Resolution, softness and back focus...

[Jannard]

My bet is that there is plenty of confusion on this issue. Here's my take on how to get the best image from a RED ONE.

1. Back focus needs to be set correctly and checked regularly (depending on amount of use and conditions).

2. Lenses need to be checked if you use focus scales to set focus. Most assume that all PL mount lenses are correct. I assume they are not until I have checked them.

3. All Bayer pattern sensors should have an OLPF which defocuses the image a bit. Sharpening is mandatory somewhere in the chain if you want maximum resolution and sharpness (not necessarily over-sharp to the point of looking like hyper-video)... (see Canon's words on this below). Since we do NO in camera sharpening, it MUST be done somewhere along the line. If you just open a RAW RED file... it will look soft. There are OLPF Compensation options in RED Alert! and REDCINE, but they are mild right now and not automatic. We will add a better set of tools for this soon.

In contrast, most other digital cinema cameras have in-camera sharpening. So if you just open and compare, our image will look soft. Was it the back focus? Or the lens? Or the fact that no OLPF compensation was used? I think a lot of what has been blamed on back focus lately is actually no OLPF compensation. It is very easy to find out. Just open a frame grab in Photoshop, add 300, 0.6, 1 of Unsharp Mask... and you will know right away.

Unless everyone understands this, RED is at a distinct disadvantage for comparisons.

This (below in italics) comes from the Canon manual. If I am not supposed to post this... let me know and I'll take it down. With great respect for Canon, we think they have the best handle on digital stills. Maybe this endorsement will help them relax on me posting a piece of their manual?

Please note. You may choose to leave the 4K image alone with no sharpening because you like the way it looks. That is an option we are consciously giving our customers. There is just more to the story you should know.

Another note... using an OLPF Compensation (sharpening of some kind) does not necessarily take away the "film-like creamy look" of RED footage. If you go way to far... of course it can. But there is a lot of room for compensation before that happens. It might make a good thread just to see what people are having the best luck doing...?

Jim

Regardless of how the camera’s focusing system is set-up, there are aspects of image quality for Canon’s EOS-1D Mark III that need to be established and optimized by each photographer or organization.Particularly for shooters working in a JPEG workflow, the in-camera sharpening levels are vital. Furthermore, even though the EOS-1D Mark III is one of the finest digital SLRs in the world in terms of digital “noise” at high ISO settings, there’s an additional noise reduction setting some users should experiment with.

Anti-aliasing filter and inherent sensor sharpness — EOS-1D Mark III
The EOS-1D Mark III has a multi-layer low-pass / IR-cut filter positioned immediately in front of its CMOS imaging sensor.This filter enhances the camera’s ability to generate proper color, and minimize problems with moire. In doing so, it slightlyreduces the apparent sharpness of the image.
To counter this, users need to expect to apply some additional sharpening to EOS-1D Mark III files to optimize the inherent detail in its 10-million pixel sensor, and the lens’s detail as well. This can be done using in-camera sharpening, within whicheverPicture Style setting you choose, or alternatively it can be done afterward in the computer.

Suggested in-camera sharpening settings
For JPEG shooters: Picture Style Neutral or Standard > Sharpness level 2 or 3 (keeping it at level 2 will minimize the effect of any noise at ISO 1600 or above)
For RAW shooters (if processing images in Canon’s Digital Photo Professional software): Picture Style Neutral or Standard; Sharpness level 0~3
• If further optimizing images in Photoshop, in-camera sharpness should ideally be left at zero • If no further image-editing is anticipated, raise in-camera sharpening to level 2 or 3 • For RAW shooters who process in another company’s software, the in-camera sharpening settings are ignored — expect to do any sharpening during RAW file processing, or in image-editing software after processing.
In all instances, rely on the recommendations of your photo desk if you shoot for any news or photo organization. If the Photo Desk says that sharpening will be done at time of processing, we strongly suggest setting in-camera sharpening to “zero” unless testing by your organization leads to other instructions from your photo desk.

Suggested starting points for Unsharp Mask sharpening in the computer
For shooters who anticipate making further sharpening adjustments in Adobe Photoshop™ or similar software programs, always bear in mind that ideal sharpening settings will be very much dependent upon subject matter, lighting, ISO setting used, and of course the intended type and size of final output. As a typical, initial starting point for sharpening using Photoshop’s Unsharp Mask command, you might want to consider the following :
High ISO images (no initial in-camera sharpening) Low ISO images (no initial in-camera sharpening) Amount — 250% Amount — 250% Radius — 0.3 pixels Radius — 0.3 pixels Threshold — 4 levels Threshold — 1 level

"from Canon 1D MKIII manual"

[Manfred Lopez]

Thanks for clearing up these issues, Jim. By the way, merry christmas (or happy holydays, depending on faith :innocent: ).

[Manfred Lopez]

This (below in italics) comes from the Canon manual. If I am not supposed to post this... let me know and I'll take it down.

By the way, I think that you are okay in posting it, since it is a small portion to illustrate one point in an academic setting (the main intent here is education). All this is covered under fair use.

This thread is going to be very interesting for me.

[Graeme Nattress]

Jim's right that if you're not used to seeing a totally unsharpened image, you're in for a surprise. The OLPF is necessary to avoid aliasing, and even more necessary on a motion camera than a stills one. Some people try to avoid using them to gain that extra "edge", but it's not the best (in my own personal opinion here) engineering to try to avoid using an OLPF.

As Jim mentions, we're working on a better set of tools to compensate for the slight softness you get from using an OLPF.

It's important to remember, no matter what the camera, be it 3CCD, CMOS, Bayer Pattern single chip, Foveon or what, you cannot simultaneously have 100% resolution and be 100% free of aliasing. Importantly, all cameras should have optical low pass filtering. Many do not, and especially cheaper cameras don't as OLPFs are not cheap.

Graeme

[Sanjin Jukic]

Thanks Jim.

Very good to know all in advance before I get the camera.

[I Bloom]

Jim,

Merry Christmas. Thanks for starting this thread. This has been on my mind alot recently.

