Double exposure question

[sfjphotography]

What's the best way to calculate exposure for a double exposure, so as to not overexpose the film with the camera set a say F22 for the first shot and F 5.6 for the second? Double exposure is something new to me and could use a little help.

[sfjphotography]

Sorry, I wasn't paying attention to where I was posting.This should be in the Style & Technique board.

[Vaughn]

Generally, I would keep both exposures the same (assumimg the light was the same) -- basically photograph each scene at its normal exposure. That way, light objects will be exposed correctly when superimposed over a dark area. Two light equally bright areas will only be over-exposed by one stop.

But it depends if you want one of the scenes to dominate over the other, etc.

Vaughn

[Bruce Watson]

Generally, I would keep both exposures the same (assumimg the light was the same) -- basically photograph each scene at its normal exposure. That way, light objects will be exposed correctly when superimposed over a dark area. Two light equally bright areas will only be over-exposed by one stop.

But it depends if you want one of the scenes to dominate over the other, etc.

Vaughn

What Vaughn says.

[Vlad Soare]

It depends on what you're trying to achieve. For the picture below the correct exposure would have been 1/2s at f/32. Instead of making one 1/2s exposure I made 16 exposures of 1/30s each, at f/32.

Why 16 and not 15? I don't know. It depends on how you calculate. You can regard 1/30 as being 15 times shorter than 1/2, so you would need 15 exposures.
My reasoning was a little different. I thought that 1/2 and 1/30 were four exposure stops apart (1/4 - 1/8 - 1/15 - 1/30). A four stop difference means 16 times less light, so I made 16 exposures.

[sfjphotography]

Thank you for responding, I now have a better idea as to going about doing multiple exposures. The effect I'm looking to get is an image that is in sharp focus though has a blurred exposure over it creating a sort of glow around everything. I've done this digitally though never on film, so I was a bit confused about getting the exposure right without blowing the highlights out. thanks for taking the time to help me out.

[drew.saunders]

Why 16 and not 15? I don't know. It depends on how you calculate. You can regard 1/30 as being 15 times shorter than 1/2, so you would need 15 exposures.
My reasoning was a little different. I thought that 1/2 and 1/30 were four exposure stops apart (1/4 - 1/8 - 1/15 - 1/30). A four stop difference means 16 times less light, so I made 16 exposures.

Since the speed indicated by "30" is really (supposed to be) 1/32nd of a second, you got it right anyway. "15" and up lie to you. I guess, long ago, someone decided that people liked shutter speeds that ended in a 5 or 0, so 1/16th became "15" and 1/32nd became "30" etc. The old 1/25, 1/50 are really those speeds (assuming your old shutter is accurate, and it isn't), so I guess that's where the idea of ending all the speeds in a 5 or 0 came from.

[Jim Becia]

What's the best way to calculate exposure for a double exposure, so as to not overexpose the film with the camera set a say F22 for the first shot and F 5.6 for the second? Double exposure is something new to me and could use a little help.

Here's the way I do it when I'm trying to do it intentionally. (Seems to happen unintentionally every once in a while on its own.) If your correct exposure is 1 sec at
f22, the each exposure would be 1/2 at f22. (1/2 plus 1/2 = 1 sec.) If you want to change the second exposure to f5.6 then the exposure would be 1/30 at F5.6 if I did my math correctly. Jim

[Steve M Hostetter]

first maybe we should know what effects your trying to accomplish

[Brian Ellis]

It depends on what sort of double exposure you're planning. If you do a Google All Words search using the words "multiple" "exposure" and "photography" you'll find a lot of information for various types of double exposures.