Multiple film exposure

Ok, never tried this before, have shot this scene at 30th of a sec, and at 200. (See Below)
The 30th sec shot came out good, nice flowing water, and the @ 200 shot had more individual character, with its flow, but the droplets, where not stopped enough to get there 'individuality'.
Want a shot with a little more .. ah 'exuberance'. showing more individual water droplets. So thought we try a multi exposure that would perhaps do both.
So would like to shoot a three multi exposure of running creek water, using Arista 400 @ 200 sheet film, in a 2x3 Crown Graphic, on a tripod. All three shots would be of the same exact scene, only the flow of the water splashes would change.
Understand for a double exposure one would set meter ISO @100, that's one stop underexposed. and for a four multi exposures, would set ISO @50, two stops underexposed.

How does this scenario sound. Of course one can only know by trying, if it's workable, but would like to try a three multi exposure, so as we perceive it, one would set the meter ISO to 150?
Is this correct?
Meter.. gasp, .. Weston Ranger 9, yep, it works for me when we need one.

peter k. said:

So would like to shoot a three multi exposure of running creek water, using Arista 400 @ 200 sheet film, in a 2x3 Crown Graphic, on a tripod. All three shots would be of the same exact scene, only the flow of the water splashes would change.
Understand for a double exposure one would set meter ISO @100, that's one stop underexposed. and for a four multi exposures, would set ISO @50, two stops underexposed.

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If your "true" film speed is 200 then shooting at 100 is one stop overexposed and 50 is two stops overexposed rather than underexposed, isn't it?

pentaxuser

peter k. said:

Ok, never tried this before, have shot this scene at 30th of a sec, and at 200. (See Below)
The 30th sec shot came out good, nice flowing water, and the @ 200 shot had more individual character, with its flow, but the droplets, where not stopped enough to get there 'individuality'.
Want a shot with a little more .. ah 'exuberance'. showing more individual water droplets. So thought we try a multi exposure that would perhaps do both.
So would like to shoot a three multi exposure of running creek water, using Arista 400 @ 200 sheet film, in a 2x3 Crown Graphic, on a tripod. All three shots would be of the same exact scene, only the flow of the water splashes would change.
Understand for a double exposure one would set meter ISO @100, that's one stop underexposed. and for a four multi exposures, would set ISO @50, two stops underexposed.

How does this scenario sound. Of course one can only know by trying, if it's workable, but would like to try a three multi exposure, so as we perceive it, one would set the meter ISO to 150?
Is this correct?
Meter.. gasp, .. Weston Ranger 9, yep, it works for me when we need one.

View attachment 187663 View attachment 187664

Click to expand...

You've got the meter settings backwards, as Pentaxuser said. You'd need to do two exposures at 400, or four at 800. Remember that it's not a linear scale, but an exponential - each stop is a halving or doubling of the previous/next one. So a single exposure at ISO 800 is the equivalent of 1/4 the exposure at ISO 200.

As everyone said above. If you are making 4 exposures, I would shoot each at 1600 with ISO 200 film.

This is a technique John Blakemore used quite a lot for his wind series images quite a few years ago now, Remember that due to reciprocity failure the sum of the multiple exposures needs to be much longer than one single coreecet exposure.

Dead Link Removed
I have this as a 24"x20" print (approx) and it's around 10 multiple exposures with a lot of swirling movements in the elder bushes and particularly the flowers and the grass, by mixing the exposures some of 1/4, others faster, you get a series of fragmented exposures that better convey movement compared to a single exposure blur, which is not how we see or perceive these movements in reality.

Ian

Hahaha.. so glad we asked... Da!!!... ok.. so right.. glad we asked, we would have over exposed big time.

peter k. said:

Hahaha.. so glad we asked... Da!!!... ok.. so right.. glad we asked, we would have over exposed big time.

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I've done that exact thing...multiple times (no pun intended). Makes you feel like an idiot every time.

You need to use a slow film, it helps to use a filter to increase the exposure time -in my image above I used a Green Cokin filter I think x3 exposure factor, you need to avoid multiple fast exposures as that doesn't really work, the best balance is some shorter I'd suggest 1/30 and longer exposures 1/4, maybe one of 1/2.

I'm usually shooting LF so mainly use f22 or f32 and here in the UK with 100 ISO film my exposures are often in the 1 - 1/15 second range so adding a f green filter is enough but with smaller formats a ND filter will be more useful.

Ian

Hmmm.. Got a 2 stop green filter, and an ND filter, but need a couple of fast exposures on top of, ... say a shot at 1/30sec shot, to give that 'individual' droplet look, without the harshness. Basically trying to combine the two shots from post #1 into one image by doing a multi exposure at the same location.
But your saving:

Ian Grant said:

you need to avoid multiple fast exposures as that doesn't really work

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because, ... why?
It will just blend with the slower exposure, and not be visibly seen, or ...?

Unless one of the exposures is very long it is a bit simpler to ignore reciprocity. Then the sum of two exposures should equal a normal single exposure to avoid a dense negative. In most cases the camera must be completely steady to avoid double images.

peter k. said:

So would like to shoot a three multi exposure of running creek water, using Arista 400 @ 200 sheet film, in a 2x3 Crown Graphic, on a tripod.

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Be careful with water. The more slow Tv exposures of a dynamic subject such as water, the more the humble scene is going to resemble a disaster at the icecream factory upstream: a giant, woolly, featureless blur and blob of white. Much better to show movement of the stream (striation) (as you have in the first image) in the first and second frames (fast shutter speeds) followed by a much slower third (or more) frame to consolidate. As with many SFX, experimentation with various rates of flowing water — and taking written notes as you work, pays off.

I don't get too sweaty working multiexposures. EI200 film x 3 exposures on the same frame ... two, four, six, therefore EI640 (because of baseline EI200).
I presume you have concluded, beyond reasonable doubt, why you are exposing Arista 400 at EI200? Otherwise, leave it at ISO400 and hop from there.

The flow rate of water can greatly determine how the finished image looks. It should be given thought when considering individual frame Tv values and the end result.Your best efforts can still result in the "icecream effect" mentioned above.

I regularly multiexpose RVP50 (or Provia 100F) in my Pentax 67, which isn't more than 3 exposures on a frame, and that is 50 (base ISO)...80...100 (final EI for three exposures EI125). And the exposures are bang on. This is for slide film. For negative film you have the advantage of a good deal more latitude to cover mistakes and a 0.3 stop error in EI is not going to be remarkable, but 0.6 could well be.More critically for MEX work, you should bear in mind that the slightest movement of the camera between exposures will ruin the effort and be glaringly obvious when printed, so ensure your tripod is stabilised and resolute against any breeze or possibility of being bumped. On one recent occasion I defeated my own efforts by elbowing the camera while I was taking my jumper off!!

Gerald C Koch said:

Unless one of the exposures is very long it is a bit simpler to ignore reciprocity. Then the sum of two exposures should equal a normal single exposure to avoid a dense negative. In most cases the camera must be completely steady to avoid double images.

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Actually the sum of two exposures doesn't equate to one single exposure (of the same sum) but the difference is slight less than a 1/3rd of a stop and will not be significant, however when you increase the umber of multiples to say 4 you very significantly increase the reciprocity failure so you need to add about 1/2 a stop or 6 exposures rather than 4, 8 exposures more like a stop.

It's exactly the same using multiple flash to build up exposure and somewhere there's a table showing the increases needed. This is something I've used a lot *successfully) both with ambient light and flash and you really do need to account for reciprocity failure. I'm using 5x4 where I can easily re-cock the shutter and have robust tripods.

Ian

For clarity, reciprocity failure happens (in these cases) when the intensity of the light is below a threshold. That threshold is different for each film.
The reason you encounter reciprocity failure with multiple exposures is that you are intentionally choosing individual exposures that are very low in intensity, with the hope that when the exposures are added together, they will sum to a useful total exposure.
So in Ian's scenario, the reason that 4 or more exposures requires more correction for reciprocity failure is that the smaller, individual exposures are too low in intensity to get the film into its well behaved (with respect to reciprocity) state.

I think the effect is called “intermittency effect”. As fare as I understand it has nothing to do with too low light intensity.

I’ve found the following table in an old Ektachrome 100 plus datasheet:




I guess a prontor professional shutter would be perfect. You even don’t have to clock the shutter.

chrisaisenbrey said:

I think the effect is called “intermittency effect”. As fare as I understand it has nothing to do with too low light intensity.

I’ve found the following table in an old Ektachrome 100 plus datasheet:

View attachment 187836


I guess a prontor professional shutter would be perfect. You even don’t have to clock the shutter.

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Yes the intermittency effect is a form of reciprocity failure because each individual exposure is seriously under-exposed with 4+ exposures. You must allow for it and more so when you mix some shorter exposures with some longer, I've never had an issue of over-exposure but I err on the safe side to ensure I don't have under-exposed negatives, so I tend to give a stop extra exposure with 10+multiple exposures.

I've been OK using Copal shutters no problems, I've a few Prontors could use if I had the aperture scales.

Ian

Poisson Du Jour said:

slightest movement of the camera between exposures will ruin the effort

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Yes went out and tried a few.. very interesting.. didn't really give me wanted I wanted,but will try again. On one shot could tell that I slightly moved the camera when doing the dark slide, when resetting the the f stop and timing, between shots.

MattKing said:

So in Ian's scenario, the reason that 4 or more exposures requires more correction for reciprocity failure is that the smaller, individual exposures are too low in intensity to get the film into its well behaved (with respect to reciprocity) state.

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Yep.. that a good explanation... think I could see that in one of the shots. Just didn't add up to a full exposure.

Thanks for your replies its an interesting scenario, will try some more.