Efke ir820 recprocity and long exposure

[markrewald]

Hello. I am down to my last rolls of this stuff and I would like to try and do some long exposure photography with it. All of the searches on the net have been basic sunny 16 rule stuff. Not what I am looking for. I am thinking of putting at strong nd filter with the r72 filter. So I would need to know how much longer I need to compensate for the extra stops. I would also like to transfer this info to Rollei's infra red film when my stash of efke runs out.

Or am I just wasting this rather valuable film?

 

[Alex Muir]

If you are doing low light or night work, there may not be much IR around to record on the film. There was very detailed info including reciprocity characteristics published online by Maco, when the film was available. Try to find that, if you haven't already seen it. Alex

 

[markrewald]

Thanks Alex. No this is daylight long exposure work I want to try. I will see what I can find on Maco.

 

[Alex Muir]

I have located a copy of the data sheet. It gives the following table;
Time measured (s) Time required(s)
1 1-2
2 3-4
4 8
8 24
15 60
30 180
The document indicates that these are suggested corrections for guidance, and recommends bracketing. Unfortunately, I'm unable to scan the document, but it may still be online. It is the data sheet for IR 820c and IR 820c AURA.
Alex

 

[DWThomas]

At the moment, Freestyle still has a sheet online, but if that goes away it might be found here.

 

[markrewald]

Awesome! Thanks guys!