Is there a full SLR frame adapter at all?

T

Toenis

Well-known member
The more I see posts about cinema frame size and FOV and etc I wonder if any of the DOF adaptors would actually utilize as wide and corrected image as even SLR`s viewfinder. I mean 30 years ago there were full frame SLR viewfinders that did not vignette with most lenses and did a bit with others but as I see it today no one is able to use full 36mm by 24mm frame size specially the full frame width the SLR lenses are designed for.

Am I missing something or there really is no such DOF adapter that wouldn`t vignette at the full SLR (still photography) frame width why is it impossible to design proper vignette free frame and let users choose their format (by zooming in or out) giving at least some edge to adaptor users.

I am quite frustrated to see super hi quality glass suffer from vignetting due adaptor design - shouldn`t it be written in caps - all your 35mm SLR lenses do work with (Academy) cinema size frame only and not as you could be used to in still photography word?

T
 
weixiang623 said:
...they have vignette-free adapters.
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No adapters are "vignette-free"!
When that is said, it intends you zoom in past any vignetting, which may be caused by the adapter in general or the lens itself.

Yes, it is 'frustrating' at first as you feel you are 'missing out' on that extra area that you have become accustomed to with still photography, but it's not as if the area is blocked with black, you still get to use the full resolution of your video censor.

The adapters are designed to use 35mm slr lenses BUT they are not for taking 35mm 'still' images, we just borrow part of the lenses to make video with 'better' depth control :)

It's a bit the same for digital slr's (without full frame censors = most),
They should also make the "crop factor" very evident and clear as that was a huge shock/upset.
 
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Sure when I mask 14mm (104deg hFOV) SLR lens footage to 2.40:1 ratio I will get quite OK image with FOV almost close to the widest 10mm (100deg hFOV) cine lens.

But the fact that most adaptors claim to have full SLR (or vistavision) frame width and vignette free performance has quite a catch cause you can not have both at the same time misleading users therefore.

My quess is that if there is one of the four cheaper DOF adaptors that can have both at the same time it could give it`s marketing an edge, so Dennis where are you ;)...
... if I get the time I´ll discuss that with the people from local optics lab cause given the amount of vignette, target imager size and object distance it could be fixed for sure but for what compromises to overall image quality I don`t know yet.
I am using the newest Letus with 1/3" sensor camcorder btw and given that the 1/2" EX1 had additional problems with image softness etc it could very well be related to the optical design of the adaptor itself.

Cheers,
T
 
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Barry_Green said:
Brevis and Letus Extreme both offer full-frame SLR or "VistaVision" frame sizes.
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That`s what I`m wondering about - but is it usable without vignetting - my quess/experience is that one can not have a VistaVision frame width available without vignetting with all the 35mm SLR focal lengths. No one just talks about the compromise - you can have vignetted full frame (in 35mm SLR terms) or not so vignetted Super35 frame. Absolutely every lens I have has something close to tunnel vision when used on VistaVision frame width on the latest Letus - sure everyone can help me, and everyone else in that matter, out with the "zoom in" fix that only crops about 1.7x field of view. One of the best kept secrets or if rephrased not so known about maybe.

Sure the 50mm and 85mm f1.2 almost don`t vignette but you can not use anything wider without cropping (zooming in) the visible GG frame width. My slowest lens are f2.8 one of them being tilt-shift with image circle close to medium format (when not tilted or shifted) and still it vignettes a bit on full visible frame. I am talking about Canon FD lenses that do not vignette when used in still photography.

Maybe it is the fault of FD mount on my adapter that has an image path at least 1/3th smaller than "full frame" but I can not test any of my FD lens without the lens mount as one can not open up the lens aperture without the mount itself. Theoretically this can cause the tunnel-vision-like vignetted images on full frame GG in DOF adapter configuration.

Any ideas?
T
 
On my DIY adaptor I can use anything from a 20mm 2.8 up without vignetting with my EOS lenses and get full frame out of them. I have yet to try and FD or Nikon lenses because I dont have any, but I dont really see why they would be much different. Im no engineer either, lol. I just made a static adaptor.
 
DREWjoseph82 said:
On my DIY adaptor I can use anything from a 20mm 2.8 up without vignetting with my EOS lenses and get full frame out of them. I have yet to try and FD or Nikon lenses because I dont have any, but I dont really see why they would be much different. Im no engineer either, lol. I just made a static adaptor.
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Actually I have "engineered" many DOF adaptors over the past three years, static and vibrating, without flipping image that utilized the pre-engineered frensel focusing screens, off the shelf lens mounts and none of those showed any more vignetting than caused by the actual lens design itself - I am skeptical therefore.

