The table I posted above was from the Fomapan 100 classic data sheet, I believe.Originally Posted by StoneNYC
Each film has its own characteristics so check foma's chart on this. It isn't the same for all films.
BUT you've got the idea now
Thanks, will keep that tip in mind for the next experiments.
Certainly a lot to keep in mind and it does take much more time than digital, but from my very limited experience with LF so far well worth the effort.
If you are working close then you also need to account for the bellows extension factor, which is widely published as well.
Between the that and reciprocity you could easily be many stops off.
Yes, I just learnt about the bellows extension factor.
Not sure if I completely understand how to calculate it but just tried the following and the resulting negative looks, to my amateur eye, fantastic.
210mm = total belows length
lens = 135mm
diff = 210 - 135 = 75
75/135 = 0.56
0.56 + 1 = 1.56 **2 = 2.4336 Bellows FACTOR
Recalculated original settings (in OP) using EV pairs app down to f 8:
f 8 @ ISO 80 = 10 seconds
10 x 8 = 80 seconds
80 x 2.43 = 195 seconds
There's a simpler way in most cases (not telephoto lenses but normal ones, telephoto almost always have a T in their designation and are usually huge, so don't worry about mixing them up, you won't).
At infinity focus, your bellows distance should roughly equal your focal length.
So, 135mm lens should have 135mm bellows extension at infinity (focused on a far away mountain
Every time you double the bellows, you add two stops of light loss, SO
Assume you are shooting the 135mm and your meter says 1/60th if a second, then you're focussing close so your bellows are at 270mm, your exposure would be 1/15th of a second. That's double = 2 stops.
Get it? So say your bellows are at 200mm that's about half MORE bellows than infinity, so that would be 1 stop, so 1/30th of a second.
It's much easier to think about it that way (think) than making crazy equations, but I'm not a math guy, some people find my way crazy, it's really very individual, everyone has their own method that works easiest for them.
EDIT: also remember to calculate in the RIGHT ORDER, that order being in the path of light, so star with the aperture and shutter speed (light traveling through the lens) THEN the bellows compensation (light traveling through the bellows) THEN the reciprocity (light hitting the film).
If you do reciprocity first and then bellows extension, you'll get it wrong.
Got it. That does make it a bit easier to figure out without a calculator handy.There's a simpler way in most cases (not telephoto lenses but normal ones, telephoto almost always have a T in their designation and are usually huge, so don't worry about mixing them up, you won't).
At infinity focus, your bellows distance should roughly equal your focal length.
So, 135mm lens should have 135mm bellows extension at infinity (focused on a far away mountain
Every time you double the bellows, you add two stops of light loss, SO
Assume you are shooting the 135mm and your meter says 1/60th if a second, then you're focussing close so your bellows are at 270mm, your exposure would be 1/15th of a second. That's double = 2 stops.
Get it? So say your bellows are at 200mm that's about half MORE bellows than infinity, so that would be 1 stop, so 1/30th of a second.
It's much easier to think about it that way (think) than making crazy equations, but I'm not a math guy, some people find my way crazy, it's really very individual, everyone has their own method that works easiest for them.
Hmmm, good point and good way to think about it. But, I thought for basic multiplication, if only using multiplication, the order does not matter. As in:
10 x 2.43 x 8 = 194.4
10 x 8 x 2.43 = 194.4
Anyway, had a fun night of shooting, best results so far thanks to yours and others' advice - really appreciate it. Much to learn yet though.
On the math.Got it. That does make it a bit easier to figure out without a calculator handy.
Hmmm, good point and good way to think about it. But, I thought for basic multiplication, if only using multiplication, the order does not matter. As in:
10 x 2.43 x 8 = 194.4
10 x 8 x 2.43 = 194.4
Anyway, had a fun night of shooting, best results so far thanks to yours and others' advice - really appreciate it. Much to learn yet though.
PEMDAS, math order does matter.
Light is also directional, order matters
For strictly multiplication, the order does not matter.On the math.
PEMDAS, math order does matter.
Light is also directional, order matters
You might also want to try Fuji Acros 100. Really good reciprocity characteristics.
Newly made large format dry plates available! Look:
https://www.pictoriographica.com
The Reciprocity Timer app makes these calculations simple.
135mm lens at 210mm means you add 1.33 stops.
For Foma 100 with a metered exposure of 3 mins and 20 secs (the closest the app has to your time) the recommended exposure time is pretty much 4 hours.
For Fuji Acros 100 the exposure time would be 13 minutes.
I think I'd crank the lights up a little brighter. Ha!
Reducing the reflected light behind the subject can be accomplished by not having anything behind the subject that reflects light. Hint, hint. ;-)
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