As far as I can see, the chain affecting focus perception we have:
1. Quality of the lense
2. Precision of set focal distance
3. Precision of back focus
4. Degree of OLPF
5. Quality of Debayering
6. Amount of Sharpening

That's alot of variables. Since most of us are interested in maximizing 1,2 and 3 it seems like we need to start with understanding exactly what to we can get from 4,5 and then how much we need to come up with 6.

My question is: how can we establish a baseline of sharpness for Mysterium+OLPF+Debayering? Something to measure everything else against.

IBloom

[Deanan]

We've also seen lots of tests comparing cameras by using vastly different lenses with critical judgements being made about resolution. Regardless of which camera comes out ahead, it's just misleading.

No OLPFs or weak OLPFs means that you are guaranteed to have aliasing artifacts in a reasonable amount of your footage. Aliasing, especially chromatic aliasing, is really hard to remove even with downscaling.

While sharpness is the holy grail for some people, maximum sharpness without enough supporting resolution ends up being to harsh. It also tends to make people look 10 years older and make it really hard to pull focus (steep perceptual depth of field falloff). The right balance between sharpness and resolution is what gives you a beautiful buttery image that can be sharpened in post easily without leaving you without any means to back it off.

[Jannard]

One thing that will help is a more interactive OLPF Compensation tool in RED Alert! and REDCINE... we are working on that. That will make the job a lot easier.

Then all you have to do is:

1. Check back focus
2. Check your lenses (re-mark if necessary)
3. Shoot
4. Open and then decide if you want the look of "none to a ton".

Jim

[LEON]

Jim,

Merry Christmas. Thanks for starting this thread. This has been on my mind alot recently.

As far as I can see, the chain affecting focus perception we have:
1. Quality of the lense
2. Precision of set focal distance
3. Precision of back focus
4. Degree of OLPF
5. Quality of Debayering
6. Amount of Sharpening

That's alot of variables. Since most of us are interested in maximizing 1,2 and 3 it seems like we need to start with understanding exactly what to we can get from 4,5 and then how much we need to come up with 6.

My question is: how can we establish a baseline of sharpness for Mysterium+OLPF+Debayering? Something to measure everything else against.

IBloom

I feel you might add:

7- CONTRAST OF THE SCENE (original or in made in PostProd )

[Manfred Lopez]

"none to a ton"


I like that! :)

[Deanan]

Also, when comparing the 4k to 2k, the scaling algorithm is another important variable as some algorithms like gaussian, mitchell and bicubic are nice and smooth while other like lanczos, sinc, and catmul-rom are sharper.

[Nathan Buxton]

Red should make a custom focus chart box with its own built in light source they can sell to allow users to test their focus on a 100% uniform standard. Red could produce baseline tests ans provided these results to customers with detailed instructions on how to replicate the test.


might be cheap i don't know how much light and what quality would be required.

[Jim Arthurs]

If the goal of RED footage is always a 3K or 2K or HD final, won't the simple act of downsampling be enough to provide natural sharpening?

Of course experimentation with the various downsampling methods is important, but all things being equal, I can't see adding anything in addition to the act of scaling... That's what I love about having the RED have NO in camera sharpening and a generous 4K sampling container to work with in the first place...

Now windowed 2K is a horse of another color and needs help to look sharp, of course...

[Simon Valderrama]

Then all you have to do is:

1. Check back focus
2. Check your lenses (re-mark if necessary)

Jim

Thanks Jim.
What probably has created a bit of confusion is that RED has attracted a lot of people coming from prosumer video world who see in RED a chance to to make the big leap, people completely unaware of back focus and lenses issues. What we probably need is some sort of sticky thread that could work as a BASIC tutorial for checking back focus, lenses and make needed adjustments to lens mount and/or lenses. Probably going through all threads one could find necessary info and put all pieces together but a quick summary for the lenses uninitiated would be really great.
Unfortunately i'm no good for it ... any volunteer? :innocent:

[Mark L. Pederson]

I think it's great to put sharpening features in Red Alert and Redcine.

IMO it's also VERY important to remember that there are some advantages to NOT sharpening at all until the very end of your post pipeline - and that would be my recommendation.

[Raul Gonzo]

Thanks Jim.
What probably has created a bit of confusion is that RED has attracted a lot of people coming from prosumer video world who see in RED a chance to to make the big leap, people completely unaware of back focus and lenses issues. What we probably need is some sort of sticky thread that could work as a BASIC tutorial for checking back focus, lenses and make needed adjustments to lens mount and/or lenses. Probably going through all threads one could find necessary info and put all pieces together but a quick summary for the lenses uninitiated would be really great.
Unfortunately i'm no good for it ... any volunteer? :innocent:

Yes, I am such a person and would very grateful if someone provided something like this.

[Jannard]

We are working on a full solution... lots of things to do. Can't sleep. Must solve problems... must solve problems...

Happy Holidays.

Jim

[Manfred Lopez]

I wonder how sharpening would be dealt with if one was planning a film-out to 35mm for release prints.

[Elizabeth]

What probably has created a bit of confusion is that RED has attracted a lot of people coming from prosumer video world who see in RED a chance to to make the big leap, people completely unaware of back focus and lenses issues. What we probably need is some sort of sticky thread that could work as a BASIC tutorial for checking back focus, lenses and make needed adjustments to lens mount and/or lenses. Probably going through all threads one could find necessary info and put all pieces together but a quick summary for the lenses uninitiated would be really great.
Unfortunately i'm no good for it ... any volunteer? :innocent:

I agree that it would great to have all the purely technical information culled out of all the opinion and conversation and joke and philosophy threads on this site and posted it in one technical thread ... it would make everything so much easier. This WOULD take one or two people stepping forward to volunteer make this happen (I would be interested in helping, but would need direction and training in forum management).

However, I really do not think that it is RED's responsibility to train every person who has purchased their camera as to how to use it.
Give them a break! Let them build the equipment.
It is OUR job as professionals to get the training we need to function as professionals, not RED's

Although, I have been thinking that a RED BOOT CAMP is greatly needed. It would be invaluable to be able to get instruction from the RED masters.
I would be interested in opening discussions on making this happen.

