Re: [pinhole-discussion] reciprocity and TMY film
Guillermo, Your persistence is admirable. Yes TMY does need very much less compensation than my usual HP5+ as I found out in trying to print bullet-proof 120mm film negs. I had to develop for the general exposures on the roll and not the 300sec. exposures done inside an almost completely darkened medieval chapel with just a glint of light thru narrow windows. Thanks for the url for the chart from Kodak. As it is, I have been plotting the curve on an excel spread sheet for TMY and playing connect the dots. Thanks for the reminder that it is indeed a curve and not a straight line. And cheers for that AXIS OF EVIL: Hurter and Driffield, those demons of the d log e curve. Ishmael Zarkov _ Join the worlds largest e-mail service with MSN Hotmail. http://www.hotmail.com
Re: [pinhole-discussion] reciprocity and TMY film
Allow me just 1 more try, pls: corrected time | (100,300) P | _ |_ | _ | _ | _ | _ | _ | _ | _ | _ |_ | _ | _ | _ P --- (10,15) |_P ^ indicated time |
Re: [pinhole-discussion] reciprocity and TMY film
Told you they were axis of evil, can't get the chart to format correctly, here is the last try: corrected time | (100,300) P | _ | _ | _ | _ |_ |_ | _ | _ | _ | _ | _ | _ |_ | _ P --- (10,15) |_P ^ indicated time | | (1,1.25)
Re: [pinhole-discussion] reciprocity and TMY film
** Resending the message, hopefully the ascii chart won't break up this time. - Original Message - From: I Zarkov dr_izar...@hotmail.com Unfortunately the Kodak product search engine gives nothing for the topic of 'reciprocity'which is too bad because they once had a very good chart in an old professional products catalogue that gave a good long and short range adjustments for reciprocity [ i.e.: 1-10 sec and 10-100 sec ranges]. I'll see if I can find it somewhere else. Zarkov, TMY film needs relatively weak reciprocity corrections. If you, judiciously, add between 25% and 50% more exposure for indicated times between 1 to 10 secs, and between 50% and 150% between 10 to 100 secs, your exposures should be -enough- well corrected. For non T-Grain films (i.e. Tri-X), you'd need to increase the exposure 1200% for an indicated time of 100 secs. Clearly, the need for better charts is there more for Tri-X than for TMY, for the range 1 to 100secs indicated, at least. I've seen the chart you mentioned, you can still pull it from Kodak's site, here is the URL (cut and paste it if it breaks): http://www.kodak.com/global/en/professional/support/techPubs/f9/f002_0062gc. gif Another issue in the case of TMY and TMX, for that matter, is they (Kodak) only gives us 3 correction values (1, 10, and 100). We need at least 3 points to plot a curve and that is what Kodak gives us (it'd be nice to have at least y more between 10 and 100). Now, by seeing many other reciprocity correction charts for other films, we know that this reciprocity phenomenon is not linear but exponential, so we use that knowledge to plot a curve for TMY based on the 3 points we have [( 1,1.25), (10,15), (100,300 )]: corrected time | (100,300) P | _ | _ | _ | _ | _ |_ |_ | _ | _ | _ | _ | _ | _ |_ | _ P --- (10,15) |_P ^ indicated time | | (1,1.25) Once you have your graph, it is just a matter of drawing vertical lines from the indicated time axis and from where this vertical line intersects the curve, horizontal lines to the corrected time axis to find/read the, reciprocity corrected time. MAKE NO MISTAKE, this 2 axis are photography's AXIS OF EVIL, I am, as we speak, writing my Pres. requesting military action against them! The same treatment can be made to any other film for which you know at least 3 corrections. Guillermo
Re: [pinhole-discussion] reciprocity and TMY film
- Original Message - From: I Zarkov dr_izar...@hotmail.com Unfortunately the Kodak product search engine gives nothing for the topic of 'reciprocity'which is too bad because they once had a very good chart in an old professional products catalogue that gave a good long and short range adjustments for reciprocity [ i.e.: 1-10 sec and 10-100 sec ranges]. I'll see if I can find it somewhere else. Zarkov, TMY film needs relatively weak reciprocity corrections. If you, judiciously, add between 25% and 50% more exposure for indicated times between 1 to 10 secs, and between 50% and 150% between 10 to 100 secs, your exposures should be -enough- well corrected. For non T-Grain films (i.e. Tri-X), you'd need to increase the exposure 1200% for an indicated time of 100 secs. Clearly, the need for better charts is there more for Tri-X than for TMY, for the range 1 to 100secs indicated, at least. I've seem the chart you mentioned, you can still pull it from Kodak's site, here is the URL (cut and paste it if it breaks): http://www.kodak.com/global/en/professional/support/techPubs/f9/f002_0062gc. gif Another issue in the case of TMY and TMX, for that matter, is they (Kodak) only gives us 3 correction values (1, 10, and 100). We need at least 3 points to plot a curve and that is what Kodak gives us (it'd be nice to have at least y more between 10 and 100). Now, by seeing many other reciprocity correction charts for other films, we know that this reciprocity phenomenon is not linear but exponential, so we use that knowledge to plot a curve for TMY based on the 3 points we have [( 1,1.25), (10,15), (100,300 )]: corrected time | P --- (100,300) | _ | _ | _ | _ |_ |_ |_ | _ | _ | _ | _ | _ | _ |_ | _ P --- (10,15) |_P ^ indicated time | | (1,1.25) Once you have your graph, it is just a matter of drawing vertical lines from the indicated time axis and from where this vertical line intersects the curve, horizontal lines to the corrected time axis to find/read the, reciprocity corrected time. Make no mistake, this 2 axis are photography's AXIS OF EVIL, I am, as we speak, writing Pres.Bush requesting military action against them! The same treatment can be made to any other film for which you know at least 3 corrections. Guillermo
Re: [pinhole-discussion] reciprocity and TMY film
Dear 'Z', I want to try HP5+ sheet film and need the chart for conversation. Please share it for me. Regards Ingo - Original Message - From: I Zarkov dr_izar...@hotmail.com To: pinhole-discussion@p at ??? Sent: Monday, February 25, 2002 6:25 PM Subject: [pinhole-discussion] reciprocity and TMY film Dear List, Folllowing on recent discussion on Polaroids and reciprocity: I have receently changed from Ilford HP5+ to TMax 400 4x5 sheet film in my home made 'soup can and film box' pinhole cameras. HP5+ has a pretty well defined chart for conversion from indicated to adjusted exposure times but TMY is pretty general, showing adjustment from 10 to 15 sec. and 100 sec to 300. Has anyone charted or know of a chart from Kodak or elsewhere that might show a more detailed compensation factor for the 10 to 100 indicated exposre range? I don't want to assume that it's a simple straight line adjustment along that range. TIA. 'Z' _ Chat with friends online, try MSN Messenger: http://messenger.msn.com ___ Post to the list as PLAIN TEXT only - no HTML Pinhole-Discussion mailing list Pinhole-Discussion@p at ??? unsubscribe or change your account at http://www.???/discussion/
Re: [pinhole-discussion] reciprocity and TMY film
Guillermo, Thanks for the times. I'll give them a try. Zarkov _ Get your FREE download of MSN Explorer at http://explorer.msn.com/intl.asp.
Re: [pinhole-discussion] reciprocity and TMY film
Try this values: Indicated,Corrected 10,15 12,21 15,27 20,35 25,47 30,62 40,1:24 50,1:50 60,2:25 80,3:10 100,4:10 Guillermo