Cheers,
T
 
DREWjoseph82 said:
The lens design of the adaptor lens or the camera lens?
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Interchangeable 35mm still photography SLR lens in that matter.

Only "lens" an adaptor actually needs is the one that could enable close enough focusing or in the case of non-frensel focusing screen it would add a plano convex lens to get the image straight (no vignetting) for that planar imager (CCD or CMOS sensor) found in our camcorders that could differ is size and would give some more sharpness and vignette obstacles therefore.

But most of dof adaptor users are using 1/3 inch sensor camcorders nowadays so it could be called most universal sized sensor to adapter design to stick to at the moment in the small and most affordable market. And still it causes problems.

T
 
Toenis, providing the correct version of our CINEFUSE elements are matched to the camera, I believe the Brevis offers one of the best usable frame widths in the business. From 28mm f2.8 primes (and slower 28mm zooms) right up to 500mm we can normally maintain a frame width at about 38mm...so a bit wider FOV than the film camera. With faster wide angle lenses, our users are getting great results right down to 16mm.
 
Dennis Wood said:
Toenis, providing the correct version of our CINEFUSE elements are matched to the camera, I believe the Brevis offers one of the best usable frame widths in the business. From 28mm f2.8 primes (and slower 28mm zooms) right up to 500mm we can normally maintain a frame width at about 38mm...so a bit wider FOV than the film camera. With faster wide angle lenses, our users are getting great results right down to 16mm.
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Dennis, I just wanted to hear that!
This alone would give cinematographers a wider choice of 35mm SLR lens options - one can always crop-zoom to Academy if wanted.

Cheers,
T
 
Thanks Toenis. Our R&D efforts in the imaging element department have been concentrated on five things:

1. Full SLR frame performance for both small/large cams in one adapter package, with flexibility to zoom "down" to motion film gate sizes.
2. Edge to edge sharpness.
3. Low/no vignetting on not just primes, but slower zooms too.
4. Light efficiency...with the options for shallower rendering bokeh too (CF2Le, CF3Le)
5. Retrograde compatablity with every unit we've sold to date.

You're quite correct in that all 35mm lenses show some level of edge falloff, particulary wide open, and this must be accounted for in testing.
 
The size of the focussing surface means nothing. The usable image size is a function of the 35mm image cone combined with the adapter's efficiency with regard to edge falloff. From what I've seen here, the Letus cannot use an image frame width at 16:9 ratio anywhere close to 46mm...nor can we. With fast primes our users can exceed SLR frame width (36mm) an honest 10%, but beyond that you are into nastiness as you push the edge of the design specs for most 35mm lenses.

In fact, if you can get even 36mm image frame width, no vignetting, using a 28mm f2.8 lens with your setup, I'll gladly eat one of our Cinevate hats. The 35mm image circle is theoretically 50mm wide...assuming a 16:9 frame, zero edge falloff from the lens (I've yet to see anywhere close to that), and a perfectly centered adapter, here's what you've got:

usablewidth.jpg


As far as any claims that a given adapter has "zero" vignetting, I'd suggest a search here for many posts to the contrary.
 
Dennis, if you managed to use a full SLR frame, how would one go about getting rid of this:
LensHotSpot.png


Anywhere from 14mm - 35mm will exhibit this. I'm assuming once you use a 35mm SLR frame then you're gonna have to deal with natural vignetting caused by the glass. Is there a way to bypass that?
 
These adapters require a surprisingly lot of knowledge to be used efficiently. What Dennis is saying is true to all the adapters out there. I have a LEX and am really happy with it and Im still learning to use it.

Sami
 
Kholi said:
Wtf are you talkin' about? I asked Dennis a question. And BOY aren't you a flagrant hypocrite. You want me to go and dig up your post in the thread about the BRevis not losing light between wide open and 2.8? Weren't you right along with EVERYONE ELSE disputing the possibility? LuLLz. And I wasn't even refuting his claims about SLR frame size. I just had a question.

has nothing to do with Brevis, Letus, M2 or your right leg stuck in a bear trap.

HOW WOULD YOU GET BY THE NATURAL CHARACTERISTICS OF A LENS!?!?
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Ko Lee I wasn't responding to you, so shill.

I was talking about Dennis responce to "The frame size on the Letus35 Extreme 46mm x 30mm which is even larger than Vista Vision."

In reference to what I supposedly said about the Brevis. I said and continue to say that there is no light improvement from f4 to f1.4 according to the video shown by Dennis. (You can research it).

Dennis I'm sorry I jumped on your back. I took a fight that wasn't mine.

Ko Lee lets just learn from each other and have some fun. Post some of your stuff so we can see your style and what you do with your camera.
 
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