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Tina G
19-Sep-2006, 14:57
I am a new student to LFP and was told that I could not use TMAX 100 because I did not test for the correct ASA and development times for TMAX 100. At this point I am not sure how to test for this.

I wanted to know if anyone knew the ASA and development times for TMAX 100 (I will be using a jobo and D76 developer at 1:9 ratio)?

Thank you
Tina

Ron Marshall
19-Sep-2006, 15:49
Below is a simple method, without using a densitometer, to determine the speed of your film and developer combination. You will need to make three exposures. You can do that on three sheets of film or on one sheet by partially inserting the darkslide to cover one third and subsequently two thirds of the sheet.

But first, you stated that you will use D76 1:9. That may be a typo. If not use 1:1, 1:9 is too dilute.

Take a light-meter reading of a uniform white or light coloured flat surface, for example a wall. Make sure the area you will photograph is evenly illuminated. Set the
ASA on the meter at 100.

The three exposures will be three, four and five stops less light than your meter reading. For example if your meter reading is f11 1/4 second then three stops less is f11 1/30 second, four stops: f11, 1/60, five stops: f11 1/125 second.

If you are using one sheet of film begin with the darkslide completely out. The first exposure must be the one five stops less. Then push the darkslide one third in. Repeat the same exposure (five stops below meter reading). This will result in the the uncovered two thirds of the sheet now having four stops less than the meter reading of exposure. Put the darkslide 2/3 of the way in. Now give an exposure equivalent to four stops less than the meter reading. This will result in the final third getting a cumulative exposure equal to 3 stops less than the meter reading.

Process the sheet.

Look for density in the negative above that of the film base. If the strip on the negative corresponding to the exposures 4 and 5 stops below the meter reading do not show any density, but the 3 stop below strip does then the film speed (EI) is about 50. If the 3 and 4 stop below do show density but not the 5 then EI is about 100. If all three show density then the EI is about 200.

Amund BLix Aaeng
19-Sep-2006, 15:54
The ISO is 100. I`d say shoot at 100 and develop as Kodak Tech pub. says
here (http://www.kodak.com/global/en/professional/support/techPubs/j78/j78.jhtml?id=0.2.20.14.18.14.7.14.14&lc=en)

And you want to use D76 at a 1:1 ratio, not 1:9, that would be a disaster.

Chris Strobel
19-Sep-2006, 18:33
I bought the film test kit from Bruce Barlow for twelve bucks shipped.Very easy to use and will give you your Zone I density (proper asa).Just type in film test kit in ebay search and you'll find it.

Chris