I could offer to host it at a 160 acre cabin facility in the Tahoe National Forest in the Sierra Mountains. Anybody interested?

[Joe Vinson]

Dude, get some sleep! Santa won't come if you're still awake! (Unless... Jim is Santa...!)

[mdo]

Unless... Jim is Santa...!

Probably as close as it gets.

[Stephen Pruitt]

I would be VERY interested in a RED Boot Camp. . . and I'm one of those who will defiinitely need it!

Merry Christmas to all. . . and to all. . . a RED night.

:-)

Stephen

[Warren Kommers]

I wonder how sharpening would be dealt with if one was planning a film-out to 35mm for release prints.

Testing testing resting and then more testing.

[Gavin Greenwalt]

As far as I can see, the chain affecting focus perception we have:
1. Quality of the lense
2. Precision of set focal distance
3. Precision of back focus
4. Degree of OLPF
5. Quality of Debayering
6. Amount of Sharpening



7. Contrast of the Scene (original or in made in PostProd )

8. Resolution shot/displayed at. (A 2k image will look softer than a 4k image)
9. Amount of noise/grain. (Noise and grain act as a light amount of perceptual sharpening.)
10. Shutter Speed.
11. Amount of movement in scene.
12. Aperture size.

[BASSAM MSSALATIE]

Thanks Jim.
What probably has created a bit of confusion is that RED has attracted a lot of people coming from prosumer video world who see in RED a chance to to make the big leap, people completely unaware of back focus and lenses issues. What we probably need is some sort of sticky thread that could work as a BASIC tutorial for checking back focus, lenses and make needed adjustments to lens mount and/or lenses. Probably going through all threads one could find necessary info and put all pieces together but a quick summary for the lenses uninitiated would be really great.
Unfortunately i'm no good for it ... any volunteer? :innocent:
:love: nice i think we have to suggest that ...:shifty: maybe we could
ask david
thread maybe he will help :construction:

[BASSAM MSSALATIE]

... lots of things to do. Can't sleep. Must solve problems... must solve problems...

Jim

Jim GO sleep well man we:love: need you healthy:cold: happy solving problems .thanks
Happy Holidays.:blush:

[Jannard]

1. The new mount helps a ton.
2. Realization is the 1st step to the road to recovery.
3. We will develop tools for easy checking of the back focus.

Jim

[Jannard]

Jim GO sleep well man we:love: need you healthy:cold: happy solving problems .thanks
Happy Holidays.:blush:

I refuse to shave, shower, sleep or change my underwear until every RED customer is happy...

Well, the sleep part is true.

Jim

[BASSAM MSSALATIE]

for me iam happy even i am late for Red . ithink most of us here are happy with red and it's team ,unless he is selfish..
just take a rest :angry03: and everything will gonna be fine .:detective2:

[Gavin Greenwalt]

I refuse to shave, shower, sleep or change my underwear until every RED customer is happy...

Well, the sleep part is true.

Jim

In unrelated news all RED cameras will now ship with an air freshener in the box.

[Mark L. Pederson]

3. We will develop tools for easy checking of the back focus.
Jim

THAT is fantastic Jim.
You never stop impressing me.

Merry Xmas and Happy Holidays to you, your fiance and and your family. Wishing you much success in all matters in 2008.

Looking forward to a 4K projector ...

[Stephen Williams]

.

Then all you have to do is:

1. Check back focus
2. Check your lenses (re-mark if necessary)

Jim

Hi Jim,

Can you outline your recommended procedure for the above.

Happy Christmas

Stephen

[Jannard]

1. Until we get a tool out for our customers to use, you will need the factory (that would be us) to set it right and a good tech to check and set if necessary.

2. This is usually done at a good rental house or by a qualified lens tech.

After we release our tool, it will be very easy to check/set back focus of the camera, then check lenses using a chart setup referencing the camera.

Jim

[Mardi_Gras]

I refuse to shave, shower, sleep or change my underwear until every RED customer is happy...

Well, the sleep part is true.

Jim

With the risk of coming accross as an uber "drunk fanboy" :) like some of us have been so labeled, I have to say Jim, your statement above nulls all of my wait-anxiety and other pressures associated with shooting on the Redone, if you know what I mean.

Thanks for being so passionate about something we're mostly all passionate about - a great tool for the struggling filmmakers here.

[Jannard]

Passion begets passion.

Jim

[Michael Lindsay]

After we release our tool, it will be very easy to check/set back focus of the camera, then check lenses using a chart setup referencing the camera.

Jim

thank you...!

Michael Lindsay

[Tim Lüdin]

Yeah it's realy Christmas. A new back focus tool for all of us. This is exactly what I was hoping for.
This will make life a lot easier.

Thanks guys. This is great news.
Merry Christmas

Tim

[Mardi_Gras]

Passion begets passion.

Jim

Indeed my friend... indeed.

[Rudi Herbert]

Jim refuses to shave, shower or change underwear (maybe that's how he can get so close to those bald eagles) and Mark is supposed to be in the south of France and still he's posting more than most...what is the world coming to?

Ah, the wonderfully demonical viscious circle of creation has finally engulfed Jim whole, whereby problems are now nothing more than blessings in thin disguise, for as they arise, a solution is feverishly sought, found and proved, and then all that is left is creating it and implementing it, leaping the RED in forward quantums to its ultimate goal. It was good knowing Jim while we was still sane...:-)

[I Bloom]

I think I started a monster with these numbered lists:


1. Quality of the lense
2. Precision of set focal distance
3. Precision of back focus
4. Degree of OLPF
5. Quality of Debayering
6. Amount of Sharpening



7- CONTRAST OF THE SCENE (original or in made in PostProd )



8. Resolution shot/displayed at. (A 2k image will look softer than a 4k image) (depending on the degree of magnification, aye)
9. Amount of noise/grain. (Noise and grain act as a light amount of perceptual sharpening.)
10. Shutter Speed.
11. Amount of movement in scene.
12. Aperture size.

Yeah there are alot of things that affect perception of focus, I didn't bring these up because they aren't really related to the quality and calibration of your imaging setup.
#9 is a good thing to bring up though Gavin. Because noise through Redcode seems to be naturally softened and that is perhaps affecting overall perception of sharpness. So lets add one more:

13. Ratio of compression.

IBloom

[Elizabeth]

and then there is the softness for the still lovely, yet aging actresses ...

