Multiple Exposure?

Morning all,

Only my second post, hopefully found the right thread this time!!

I’ve been thinking about a series of images utilising the multiple exposure setting on my camera (mamiya rz pro2). I’m very much starting out with film and medium format and so picking bodies of work to explore each feature/aspect of the camera, try and enhance my understanding. My questions is about how to expose for multiple exposures with film (colour or b&w). I’ve shot quite a lot of long exposure, using time to paint certain aspects of my shot (waterfalls to a misty haze for example) and understand the mechanics of reciprocity failure. I’m pretty sure I’m making the right calculations in that regard but let me propose this process…

· Shooting in daylight I shoot one shot of sea waves as a long exposure, on a tripod, nd filter, for say 10 seconds. I get a hazy effect to exposure 1.
· I don’t move the tripod, my framing is still the same and I’m on multiple exposure.
· I take a second shot at the ‘correct exposure’ (fast shutter but same dof) for the lighting conditions, giving me a frozen crisp snapshot of the waves (exposure 2).

This is where my newbie brain struggles to understand what’s going on here. Do I need to compensate for exposure 1 when shooting exposure 2, hence exposure 2 isn’t as straightforward as if it were a fresh bit of film? The film has already been exposed for 10 seconds and therefore does it react in the right way if I try and take a ‘normal’ exposure for exposure 2. I understand that varying films will react in differing ways and that a 10 second exposure probably won’t eat into any reciprocity issues but it’s the theory of multiples that I’m trying to explore. Will my shot be a perfect blend between the two exposures or will the longer one dominate the effect? Sorry if these are dumb questions!

I’ll shoot some test anyway but thought it worth asking.

Thanks

I'm not an expert but I would assume that you should get a balance between the exposures as long as the metering for both is calculated properly. Like you said; at 10 seconds you shouldn't have reciprocity worries.
You will likely be aware of this but remember; give 'one stop' less exposure for each individual metering.
I'll be interested as to which exposure dominates. I have been mulling over something similar; a long exposure including flash and also a double exposure using flash in one of the two exposures. But shooting 4x5 on a budget kind of curtails my practical applications somewhat.

Anyway, best of luck with it and do upload the results for us to see.

Properly it should be camera exposure A + camera exposure B = a single full exposure

So 1/2 + 1/2 = 1 or 1/4 +3/4 = 1 or ...

1/3 + 1/3 + 1/3 also works.

Often 1 + 1/2 or 1+ 1 works fine.

It will take some practice.

I agree with mark, the effect of light on the film is additive, the first exposure produces a certain negative density, the second exposure increases the density in proportion. perhaps a thought experiment will help. Imagine the scene is a gray card. We make two identical exposures. Exposure one produces a mid gray. Exposure two adds to exposure one in exactly the same way as it would if exposure one had been twice as long.

With real world subjects that have patterns of light and shade the effect is the same but the result is visually complex because bright areas that fall on other bright areas have a different appearance to bright areas that fall on dark areas.

This is probably one of those processes that needs experiment in order to build up experience. It might be helpful to eliminate as many other variables as possible, for example pick a film and a development time and stick to them while experimenting with changes in subject, and take careful notes

The effects are local and the interplay is art so yeah, practice and experiment is needed.

Thanks for the tips. I'm going to do some controlled test as suggested and see where I get. You've certainly given me a good place to start experimenting! Thanks

If the first exposure is 10 secs and the second "normal" exposure is say 1/100th would any kind of proportionality to get to a correct total exposure be required as the second exposure while correct for the effect required in the second instance adds so little to the overall exposure?

pentaxuser

an easy way to think about this is also by
taking different negatives and sandwiching them together.
it will give you an idea what softening the first or intensifying the 2nd exposure
might do, or if photographing something dark or shadowy ... sometimes some things work well, and other times
they ....
don't

Or not worry about it -- two 'correct' exposures on top of each other is only one stop 'over-exposed'. Well within the film's latitude. And as Mark suggested -- try different exposure relationships and see what happens!