Re: [pinhole-discussion] Determining exposure beyond.....................
- Original Message - From: Ricardo Wildberger Lisboa wildber...@svn.com.br Can I find that Ilford reciprocity failure table on the web? If it is Ilford film tables you are looking for, yes you can find them at www.ilford.com If what you are looking for is reciprocity tables for ilford paper, you can find the table I use in an article I wrote about pinhole exposures: http://members.home.com/penate/pinhole.html (link is almost at the end of the page) ? Is there a similar table for T-max 100 ? That one is at www.kodak.com Reciprocity failure is really a problem. If you are into pinholing, just learn to live with it! or shoot Ilford delta 3200 and push it to 25000, it will give you exposures of 1/100th of a sec under sunny skies with a pinhole camera f/256.forget about the electric tape shutter, though! :-) What if I'm working with lith film for half tone development later on ? Thank you for any help. You got me here, my guess is that reciprocity may be close to what for ilford paper emulsion is, but that is just a guess. Guillermo
Re: [pinhole-discussion] Determining exposure beyond.....................
Dear friends, Can I find that Ilford reciprocity failure table on the web? On which sites ? Is there a similar table for T-max 100 ? Reciprocity failure is really a problem. What if I'm working with lith film for half tone development later on ? Thank you for any help. Ricardo. - Original Message - From: Guillermo pen...@home.com To: pinhole-discussion@p at ??? Sent: Monday, September 17, 2001 2:34 PM Subject: Re: [pinhole-discussion] Determining exposure beyond. - Original Message - From: Rune Tallaksen tall...@alfanett.no Can anybody help me with how to determine exposure when correcting for resiprosity failure when the measured esposuretime exceeds that of the table from the filmvendor? For instance when using Ilford HP5 Plus, the film data sheet gives the added time for resiprosity failure until initial measured 35 secs(corrected for pinhole f stop). How can I calculate the correct exposure time beyond this point? Tiral and error until now has not been satisfactory for me. One way to do it is by extrapolating the curve Ilford is giving you. You can do that mathematically or graphically. I usually do it graphically. Take the Ilford curve and reproduce it on a piece of paper, extend the X or horizontal axis to read the maximum uncorrected time you want and then extend the curve with pencil trying to follow the same tendency, then is just a matter of extending the Y axis and graduating both axis. I just did that very quickly and the resulting extended curve gives me the following values, for 60, 90 and 120 secs of uncorrected exposure: 60 secs uncorrected = 475 secs corrected 90 secs = 925 secs 120 secs = 1900 secs Once you have the extrapolated curve, use it and if you get consistently somewhat overexposed film, that means the curve was done a bit to steep. If film is underexposed consistently then the curve needs to be re-done a little more steeper. One thing for sure, extrapolating the curve would give you better reciprocity corrections than trial and error. Hope it helps. Guillermo ___ Pinhole-Discussion mailing list Pinhole-Discussion@p at ??? unsubscribe or change your account at http://www.???/discussion/
Re: [pinhole-discussion] Determining exposure beyond.....................
I've had no experience with ilford HP%, and each BW film has it's own requirement. my general advice is expose longer than you think necessary and it'll probably be OK. The reciprocity failure you're trying to compensate for in fact buffers the overexposure error. - Original Message - From: Rune Tallaksen tall...@alfanett.no To: Pinhole-Discussion pinhole-discussion@p at ??? Sent: Monday, September 17, 2001 11:01 AM Subject: [pinhole-discussion] Determining exposure beyond. Hi list! Can anybody help me with how to determine exposure when correcting for resiprosity failure when the measured esposuretime exceeds that of the table from the filmvendor? For instance when using Ilford HP5 Plus, the film data sheet gives the added time for resiprosity failure until initial measured 35 secs(corrected for pinhole f stop). How can I calculate the correct exposure time beyond this point? Tiral and error until now has not been satisfactory for me. Any help will be appreciated. Rune Norway __\/__ ./ ^ _ \. |\|(o)(o)|/| #--.OOOo--oo--oOOO.# # Rune Tallaksen # # # # # #---Oooo.--# .oooO ( ) ( ) )/ \( (_/ \_) ___ Pinhole-Discussion mailing list Pinhole-Discussion@p at ??? unsubscribe or change your account at http://www.???/discussion/
Re: [pinhole-discussion] Determining exposure beyond.....................
- Original Message - From: Rune Tallaksen tall...@alfanett.no Can anybody help me with how to determine exposure when correcting for resiprosity failure when the measured esposuretime exceeds that of the table from the filmvendor? For instance when using Ilford HP5 Plus, the film data sheet gives the added time for resiprosity failure until initial measured 35 secs(corrected for pinhole f stop). How can I calculate the correct exposure time beyond this point? Tiral and error until now has not been satisfactory for me. One way to do it is by extrapolating the curve Ilford is giving you. You can do that mathematically or graphically. I usually do it graphically. Take the Ilford curve and reproduce it on a piece of paper, extend the X or horizontal axis to read the maximum uncorrected time you want and then extend the curve with pencil trying to follow the same tendency, then is just a matter of extending the Y axis and graduating both axis. I just did that very quickly and the resulting extended curve gives me the following values, for 60, 90 and 120 secs of uncorrected exposure: 60 secs uncorrected = 475 secs corrected 90 secs = 925 secs 120 secs = 1900 secs Once you have the extrapolated curve, use it and if you get consistently somewhat overexposed film, that means the curve was done a bit to steep. If film is underexposed consistently then the curve needs to be re-done a little more steeper. One thing for sure, extrapolating the curve would give you better reciprocity corrections than trial and error. Hope it helps. Guillermo
[pinhole-discussion] Determining exposure beyond.....................
Hi list! Can anybody help me with how to determine exposure when correcting for resiprosity failure when the measured esposuretime exceeds that of the table from the filmvendor? For instance when using Ilford HP5 Plus, the film data sheet gives the added time for resiprosity failure until initial measured 35 secs(corrected for pinhole f stop). How can I calculate the correct exposure time beyond this point? Tiral and error until now has not been satisfactory for me. Any help will be appreciated. Rune Norway __\/__ ./ ^ _ \. |\|(o)(o)|/| #--.OOOo--oo--oOOO.# # Rune Tallaksen # # # # # #---Oooo.--# .oooO ( ) ( ) )/ \( (_/ \_)
