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05-21-2020, 07:30 PM   #1
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Do Cokin P size filter holders vignette with 35 wideangle?

The DFA 645 35mm has a 82mm filter thread. Cokin filters are 84mm across. With a Cokin single slot wideangle holder will there be vignetting? I have glass graduated filters in Cokin P size. Also considering a reverse graduated ND filter. Any recommendations?
Thanks,
barondla


Last edited by barondla; 05-21-2020 at 09:01 PM.
05-21-2020, 08:27 PM - 1 Like   #2
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I wouldn't recommend the Cokin P filters on lenses with filter threads wider than 72mm. I've done it with 77mm filter threads and wound up damaging the filter holder.
05-22-2020, 02:23 AM   #3
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Cokin states that on full format cameras with the M-Filter system (which is the former P-system) there is no vignetting down to 25 mm focal length. 35 mm on 645 are about 22 mm on full format. Thus the M-Filter holder will probably cause vignetting on the 35 mm. AFAIK there is no single slot wideangel holder in the cokin system.
Perhaps you can strip down the EVO M-size holder to 1 Filter, but for its price, it is cheaper to buy the Gradual ND Kit for L size (100 mm).

The Cokin System: A Beginners Guide To Cokin Filters
05-22-2020, 04:01 AM - 1 Like   #4
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I've used a Cokin P holder on my 645 FA33-55 with a circular polariser (also 82mm). The Cokin adapter ring is slightly smaller than the filter thread, but I can't remember any obvious vignetting (haven't really tested all focal lengths and aperture combinations). Not sure I'd recommend it, but I happened to have it lying around.

Depending on the length of grad filters, they may be limited as to where you can put the transition in the frame (I think Cokin's P are square?). Lee's are 100mm x 150mm for comparison (I think?).

Update: Forgot to mention this is on my 645D.


Last edited by johnha; 05-22-2020 at 07:02 AM.
05-22-2020, 05:26 AM - 1 Like   #5
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Is this for digital or film? The DFA 645 35mm is designed for 645 film and has a diagonal FOV of 90. That means that for every mm the filter adds to the front of the filter ring, the filter must have 2mm of added aperture to work on 645 film. The Cokin P size filter holders look pretty thick to me and would likely vignette on film 645.

The smaller sensor of the 645D & Z means they can tolerate a smaller image circle from the lens-filter system. With an FOV of only 76, the current 645 digital cameras probably only uses about 66.3mm of the 82mm diameter of the filter ring. And the required clear aperture of the filter system only grows by 1.6mm per mm of thickness.

You can test all this with some homemade paper disks & cardboard/foamboard spacers with various size holes and shooting a blank wall. Look for subtle shading of the corners with the lens wide-open (and double check that you don't get very dark corners with the lens closed down).

TL;DNR: The Cokin system on DFA 645 35mm will probably work on the 645D or Z but not on the 645 film cameras.
05-22-2020, 06:05 AM   #6
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QuoteOriginally posted by Papa_Joe Quote
Cokin states that on full format cameras with the M-Filter system (which is the former P-system) there is no vignetting down to 25 mm focal length. 35 mm on 645 are about 22 mm on full format. Thus the M-Filter holder will probably cause vignetting on the 35 mm. AFAIK there is no single slot wideangel holder in the cokin system.
Perhaps you can strip down the EVO M-size holder to 1 Filter, but for its price, it is cheaper to buy the Gradual ND Kit for L size (100 mm).

The Cokin System: A Beginners Guide To Cokin Filters
Wow, they have really changed the Cokin system. Apparently the smaller A system (up to 62mm filters) is gone. Since the 645Z is a crop format it might work with the holder without vignetting. Back in the P days, photographers were cutting the cheap plastic holders down to single filter thickness. Cokin got the message and brought out an official holder. Cokin Wide-Angle Filter Holder ? Cokin Filters. I don't remember if mine is stock or cut down, will have to look.

Guess I'll have to wait until the 35 arrives, if it ever does. It has spent a month in Australia Post's warehouse, without moving an inch. The person running that mess would be fired in the US.

Thanks for the Cokin link,
barondla
05-22-2020, 06:15 AM - 1 Like   #7
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Check the lens specs. If the filters are 84mm and the lens field of view is close, or, over that, it will vignette. Its all about how wide your lens "Sees".
Just checked, the DFA 645 35mm digital has a diag fov of 76, so the cokin single wideangle holder (84mm) is unlikely to vignette.

Last edited by Roadboat24; 05-22-2020 at 06:28 AM.
05-22-2020, 06:25 PM   #8
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QuoteOriginally posted by Papa_Joe Quote
AFAIK there is no single slot wide angle holder in the cokin system.
Cokin Wide-Angle Filter Holder ? Cokin Filters

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