Epic in camera filter assembly

[Michael Brennan]

Given the proposed mechanical design of the Epic sensor module I am hoping that a in camera ND/CC filter assembly could be a feasible option.
Either as a third party product or as a RED accessory.

I would pay a few '000 to have the functionality of changing filters in camera for remote head work, increased speed it would give in docs, increased reliability (dust) for the rest of the time, not to mention (in theory) improved optical performance on the edges of frame with many wide angle lenses.

In normal use one can't drop, smudge or scratch an internal filter:)

Mike Brennan

[SF Geek]

I second this idea.

[LEON]

This would be a great relief !
In Epic but in Scarlet too !

[Brook Willard]

I'd love to see this in the fixed lens Scarlet.

As for the Epic... it doesn't seem as fitting or - frankly - very easy to implement. My disagreeing with it is one thing - my cranky "film cameras don't have it so I don't want it" bias comes into play there.

But from a technical perspective, think about the 645 Epic. In order for the filter to work, it would have to be right up against the sensor [which moves, of course] in order to preserve the camera's ability to have multiple lens mounts with different flange focal depths. Also note that the camera body is barely wider than the sensor itself - it's only wider by about 25-30% rather than the 100%+ that would be required for a filter wheel.

Sure there is a way to design a filter wheel that wasn't actually a wheel... something that could be smaller and more subtle for the overall design of the camera. No matter what, it'd add to the mechanical complexity of the overall system... resulting in more moving parts, more parts to fail, more parts to clean and lubricate and more vibration sensitivity.

One should also note that the Epic is not a video camera.

I think that the filter wheel would be most fitting on the 2/3" fixed lens Scarlet - a camera that will never need to have an adjustable sensor, a camera whose sensor is small enough to allow for a filter wheel and a camera that will be used much of the time without a mattebox. As convenient as screw-in filters are, I'd rather be able to flip a switch on that camera. Frankly, I'd love to see consumer features like nightvision and a built-in microphone added as well... but that's for another forum.

Leave a filter wheel out of Epic, please. :)

[LEON]

Filter wheel out, I can understand,
and why not sliding a glass filter ?
There is a lot of space between the Cmos or OLPF and the mount.

[chuck colburn]

Filters behind the lens have some inherent problems when using wider lenses and even bigger problems with zoom lenses espically higher speed ones. The thickness of each individual filter has an effect on the flange focale depth of the camera body. So this means that the filters in your package must match each other in thickness or you will have erorrs in flange depth when changing from one to another. The quality of the behind the lens filter is also a factor with high speed and wide angle lenses, they must match each other in flatness and parallelism or optical degradation of image will result. This is not generally a problem with drop in filters on longer focale lengths as the depth of focus (not to be confused with depth of field) inherent in longer focale lengths takes care of these problems. The whole behind the lens filter concept is not in my way of thinking worth the potential problems that can result.

[LEON]

The whole behind the lens filter concept is not in my way of thinking worth the potential problems that can result.

Well, have you ever tried working with COOKE 20-100 or 18-100
and a filter behind the lens ?
Cooke is not the worst of lens maker.
They even have a gel holder. This is a bit dangerous but efficient too.
Although from a theoretical point of view I could agree with you,
practically when it is professionally managed, its a great relief to have the ND filter there, at the back of the lens.
Did you ever try ?
I forgot one detail: if a filter slot is there, in the camera body, nobody forces you to use it and
many could be pleased, so what is there for you to lose ?

[Paul Hazlett]

While I can appreciate the need for consistant filters, I think the filters called for here are not of the outside the camera design. these would be akin to a filter wheel on any professional video camera.

The problem I see is space. a 2/3inch filter wheel is much smaller than the required 4k
sensor size filter wheel. Given the Epics size, I just dont think this is possible. Scarlet might be able to use this though.

[Bill Goehring]

I'd love to see this in the fixed lens Scarlet.

But from a technical perspective, think about the 645 Epic. In order for the filter to work, it would have to be right up against the sensor [which moves, of course] in order to preserve the camera's ability to have multiple lens mounts with different flange focal depths.



Where did you get the idea that the sensor will move to accommodate different flange focal depths?

From what little I've seen on the forums on the topic, my understanding is that this will be accomplished by placing the various mounts at the appropriate distances from the sensor within the various mount assemblies. In other words, the sensor remains fixed and the mounts will be farther forward or farther back in the mount assembly, depending on what is appropriate for each type of mount.

[Brook Willard]

Bill, Jim said it. The sensor will move for fine-tuning the FFD.

