BTZS and View Camera Article

[Michael Heald]

Hello! I am confused about BTZS and the recent View Camera article. From the article, I presumed that the goal of the testing was try to achieve exposures, development times, etc. that contracts or expands a scene as appropriate to try and get it to match the seven stops available on most film.
The final chart shows developing time vs SBR. For SBR=3.5 the developing time is 16 minutes (expansion?) and for SBR=10.5, teh developing time is 4 minutes (contraction?).
Since the example is given for TMax 400, this chart seems to imply that TMax 400 can be expanded and contracted 3.5 stops. That seems a bit excessive. I've heard modern emulsion films can go between 1 and 1.5 stops. 2 stops is pushing it.
As a result, I'm not sure that I am interpreting this chart correctly. For example if I have a low contrast scene with only 3.5 stops (or a SBR=3.5) and I develop it for 16 minutes, what will I end up with? Thank you and best regards.

Mike

[sanking]

Hello! I am confused about BTZS and the recent View Camera article. From the article, I presumed that the goal of the testing was try to achieve exposures, development times, etc. that contracts or expands a scene as appropriate to try and get it to match the seven stops available on most film.
The final chart shows developing time vs SBR. For SBR=3.5 the developing time is 16 minutes (expansion?) and for SBR=10.5, teh developing time is 4 minutes (contraction?).
Since the example is given for TMax 400, this chart seems to imply that TMax 400 can be expanded and contracted 3.5 stops. That seems a bit excessive. I've heard modern emulsion films can go between 1 and 1.5 stops. 2 stops is pushing it.
As a result, I'm not sure that I am interpreting this chart correctly. For example if I have a low contrast scene with only 3.5 stops (or a SBR=3.5) and I develop it for 16 minutes, what will I end up with? Thank you and best regards.

Mike

Mike,


I think you are reading the chart correctly. What it shows is that TMAX-400 has great expansion potential, a very desirable quality and one of the reasons many people like this film so much for alternative printing. However, while the film is potentially capable of handling an SBR scene of 3.5 you should bear in mind that an SBR this low would only be found in highly unique lighting situations. In actual practice it is extremely rare to encounter a scene with a real SBR of less than 5.

Sandy King

[Colin Robertson]

Shit, Sandy- come visit the Hebrides. The landscape is one of grey rock, no trees (so no deep shadow) and sometimes we have days and days of continuous flat overcast. The sky shows no features, with such dense cloud cover that it can actualy be hard to identify the position of the sun through it. Good SBR is 5 stops, and If I get 7 stops I feel like my birthday has come round. Even though I have calculated a dev time for a 9 stop SBR I've NEVER actualy used it. When I read the threads about how to handle brutal, contrasty light I give a little sigh.
(Oops- hope no would-be tourists read this)

[sanking]

Shit, Sandy- come visit the Hebrides. The landscape is one of grey rock, no trees (so no deep shadow) and sometimes we have days and days of continuous flat overcast. The sky shows no features, with such dense cloud cover that it can actualy be hard to identify the position of the sun through it. Good SBR is 5 stops, and If I get 7 stops I feel like my birthday has come round. Even though I have calculated a dev time for a 9 stop SBR I've NEVER actualy used it. When I read the threads about how to handle brutal, contrasty light I give a little sigh.
(Oops- hope no would-be tourists read this)

Colin,

In that case you should stock up on TMAX-400 before Kodak pulls the plug on all of their film production. For the kind of expansion you need there is no better film.

Actually, what you describe does not sound all that dismal to me. Sounds like perfect conditions for making negativs you will never have to dodge and burn.

Sandy King

[sanking]

BTW, I want to congratulate Steve Simmons for having Phil Davis do Part II of the article on BTZS. What you get from Phil is the best technial advice available, and it is always nice to see people who have contributed so much to the field get the recognition they deserve. BTZS has been a great aid in helping me to make the best negatives possible for my needs and I feel very indebted to Davis. He actually did several of the BTZS workshops at Clemson many years ago, but unfortunately I was never able to attend any of them because of scheduling, though I did observe enough if the workshops to have a good understanding of the process of BTZS.

Sandy King

[Michael Heald]

Hello! I sent TMax 400 to BTZS after developing it in TMax. At 1:7 and 70 degrees, and 1:9 at 75 degrees, it gives +/- 1 and 1/3 stops and this is what I shoot for. However, the chart on development vs SBR extends from 4.7 to 9.3. If SBR is equivalent to N nmbers, then this would be about 2.3 stops above and below 7 - an extra stop.
I'm not sure that I'm interpreting the chart correctly. Is there a difference between n-stop and SBR for these charts? Best regards.

Mike
Can additional expansion

[sanking]

Hello! I sent TMax 400 to BTZS after developing it in TMax. At 1:7 and 70 degrees, and 1:9 at 75 degrees, it gives +/- 1 and 1/3 stops and this is what I shoot for. However, the chart on development vs SBR extends from 4.7 to 9.3. If SBR is equivalent to N nmbers, then this would be about 2.3 stops above and below 7 - an extra stop.
I'm not sure that I'm interpreting the chart correctly. Is there a difference between n-stop and SBR for these charts? Best regards.

Mike
Can additional expansion


SBR and N numbers are not equivalents, and in fact both vary according to paper ES. For a given range of development times, with a specific paper ES, SBR values could range from SBR 10 to SBR 4, while N numbers might be N-2 to N+2. CI values for the same negatives could range from as low as .35 to as high as 1.0.

TMAX-400 is capable of CI values as high as 1.2, so in theory SBR values of 3.5 are quite possible with this film. For N values the range could be greater than +4 stops. This is of course much greater than you could get with films like TRI-X and HP5+.

Sandy King

[Michael Heald]

Hello! I don't seem to get this kind of expansion. When I've tried 2 or more stops, the negtatives look thin when I use the exposure recommended by BTZS for significant expansion. Would expansion of TMax 400 work better with a different developer than TMax RS? Best regards.

Mike

[sanking]

Hello! I don't seem to get this kind of expansion. When I've tried 2 or more stops, the negtatives look thin when I use the exposure recommended by BTZS for significant expansion. Would expansion of TMax 400 work better with a different developer than TMax RS? Best regards.

Mike

Mike,

Developer, or developer dilution, may make a difference.

However, my own tests of TMAX-400, in a number of staining and non-staining developers (but not TMax RS) , indicate that EFS remains fairly constant over a wide range of SBR conditions. Where N or SBR 7 is normal EFS, I have found that you need only about +1/4 stop more for high SBR values (contraction) and about 1/4 stop less for low SBR values (expansion).

Sandy King

[Michael Heald]

Hello! I just tried a contraction of TMAX 400 - the scene read about 8 1/2 stops, so I set the ISO to 250 and compared the f-stop and shutter speed from my meter to that which the BTZS dial gave, and they were pretty close. ISO of 250 was what the BTZS testing gave for this contraction. The development time was 4 minutes. It turned out fairly good. I'm not sure why I thought my negatives were thin before.
Anyway, with TMAX RS at 1:7 at 70 degrees and 1:9 at 75 degrees, both with BTZS testing, I've found TMax 400 can contract and expand about 1 1/2 stops.
Have other folks tested TMax 400 and found that it gives more expansion and contraction? Best regards.

Mike

[Andrew O'Neill]

Yes...and you can really bend it's curve too, depending on chemistry used.