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05-30-2016, 10:11 AM   #1
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Variable ND Filter Question

Hi All...

I recently picked up a variable ND filter and while I kind of know how to use it, I'm pretty foggy on how to determine the shutter speed when it needs to be longer than 1 second.
My basic setup is my K1000, a 35-200 mm f3.5 lens and shooting 400ASA film. The filter is a Promaster Variable NDX. I'm just experimenting and don't mind shooting a couple of all black or white frames, but I'd like to get a couple of "okay" images too!

I'm not asking for exact settings. Just something to get me in the ballpark.

Appreciate any guidance!

Amanda Ward

05-30-2016, 10:44 AM   #2
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Well I was all set to give an explanation until I saw you are shooting film, but my method will not work for film.

Regardless, if you were using a fixed ND (3 stop, 6 stop whatever) the math is straightforward. But with a variable ND filter, I'm not so sure. Are there marks on the filter to show how many stops you get at a particular place? I've never used variables, only fixed strength ones.

If there are markings then just take a meter reading without the filter and adjust exposure by the number of stops needed for the filter, usually by slowing the shutter speed. I'm not familiar with the k1000 but I assume you are using bulb mode above 1 second?

If there are no markings, I'm stumped. Unless you can set up a controlled test taking test shots and marking the filter so in the field you have a good idea of the filter strength.

Hope that helps, if not I'm sure someone with more experience with variable filters (and film) will step in.
05-30-2016, 01:35 PM   #3
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QuoteOriginally posted by ajward Quote
Hi All...

I recently picked up a variable ND filter and while I kind of know how to use it, I'm pretty foggy on how to determine the shutter speed when it needs to be longer than 1 second.
My basic setup is my K1000, a 35-200 mm f3.5 lens and shooting 400ASA film. The filter is a Promaster Variable NDX. I'm just experimenting and don't mind shooting a couple of all black or white frames, but I'd like to get a couple of "okay" images too!

I'm not asking for exact settings. Just something to get me in the ballpark.

Appreciate any guidance!

Amanda Ward
Are you talking about film reciprocity? The little graph you had to use to extend long exposures, and it was dependent on the film? Maybe this would be helpful:
https://itunes.apple.com/us/app/reciprocity-timer/id459691262?mt=8

---------- Post added 05-30-16 at 01:36 PM ----------

Nice bear cub shot btw.
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