[Bill Goehring]

Okay, Brook. Guess I got it wrong. Seems like the long way around the block to me, though. With the change to modular interchangeable mount assemblies that all mount to the camera in the same way and stay fixed to the mount both on and off the camera, doesn't it make more sense to leave the sensor fixed and vary the FFD on the mount assembly?

Maybe the problem is tolerances of the mount assemblies? And difficulty to fine tune FFD?

[chuck colburn]

Well, have you ever tried working with COOKE 20-100 or 18-100
and a filter behind the lens ?
Cooke is not the worst of lens maker.
They even have a gel holder. This is a bit dangerous but efficient too.
Although from a theoretical point of view I could agree with you,
practically when it is professionally managed, its a great relief to have the ND filter there, at the back of the lens.
Did you ever try ?
I forgot one detail: if a filter slot is there, in the camera body, nobody forces you to use it and
many could be pleased, so what is there for you to lose ?

Hi Leon,

Yes I have worked with and repaired the Cooke zooms. When you have a "selected" set of behind the lens filters they work just fine. Keep in mind that these are not speed lenses nor really very wide angle. So far as not using a behind the lens filter slot you still have to have a filter in there if only a clear one or you lose proper flange focale depth.

[J. Eric Camp]

Bill, Jim said it. The sensor will move for fine-tuning the FFD.

R-e-a-l-l-y?!

Interesting. I think I like this, depending on how much shock the assembly can withstand and maintain FFD.

[Cail Young]

Sure there is a way to design a filter wheel that wasn't actually a wheel... something that could be smaller and more subtle for the overall design of the camera.

Really the only alternative is a miniature gel scroller.

http://www.wybron.com/products/color_changers/cxi/

[JonathanF]

Please, please don't do this on Epic.

For all the reasons Chuck mentioned and more this is just a bad idea. If you want to do this with a fixed lens camera have at it, but please don't do this on Epic.

[Jeff Kilgroe]

Internal ND or filter ability only belongs on the fixed-lens Scarlet. Or at least that is the only camera I would like to see it on.

[Birns and Sawyer]

R-e-a-l-l-y?!

Interesting. I think I like this, depending on how much shock the assembly can withstand and maintain FFD.

Exactly. But a moving sensor to fine-tune FFD is a great option, because with the current design, if your backfocus/FFD is off just a touch, you pretty much have to pull it way out and try again. Thus, there is really no 'close'. Only correct or incorrect. A finely-tuned moving sensor adjustment would allow you to make very minor adjustments to correct if it is joust out.

[JonathanF]

Exactly. But a moving sensor to fine-tune FFD is a great option, because with the current design, if your backfocus/FFD is off just a touch, you pretty much have to pull it way out and try again. Thus, there is really no 'close'. Only correct or incorrect. A finely-tuned moving sensor adjustment would allow you to make very minor adjustments to correct if it is joust out.

I am not in favor of this either. We're talking about adjustments in the department of 5/10,000ths of an inch here. I'm not comfortable with that delicate or accurate a mechanism in the front of a camera I'm going to put on a camera car or do heli with.

I want the sensor bolted down to a nice rigid block of stainless and a rock solid shim adjustable mount.

This is just one more thing to break and I'd rather see them keep it simple and reliable. All this super duper adjustable everything is going bite people in the hindquarters if we're not careful.

Another $0.02...

J

[rod bradley]

I agree about the backfocus being on the sensor. This also allows for a uniform mounting system for a greater variety of mounts, I would think.

[tj williams]

Just putting in my vote for a behind the lens filter slot. when not using filter clear glass would protect the sensor during lens changes an d could be removed for cleaning, also is traditional film tech. so so certain older folks here won't be offended. This is old Panavision trick and also done to some Arris by DennnyC. no mechanicals like filter wheel and filters impossible to clean! Also selling filters is another accessory so very appealing to RED

[JonathanF]

I agree about the backfocus being on the sensor. This also allows for a uniform mounting system for a greater variety of mounts, I would think.

First, I have NEVER, EVER seen a mount changed on a camera mid production. If it was necessary for some esoteric piece of glass for one shot, a special camera was brought in. Rentals just aren't that big of a deal in this situation.

How solid you think this is going to be on say a camera car vibrating around all day, or let's consider heli work?

The mounts in use by Arri and Panavision are the way they are for a VERY good reason. Maybe it can be reinvented and made better, but it's not something I typically ever worry about when I use their cameras. So why bother.

With the R1 IT IS something we have to worry about and that is something I have found troubling.

The aftermarket will be thick with options for people shooting with a variety of lenses if the new design is as described so please make the mount and sensor stage that ships with the camera as relaible and stable as can be. P+S already has a great option for people who need this capability and the next gen of that mount will likely be even better.

