polarizer - once again

[Nicola]

Hi
I've looked for similar threads in that site searching by tags, and I've read many of these. But I would like to do a direct question. I'm sorry if I've not read enough and the answer was already present in some other thread, please feel free to re- direct me there.
my interest on polarized filter is growing and I'm going to buy it , when all my doubts are vanished.

I have read that kind of filter can have a problem of vignetting in wide angle lenses: I have got a 17-40mm L used on APSC (50D), the issue should be less visible due to crop factor, isn't it?
A friend of mine, who has the 17-40 on a full frame (5D), told me that he never saw vignetting. He has also a B&W MRC pol filter. does the quality of pol. filter influence that issue?

I've found Hoya pro1 digital 77 (at 95eur), some of you should have that kind of filter, is it good? do you know what's the diffference with the more expensive B&W slim MRC 77 E (142 eur)?
which filter do you suggest me (not only one of the previous one)?
can I go for something less expensive (i've seen also other B&W for 70eur i.e.)?

many thanks to all!

[bambleweeney]

Is the 17-40mm L a full frame lens ? If so then I shouldn't imaging vignetting would be a problem as it should occur off the sensor. 17-40mm I guess would be around 25-60 equivalent on a non full frame sensor. Not particularly wide, I use a Hoya sometimes on a 10-20mm with no obvious problems. The 'problem' with polarizers is that they are quite thick to enable the filter to rotate so there is a remote possibility that the edge of the filter could intrude, people have had problems from what I can make out by stacking filters (a UV on the lens and a polarizer on top of that) which could cause part of the filter ring to intrude into the picture due to the extra depth of stacked filters, step up rings to allow a larger filter to fit on a smaller lens could also conceivably cause a problem I guess. If you could try both filters out that would be the best bet. Otherwise get the Hoya from somewhere that would exchange it for the B&W if you did have vignetting problems.
To test I think I'd have the lens wide open and take a shot of a uniformly coloured wall without the filter (to see what extent the lens vignettes on its own) then another shot with the filter in place to see if there's any difference.
Other than that I'm afraid I've no experience with Canon lenses so can't offer further help.

[Nicola]

Paul
yes 17-40 is a full frame L grade lens.
anyway your help is very appreciated!!
thanksa lot!

[Boatman]

Nicola:

I think the problem with many polarizing filters is that they are relatively "thick" due to the need to be able to rotate. This extends the filter a couple of millimeters ahead of your lense. Your wide angle range then catches the filter in the corners of the image. Try to find one that is very slender and you should be OK except possibly at mimimum focal length. Of course, Photoshop and other software, do have vignette reduction features that you can use to eliminate minor vignetting.

BTW, here's a tip you may want to know when you do get the filter. The filter should have a mark on the rotating ring that marks the "top" of the polarizer. To get maximum contrast darkening, always point the mark towards the sun. Another tip: don't wear polarized sunglasses, they'll make your viewfinder go black ;-)

[rpcrowe]

The 17-40L is an equivalent 27.2mm at the wide end. As such, it isn't extremely wide. If my memory serves me well, I did not experience any vignetting problems when I shot with a standard CPL on on that lens when using a 1.6x camera.

[Klickit]

BTW, here's a tip you may want to know when you do get the filter. The filter should have a mark on the rotating ring that marks the "top" of the polarizer. To get maximum contrast darkening, always point the mark towards the sun.

Uh. I always wondered what that mark was for.....

[JK6065]

I also have the 17-40 with the B&W slim polarisor for my Canon 400d. On a APS-C you indeed won't have a problem at all with vignetting. I chose the slim edition since I stack filters quite often, for example an ND with the CPL, and to be still able to do that when upgrading to Full Frame.

Keep in mind that a slim polariser is really 'slim'. Sometimes it's difficult to screw it on and when you screw it on too tightly it might get a hell of a job to get it off. Also some care is necessary to turn the front part of the filter.

[Nicola]

many thanks to all!
I'm starting the research on the web in order to find a slim one... and at the same time I'mgoing to look for a cheaper one for the 70-300 ...
have a nice day
N

[Peter Ryan]

Hi Nicola,

Personally I use the Cokin system (P series) so I only have to buy one filter (of any type) and then if he I buy a lens with a different diameter size I only have to buy the attachment ring and not all the filters again for that lens.