I have done night exposures of up to about an hour using TMax 100. I have also been thinking about working up a system for Acros 100, but have gotten distracted by other endeavors. Both TMax 100 and Acros 100 have far better reciprocity characteristics than more traditional films, so for this kind of exposure, they are faster than most 400 speed films. I think that Acros is the better of the two for reciprocity.
I am not sure that I understand exactly what your objective is. If you truly need a 3 to 4 hour exposure and your scene includes people moving while carrying some sort of lanterns, I cannot see how the people will record. It seems that you will have many streaks of light on the film from the moving lanterns, but no evidence of what is moving them.
I am not sure that I understand exactly what your objective is. If you truly need a 3 to 4 hour exposure and your scene includes people moving while carrying some sort of lanterns, I cannot see how the people will record. It seems that you will have many streaks of light on the film from the moving lanterns, but no evidence of what is moving them.
Does Velvia 100 go green like it's 50 cousin? -K
Marco, when you say that you "visually" checked the densities, are you saying that you did measurements of the tonal ranges, not just how dense the neg looked, with a densitometer? Checked the total range, including FB&F, not just zone I? Higher speed films tend to look denser than slower speed films regardless of reciprocity. I am willing to bet that the FB&F of the T-Max400 is already higher than that of the Acros, and would lend a look of greater density to begin with.
In looking at the reciprocity failure data reported by Kodak and Fuji, for exposures of 100 seconds in length, Kodak does not indicate ANY times longer, the correction for Tmax 400 is 1 1/2 stops. So the effective EI drops to about 150 for a less than 2 minute exposure.
For Fuji Acros the data given is for exposures up to 1000 seconds, or nearly 17 minutes, and the correction recommended by Fuji is only 1/2 stop, or an effective EI of 50. However the data also indicates that NO compensation is required for exposures shorter than 2 minutes. Whereas the T-Max 400 a +1/3 at 1 sec, a +1/2 at 10 seconds, and a plus 1 1/2 at 1000 seconds. This indicates to me that compared to the fuji, there is a more rapid decrease in film sensitivity as exposure time increases, whereas the fuji seems to stabilize.
Fuji Acros has a RMS granularity value of 7, and a resolution of 60 LP/mm, T-max400 has an RMS of 10 and a resolution of 50 LP/mm. Personally, I'd rather wait a little longer, or open up a half a stop, to use a superior film.
For Fuji Acros the data given is for exposures up to 1000 seconds, or nearly 17 minutes, and the correction recommended by Fuji is only 1/2 stop, or an effective EI of 50. However the data also indicates that NO compensation is required for exposures shorter than 2 minutes. Whereas the T-Max 400 a +1/3 at 1 sec, a +1/2 at 10 seconds, and a plus 1 1/2 at 1000 seconds. This indicates to me that compared to the fuji, there is a more rapid decrease in film sensitivity as exposure time increases, whereas the fuji seems to stabilize.
Here's one result.
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