Welcome to our community

Be a part of something great, join today!

Log in
  • Hey all, just changed over the backend after 15 years I figured time to give it a bit of an update, its probably gonna be a bit weird for most of you and i am sure there is a few bugs to work out but it should kinda work the same as before... hopefully :)

Epic in camera filter assembly

M

Michael Brennan

Well-known member
Joined
Mar 13, 2007
Messages
724
Reaction score
0
Points
0
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
 
This would be a great relief !
In Epic but in Scarlet too !
 
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. :)
 
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.
 
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.
 
chuck colburn said:
The whole behind the lens filter concept is not in my way of thinking worth the potential problems that can result.
Click to expand...

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 ?
 
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.
 
Brook Willard said:
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.
Click to expand...

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.
 
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?
 
LEON said:
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 ?
Click to expand...

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.
 
Brook Willard said:
Bill, Jim said it. The sensor will move for fine-tuning the FFD.
Click to expand...

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

Interesting. I think I like this, depending on how much shock the assembly can withstand and maintain FFD.
 
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.
 
J. Eric Camp said:
R-e-a-l-l-y?!

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

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.
 
Red@BirnsAndSawyer said:
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.
Click to expand...

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
 
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
 
You must log in or register to reply here.
Back
Top