Ancient info for film dinosaur!
Anyone out there have any information on Kodak film development times pre-1960 when film speeds were 1/2 what they are today?
Looking for TX/PX in D76 times pre-1960.
I suspect the info I am after is probably in a 50s Photo Lab Index.
Last edited by Fred Aspen; 12-15-2012 at 07:59 PM. Click to view previous post history.
From KODAK Films for B&W Databook 1958: PX EI Daylight 80 7 / 8 / 9 minutes at 68F Continuous/ 30 sec Intermittent / 60 sec. intermittent
From KODAK Films for B&W Databook 1958: TXP EI Daylight 200 10 / 11 / 13 minutes at 68F Continuous/ 30 sec Intermittent / 60 sec. intermittent
The change that took place in the late 1950's was not a change in the films. The ASA rating change was an elimination of the exposure safety factor that had been used to reduce the risk of under-exposure.
I hope this is what you are looking for. If not let me know.
My email is listed at: makingKODAKfilm.com
Development to a specific gamma was not specified in the pre-1960 ASA. In the older system speed and development were independent. In the current fixed density method it can appear to the uninformed that speed changes with changes in development you can only use the fixed density measurement at a specified gamma.
Originally Posted by Fred Aspen
I have a 1950s photo lab index I'm thinking of getting rid of. I can look this up, but if this is information you need often you really really need to own it.
name your price plus postage...or better yet, make a donation to the Red Cross for $30 and I'll mail it to you for free if you live in the continental us of hay.
Here you go - good old fleabay -
It seems to me Kodak changed their film speeds about 1957. I was in college using Verichrome Pan in my Voigtlander Baby Bessa, and noticed the change. Might be wrong, though.
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Thanks, all, just the numbers I was looking for.
Any suggestions for reading material to further describe in detail what you are referring to in your response (the methodology for exposure/development for those early systems).
I should have times for pre-WWII Tri-X somewhere, I'll try and find them
I think TX came out in 1954. The film of choice prior to that was Super XX, I think. Laser's numbers above were for TXP; if you have numbers for TX I would appreciate it.
Tri-X, Plus X, Super XX etc all came out in 1938/9 as a complete new family of films. I've posted the data page from the 1940 Kodak Ltd Professional Catalogue here on APUG in the past (not sure where). In fact they were coated in at least 3 facilities at that time, Rochester (Eastman Kodak), and Kodak Ltd's UK Harrow facory and their Hungarian plant, possibly at the Candian plant as well.
So it was rather a shock to see Kodak celebrating 50 years of Tri-X many years too late In fact it wasn't initially sold as a 35mm emulsion probably becuase earlier versions were felt to be to grainy for the format.
Plus-X Panchromatic, Super-XX Panchromatic and Tri-X Panchromatic are the original names, I'm looking at a 1940's Dataguide. They were released after Iflord had upgraded their films with the first generation of Fine Grain Panchromatic and Hypersensitive Panchromatice which became FP2, FP3 then FP4 and HP2, HP3, HP4 and now HP5. Tri-X has been through as many revisions over the years.
Tri-X was 200 ASA Daylight and 160 ASA Tungsten light, for sheet film Kodak recommended DK60a, 6 mins intermittent agitation. However when the speed changed it was down to a change in the ASA (also BS) testing which removed a safety factor of a stop, the emulsions themseves didn't change and this affected every manufacturers films and ASA/BS rating
It's possible the research etc for these films was done in the UK there does appear to have been a wider range available here in 1939/40 than is shown in US publications.
Incidentially the Fortepan 400 was derived from Tri--X, the Fortepan 200 from Supper-XX, both were made in Kodak's Hungarian factory which later became Forte.
Okay, Ian, now I am befuddled! I got my info from this page and I am totally confused. Take a look and see if you can sort this out.
Are we talking about a different name here?
Edit: Okay, got it, TX was released in 35/120 in 1954; it was released as a sheet film much earlier. I am interested in the exposure/dev times for the 35/120 film. Thanks for the info!