- Joined
- Jul 4, 2005
- Messages
- 383
- Format
- Medium Format
pre-soaking GP3 / Diafine / Box Tengor
I have happily found that Shanghai GP3 when presoaked, THEN developed in Diafine 75 degrees F, for 3 Min. + 3 Min. has a working ISO of 30 to 40.
No good reason to presoak other than I did not want the blue dye the color and intensity of fountain pen ink in my Diafine part A.
Why the GP3 DROPS in ISO from 80-100 down to 30-40 instead of staying the same OR increasing, I don't know!
My Zeiss Box Tengor model 56-2 has a shutter speed of 1/30 second and f stops of 9, 11 and 16. Shanghai GP3 developed in Diafine exposed at 30-40 asa/iso in Diafine with a presoak matches the shutter speed and "Sunny 16" rule perfectly when processed in this manner. Negatives are great!
I wish I were smart enough and had a Sensitometer and Densitometer to expose and read a strip of this film to plot a curve and find the TRUE speed and Contrast index of this GP3 film processed in Diafine with presoak.
It sure makes a nice old style film to use in a old style camera at the speeds and f stops as they were intended. Plus the price is great.
All the best,
Sam H.
I have happily found that Shanghai GP3 when presoaked, THEN developed in Diafine 75 degrees F, for 3 Min. + 3 Min. has a working ISO of 30 to 40.
No good reason to presoak other than I did not want the blue dye the color and intensity of fountain pen ink in my Diafine part A.
Why the GP3 DROPS in ISO from 80-100 down to 30-40 instead of staying the same OR increasing, I don't know!
My Zeiss Box Tengor model 56-2 has a shutter speed of 1/30 second and f stops of 9, 11 and 16. Shanghai GP3 developed in Diafine exposed at 30-40 asa/iso in Diafine with a presoak matches the shutter speed and "Sunny 16" rule perfectly when processed in this manner. Negatives are great!
I wish I were smart enough and had a Sensitometer and Densitometer to expose and read a strip of this film to plot a curve and find the TRUE speed and Contrast index of this GP3 film processed in Diafine with presoak.
It sure makes a nice old style film to use in a old style camera at the speeds and f stops as they were intended. Plus the price is great.
All the best,
Sam H.