14. Vasoline, hairspray, black netting, etc.

[Elizabeth]

Passion begets passion.

Jim

Now would ya just look at the all the crazy passion your Passion begets ...

Jim Jannard, THE BEGETTER OF RED (a very noble title indeed), you have every reason to be proud!!

Thank you and Merry Christmas.:biggrin:

[P Andersson]

13. Ratio of compression.

IBloom

yes, it might be interesting as some people have suggested multiple times that it could be possible for the RED to have selective amount of compression available, so if you are doing a very detail oriented image where storage is not a problem you could select a lesser compression

here is an image of how jpg2000 reacts to differents amount of compression

http://www.reduser.net/forum/uploaded/251_1177422924.jpg

[Andrew M.]

This is bit outdated since RED has easy adjustment ring now, but it looks like simple way of checking backfocus.

http://www.projectred.net/forums/viewtopic?id=35

Also exporting to tiff is not necessary if you can zoom 1:1 on the LCD or EVF

[Mark L. Pederson]

and Mark is supposed to be in the south of France and still he's posting more than most...what is the world coming to?


Merry Xmas Rudi - it's rather relaxing over here -

[Rich Schaefer]

Jim , do you check back focus on camera like a film camera? With a Flange depth tool? Any issues scratching the sensor with the feeler?

Marry Christmas!

[albert rudnicki]

I refuse to shave, shower, sleep or change my underwear until every RED customer is happy...

Well, the sleep part is true.

Jim

You mention that you're spending some time off with your fiancee; she must be very tolerant woman :)

Merry Christmas

[Stephen Williams]

This is bit outdated since RED has easy adjustment ring now, but it looks like simple way of checking backfocus.

http://www.projectred.net/forums/viewtopic?id=35

Also exporting to tiff is not necessary if you can zoom 1:1 on the LCD or EVF

Hi,

Only problem is that the Red lenses don't have a witness mark for the focus, so where exactly is 3'.

Stephen

[Kevin Halverson]

...do you check back focus on camera like a film camera? With a Flange depth tool? Any issues scratching the sensor with the feeler?

You can't set FFD with a depth tool as the imager plane is considerably behind the physical surface of the OLPF/IR filter assembly (2mm in the earlier design, 8mm in the later one).

For digital cameras, there are several methods that can be used, however all involve optical targets not mechanical means.

We have been developing a system to go along with the various mounts for the RED that we have developed. The best method involves a laser drilled aperture and a high intensity coherent illumination source.

[Matt Uhry]

We have been developing a system to go along with the various mounts for the RED that we have developed. The best method involves a laser drilled aperture and a high intensity coherent illumination source.

Is this 2 light targets that converge to a point on the sensor at the correct distance, a kind of optical depth gauge?

I've been trying to figure out how one could set the depth on a EC camera - at least beyond the resolution of the sensor which you could get with a tape measure, trusted lens and chart.

Matt Uhry
www.mattuhry.com

[Kevin Halverson]

Actually no. What you are describing would be a methodology to calibrate using the focus distance marks. This makes the assumption that the marks are correct in the first place. Rather than make that assumption, our approach allows for a very quick method of finding the absolute FFD (or 'back focus') and makes no reliance on the accuracy of the lens barrel markings.

[BASSAM MSSALATIE]

. The best method involves a laser drilled aperture and a high intensity coherent illumination source.


Kevin :shifty:
Is Laser thing helping things to be much accurate ?or what ? will you explain a bit please ?:innocent:

[Matt Uhry]

Actually no. What you are describing would be a methodology to calibrate using the focus distance marks. This makes the assumption that the marks are correct in the first place. Rather than make that assumption, our approach allows for a very quick method of finding the absolute FFD (or 'back focus') and makes no reliance on the accuracy of the lens barrel markings.


We are talking about the same thing, I did not write it out very clearly.

Is this a product or service that you plan to offer ?

Matt Uhry
www.mattuhry.com

[RCFisher]

For testing lens mount depth something like a collimator works well, Zeiss(sharpmax) and Century make such devices for checking backfocus on HD cameras. This is basically a collimator that is calibrated to infinity. Place the lens focus to infinity and the view the pattern in the viewfinder or on a large monitor. Also if the camera has a way to check sharpness of the image like Panasonics where you null out the noise of a pattern, that can be just sharp blocks of black against white since you are looking at the contrast in the transition. More contrast more sharpness. There are machines called MTF machines which do a similar thing to quantify sharpness over the optical range of the lens.

When I worked as an assistant many years ago I made my own sharpness charts and test charts to check lenses and distance scales on lenses. I worked at a studio that had a set of Zeiss primes that were marked in meters so I remarked them with feet and had to recheck them often during a show, tedious but worth the effort to ensure my dailies looked good as far as focus. To get the best performance out of any camera you really have to know a lot of technical stuff as a starting point, a set of rules so to speak, which after you learn them you can then break to your advantage. Otherwise it's all hit or miss.

[Matt Uhry]

For testing lens mount depth something like a collimator works well, Zeiss(sharpmax) and Century make such devices for checking backfocus on HD cameras. This is basically a collimator that is calibrated to infinity.

This depends on the lens being set correctly in the first place and you are limited to the max resolution of the cameras output - neither are huge problems and you can get it reasonably close. Probably could record a few second and look at it in RedCine and see how well you hit infinity or your known distance

In a perfect world you would have something much more accurate to work with. Hopefully that's what Kevin is working on.

Matt Uhry
www.mattuhry.com

[I Bloom]

Kevin :shifty:
Is Laser thing helping things to be much accurate ?or what ? will you explain a bit please ?:innocent:

Well I don't know how Khmuse is doing it. But if you laser cut a flat piece that fit into your PL mount, with two tiny slits and a light source with a very thin spectrum such as an LED, it would create an interference pattern on the sensor. The pattern would vary as the depth was modified and could be used to measure distance. Gotta work out the details.... Hope that helps.

http://en.wikipedia.org/wiki/Double-slit_experiment (this contains a broad explanaition of how an interferometer is used, which includes the relationship of the interferometer to distance, and then a bunch of other stuff about physics that don't apply here.)

