How to expose 20 y/o Konica Infrared?

[J Rollinger]

I have a 20 y/o old roll (not properly stored) that i want to shoot but dont know how to exposed it due to the loss of speed. I will be using Rodinal. Any ideas?


Thanks
Jim

 

[frobozz]

Overexpose and underdevelop (pull it) a couple of stops as a start, but the IR fogging might overwhelm any attempts to get usable images. Do you have more than one roll? Is it 35mm and you can shoot and develop a few frames at a time and cut a new leader for the next test?

Duncan

 

[J Rollinger]

Its a single roll of 120. I dont expect anything good from the roll but i dont want to toss it either. The only info i can find is ISO 6.... Rodinal 1+100 for 4.5 minutes. DO you think i can shoot it at ISO25.. 1+100 for 4.5 minutes?

 

[frobozz]

To combat fog, you need to pull it, which would require overexposing it before underdeveloping it, which would mean using an ISO lower than 6, and a time less than 4.5 minutes (if those are in fact known to be reliable values for the film originally.) But hey, you only have the one roll so it's not like you need to scientifically hone in on the optimum specs for it. Maybe just try shooting it at ISO 6 and developing for 4.5 minutes and see what you get!

Is that ISO of 6 taking into account the IR filter? I often see IR films stated that way - it's really ISO 100 but when using the filter you need to adjust by a bunch of stops so when using an external meter or an internal meter that doesn't "see" IR, you need to use a much lower ISO value. In any event, like any IR film, you'd be well served to bracket the heck out of any shots you make!

Duncan

 

[J Rollinger]

To combat fog, you need to pull it, which would require overexposing it before underdeveloping it, which would mean using an ISO lower than 6, and a time less than 4.5 minutes (if those are in fact known to be reliable values for the film originally.) But hey, you only have the one roll so it's not like you need to scientifically hone in on the optimum specs for it. Maybe just try shooting it at ISO 6 and developing for 4.5 minutes and see what you get!

Is that ISO of 6 taking into account the IR filter? I often see IR films stated that way - it's really ISO 100 but when using the filter you need to adjust by a bunch of stops so when using an external meter or an internal meter that doesn't "see" IR, you need to use a much lower ISO value. In any event, like any IR film, you'd be well served to bracket the heck out of any shots you make!

Duncan

Thanks Frobzz.. I wasn't thinking when i said iso25... I'm a bit backwards today. I will shoot it at 6 and see what happens. Thanks for the advice!