Extremely Long Exposures
I'm just starting a project where I'm trying to get exposures in broad daylight of up to an hour.
so I purchased a cheap foil solar filter, and constructed some sort of way to mount in on the front of my schneider angulon 90mm.
I'm doing tests out the window as we speak because it's still cold out.
It worked fine using efke 25 black and white film (I think at f/11 and 1 hour) but the slowest color film I have is 160s. I hesitate to use Velvia because I have no confidence in the process's ability to get a technically correct exposure.
Anyways, anything I should be aware of? I'm worried about color shifts from the filter or the long exposure times.
here's the black and white version
That would be a 10 stop, right?
Originally Posted by ic-racer
I actually calculated my solar filter to be 16 2/3 stops.
then get two ND3 filters, lol.
Huzzah! I knew that overpass looked familiar. It's always exciting to see people from Baltimore online, haha.
</completely useless post>
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Awesome. Are you a MICA student as well?
Originally Posted by zrisso
Yeah, taking this year off though to work on my freelancing business and getting into galleries.
Velvia will have strong colour shifts after an hour, perhaps tonthe point where it's just green. The 160S may or may not be any better - an hour is so long that the subtlest difference in reciprocity characteristics between the layers will cause extreme shifts. At least you can filter a neg while printing though, which might be enough in combination with some colour filtering on the camera. And C-41 is cheap enough to experiment with.
You can buy a Hoya ND400 filter, which is about 9.7 stops. Not cheap, but you'll get less flare than stacking three 3-stop NDs.
Have a go at crossing polarisers - you can get 1000x without too much trouble but there can be some very weird colour effects if you go too far.
Try Ektar 100...
Shoot as normal and correct if you run into any problems.
I've crossed polarisers before... on my digital SLR.. the histogram had a very thin range, and the range of colours were very thin as well, and very strange.
I've pulled colour neg 14 stops before, reciprocity occurs when a certain light level is hitting the film, less % is absorbed to form the image, afaik it doesnt drop absorbing all wavelengths evenly, hence colour shift.
A strong pull would avoid this. Sounds like for 160S, you want 18 or 19 stops of reduction or pulling.
You'd need to use a first developer, or very dilute C41/colour dev to develop with such a pull.
Rodinal 1+100, 1 hour, 20c stand is good for box speed as a first dev for colour negs, so I'd suggest, maybe 1+100, 9min with agitation perhaps.. would need a test.
After that you may fix, bleach, then colour develop (C41 or E6 CD), bleach, fix.
Otherwise, at +18 stops of exposure.. I imagine the image might even be 'burned' onto the film already, so you could possibly fix, bleach, then colour develop, bleach fix.
May sound like odd suggestions, but seeing as you want to do something odd... Actually I might give this a test tomorrow!