IBloom

[Gavin Greenwalt]

Why use a small spectrum light like an LED when you can go for the gold. Lasers. Also makes focusing that much easier and the interference pattern that much clearer.

[I Bloom]

Makes sense. A device like this seems like the best solution overall.

[number6]

If the goal of RED footage is always a 3K or 2K or HD final, won't the simple act of downsampling be enough to provide natural sharpening?

Of course experimentation with the various downsampling methods is important, but all things being equal, I can't see adding anything in addition to the act of scaling... That's what I love about having the RED have NO in camera sharpening and a generous 4K sampling container to work with in the first place...

Now windowed 2K is a horse of another color and needs help to look sharp, of course...

Jim, this what what I was wondering as well, and since no one from RED has disputed what you said I assume it to be true.

[Kevin Halverson]

We are talking about the same thing, I did not write it out very clearly.

Is this a product or service that you plan to offer ?

Matt Uhry
www.mattuhry.com

We will test it out in the next week or so and if it works out well, it might become a product (at a minimum, I want one). I won't say much more until I have a chance to test it out. Its a somewhat different approach than the assumptions being made here, and as such, has to be confirmed to be a viable and quick to use device before I am comfortable sharing more.

[BASSAM MSSALATIE]

as i know this is physics experimental theory ..:shifty:
if test works fine . is it will proof correct collimation ..?:pinch: ?
or what it will proof ? :devil:

[David Birdy]

I agree that it would great to have all the purely technical information culled out of all the opinion and conversation and joke and philosophy threads on this site and posted it in one technical thread ... it would make everything so much easier. This WOULD take one or two people stepping forward to volunteer make this happen (I would be interested in helping, but would need direction and training in forum management).

However, I really do not think that it is RED's responsibility to train every person who has purchased their camera as to how to use it.
Give them a break! Let them build the equipment.
It is OUR job as professionals to get the training we need to function as professionals, not RED's

Although, I have been thinking that a RED BOOT CAMP is greatly needed. It would be invaluable to be able to get instruction from the RED masters.
I would be interested in opening discussions on making this happen.

I could offer to host it at a 160 acre cabin facility in the Tahoe National Forest in the Sierra Mountains. Anybody interested?



Happy Holidays Everyone !

Some great points here. Every user will need a "routine" for shooting, and yes many RedCam owners will need to forget some of the DV style shooting tactics in favor of more standard practices.

Above all we need to understand that this is a very different camera, (Brilliant) and adapt our routine around the technology. Pick up a copy of Photo shop to understand how the images captured by this camera can be used and transformed. Lossless Compression, Wavelet based compression, Motion JPEG are all great ways to process and preserve our HD images..Cheers Jim!

I will work on a User manual similar to the "Cook" Manuals when I receive my cameras...1st quarter of 2008.. or sooner I hope!..(Fingers crossed). Nothing under my tree Tuesday Morning!
We are also putting together a series of two Day RedCamp retreats...Elizabeth E-mail me with some Details, we can get some great images in the mountains !

Redrentals@aol.com

[I Bloom]

as i know this is physics experimental theory ..:shifty:
if test works fine . is it will proof correct collimation ..?:pinch: ?
or what it will proof ? :devil:

It's just a precise way of measuring distance, that we are seeking.

[BASSAM MSSALATIE]

Thanks ..understood.:weight_lift:

[I Bloom]

Thanks ..understood.:weight_lift:
Just to be clear, I linked that wikipedia article because it includes an explanation of a double slit interferometer. The fact that that setup was used for a famous experiment in quantum mechanics doesn't apply here.

[Wes Printz]

Before one can do any calibration of the Camera's FFD, as you can not measure the FFD as is done on a film camera, this can only be done optically. to do this, you have to ensure the lens is 100% correct, and the datum lines on the lens line up.

To acheive this on Cine prime and zoom lenses, the back focus is set using an autocollimator and a focal plane micrometer for measuring any error which there may be. Such as made by Richter Cine Equipment. If there is any error, it is then removed with the use of shims either adding or removing to bring the lens in focus at infinity.

The next step is to project the lens using a lens projector such as made by Chrosziel or Century, (there may be others) to check the lens for any errors at various distances, 6' 10' 15 ft etc... you will be looking for any problems with resolution, breathing, datum line alignment, if a zoom, tracking errors, focus shifts through the zoom curve etc as well.

Also bearing in mind the lens manufacturer has specifications for their lens at a particular T-stop. All the calibration must be done at this setting to ensure proper adjustment of the lens to spec. Just because it goes to t1.9, does not mean you will have a proper image there. Look at your image with the lens wide open then stop down to say 2.8, you will notice an improvement in image quality.

Once you are confident the lens is spot on, I.E. your chart at 10 feet is in perfect focus, good resolution and the datum line is on the 10' mark not above or below, If the marks don't line up.. correct the lens before proceeding. Close enough does NOT work here, only then, can the lens be put on the camera.

Once you have the lens PERFECT, you can then adjust the FFD of the camera, by whatever method developed by the camera manufacturer, in this case RED has a new adjustable mount.

The above is only an overview of what is required for Cine lenes which do not have back focus adjustments. This is also not something for someone without the proper equipment and training should attempt. Leave it to the professionals. I'm sure as more cameras are released, there will be rental houses that for a fee, may check and adjust the FFD of your camera. You should be able to put any range of PL mounted lenses on your camera, and shoot with confidence. Remembering your focus puller HAS to trust the marks on the lens. They don't see the same as what you do, they are looking at the barrel of the lens and the distance of the object from the camera.

Again, since you can not physically measure the FFD of digital cameras to the focal plane, it must be done optically. An auto collimator will not work on the camera as the image will be reflected off the OLPF giving you a false reading.

Once the lens is calibrated, and the FFD checked and set with what ever tooling / equipmment RED is developing, you should have some pretty darned nice images produced.


Just my thoughts on the subject.

