Lachlan Young
Member
I suspect Henning mentioned a lower lp/m on Foma's film than that companies' data sheet because he tested a good amount of film himself and the results were as such.
He got a lower (more realistic) result because he wasn't testing for resolution at contrast extinction - I recall it was a target that was claimed to deliver a result closer to 'real-world' resolution of materials. Overall, resolution testing has been of questionable use since the 1950's and should only be seen as a very limited component of the 'information capacity' of an emulsion set - which interrelates MTF, RMS Grain, latitude etc in a mathematical relationship to attempt to understand the overall behaviour of an emulsion. Some modern emulsions (especially a number of the ISO 100 BW ones) may actually be operating closer to a noise-limited resolution limit (at a certain point the grain/ noise stops any further resolution of information) as opposed to the older emulsions which may stop resolving useable information long before that point because their MTF response falls off a cliff beyond a certain resolution level.