Let's keep the standard PL mount simple and reliable.

PS - I know this belongs over in the mount discussion, but Rod brought it up ;)

[Scott Brown]

100% for built in ND's on the fixed lens + 2/3 Scarlet models. These are really going to be used in TV documentary run and gun situations where manually adding/removing ND's via a matte box is not really practical.

Jim, PLEASE consider this...it will make Scarlet a Sony/Panny :tongue: killer

Scott

[Nick Gardner]

These are really going to be used in TV documentary run and gun situations where manually adding/removing ND's via a matte box is not really practical.

Just out of curiosity why isn't this practical? I've done it on dozens of documentaries and so did every one else. I can see not having the time to do it on reality TV, but docs are not reality TV.

Just saying.......

Nick

[JonathanF]

PLEASE don't do this on Epic.

Scarlet fixed lens, sure, Epic, no way.

If you use filters behind the lenses then you are always going to have to always keep one in there even if it's just a clear because they increase the flanged focal depth optically by one third the thickness of the filter.

This is way to much of an error with high speed lenses and this is amplified as the focal length decreases.

:J

[JonathanF]

Just out of curiosity why isn't this practical? I've done it on dozens of documentaries and so did every one else. I can see not having the time to do it on reality TV, but docs are not reality TV.

Just saying.......

Nick

Thank you Nick. I didn't want to bring up the fact that we're using an MB14 and an MB5 on our current Doc now (depending on the situation) and we haven't had a single issue swapping out filters in the matte box.

:J

[Are Pilskog]

Just out of curiosity why isn't this practical?

At least when shooting wildlife through a camuflage, it would be nice to have internal ND filters.

I also think it would be faster/easier for a one man doc team. There is a lot of doc filmmakers out there that would find it troublesome to use external filters.
And this is a large marked Red!

So... my vote also goes for internal filters. Maybe it would be possbile to have an optionally filter module? :)

[JonathanF]

At least when shooting wildlife through a camuflage, it would be nice to have internal ND filters.

I also think it would be faster/easier for a one man doc team. There is a lot of doc filmmakers out there that would find it troublesome to use external filters.

I think there are a lot of "videographers" out there that find it troublesome, but think there are a lot of fimmakers out there that understand the technical reasons for not putting extra glass between the rear element of their $20,000 primes and the sensor that would disagree with you.

Docs are the core of our business but we grew up on film cameras and after talking to 4 other DoP's on this very issue today, many of whom we work with often, not one of them wants this feature. Every one of them said they would not want a camera with integral filtration and would rip it out if it was possible. Most of them came from film, not video backgrounds so that may explain things.

Either way, how would you envision this working, we're going to have a drop in set of lenses in the brain? How do you keep dust out of it?

If it's not drop in but integral, how would you clean them? Imagine a high humidity environment where you're filming from a vehicle on a dirt road. You change lenses... dust IS going to get in there.

How about situations where you are going between temp changes where the cold and warm temps are on either side of the dew point?

If you make it self contained to avoid all those issues what will you do for people who want nothing between their Master Primes and the sensor?

It's pretty small item on a 1/2 or 1/3 inch sensor, but on a ff35 of s35 sensor we're talking about a lot of glass. Are they stacked? If so how would you deal with the increase in the flanged focal depth? If not, how are you going to fit 3 (or 4 with a clear) independent pieces of glass in there?

Finally, will these filters be robust enough to withstand periodic blasts with compressed air when blowing out the sensor?

What do you do in the field if one of them is damaged?

It all sounds nice and convenient now, but there's a reason you don't have them on Arri or Panavision cameras. You may want to go down and ask one of their technicians why it's a bad idea. Perhaps they can convince you.

:J

[Alexander Nikishin]

In camera filters on an Epic? Seriously? Cmon.

[Zakaree Sandberg]

worst idea ever

[Alexander Nikishin]

worst idea ever

I hate to be over-bearing but, yes, I very much so agree.

Why add additional weight?

Why add moving parts?

Why not give people the option of choosing which ND's they use?

Just buy a clip on if it's that much of a hassle.

In Scarlet's case, there's the Tiffen still camera clip-on tray also, or a tiny clip-on MB.

[Birns and Sawyer]

IFinally, will these filters be robust enough to withstand periodic blasts with compressed air when blowing out the sensor?


Sorry, I couldn't help since this alarmed me slightly. You shouldn't be spraying any compressed air onto the sensor. You could use a small air-puffer to try to loosen any dust, but compressed air can cause much more damage to anything optical than it would potentially clean it.