[chuck colburn]

Pana-tech,

I'm not so sure you can't use an autocollimator with the RED camera. The OLPF is now (I read) 8mm from the film plane. And even if it was closer the quality of the reflected image would not appear the same from the sensor as it would from a piece of plano glass (the filter). It might take a tech a few trys to learn what the proper reflected image should look like from the sensor but I'm thinking it could be done if he/she used a quantified lens that they were sure was set up for proper infinity focus. But I might be missing something here as I've never tried it. lol

[Wes Printz]

I'm not so sure you can't use an autocollimator with the RED camera. The OLPF is now (I read) 8mm from the film plane. And even if it was closer the quality of the reflected image would not appear the same from the sensor as it would from a piece of plano glass (the filter).

The Auto collimator projects the image onto the film plane which is then reflected back to the collimator optic block. The lens is set to Infinity, the collimator is calibrated to infinity. This process is also used to check the Ground Glass height which can not be physically measured, to ensure it is at the same distance as the film plane. If the GG height is off by .001" you will see it and the image will be out of focus, resulting in a difference between tape and eye focus.

With the OLPF being 8mm in front of the focal plane, I don't see a way to get an image in focus at the focal plane, as the reflected image is coming from the OLPF. Yes, one could guestimate, but again close enough is NOT good enough.

[chuck colburn]

Yeah it will work. We use to check for parallelism of the lens mount seat to the film plane by putting a first surface mirror in the gate and an optical flat on the lens seating surface of the mount. Both images would bounce back through the eyepiece of the Richter and any slight diviation of parallelism would show up as to seperate images of the resoution target in the collimator.
There is even a formula for calculating the angular diviation by reading the error of overlap of the two images. You can use this test to check filters also. Hell you could use to check for parallelism error of the OLPF to the sensor plane. All this with out any lens at all. So what I'm saying is that since the OLPF is so far from the film plane that a lens focused at infinity will not even present a bounce back to the eyepiece of the collimator from the OLPF. I use to set up infinity focus on lens with cameras that had behind the lens filters (gels) and they no way interfered with the collimation of the lens.

Let me just add here that all the above only holds true if the autocollimator itself is in proper calibration. But that's easier to check then a lens itself.

[Jan Reiff]

jim,

the (very sharp) footage you already sent to us from your own redone, is it sharpened in the post or native from camera?

[I Bloom]

jim,

the (very sharp) footage you already sent to us from your own redone, is it sharpened in the post or native from camera?

Are you referring to the R3D files that Jarred posted? (then they wouldn't be sharpened.)

[Jannard]

Correct... any RAW .r3d file has NOT been sharpened. Where trouble begins is when our footage is compared in tests against cameras that DO HAVE in camera sharpening. As long as you know it is apples to oranges, it is OK.

If we had it to do over again, we would always choose to NOT sharpen in camera. The RAW non-sharpened look is great. And the user has all the controls if he wants to "snap it up" a bit.

Jim

[Emmanuel Cambier]

Correct... any RAW .r3d file has NOT been sharpened. Where trouble begins is when our footage is compared in tests against cameras that DO HAVE in camera sharpening. As long as you know it is apples to oranges, it is OK.

If we had it to do over again, we would always choose to NOT sharpen in camera. The RAW non-sharpened look is great. And the user has all the controls if he wants to "snap it up" a bit.

Jim

PERFECT

[Mike Prevette]

and since the sharpening amount and style are all variables of the OUTPUT format they will be very different for a SD broadcast VS a theatrical presentation. This has become a common practice among still photographers when creating presentation prints. A 4x5" print needs totally different sharpening than a 16x20". So it indeed makes the most sense to do it in post.

[Anders Holck]

Again a vast number of RAW still photographers use a two step sharpening routine: Input and output sharpening.

Input sharpening is done to make the image seem sharp after capture and is the only sharpening done before archiving the final image.

Output sharpening is done just before delivery for the specific target media and image size.

[Jan Reiff]

red made the very right decision.

[Graeme Nattress]

If you're downsampling, the down filter should be designed to provide optimum sharpening without ringing or halos in the lower resolution.

Input sharpening should be very subtle...

Graeme

[I Bloom]

Jim,

Is there a difference in the new cameras, because of the placement or type of OLPF, that might affect the percieved sharpness of untouched .R3D files? Or should we be expecting about the same as the original cameras.

And also, is the .6, 300% formula you suggested something that you discovered through trial and error or something that is sort of a scientific match for the OLPF.

Ian

[Cüneyt Kaya]

Jim,

Is there a difference in the new cameras, because of the placement or type of OLPF, that might affect the percieved sharpness of untouched .R3D files? Or should we be expecting about the same as the original cameras.

And also, is the .6, 300% formula you suggested something that you discovered through trial and error or something that is sort of a scientific match for the OLPF.

Ian

i missed this formula, and my question is where in redcine i should add .6 and 300 %...thanks

[Graeme Nattress]

OLPFs don't really change their effect on change of distance. It's more to make any dust less visible and to deal better with flare I think.

Graeme

[I Bloom]

i missed this formula, and my question is where in redcine i should add .6 and 300 %...thanks

Those are photoshop Unsharp Mask parameters that can be used on 4K Tiffs. RedAlert just has a few options for sharpening in the menu's. I don't know of any in Redcine... yet.
But on down converting, some scaling algorithms are sharper than others.


OLPFs don't really change their effect on change of distance. It's more to make any dust less visible and to deal better with flare I think.

Graeme
That makes sense. I guess I had read that they were using a slightly different filter. I think Evin referred to it in the Red vs. Red thread. But maybe that's mis-information.

IBloom

[Evin Grant]

Here is a 100% crop from a frame shot on Zeiss Ultra Primes. It's the sharpest frame I've seen from the Red so far. The first is no sharpening applied the second is with Jim's 300,6,1 USM in photoshop.
http://www.reduser.net/evin/eyecomp.jpg

[David Mullen ASC]

I'm a little disturbed... did the RED camera or the Zeiss UP lens eliminate the man's eyelashes? :)

[Rudi Herbert]

I'm a little disturbed... did the RED camera or the Zeiss UP lens eliminate the man's eyelashes? :)

Darn it, now I realize what was wrong with the photo! Maybe the black shading calibration exfoliated them?

