Now that ADOX CHS 100 II film is available on 120 format (as well as on 135 format and many, many different sizes of sheet film) it is getting really interesting. I have used a lot of ADOX CHS 100 ART on 120 format and loved the results and ADOX CHS 100 II film is said to be just as good. As a medium and large format shooter, I’m really happy that this film is now available in all formats.
ADOX provided a technical sheet for this film here, but crucially, the reciprocity failure correction information was missing. I emailed them, and they kindly obliged and provided me with the following information. I have not been able to verify any of this, I hope that you can let me know how you got on with the information below; it will certainly be a good start:
|Up to 1 second, no correction required.|
|2 seconds: 1.5x (3 seconds)|
|4 seconds: 2x ( 8 seconds)|
|8 seconds: 2.5x (20 seconds)|
|15 seconds: 3x (45 seconds)|
|30 seconds: 4x (120 seconds)|
|60 seconds: 6.5x (6 minutes 30 seconds|
In a graph it looks like follows (time metered on the horizontal axis versus the required exposure time on the vertical axis):
See also Howard Bond’s article on reciprocity departure for a really good article on the subject which is also referred to as the Schwarzschild effect.