Using CPL on Sigma 10-20? Cokin CPL?

[PeterAM]

I know that some of the members use the Sigma 10-20mm lens; discussion and pictures on the forum helped me make the decision to buy it. Is anyone using a circular polarizer on this lens? Are there any problems doing so, such as being limited at the lower end focal length(s)?
To be more specific, I'm thinking about getting a Cokin system to use with this lens (77mm) and with a different adapter, on at least one other lens. It would be helpful to get feedback from members using this system even if not on the 10-20.
Thanks.

[Talisker]

Well, I don't have a Sigma 10-20mm, and I haven't got a Cokin CPL, but... I've just bought a 14mm DA and first (very limited) experiments suggest slight vignetting with a Cokin P series 'wide angle' (ie single slot as opposed to three slot) holder, with the lens wide open. I'm pretty sure you would have problems at 10mm unless you bought into the Z series, which would quadruple (!) the cost of the CPL, according to the SpeedGraphic catalogue...

[PeterAM]

Thanks Talisker. Pretty much what I was afraid of. Also, thought that the Cokin system might be an economical way to go; should have known that it would have to get more expensive in order to work.
I remember a pretty unique single malt called Talisker. I used to get over to the UK on business (publishing) fairly often and made it my avocation to taste every single malt that I came across. If my memory is correct, Talisker had a pretty big taste.

[axl]

there was a thread about this before, try to search it...
I think general consensus was that below certain mm settins it will vignete even with thin P series filter holder, I have 10-20 and cokin P system, but I don't have 77mm ring. Anyway when I just hang regular P holder on the lens (the outer diameter of the lens is just a bit smaller then space for the ring) it was visibly vignetting in all 4 corners. You may try with slim holder but I think you won't be able to use it below 12mm or so. Anyway, to get evenly polarized sky anywhere under 16mm, well, good luck...

[Gruoso]

You have to be careful using polarizers in ultrawide lenses. If you dont position the camera right you might have inconsistent polarization (i.e., a wide band of sky darker than the extremes)

[roy]

to avoid vignetting get a CPL larger that your filter size and use a stepup ring. this works well for me..

[tybeck]

Originally Posted by roy

to avoid vignetting get a CPL larger that your filter size and use a stepup ring. this works well for me..

What are the specs of your setup? Focal length? I'm interested in this as well and am trying to tell if a set of step up rings gives the same results as a Cokin or Lee system. For sure it's a lot cheaper.

[axl]

Originally Posted by roy

to avoid vignetting get a CPL larger that your filter size and use a stepup ring. this works well for me..

good advice,
you could get, say 82mm CPL and step up ring from 77 to 82. I'm not sure though if 82mm CPL would be cheaper than Cokin P size CPL.
The only problem then will be to be careful with even polarization!

[RodConn]

If you are using a screw in polarizer rather than a Cokin frame there are no vignetting problems if you use a slim fram polarizer such as the Hoya/Kenko PRO1 Digital series.

HOYA 77mm Clear PRO1 DIGITAL Protector Filter DMC LPF * NEW is a good source for these with very good pricing for those not in the USA.

A good local source for the USA (cheaper postage) is Camera filters. Hoya, Tiffen, B+W, Heliopan Low prices on filters for your camera and you will find they also carry the PRO1 Digital series.

See this page Hoya Pro 1 Digital Camera Filters - they have a weird site in that you only find the real (lower) price by putting the item in the shopping cart by clicking on the much higher price displayed on the web page

BTW - I do have the 10-20mm and do use a Hoya CPL

Rod