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Photo Forum / Digital Photography / DSLR Cameras / November 2006Digital Cemera Medium Reciprocity Failure
I was doing some night work last night at about 1130 pm and after I'd finished I was wondering if there's a need to factor in reciprocity failure for the exposure times when using a digital slr. Any info would be interesting  SignatureMartyn > I was doing some night work last night at about 1130 pm and after I'd > finished I was wondering if there's a need to factor in reciprocity failure > for the exposure times when using a digital slr. No. Night and Low Light Photography with Digital Cameras http://www.clarkvision.com/photoinfo/night.and.low.light.photography Roger "Roger N. Clark (change username to rnclark)" <username@qwest.net> observed >> I was doing some night work last night at about 1130 pm and after I'd >>finished I was wondering if there's a need to factor in reciprocity [quoted text clipped - 4 lines] >Night and Low Light Photography with Digital Cameras >http://www.clarkvision.com/photoinfo/night.and.low.light.photography Fascinating! Thanks, Roger. Mike [The reply-to address is valid for 30 days from this posting] SignatureMichael J Davis <>< Some newsgroup contributors appear to have confused the meaning of "discussion" with "digression". <>< > I was doing some night work last night at about 1130 pm and after I'd > finished I was wondering if there's a need to factor in reciprocity failure > for the exposure times when using a digital slr. > > Any info would be interesting My understanding is no, silicon doesn't have that effect, just thermal noise. Cheers, Wayne SignatureWayne J. Cosshall Publisher, The Digital ImageMaker, http://www.dimagemaker.com/ Blog http://www.digitalimagemakerworld.com/ > I was doing some night work last night at about 1130 pm and after I'd > finished I was wondering if there's a need to factor in reciprocity failure > for the exposure times when using a digital slr. > > Any info would be interesting No. Reciprocity failure is an effect due to the fact that the different colours in a film emulsion are designed to work in the 'normal' speed range, say 1/30th - 1/500th give or take (and will work comfortably over a wider range than that) but when you start to get to very long exposures the rate at which they work starts to differ and you get colour casts. CCDs don't suffer that problem - just noise, which is mainly thermally generated. SignatureWoody harrogate3 at ntlworld dot com > No. Reciprocity failure is an effect due to the fact that the > different colours in a film emulsion are designed to work in the > 'normal' speed range, say 1/30th - 1/500th give or take (and will work > comfortably over a wider range than that) but when you start to get to > very long exposures the rate at which they work starts to differ and > you get colour casts. While you're right that colour casts are introduced for long exposures (depending on the film), reciprocity failure refers to the fact that a film essentially becomes less sensitive to light as the exposure time is increased. > CCDs don't suffer that problem - just noise, which is mainly thermally > generated. You're right. There is no reciprocity failure with digital. >> No. Reciprocity failure is an effect due to the fact that the >> different colours in a film emulsion are designed to work in the [quoted text clipped - 12 lines] > >You're right. There is no reciprocity failure with digital. There may not be reciprocity failure, but there is the question of whether the noise that increases with longer shutter speeds is as bad, better or worse than the noise that results from higher ISOs. In other words, from a noise point of view, is it better to stick to lower ISOs with longer exposure times, or increase the ISO and reduce the exposure time? I have done some tests with my Canon EOS 5D but they were not conclusive. The results may well be different for DSLRs with greater noise at higher ISOs. > There may not be reciprocity failure, but there is the question of > whether the noise that increases with longer shutter speeds is as bad, > better or worse than the noise that results from higher ISOs. Yes, I think it depends on the sensor, and some experimentation with one's camera is needed. > In other words, from a noise point of view, is it better to stick to > lower ISOs with longer exposure times, or increase the ISO and reduce [quoted text clipped - 3 lines] > conclusive. The results may well be different for DSLRs with greater > noise at higher ISOs. Well, I have found that my D200, for example, is always better at ISO 100 and arbitrarily long exposures than at higher ISOs and shorter exposures (this is with DFS on, if off, things may change at very long exposures). >> There may not be reciprocity failure, but there is the question of >> whether the noise that increases with longer shutter speeds is as bad, [quoted text clipped - 15 lines] >exposures (this is with DFS on, if off, things may change at very long >exposures). What is DFS? >>>There may not be reciprocity failure, but there is the question of >>>whether the noise that increases with longer shutter speeds is as bad, [quoted text clipped - 16 lines] > > What is DFS? Dark Frame Subtraction. >>>In other words, from a noise point of view, is it better to stick to >>>lower ISOs with longer exposure times, or increase the ISO and reduce [quoted text clipped - 10 lines] > > What is DFS? Dark Frame Subtraction -> a second black pic taken for the same length under the same conditions (temperture) used to subtract that noise. >>>>In other words, from a noise point of view, is it better to stick to >>>>lower ISOs with longer exposure times, or increase the ISO and reduce [quoted text clipped - 13 lines] >Dark Frame Subtraction -> a second black pic taken for the same length >under the same conditions (temperture) used to subtract that noise. Thanks. |
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