77mm Filters (UV and/or CP)

[ziggy53]

Originally Posted by Richard

I'm a little late to this party, but I was wondering if there are any problems with using CPs on a step-up ring? I work with two 67mm lenses most often, but I also have a 77mm wide angle (17-40 f/4L). I don't have a lot of money to spend, so I was thinking of getting one 77mm CP and an adapter for the others. Since I will probably be using the filter more often on the 67mm lenses, perhaps it would be a mistake.

Opinions welcome.

There are different thicknesses in step adapter rings and different materials used for their construction. I suggest getting a better quality brass adapter and mounting/demounting should not be a problem. The better brass adapters also tend to be somewhat thinner than the aluminum and definitely thinner than the plastic, so they tend to produce less vignetting as well.

On a crop camera, I should not think that vignetting would be a problem with the 17-40mm zoom, but test to be sure. On a FF sensor I would be more particular.

I use a 67-77 step-up ring myself and have no problems with my applications (but I don't use a polarizer with the 17-40mm so I haven't tested that.)

A very good explanation of the issues here:

http://www.2filter.com/prices/products/rings.html

[Richard]

Originally Posted by ziggy53

There are different thicknesses in step adapter rings and different materials used for their construction. I suggest getting a better quality brass adapter and mounting/demounting should not be a problem. The better brass adapters also tend to be somewhat thinner than the aluminum and definitely thinner than the plastic, so they tend to produce less vignetting as well.

On a crop camera, I should not think that vignetting would be a problem with the 17-40mm zoom, but test to be sure. On a FF sensor I would be more particular.

I use a 67-77 step-up ring myself and have no problems with my applications (but I don't use a polarizer with the 17-40mm so I haven't tested that.)

A very good explanation of the issues here:

http://www.2filter.com/prices/products/rings.html

Thanks, Ziggy. I'm currently shooting with a 50D so it seems like 77mm would work for me.

Another question: does multi-coating improve the image quality or just the durability? There is a (for me) big difference in price in the Hoya and B+W 77mm CPs if you go to multi-coating. My primary interest is to control reflections when shooting through plate glass windows on the street.

[Dan7312]

I just got some filters from http://www.2filter.com and their site has some info/examples of using coated/non-coated filters, in fact they have quite a bit of info there. But the coating only affects reflections within the filter itself which can end up appearing in the image, not reflections off of the the things you are taking a picture of.

A polarizing filter can eliminate reflections off a window, but how well it will do it depends on the angle the light is hitting the window and where you are standing.

BTW 2filter.com says that B+W filters are available in aluminum or brass and they sell only the brass ones.

Originally Posted by Richard

Thanks, Ziggy. I'm currently shooting with a 50D so it seems like 77mm would work for me.

Another question: does multi-coating improve the image quality or just the durability? There is a (for me) big difference in price in the Hoya and B+W 77mm CPs if you go to multi-coating. My primary interest is to control reflections when shooting through plate glass windows on the street.

[ziggy53]

Originally Posted by Dan7312

I just got some filters from http://www.2filter.com and their site has some info/examples of using coated/non-coated filters, in fact they have quite a bit of info there. But the coating only affects reflections within the filter itself which can end up appearing in the image, not reflections off of the the things you are taking a picture of.

A polarizing filter can eliminate reflections off a window, but how well it will do it depends on the angle the light is hitting the window and where you are standing.

BTW 2filter.com says that B+W filters are available in aluminum or brass and they sell only the brass ones.

Additionally, multi-coated filters tend to have less effect on global image contrast, which affects our perception of image sharpness.

[craig_d]

Originally Posted by Richard

I'm a little late to this party, but I was wondering if there are any problems with using CPs on a step-up ring? I work with two 67mm lenses most often, but I also have a 77mm wide angle (17-40 f/4L). I don't have a lot of money to spend, so I was thinking of getting one 77mm CP and an adapter for the others. Since I will probably be using the filter more often on the 67mm lenses, perhaps it would be a mistake.

I don't see why a step-up ring wouldn't work; the polarizer doesn't care, and the step-up ring shouldn't cause any extra vignetting. You probably won't be able to use the step-up ring and a lens hood at the same time. Your call whether that's a deal-breaker or not. For me it would be. In your place, particularly since I tend not to use a CP on the 17-40 because of the dark-band effect that can occur with wide-angle CP shots, I would buy a 67mm CP and maybe get a 77mm CP later.

[craig_d]

Originally Posted by Dan7312

But the coating only affects reflections within the filter itself which can end up appearing in the image, not reflections off of the the things you are taking a picture of.

Well, there's no such thing as a reflection "within the filter itself" -- I think what you probably mean is reflections within the camera, such as when light comes in through the filter and lens, bounces off the sensor, reflects back off the filter, and bounces back to the sensor again, creating a ghost image. But I believe you are right that the coating does not affect the polarizing function itself.

Originally Posted by Dan7312

A polarizing filter can eliminate reflections off a window, but how well it will do it depends on the angle the light is hitting the window and where you are standing.

And it also depends on what angle you have the CP set to. Polarized light can be oriented at different angles, and you rotate the CP to eliminate the light you don't want.

[Richard]

Originally Posted by craig_d

... In your place, particularly since I tend not to use a CP on the 17-40 because of the dark-band effect that can occur with wide-angle CP shots, I would buy a 67mm CP and maybe get a 77mm CP later.

I think you may be right, Craig. My immediate interests are for the 67mm lenses and I don't really know whether I would ever use it on the 17-40. So with the money I'm "saving" I can get a multi-coated one. Excellent!