Dear All,
Good photographic practise dictates that you should process all films as soon after exposing as possible to obtain optimum results, in addition they should also not be left 'in camera'.
In saying that.......modern monochrome films have outstanding LIS ( Latent Image Stability ) but ALL films ( and papers as well ) without exception, are subject to latent image regression.
As I have stated, ILFORD PAN F + is an outstanding film with unique attributes and a fine film for portraiture and where minimal grain and excellent sharpness are required, but its LIS is a compromise performance area whereby we DO recommend PAN F+ is processed within 3 months of exposure and our Technical Information sheets available on our website state that, as well as masses of other product related information for PAN F+.
LIS is also not directly related to the film speed emulsion or type, so where a photographic norm would be the faster the emulsion the more 'sensitive' it is may indeed be correct that does not corelate directly, in all cases, to its LIS characteristics.
A couple of other things LIS is not linear, it does not mean that LIS starts immediately and continues at the same rate.
Keeping film cold or frozen, can assist in lessening the affect of LIS but it cannot STOP the process. Heat and / or humidity can also accelerate the process, but not in all cases.
To put it in perspective, meaningful change in the density and characteristics of a modern monochrome negative due to LIS would not be readily noticable to 95% of photographers in 99% of cases...
As you will see in many aspects of photography and in hundreds of posts on APUG
Good technical results for the photographic negative and print can be ensured and enhanced by good practise.
Simon ILFORD Photo / HARMAN technology Limited :
Simon ILFORD Photo / HARMAN technology Limited :