Oscura - calculating the new exposure times is simple once you have the multipliers for the f stop adjustments you want to make. If your base exposure is 16s and you want to reduce the exposure time by 1/2 stop multiply 16 by .71 = 11.36. To increase the time by the same amount use 1.41 as the multiplier (1.41 X 16 = 22.56). These are other multipliers I regularly use: -1/4 - .84, +1/4 - 1.19, -1/8 - .92 and +1/8 - 1.09. Deep pockets buys you an f stop timer that does this with the push of a button but, frankly, I kind of enjoy the process of calculating my own adjusted times.
Good morning rick johns !
Thank you very much for your explication.
So if i understand well, my standard time is 20 s, if i want to push +1/4 stop the time will be 25 s.
Thank you very much because i didn't know before this notion and i hope i will have time to make this experiencem it seems to be very interesting !
All the best
Ralph Lambrecht is just too modest .
Go to his website:
darkroomagic (warning, some nudity) and then click on the link labelled "Library".
In that Library, there is a whole bunch of useful stuff, including an extremely useful f/stop timing table in pdf format.
Download that, and it will help you calculate all your necessary changes.
It's in Ralph's book as well (Way beyond Monochrome) which I would recommend highly. I've got a copy of the 1st edition, and hope to get a copy of the second edition when it comes out.
oscura - 20.0s X 1.19 = 23.8s representing a 1/4 stop increase in exposure. As Matt suggested, print Ralph's f stop timing table. That will eliminate dealing with my multipliers and make life a lot easier.
I think it's more common that a faulty darkroom environment (lighting) is to blame for the NEED for #5 to get a reasonable print rather than negs themselves.
Originally Posted by Ronald Moravec
Stop worrying about grain, resolution, sharpness, and everything else that doesn't have a damn thing to do with substance.
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