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08-18-2010, 12:15 AM   #1
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Join Date: May 2010
Location: Hong Kong
Posts: 19
Pentax 6x7 45mm: Vignetting using Cokin Z-Pro filter holder?

Buddy, I just bought one Cokin Z-Pro filter for my Pentax 6x7 45mm F/4. No filter yet...they are on the way to my home. I bought Hitech GND by the way.

As instructed on Cokin website, for ultrawide they prefer or suggest us to install the holder from the opposite way to prevent vignetting. Is there anybody having experience of using Cokin Z-Pro on this 45mm before? Coz' I want to use the GND with the Lee Filters Big Stopper Filter (10-stop ND) later on.

08-18-2010, 08:26 AM   #2
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Join Date: Jul 2009
Location: Seattle
Posts: 7,147
Nope, no Cokin experience. But I can empathize with your 10-stop ND problem and a 45mm lens. I found a low profile, adjustable screw mount ND filter (don't remember its name and not at home). It blocks up to about 6-stops though it advertises more and I also put on a 3-stop ND filter that you can still get in 82mm and I get no vignetting with the stack. That's not much help for your grad ND problem though.

So one solution that has crossed my mind at one point was to buy a 82mm filter, knock out the glass and bond on a square Cokin type filter. Might work for your grad ND case if it is a rotating adjustable filter like a polarizer
08-19-2010, 08:04 PM   #3
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Join Date: Feb 2008
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Checked a few old beach shots with a bright gray sky shot with the late model 45/4. I experimented with a couple different Cokin XPro neutral density grads. Almost no vignetting...as in mild enough to be overlooked and mild enough to not be noticeable to non-photographers. Actually, only noticeable to picky photographers.

To really check I placed the "bright gray sky" transparency on the light table right next to a 2 stop Blue and a 2 stop Tobacco filtered view of the same framing. The vignetting is maybe 1/3 stop or less.

Note that this is with the filter slipped into the closest slot to the front of the lens.

Note also that this setup produced severely defocused shots in front of the M*400/4--apparently the tele's don't like filters in front of the lens.

My shots that show the great results are not strong enough to have ever scanned them. Sorry for the laziness, but can't justify scanning several to show. You'll have to take my word for it. Very acceptable results for the pairing you have mentioned in your post. I wouldn't hesitate to purchase the system you mention based on my experience with it.
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