Combining ND Filters

philipw · April 7, 2008

I have a Hoya .9 ND filter for my 82mm lens, and under bright conditions with moving water, I can't leave the shutter open long enough to the get effects I want, so I was wondering about stacking filters. I know B+W makes a 77mm that will let you reduce ten f-stops, but I can't really find filters that will do that for an 82mm. So, does combining work, or would there be ill effects from doing this?

I googled and found one site on the web that said it's not a good thing to do, but a lady working at a local camera shop said it shouldn't be problem. Other than those two sources of input, I can't really find anything else.

Thanks for your help!

Philip

pathfinder · April 7, 2008

Do you need 10 stops?? Be aware that it is difficult to even see through a 10 stop filter, or focus sometimes in less than bright sunlight with a fast lens. With a slow lens - say f5.6, AF may not work at all. Just a thought.

Fliter House shows 82mm Hoya ND filters in ND2, ND4 and ND8.

B&H Photo lists three pages of 82mm ND filters

Singh-Ray makes lovely Variable NDs that go from almost clear to black, but they are not inexpensive, and I am not sure from their website whether the 82mm Variable ND is even available.

I usually use a 77mm B&W 106 ND 1.8 64x for satisfactory shutter speeds - depends on whether you are shooting before sunrise or in bright sunlight too. Overcast day, shade, all play a role in shooting moving water. In shade, I get 8 second shutter speeds at f22 at ISO 200 with the ND 1.8

Adding one ND filter to another adds two more air-glass interfaces to lose light and create reflections, so I am not really a fan of stacking NDs or other filters. It can be done, but there is always a small price to pay somewhere in image quality.

I certainly would not want to add a 77mm filter to an 82 mm filter due to concerns about vignetting.

jfriend · April 7, 2008

philipw wrote:

I have a Hoya .9 ND filter for my 82mm lens, and under bright conditions with moving water, I can't leave the shutter open long enough to the get effects I want, so I was wondering about stacking filters. I know B+W makes a 77mm that will let you reduce ten f-stops, but I can't really find filters that will do that for an 82mm. So, does combining work, or would there be ill effects from doing this?

I googled and found one site on the web that said it's not a good thing to do, but a lady working at a local camera shop said it shouldn't be problem. Other than those two sources of input, I can't really find anything else.

Thanks for your help!

Philip

It is perfectly fine to combine ND filters. The effect is cumulative.

I sometimes combine an ND filter with my polarizer when either one by itself isn't enough.

The reasons not to combine ND filters are simply that the more glass you put between the subject and your sensor, the more chances you have for imperfections in the glass or undesirable reflections off a glass surface to affect your image. If you have medium or low quality ND filters or are shooting into the sun, you are more likely to notice additional optical quality degradation than if you have very high quality filters. High quality fitlers are more optically flat (less distortion caused by the filter), more transmissively pure (less coloration of the transmitted light) and have better anti-reflection coatings (less chance of optical reflections reducing contrast or causing flare). Even with high quality filters, two is worse than one but you can probably still get a very good image if the conditions are right.

philipw · April 7, 2008

Do I really need 10 stops? Not sure. Stuff like this is what I'm after: http://www.dgrin.com/showthread.php?t=86376&highlight=waterfall

I've created some pretty cool waterfall and moving water shots when the light is low, but I don't like getting someplace and waiting for the sun to start to set.

Thank you both so much for your input. I really appreciate it.

Philip

RogersDA · April 7, 2008

philipw wrote:

Do I really need 10 stops? Not sure. Stuff like this is what I'm after: http://www.dgrin.com/showthread.php?t=86376&highlight=waterfall

I've created some pretty cool waterfall and moving water shots when the light is low, but I don't like getting someplace and waiting for the sun to start to set.

Thank you both so much for your input. I really appreciate it.

Philip

Stacking can be fun, easy, and neat in the daytime: http://www.dgrin.com/showthread.php?t=88719

pathfinder · April 8, 2008

I liked those photos, David.

Combining ND Filters

Comments