[Greg M]

Here is a 100% crop from a frame shot on Zeiss Ultra Primes. It's the sharpest frame I've seen from the Red so far. The first is no sharpening applied the second is with Jim's 300,6,1 USM in photoshop.
http://www.reduser.net/evin/eyecomp.jpg

this was shot w/ #199?

[Evin Grant]

No, #87.

[Deanan]

I'm a little disturbed... did the RED camera or the Zeiss UP lens eliminate the man's eyelashes? :)

That obviously a result of the OELF.
(Optical EyeLash Filter)

[Greg M]

No, #87.

and has #87 been updated?

[Evin Grant]

With the new OLPF? No. And according to Graeme there really is no difference in rez, only flare and dust.

[Graeme Nattress]

AFAIK, from my limited knowledge of optics, within reason, distance doesn't alter the anti aliasing strength of an OLPF as the rays go through it parallel.

Graeme

[I Bloom]

MY THEORY BELOW:
I thought the OLPF was a very fine grained form of diffusion, randomizing the path of the rays slightly and thus creating a mild blur effect as the light is scattered and preventing high frequencies from resolving on the sensor.

Moving it forward without then constricting the light with an aperture, would increase its effect. Kind of like trying to peer out through a frosted shower door at someone resting their palm on it. You would need to use a milder diffusion to compensate for the move.
END OF MY THEORY.

Evin, if your results from the other night with Bear turned out inconclusive, have you had other experiences with #102 that make you feel like it's resolving differently, maybe a wider lense or tighter aperture?

Ian

[Deanan]

It's a very specific square pattern. First the rays are split along one axis and then those two are split along the other axis (per most OLPFs). The rays are essentially parallel coming out so there no significant change in low pass performance by moving the OLPF.

Why we moved the OLPF was for other reasons.

[I Bloom]

It's a very specific square pattern. First the rays are split along one axis and then those two are split along the other axis (per most OLPFs). The rays are essentially parallel coming out so there no significant change in low pass performance by moving the OLPF.

Why we moved the OLPF was for other reasons.

Got it.
So the rumors of a difference in resolution are just that, rumors.

Once I told my recent clients, "Fellas, you need to sharpen it. That's how it works." They got really happy.

Ian

[David Mullen ASC]

The reduction in flare / improvement in contrast with the new OLPF would give the impression of better resolution.

[Deanan]

Got it.
So the rumors of a difference in resolution are just that, rumors.


Not specifically from moving the low pass but there are
other variables involved which make it more complicated.

[Jannard]

The reduction in flare / improvement in contrast with the new OLPF would give the impression of better resolution.

We have a new OLPF in a different location. As David points out, flare is reduced, contrast is improved, and small dust particles on the filter will not be as apparent. Grand total = much better. As Deanan points out, there is a bit more we are not likely to share.

Jim

[Evin Grant]

Evin, if your results from the other night with Bear turned out inconclusive, have you had other experiences with #102 that make you feel like it's resolving differently, maybe a wider lense or tighter aperture?
Ian

No, I no longer think there is a resolution difference. I'll be getting #199 on Monday (fingers crossed) and I'll try to torture test the new OLPF this comming week.

[Michael Lindsay]

Hi (those cleverer than I)

Does moving the OLPF closer to the lenses make the camera more sensitive to portholing from the least telecentric lenses?

thanks

Michael Lindsay

[Jonathan Cruz]

No, I no longer think there is a resolution difference. I'll be getting #199 on Monday (fingers crossed) and I'll try to torture test the new OLPF this comming week.

Hi Evin please post your results when you have them, thanks

[Pol Turrents]

using telecentric lenses will help the sensor as well?

[Elizabeth]

This is a very informative thread ... terrific!

I absorbed as much as I could with my rudimentary scientific knowledge of optics and was still puzzled. A resulting internet search helped fill in the gaps in my understanding of OLPFs and such. I thought I would share a link to a site I found with a definition for the specifics of "Optical Low Pass Filters" (as well as other info), just in case I am not the only one wading through the knowledge that others much more experienced just take for granted.

http://www.optics-online.com/CCDlens.asp

The exact definition for OLPF is found at the bottom third of the page. Downloading the application note on OLPF is also very instructive.

[I Bloom]

This is a very informative thread ... terrific!

I absorbed as much as I could with my rudimentary scientific knowledge of optics and was still puzzled. A resulting internet search helped fill in the gaps in my understanding of OLPFs and such. I thought I would share a link to a site I found with a definition for the specifics of "Optical Low Pass Filters" (as well as other info), just in case I am not the only one wading through the knowledge that others much more experienced just take for granted.

http://www.optics-online.com/CCDlens.asp

The exact definition for OLPF is found at the bottom third of the page. Downloading the application note on OLPF is also very instructive.

That's a great link. The wikipedia page on "Anti-aliasing filter" has this excerpt


The typical implementation in digital cameras is a two layers of birefringent material such as lithium niobate, which spreads each optical point into a cluster of four points. The choice of spot separation for such a filter involves a tradeoff among sharpness, aliasing, and fill factor. In a monochrome or three-CCD or Foveon X3 camera, the fill factor alone, if near 100% effective with microlenses, can provide a significant anti-aliasing effect, while in color filter array (CFA, e.g. Bayer filter) cameras, an additional filter is generally needed to reduce aliasing to an acceptable level.

The birefringent material, I believe creates several images that are shifted relative to one another.
http://upload.wikimedia.org/wikipedia/commons/7/7a/Calcite.jpg

The example of color aliasing in the image from the application note you posted is really interesting. I hadn't fully understood how much aliasing can reek havok on the bayer pattern.

[Graeme Nattress]

It's is incorrect that fill factor alone provides for an AA effect. It can only maximize the potential AA effect of the OLPF. Chroma aliasing can be nasty, but good demosaicing can really help there. However, remember all sensors need OLPFs (or really bad lenses) to avoid aliasing. You can get strange chroma artifacts too on 3 chip cameras using pixel offsets too. There's no perfect solution to problems in this field, but there are some solutions more optimum than others, especially if you want to use standard lenses.

