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14mm lens - filter behind back element?


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#1 Mike Medavoy

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Posted 17 November 2008 - 06:56 PM

Hi!

I have a Canon 14mm lens in BNCR mount. It's quite hard to put too many filters in front of this lens... after 1-2 filters, it starts to vignette.

At the back element, this lens has a thread - I think the diameter of it is about 36-37mm (see attached photo). So I think I could screw onto there a small Tiffen 37mm filter, like an ND when I need it.

Would that create image problems? Any downside or things to watch for when doing a thing like that? If not, can I stack in there 2 filters, on top of each other?

I'm using it on the RED ONE camera, so shutter clearance is not an issue at all.

Thanks for any tips!

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#2 Chris Keth

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Posted 17 November 2008 - 07:34 PM

Each filter behind the lens will change the flange focal depth 1/3 the thickness of the filter. You can do it, but with a lens that wide your shots will be soft unless you take the time to recalibrate your lens mount. It would have to be moved back to standard when you change back to another lens.

Personally, that's a huge pain in the ass and I wouldn't do it. You can use a wide-angle mattebox with 6x6 filters. I've used those on out to 10mm lenses without vignetting.

Edited by Chris Keth, 17 November 2008 - 07:36 PM.

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#3 Glen Alexander

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Posted 21 November 2008 - 03:15 PM

I put a cut piece of Kodak Wratten filter there with no problems or issues having to remount or recal.
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#4 Stephen Williams

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Posted 21 November 2008 - 03:28 PM

I put a cut piece of Kodak Wratten filter there with no problems or issues having to remount or recal.


Wide open there will be problems, if you stop down to T4 it should be fine.

Stephen
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#5 Glen Alexander

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Posted 21 November 2008 - 03:45 PM

Wide open there will be problems, if you stop down to T4 it should be fine.

Stephen


I didn't see any problems on the negative, what are you referring to??? the filter not covering the lens? moving around?vignetting?

if vignetting, there are times when i actually LIKE vignetting, it is a very nice artistic effect.

the wratten is what about ~.3mm thick?

But I'll check the answer print Tuesday.

Edited by Glen Alexander, 21 November 2008 - 03:50 PM.

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#6 Stephen Williams

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Posted 21 November 2008 - 04:03 PM

I didn't see any problems on the negative, what are you referring to??? the filter not covering the lens? moving around?vignetting?

if vignetting, there are times when i actually LIKE vignetting, it is a very nice artistic effect.

the wratten is what about ~.3mm thick?

But I'll check the answer print Tuesday.


Hi,

The FFD will be out by 1/3 of the thickness of the wratten. If you are eye focusing you will be ok, but expect issues if you focus the lens by the scales from 10' to infinity when wide open (it's very difficult to see focus).

Stephen
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#7 Glen Alexander

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Posted 21 November 2008 - 05:51 PM

Hi,

The FFD will be out by 1/3 of the thickness of the wratten. If you are eye focusing you will be ok, but expect issues if you focus the lens by the scales from 10' to infinity when wide open (it's very difficult to see focus).

Stephen



ah, ok i don't use the scales on the lens.
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#8 Chris Keth

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Posted 21 November 2008 - 08:08 PM

ah, ok i don't use the scales on the lens.


Not a problem for you then. Eye focus is eye focus.
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#9 Patrick Neary

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Posted 21 November 2008 - 09:57 PM

Not a problem for you then. Eye focus is eye focus.


No, he uses that time-honored professional AC technique of a blade of grass and a bush...
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#10 Glen Alexander

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Posted 21 November 2008 - 11:16 PM

No, he uses that time-honored professional AC technique of a blade of grass and a bush...



pfffft... go to a museum, get out into nature, music, go among people... study ART, Van Gogh, Rothko, Turner, Vermeer, Picasso, Dali, go study something that moves people on a deep emotional level, not most bullshit 'professional' techniques or training that leave releases stale, formulamatic and total crap.

art, nature, being out meeting people, living life is my buddhist honored 'technique'.

in my film, the viewer will be pulled willing or unwilling into an unknown space, the journey from that blade of grass to a bush, could unleash ones deepest fears or touch ones soul, in the most subtle quiet moments of the here and now. i absolutely guarantee the audience of film, they see images, feel such quiet moments. if you had any inkling of the power of art, the overwhelming power in the life force in simple things, the petal of a flower, a blade of grass, a solitary bush wavering in wind on the edge of a cliff. you obviously have no clue what any of these things mean as you can't teach this in a classroom, there is no 'method' to look up in a book. true artists blaze their own trail, all for the fire of an idea. i know what it feels like to be the first man on the moon. to be honest i do not care in the least what any 'professionals' think about my technique or how i shot or why, my ONLY concern is the reaction of audience in human terms. my film is made NOT for "professional" critics. i know you probably can't comprehend any of this now, maybe someday you will, if you are lucky enough to see my film.
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#11 Patrick Neary

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Posted 22 November 2008 - 12:42 AM

well now that you put it that way I hope I get to see your film.
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#12 Hunter Hampton

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Posted 26 November 2008 - 01:16 PM

I have used a 4x4 filter in front of a 14mm lens on the Red with no vignetting. This is a rehoused still lens correct? I dont think you should have any problems with a 4x5.65 or larger in front of the lens.
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#13 Ira Ratner

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Posted 02 December 2008 - 08:39 PM

I sure believe what Richard is saying, but even if it WASN'T true:

Couldn't you just use Cokin P or Z square series--HUGE filters--and mount the holder via their universal P mount adapter which doesn't screw into the filter thread at all, but attaches to the outside barrel via simple pressure thumb screws?

This is my fix for my Peleng 8mm, which you can't screw ANYTHING into.

I basically worship Cokin for an inexpensive filter solution that covers all of your lenses with the same filter--just different rings for the holders. And working in 16mm with about 10 lenses, that's a ton of savings for me.
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#14 Ira Ratner

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Posted 02 December 2008 - 09:04 PM

I sure believe what Richard is saying, but even if it WASN'T true:

Couldn't you just use Cokin P or Z square series--HUGE filters--and mount the holder via their universal P mount adapter which doesn't screw into the filter thread at all, but attaches to the outside barrel via simple pressure thumb screws?

This is my fix for my Peleng 8mm, which you can't screw ANYTHING into.

I basically worship Cokin for an inexpensive filter solution that covers all of your lenses with the same filter--just different rings for the holders. And working in 16mm with about 10 lenses, that's a ton of savings for me.


Uhhh...I just reread what Richard posted, and my post above makes no sense in regards to that. Plus, it was redundant.

SORRY!

He already said it about square in-front-of-lens filters, not the screw-ins.
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#15 Hunter Hampton

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Posted 02 December 2008 - 10:48 PM

Why do people always think my name is Richard?! :rolleyes:
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#16 Chris Keth

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Posted 03 December 2008 - 02:27 AM

Why do people always think my name is Richard?! :rolleyes:


For the same reason people think my name is Keith.
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