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Bob T View Drop Down
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Post Options Post Options   Quote Bob T Quote  Post ReplyReply Direct Link To This Post Topic: Filter sizes?
    Posted: 08 November 2018 at 22:57
I'm using a Sigma Art 24 - 105 lens on an A99. The lens is 82 mm dia. I'm currently using 84 mm square filters in a Cokin holder. However, at anything wider than about 40mm, I am getting fierce vignetting, with the filter holder clearly visible in the image/viewfinder.
If I changed to 100mm filters, would that solve the problem? Or will I still have vignetting on wide angle images?
 



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wetapunga View Drop Down
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Post Options Post Options   Quote wetapunga Quote  Post ReplyReply Direct Link To This Post Posted: 09 November 2018 at 02:08
I use 82mm lenses with 100mm Lee filters and don't get vignetting at those focal lengths.
a7R, a77ii, QX100 | Minolta 17-35mm G, 20mm, 35-105mm O, 50mm M, 70-210 beercan, 85mm G, 100mm M, 300mm G | Sony 16-50mm, CZ16-80mm, 70-200mm G, 135mm f2.8 STF | Tokina 11-16mm
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whiteheat View Drop Down
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Post Options Post Options   Quote whiteheat Quote  Post ReplyReply Direct Link To This Post Posted: 09 November 2018 at 05:44
Originally posted by Bob T Bob T wrote:

I'm using a Sigma Art 24 - 105 lens on an A99. The lens is 82 mm dia. I'm currently using 84 mm square filters in a Cokin holder. However, at anything wider than about 40mm, I am getting fierce vignetting, with the filter holder clearly visible in the image/viewfinder.
If I changed to 100mm filters, would that solve the problem? Or will I still have vignetting on wide angle images?

For a few dollars, you could test out that theory. I use the 100mm square filter system, although I don't shoot with any glass below 50mm FL. You can buy a cheap plastic 100mm filter holder and if necessary, a cheap filter. Ebay is littered with these bargain basement from China stuff. You could at very little cost obtain filter holder and see if does indeed appear in-frame at 24mm FL. If it does, you've saved yourself a lot of dollars. If it doesn't, be prepared to spend a lot of dollars. Nice filter holders are a little more expensive but the nice filters, the ones that don't colour or tint your images and don't distort the light, the ones made from Schott glass, those cost a shed load more than the cheapo from China stuff. However, they were the only filters I found to have produced the required results and that I was happy with. In my experience half measure filters give poor to atrocious results.
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waldo_posth View Drop Down
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Post Options Post Options   Quote waldo_posth Quote  Post ReplyReply Direct Link To This Post Posted: 09 November 2018 at 10:26
You are right, the regular Cokin P holder causes heavy vignetting. Fortunately a slim version Cokin P holder especially for wide angle lenses (holds only two filters) is also available. I tested it as well: There is a very small amount of vignetting in the corners at 24mm. It improves as you increase the focal length. At 28mm it's completely gone.

The 100mm filter holders have one crucial advantage: they can be disassembled and some of the shims holding the filters can be removed (reduce their holding capacity from 3 to 2 or 1) - if they still cause some vignetting. I have a Cokin Z and a third party Lee filter holder copy - that applies to both of them. But the screws and nuts are a pain to work with. I have substituted them in my Cokin Z holder with longer screws and wing nuts - very much recommended!

In case you have not been aware of the Cokin P wide angle lens holder: Here is a cheap Chinese copy.

Edit: I forgot - the easiest way to use the 100mm filter holders on WA lenses is to reverse them. But that allows only one filter to be used.

Edited by waldo_posth - 09 November 2018 at 10:31
"Stare, pry, listen, eavesdrop. Die knowing something. You are not here long." (Walker Evans)   http://www.flickr.com/photos/waldo_posth/
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momech View Drop Down
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Post Options Post Options   Quote momech Quote  Post ReplyReply Direct Link To This Post Posted: 09 November 2018 at 15:32
The 100mm filters with the Cokin holder that you can add/subtract shims will solve your problem as the guys above have suggested.

Before I did that, I bought a cheap Cokin P size holder and ground off all but the single slot nearest the lens mount - can only use one filter and I'm not sure it'll let you zoom out to 24mm, but it's a cheap solution and may be "good enough".
It's never too late to have a happy childhood.
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stiuskr View Drop Down
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Post Options Post Options   Quote stiuskr Quote  Post ReplyReply Direct Link To This Post Posted: 09 November 2018 at 17:43
I did the same, just file off the offending bits on the Cokin holder. It worked well for me but this was on the a700 with a 17-50 and I haven't used it with FF.
Rob Suits Jr.
a99M2 a99 a77 a700 KM7D|Min24/2.8 Min35/2 So50/1.4 So50/2.8 Min85/1.4G Tam90/2.8 Tam180/3.5|Tam17-50 CZ24-70G2 KM28-75D So70-200G1 So70-300G So70-400G1| SonyF60 AD200R2
 



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Bob T View Drop Down
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Post Options Post Options   Quote Bob T Quote  Post ReplyReply Direct Link To This Post Posted: 11 November 2018 at 20:13
Thanks for the replies everyone.The system was originally got for a a700 - widest lens was a Sigma 10 - 20mm. Had some vignetting at 10mm. Once I went longer than about 12mm, vignetting was gone.
Whiteheat, I like your idea. I'll try that
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