For starters it would give you a maximum development time. It would also give you a visual test of how fast the film develops. The benefits gained are only realized by experience.
PE
I habitually have a look at the leader of the films I develop. When the leader is so dense that only the bulb can be seen through it, then the film is probably overdeveloped. When the film is developed to a reasonable contrast, the surroundings of the bulb can be seen, at least to some extent. In fact, I have seen leaders which looked a bit too thin, but the film printed very nicely. Pull processed film would have a leader looking that thin. Considering your test, the 5' development time looks closer to the ideal IMHO, perhaps extending it to 7' is better.I did the daylight development maximum blacks test again tonight, but in a different way. In one tank I had the leader in a130 developer at 1-10 for 1.5 hours, in the mean time I also did cut pieces of tri-x in another tank of a130 developer at 1-10 for 30 seconds, 1 min, 2 min, 3min........and so forth till 10 mins per cut piece of tri-x 400. All have been stopped, fixed and washed. Doing a quick look threw each piece looking at the bathroom vanity lights, ZERO light gets threw leader section that developed for 1.5 hours. Each of the other pieces gets denser with each extra min of development. The 10 min one can only see the physical light bulb and nothing else. The 5 min range can see whats around the light bulb like the mirror and such.
Based on your experimental findings I would guess that minimum time for maximum black is around 12-15 minutes. Surely, 1 minute (reported in post #140) was an underestimate.
If you are in the mood to experiment, you can shoot a few frames with your camera and develop the strip for 10 minutes in daylight tank and tell us what you get.
I habitually have a look at the leader of the films I develop. When the leader is so dense that only the bulb can be seen through it, then the film is probably overdeveloped. When the film is developed to a reasonable contrast, the surroundings of the bulb can be seen, at least to some extent. In fact, I have seen leaders which looked a bit too thin, but the film printed very nicely. Pull processed film would have a leader looking that thin. Considering your test, the 5' development time looks closer to the ideal IMHO, perhaps extending it to 7' is better.
As for the second part, actually develop some negatives with pictures on them for 10mins?
Yes. As I understood it, PE's point was that the minimum time for (near) maximum black is a good starting point for figuring out the development time for a film developer combination.
I am going to do some more testing just for my own curiosity and understanding. Shoot the same scene and do part of the roll at 4 min, 7 min, and 10min. Just to get a better understanding of the overall effects that developing time has.
I did some more daylight testing out to 15 mins, from 11-15 mins each gets denser, but still able to see a light bulb. I also did another test trip for an hour, and you still can not see the lightbulb threw the film.
Does this mean that you can overdevelop your film to be too dense?
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