Efke 25 4x5, Reciprocity Compensation Test

[Andrew O'Neill]

Hi everyone, I did a little testing of Efke 25's compensation for reciprocity effect. If you want to read about it and look at my messy curves and very poorly scanned negative I posted it all over at photo.net. This is the link.

http://www.photo.net/bboard/q-and-a-fetch-msg?msg_id=008bb4

[Jimi]

Hello Andrew!

Am I right in assuming from your chart that the film overall has a shoulder at 1.4 density? That is to say, that it is quite short-scale but doesn't vary a lot with exposure? Maybe I am stating the obvious but wanted to be sure. I am interested in testing this film in the future. Used to use Agfa iso 25.

[Janko Belaj]

Andrew, have to apologize for my 1st thoughts when I have seen your 1st table (without reading text above it...). Then I realized that you are not out of your mind, but that I'm impatient reader.
Well, I'm using efke 25 film for a long time, in all formats (KB, R and PL - the last one just for a few weeks) and have never used such a long exposure compensation. As I can recall, the longest was some 20 or more years ago (in those time this emulsion was KB-14, 14 din) when I needed about 10 minutes instead of measured 3-4 minutes.
In last 10 years, 1/4 or 1/2 EV compensation was quite enough for my night shots, now using KB and R 25 (and R-20 for short period of time, 20 ASA... Fotokemika switched lately to ISO numbers).
As I'm relatively new in large format, for last year and half I have used only PL-100 and have bought large batch of efke PL 25 in 9x12cm just a month ago. Now, I'm on vacation with new camera, new film and new developer, so for last week, I'm in game (or joy) of testing those new stuff. Well, as I switched from Rodinal to Xtol right here in small and completely inadequate equipped apartment, I'm not in right position to bet on my test's, but giving tolerance of 10% (to temperature, time, dilutions) exposure compensation values are close to yours.
And yes - it seams that Fotokemika have, in one moment, slightly changed it's best emulsion - in good way, I think. So, those huge differences in exposure compensation you have found on internet (and those have shocked me) might be for "old" efke.
Of course, I can not be sure that Fotokemika changed old ADOX formula, but I see that this emulsion is different than those one I started with as kid.
Janko

[Ted Harris]

As an additional comment, I have been using EFKE films in all formats as longas Janko (also started with KB 14 in the 1960's) and my experiences also agree with his. OTOH it is difficul tto mak ecomparisons since I use Rodinal.

[Janko Belaj]

Ted, btw, have you always been using Rodinal only, or have you used any other developer (especially with efke films?)... Now I'm sorry I didn't have proper approach in using all those developers in the past, i.e. - I didn't made proper notes... I have some notes when I was young, but that's like: "mountain Velebit, R-17, FR-5 minus some methol, 1:1, minute longer"... and then, I have 6 R-17 films from that trip, and everyone is different, and there is just that one notice... and I know that in those time I was using efke developers (I liked mostly FR-e-24), Ilford, OR-WO, Kodak... and (because I had photochemistry classes in my school) a bunch of self mixed developers, mostly from my grandfather notebook...

[Janko Belaj]

(oh... bunch of typos, sorry...)

[Andrew O'Neill]

"Am I right in assuming from your chart that the film overall has a shoulder at 1.4 density? That is to say, that it is quite short-scale but doesn't vary a lot with exposure?"

Hi Jimi, I only tested out to about zone XII. Only these zones are important to me. Curves are pretty straight out to that point.

[Jimi]

Andrew,

Thanks for the info. This film is on top of the future testing-list from now on.