Reciprocity Failure

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Ian-Barber

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How do you deal with reciprocity failure.

Do you use the film manufacturers data sheets or do you do your own testing.
 
I don't make many exposures outside the "normal" limits, so I rely on the manufacturer's data as a guide. Ansel Adams would probably despair of me, but I also tend to run to slight overexposure normally, as I prefer to hold shadow details and allow myself a little leeway.
 
Like Stephen, I don't make many exposures outside the "normal" range, but if you don't want to worry about it at all, go with the "reciprocity king" of B&W films: Fuji Acros 100. I think you've got to get beyond 80 - 90 secs before it even becomes a consideration! Well, if you shoot a lot in caves... :rolleyes::D
 
In the past I used Ilford data sheets for reciprocity values, the data sheets worked quite well for me.

Fairly recently I've started using a couple of types of mammography film, so no indication of film speed / development times, let alone reciprocity failure values. At first I intended to make rigorous tests, but that quickly gave way to pretending I was using Delta 100 and processing accordingly - actually not such a bad assumption to start from.

Somewhat coincidentally I made a couple of long exposures with mammo film a couple of nights ago, that didn't work out as hoped. Live and learn...slowly!
 
The exposures were a short - I tried two exposures, one with no increase in exposure from reading, one with a bit of an increase, neither are satisfactory. Not a big deal, normally I would have taken longer to make some calculations, but light levels were dropping fast, and I also picked up four mosquito bites for my trouble. Also the location I was at (a Korean pavilion) was about to close.

I tried one exposure with no correction applied just in case I got lucky with a film with good reciprocity characteristics - I had good results with Kodak TMAX 100 a few years back, and had the idea that the mammo film I've got (also Kodak, also using t grain emulsion) might be similar. It didn't work out quite so simply. Nothing ventured...in this case four bites gained.
 
I use a great app called "Reciprocity Timer" by Pump interactive. It has reciprocity corrections for colour and black and white films from all the major manufacturers and some quite obscure ones, it also accounts for bellows extension and filter factors and gives values for meter readings up to 30 minutes.
 
My go to B&W film these days is Acros 100. It used to be Adox CHS25, which was also quite forgiving I seem to recall? Anyway, Acros needs no correction up to about 2 minutes I believe, and then it's something like a stop extra out to about 12 minutes or so.

My colour work tends to stay under about the 2-3 second mark, so not really much to worry about.
 
Keith Haithwaite said:
"Reciprocity Timer" by Pump interactive." - seems it's only available for iOS :(
Click to expand...
I found one that is simply called Reciprocity (by Hans her Horst) for my Android - it is also based on the manufacturers' recommendations and very easy to use :)
 
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