If anything RED's OLPF should be throwing old lenses out of focus no?

Michael Tiemann
09-15-2014, 12:34 PM
Why? Neither Film nor still cameras have OLPFs. If anything RED's OLPF should be throwing old lenses out of focus no?

Well...YesAndNo. The PL spec says 52mm from flange to image plane. The RED OLPF + Sensor should, as a system, honor the 52mm convergence cone and produce a perfectly sharp result according to the lens markings and object distances. If the sensor happens to be 52mm from flange to surface, then indeed one should expect a perfectly sharp result from a properly adjusted lens and no back-focus issues. But if the sensor is 53mm or 54mm back from the flange because the optical properties of the OLPF extend the convergence cone by 1mm or 2mm, then removing the OLPF is going to requires a 1-2mm sensor position adjustment, which may or may not be within the range of what the manual adjustment screw can manage.

Jeffery Anderson
04-06-2015, 07:35 PM
Am I wrong in thinking that IR contamination is only from Sun rays? and solved by using source lighting?

Lakis Amarantithis
04-06-2015, 07:46 PM
>>Perhaps RED can be convinced to make a swappable OLPF that's really just a bit of clear glass with an anti-reflective coating as an option.


That will make the RED waaaay better at night shots. I experimented with no olpf at night and telephotos and in some ranges you can get amazing results, something like over 3 f stops!

Gavin Greenwalt
04-06-2015, 11:01 PM
Am I wrong in thinking that IR contamination is only from Sun rays? and solved by using source lighting?

Yes. IR is essentially heat and if you touch a tungsten bulb... well... you can see where this is going. ;)

Björn Benckert
04-07-2015, 01:06 AM
Well...YesAndNo. The PL spec says 52mm from flange to image plane. The RED OLPF + Sensor should, as a system, honor the 52mm convergence cone and produce a perfectly sharp result according to the lens markings and object distances. If the sensor happens to be 52mm from flange to surface, then indeed one should expect a perfectly sharp result from a properly adjusted lens and no back-focus issues. But if the sensor is 53mm or 54mm back from the flange because the optical properties of the OLPF extend the convergence cone by 1mm or 2mm, then removing the OLPF is going to requires a 1-2mm sensor position adjustment, which may or may not be within the range of what the manual adjustment screw can manage.

Yes, but how much is the offset of the focus scale. My guess is not too much. So it might be possible to rip out the olpf and just get a slightly offset of the backfocus. As it is the olpf is not changing the backfocus with it´s thickness but with the index of the glass used, which I assume is not a whole lot. (I might be completely mistaken, my camera is stolen so no chance to try it out). The different indexes of the different glass used in the different olpfs are I assume compensated with thickness of the glass to all give the same light braking index so backfocus can stay the same no matter what olpf we put in. So yes a clear glass should do.

I really hope RED starts selling the olpf plastic frames for a low cost. My dad is retired now but back when he was working he was an optrician and specialized in quite obscure working glasses, everything from laser protection to deep see welding, super high contrast for military purposes, etc. He still has a storage room filled with the most crazy bits of glass and CNC kind of mill to cut it / make it fit in the frame. Would love to be able to make a RayBan OLPF for example :)

Jeffery Anderson
04-07-2015, 02:01 AM
Yes. IR is essentially heat and if you touch a tungsten bulb... well... you can see where this is going. ;)

Are some lights worse for IR?

i.e. do LEDs or Florescent provide truer color, than Tungsten bulbs, for Digital Sensors?

Detlev Eller
04-07-2015, 05:29 AM
...

I really hope RED starts selling the olpf plastic frames for a low cost. My dad is retired now but back when he was working he was an optrician and specialized in quite obscure working glasses, everything from laser protection to deep see welding, super high contrast for military purposes, etc. He still has a storage room filled with the most crazy bits of glass and CNC kind of mill to cut it / make it fit in the frame. Would love to be able to make a RayBan OLPF for example :)

Wooohooooh! ... sounds like a creative playground ... :-))

so much to explore!
loving the FS from kippertie

Gavin Greenwalt
04-07-2015, 02:11 PM
Are some lights worse for IR?

i.e. do LEDs or Florescent provide truer color, than Tungsten bulbs, for Digital Sensors?

Some are worse than others but it varies not just between types but also between individual models. That's especially true of LEDs and Fluorescents which are usually pretty narrow in their frequency output. So you can buy LEDs that are nearly 100% IR (Remote Control transmitters) or nearly 100% UV (Black Lights). Fluorescents work by creating a great deal of UV light and then exciting a phosophorous material which then creates the visible spectrum. LEDs can work the same way. So it would depend on the phorsphorous material that is being excited. In the case of LED it would be a "Remote Phosphor" LED>

Ignoring LEDs because they are so unpredictable, the worst is Tungsten. It's a "warm" light so it is weighted towards the IR spectrum. In fact some tungsten bulbs output half of their energy into IR. HMIs are a cooler light and lean more towards the UV end of the spectrum so they have less IR contamination.

http://www1.union.edu/newmanj/Physics100/Light%20Production/LampSpectra.gif

John Marchant
04-07-2015, 02:38 PM
Yes, but how much is the offset of the focus scale. My guess is not too much. So it might be possible to rip out the olpf and just get a slightly offset of the backfocus.

For paraxial rays and a flat plate of glass inserted the change in focal position is derived pretty simply.

f = t(1-1/n)

where f is the change in focal plane, t is the plate thickness and n is the refractive index.

So for the Red OLPF where t= ~2.8mm and n is ~ 1.52, the focal position is shifted by 0.96mm

The nominal backfocus travel from centre is +/- 0.75mm

Dependent on the degree to which the lens focusses past infinity you may get away with winding the backfocus all the way to its endstop, but that's not a great idea... and all things being equal, you're still unlikely to hit infinity.

Björn Benckert
04-07-2015, 02:54 PM
For paraxial rays and a flat plate of glass inserted the change in focal position is derived pretty simply.

f = t(1-1/n)

where f is the change in focal plane, t is the plate thickness and n is the refractive index.

So for the Red OLPF where t= ~2.8mm and n is ~ 1.52, the focal position is shifted by 0.96mm

The nominal backfocus travel from centre is +/- 0.75mm

Dependent on the degree to which the lens focusses past infinity you may get away with winding the backfocus all the way to its endstop, but that's not a great idea... and all things being equal, you're still unlikely to hit infinity.

Yes understood, I'm not talking about a perfectly calibrated / collimated / working setup. Just something that can focus on any distance like a few meters away or such. That would be more than enough for the ones interested to see what a "no olpf" setup would look like in terms of sharpness, light sensitivity and colors. So not something to go to work with.

So what I'm saying is, to just getting a no olpf picture should be pretty easy if you have a swapable olpf system, just take out the olpf and put on the mount and lens and try focus and shoot, focus markings will be off and according to the above focus on infinite is not really possible if the lens collimation is not altered but adjusting the backfocus could help o sort it a bit, or about 3/4 of the offset.

Lakis Amarantithis
04-07-2015, 05:26 PM
I received today the FS IR from http://kippertie.com/ and after spending some time with it on the Dragon and several lenses I must say that I'm very impressed. John did an amazing job with this product and I hope his company will produce other useful olpfs like this soon. I said about 10 times "holly s***" with the first minute I saw the results! 2 thumbs up!!

John Marchant
04-08-2015, 11:04 PM
Thanks, glad you're pleased with it :)

And yes, we have several further products on the way, some you probably wouldn't expect ;)