Graeme

[I Bloom]

It's is incorrect that fill factor alone provides for an AA effect. It can only maximize the potential AA effect of the OLPF.

Graeme

Can you clarify what fill factor is? and it says "if near 100% effective with microlenses"?

[Graeme Nattress]

Fill factor is how big the light sensing area is compared to the pixel pitch. You can see that as fill factor approaches zero, you get a point sample, and as it gets larger you get an area sample, but both have exactly the same spacing. It's that spacing that samples the spatial frequency, and that spacing that determines your maximum recordable without aliasing frequency. Increasing the fill factor will reduce the MTF of the aliases, but not remove the aliases.

Graeme

[I Bloom]

Fill factor is how big the light sensing area is compared to the pixel pitch. You can see that as fill factor approaches zero, you get a point sample, and as it gets larger you get an area sample, but both have exactly the same spacing. It's that spacing that samples the spatial frequency, and that spacing that determines your maximum recordable without aliasing frequency. Increasing the fill factor will reduce the MTF of the aliases, but not remove the aliases.

Graeme

I really quoted that paragraph because it says "such a filter involves a tradeoff among sharpness, aliasing, and fill factor." Though you made a good point in saying that non-bayer sensors need the same treatment.
Does this "tradeoff" mean that you can't experience aliasing on Red? Or is there a situation where you could?

[Graeme Nattress]

I've seen some very mild aliasing under extreme circumstances, but I've not seen any in real world images. I think that's about the right balance.

OLPF filters are very "slow" in terms of roll-off. They're not brick wall filters by any means.... They don't "ring" though, but they have to be brought in early to kill aliasing. So there's a fine balance to be achieved. I think we've done so.

Graeme

[I Bloom]

I've seen some very mild aliasing under extreme circumstances, but I've not seen any in real world images. I think that's about the right balance.

OLPF filters are very "slow" in terms of roll-off. They're not brick wall filters by any means.... They don't "ring" though, but they have to be brought in early to kill aliasing. So there's a fine balance to be achieved. I think we've done so.

Graeme

I've been looking over some footage. I was always averse to sharpening HD material, it's interesting how sharpening is essentially now one of the main tools defining the look of a project on Red. http://www.redhax.net/SharpenLooks.jpg

[Simon Blackledge]

300% R=3 looks ace :-/

[I Bloom]

Sarcasm? And this one:
http://www.redhax.net/Sharpness300rad2.jpg

[Simon Blackledge]

yes..lol.. sorry dude.

Have you tried usm on just the mids ?

450 @ .6 ?

s

[I Bloom]

yes..lol.. sorry dude.

Have you tried usm on just the mids ?

450 @ .6 ?

s

Oh, I wasn't saying it looked good. I was just looking at the spectrum of possibilities.

[Simon Blackledge]

Yeah I took it as though you were experimenting..

Maybe worth checking out neatimage, there is a movie option now I believe.

s

[I Bloom]

In any case, this is all leading up to a question: Is it possible that Red could include sharpening in the meta-data for .R3D, and put unsharp mask parameters into RC,RA and QT? I imagine this would be difficult to preview in camera, but otherwise very useful. (And great for handing over .R3D footage that is supposed to look sharp.)

IBloom

[Michel Hafner]

300% R=3 looks ace :-/

If ace=crap I agree.

[I Bloom]

If ace=crap I agree.
I'm not saying I'd go with that. But you have to think of it first across a 4K image, and second in the context of a story.

[Simon Blackledge]

I wouldn't use the term "crap" I mean it is at 300%! just ott.. but like he says.. just messing with options.. which is always a good thing...

s

[Mark L. Pederson]

In any case, this is all leading up to a question: Is it possible that Red could include sharpening in the meta-data for .R3D, and put unsharp mask parameters into RC,RA and QT? I imagine this would be difficult to preview in camera, but otherwise very useful. (And great for handing over .R3D footage that is supposed to look sharp.)

IBloom

An interesting idea Ian. But maybe the unsharp mask parameters are in an external meta-data file which is linked to the .r3d - that feels safer.

But you got me thinking ....

[Chris Swinbanks]

I wonder how sharpening would be dealt with if one was planning a film-out to 35mm for release prints.A good one to discuss with your post-house. If you're not doing much in the way of VFX then you could leave it to the DI suite to do an overall sharpen prior to output of the dpx/cineon files (normally at 2k) for filmout, and that would (should) be based on their experience having done many features already. That way it can be added only to the final conform and done pretty much real-time if on a high-end system.
If its a VFX heavy show, the VFX supervisor should be consulted so that thay can test the footage early to decide if the sharpening you plan to add is a help or hindrance to any compositing.

[I Bloom]

An interesting idea Ian. But maybe the unsharp mask parameters are in an external meta-data file which is linked to the .r3d - that feels safer.

But you got me thinking ....

Hmmm it's just meta-data right?

Put it in a menus somewhere around brightness and contrast, default it to zero. Put meta data aware sharpening into all of your .R3D apps. That way if you are handing off .R3D to a client that isn't savvy...then that phone conversation about OLPF compensation can be about the next gig they have for you....

I understand your concern about sharpening last...for a Scratch user however this would be a non-issue.

Ian

[Mitch Deoudes]

Only problem is that the Red lenses don't have a witness mark for the focus, so where exactly is 3'.
Stephen

Has there been any official word whether the Red primes / not-yet-manufactured zooms will have focus marks (and/or t-stop marks)? I've heard grumbling from more than one AC recently about this issue.

Edit: all humor aside (i.e. lebowski's reference below to the Imperial Flame War) - what I mean is the individual marks for each number... still an (officially) unanswered question, unlike the metric thing. Also - isn't a witness mark that's only on one half of an assembly technically not a witness mark at all?

[Adrian T.]

Has there been any official word whether the Red primes / not-yet-manufactured zooms will have focus marks (and/or t-stop marks)? I've heard grumbling from more than one AC recently about this issue.

...and a (choice of) metric scale. I've heard grumbling from a lot of non-imperial camera buyers recently about this issue. :whistling: