Multiple - Fragmented Exposures

So each fractional exposure creates + over exposure?
If I made eight exposures I would have to reduce my time by -3 stops?
 
Ian Grant said:
No, because of reciprocity failure, more like -2½ stops.

Ian
Click to expand...
Good idea to make the point of not forgetting reciprocity failure. Not sure if the attached method allows for reciprocity. Do you add the reciprocity first, ex.?
Metered exposure 2secs
Add 2s for reciprocity = 4s
4s 1 exposure
2s 2 exposures
1s 4 exp.
1/2s 8 exp
1/4s 16 exp.
how much would I reduce the exposure?
I found this
 

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Technically the attached is incorrect because it doesn't allow for reciprocity, but with 8 exposures and ½ a stop is not so critical, it may be close to a third..

I remember making this shot in the 1990s underground in a Manganese mine in North Wales.

1791471184640.png

We had torches and 4 hammerhead flash units. I had pre-focused my Wista & 65mm SA in daylight, and was shooting at f16 or f22.

For his image the area was painted with the 4 flash units, all set at full power, multiple flashes from each, I heard the others close their shutters way to early. I was the only person to get an image.

Somewhere I have a table for the extra exposure needed with multiple plash exposures, it was referring to multiple flash exposures to allow LF lenses to be stopped down mire in studio work. I remember it recommend 5 flashes when the calculation would be 4. it's exactly the sane with multiple daylight exposures.

Ian
 
Camerashy said:
Good idea to make the point of not forgetting reciprocity failure. Not sure if the attached method allows for reciprocity. Do you add the reciprocity first, ex.?
Metered exposure 2secs
Add 2s for reciprocity = 4s
4s 1 exposure
2s 2 exposures
1s 4 exp.
1/2s 8 exp
1/4s 16 exp.
how much would I reduce the exposure?
I found this
Click to expand...
When I went to Bristol (feb for martin parrs exhibition I shot a whole roll on my mamiya 7ii double exposure. What I found is if you have the sky in the scene the negative builds up density to the point where it starts losing detail. This happens I learnt when you layer one frame 16 times or above, I mostly do 16 and 32.

Last month or in July I did some tests near me shooting a roll like; normal, x2,x4,x8x16,x32. I learnt that the developer plays a big roll and also you have to reduce development when shooting 16 and above layers.

Once I’ve finished cooking I’ll transfer my pictures here to give a reference from my computer. I’m on phone atm.
 
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