Steve sent through to our Facebook page some test results after shooting some Kodak Tri-X for a bit of latitude experiment ... enjoy and thanks Scott
Thought this might be of interest. I conducted some Tri-X 400 135 tests of film latitude and behavior for over and under exposure. Unlike color negative, I wasn’t certain that one could safely over expose the film, particularly with regard to grain/latitude.
All was developed for ISO 400 in D76, scanned by Fotofast and tweaked in lightroom to tweak blacks / whites and exposure to give as much consistency as possible. See
I’ve provided a link to a Dropbox with 2 scenes in it. Exposure was typically measured with a Lumu light meter and cross-checked against the Leica M6 built in meter and Sunny 16 (if applicable). For each of the two scenes I’ve made 7 exposures, progressively from 2 under-exposed, to target exposure (for ISO 400), right through to 4 stops over exposed. I metered for the bike scene (above) at the basket and for the beach scene (below) in the shadows of the tree (hence why not much loss of detail even 2 stops under).
The results are pretty clear and I think can be summarised:
- Anything less than a stop under-exposed dramatically increases grain and drastically reduces shadow detail. Note the bike scene was selected for the varying light in the background room but the scene was metered at the bike basket so the background shadows would be about 2 stops lower again.
- Butter zone is similar to colour neg, 0 to 2 stops over looks good
- Can easily go up to 3-4 stops over with little detriment to the scanned image and only a very minor, almost imperceivable, loss in latitude.
- Over-exposure seems to have little effect on increase in visual grain