dtoh Posted August 2, 2012 Share #1 Posted August 2, 2012 Advertisement (gone after registration) Good day to all, may i ask If I select the exposure time f5.6 ,15 sec based on the test stripe, does it mean, technically speaking I have to expose f8 at 30 sec (15sec x 2)? Likewise does it means f4 with 7.5sec (15sec / 2)? I hope to understand this basics thru your experience, in order to explore further with the darkroom. Thanks. Regards daryl http://dtohphoto.com Link to post Share on other sites More sharing options...
Advertisement Posted August 2, 2012 Posted August 2, 2012 Hi dtoh, Take a look here Darkroom exposure timing question. I'm sure you'll find what you were looking for!
espresso Posted August 2, 2012 Share #2 Posted August 2, 2012 yes. yes. Link to post Share on other sites More sharing options...
andybarton Posted August 2, 2012 Share #3 Posted August 2, 2012 The exposure works exactly the same as on a camera. Double the sized the aperture and half the length of the exposure. Or vice versa. Link to post Share on other sites More sharing options...
stunsworth Posted August 2, 2012 Share #4 Posted August 2, 2012 The exposure works exactly the same as on a camera. Double the sized the aperture and half the length of the exposure. Or vice versa. Not double as far as f stops are concerned. F8 to f4 isn't twice the exposure it's four times. The exposure alters by a factor of two for each stop. So going from f5.6 to f8 requires a doubling of the exposure time etc. I know you know this Andy, but your original post was a bit confusing for a newcomer. Link to post Share on other sites More sharing options...
andybarton Posted August 2, 2012 Share #5 Posted August 2, 2012 Apologies Posting before my bran flakes this morning. Link to post Share on other sites More sharing options...
dtoh Posted August 2, 2012 Author Share #6 Posted August 2, 2012 Thanks you all for the quick response. I appreciate it. I guess this is the one thing most users already knew but somehow i am just unsure of, with your inputs i could speed up (i hope) the learning process, and hopefully minimise the errors in the darkroom, which i am currently fumbling with.. thanks again. Regards, daryl http://dtohphoto.com Link to post Share on other sites More sharing options...
dorman Posted August 2, 2012 Share #7 Posted August 2, 2012 Advertisement (gone after registration) I haven't done any darkroom printing for a long time, but I seem to remember that some colour papers, particularly Cibachrome, showed very significant reciprocity failure at exposures over a few seconds. Stopping down by one stop required much more than a doubling of the exposure time. I would recommend that you always do your test strip at the aperture you want to use for the final print. Link to post Share on other sites More sharing options...
fotohuis Posted August 2, 2012 Share #8 Posted August 2, 2012 Regular B&W MG paper is linear over a very wide of range. RA-4 papers too and in the past my R3 papers also. So nothing to worry about it! Greetz, Robert Link to post Share on other sites More sharing options...
Broadside Posted August 2, 2012 Share #9 Posted August 2, 2012 I think its best to aim for an exposure around 10 seconds in order to give yourself some leeway to make burning and dodging a little easier. Link to post Share on other sites More sharing options...
tobey bilek Posted August 2, 2012 Share #10 Posted August 2, 2012 Close, but not exactly. There will be reciprocity failure requiring more than doubling the time. Films do the same as exposures get long. Link to post Share on other sites More sharing options...
fotohuis Posted August 2, 2012 Share #11 Posted August 2, 2012 Films: Most films > 1 second. Papers: Over minutes. And yes, for dodging and burning 10S-20S is very practical. Keep the aperture of the enlarging lens between f/5,6-f/11 and if necessary correct with the ND filter 0,3-0,6 (1F-2F stops correction for less light) to make sharp and best prints. Link to post Share on other sites More sharing options...
too old to care Posted August 2, 2012 Share #12 Posted August 2, 2012 Films: Most films > 1 second. Papers: Over minutes. And yes, for dodging and burning 10S-20S is very practical. Keep the aperture of the enlarging lens between f/5,6-f/11 and if necessary correct with the ND filter 0,3-0,6 (1F-2F stops correction for less light) to make sharp and best prints. +1, pretty much what I do too. Link to post Share on other sites More sharing options...
pico Posted August 2, 2012 Share #13 Posted August 2, 2012 There is one thing about exposing paper to keep in mind. Two exposures on the paper (for example, two 5-second exposures @F8) is not quite the same as one ten second exposure. It becomes more apparent with multiple exposures. Link to post Share on other sites More sharing options...
dtoh Posted August 3, 2012 Author Share #14 Posted August 3, 2012 Noted with thanks on the practicality of exposure time <10 sec for dodging and burning. From my prints, I do see that it may take more than doubling the exposure time for each stop, hence this thread. The reciprocity law shall still be my basis; I shall take note about the disparity on the exposure time compensation. daryl http://dtohphoto.com Link to post Share on other sites More sharing options...
Jeff S Posted August 3, 2012 Share #15 Posted August 3, 2012 There is one thing about exposing paper to keep in mind. Two exposures on the paper (for example, two 5-second exposures @F8) is not quite the same as one ten second exposure. It becomes more apparent with multiple exposures. +1 In my darkroom days I followed the Fred Picker practice of 3 second bursts (last burst possibly less), using a foot timer switch, to maintain consistency. I also used a compensating enlarging timer to accommodate changes in light intensity over the printing session. Jeff Link to post Share on other sites More sharing options...
250swb Posted August 3, 2012 Share #16 Posted August 3, 2012 The reciprocity failure of photographic paper is so minimal that it shouldn't be of any concern until you get into ten minute exposures. Aim for an exposure time that allows you plenty of time to dodge any areas of the image, maybe over ten seconds and under thirty. Likewise burning-in after the main exposure is far easier if you can relax and know it isn't down to split second timing, as would be the case with short main exposures. Steve Link to post Share on other sites More sharing options...
dtoh Posted August 4, 2012 Author Share #17 Posted August 4, 2012 Thanks for all your pointers. My first wet print, the image looked fine when scanned on v700, but it was rather over exposed under the enlarger, the exposure time took longer than i thought. Good thing i got some guidance. Regards, daryl http://dtohphoto.com Link to post Share on other sites More sharing options...
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