Kodak T-Max 100 Sheet Film Long Exposure

[IanBarber]

I shall be attempting some coastal long exposure this week with Kodak T-Max 100 and a 10 stop ND filter.

Exposure times are estimated to be between 2 - 5 minutes.

Does anyone know if there is any contrast increase with this film when using long exposure times. I thought I read somewhere that Kodak says no but cannot seem to find where I read it.

Ian

[Michael Rosenberg]

Ian,

For that length of time you can expect about a 2-1/2 stop increase in contrast. There are charts floating around giving reciprocity and increase in exposure contrast. Try Unblinkingeye web site, and also Barnbaum ARt of Photography book.

Mike

[IanBarber]

Ian,

For that length of time you can expect about a 2-1/2 stop increase in contrast. There are charts floating around giving reciprocity and increase in exposure contrast. Try Unblinkingeye web site, and also Barnbaum ARt of Photography book.

Mike

Thanks Mike. That's more than I had hoped for. I know Fuji Acros would be the best choice here but I only have FomaPan and T-Max 100.

I Might have to rethink this one through

Ian

[loonatic45414]

You could always adjust development (or wait for the right lighting) to lessen contrast.

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[Jim Jones]

Ian, see page 20 of https://www.scribd.com/document/137483802/Kodak-Tmax-Data-Sheet.

[Kevin Crisp]

I don't make really long exposures that often, but when I do it is one of the rare times I shoot two identical negatives. Develop the first one and decide if I need to cut more time off it to tame the contrast. The first one will get 15 to 20% less time than normal.

[loonatic45414]

I like this idea. If you're going to shoot this regularly, you could work up some test curves at the new exposure.

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[Corran]

Done lots of long (longer than you are talking about) exposures on T-Max. Follow the reciprocity chart and findings and cut development for 15-20% every extra stop given for correction. Bracketing and multiple shots per scene is definitely recommended.

[IanBarber]

Ian, see page 20 of https://www.scribd.com/document/137483802/Kodak-Tmax-Data-Sheet.

Thanks Jim, will go and have a read

[IanBarber]

The first one will get 15 to 20% less time than normal.

Is this to compensate for the increase in contrast due to the length of the exposure

[Kevin Crisp]

Yes. I think that is on the reciprocity table from Kodak. If anything, on the second sheet I take some more time off. It is never too thin at 15-20% off. A lot of times it is just fine on the first sheet with this adjustment. Actually the whole process is rather forgiving.

[Doremus Scudder]

Ian,

The above advice seems sound. Kodak recommends reducing development for longer exposures. My rule-of-thumb is to develop one N-number lower for each doubling of the corrected exposure time in relation to the metered time. Example: if my meter says 15 sec and my correction table says 30 seconds, I'll develop N-1 for a situation that otherwise metered "N". The tables I use are based on Kodak's recommendations and Howard Bond's tests from some years back and confirmed and adjusted by experience in the field. I don't have to even think about developing N-2 until total exposure time gets longer than about 10 minutes (the above is all with 320 Tri-X - with T-Max I don't worry about adjusting development down until total time is more than 4 minutes).

Very often, a scene that needs long exposure is fairly flat anyway, and the contrast increase provided by the reciprocity law failure is welcome. I find that the contrast increase of scenes from reciprocity law failure is different that simply increasing development and often more pleasing/dramatic, so sometimes I'll use an ND filter to push the film into reciprocity failure instead of indicating an N+1 development.

Also note that Howard Bond, whose 2003 article on reciprocity failure adjustments can be found here: http://phototechmag.com/black-and-white-reciprocity-departure-revisited-by-howard-bond/ , says that no development adjustment is needed at all up to the limits of his testing. If you're just getting started doing this, you might want to pick a middle time between N and whatever development adjustment is indicated by whatever rule-of-thumb you decide to use. You can then adjust as needed later and your negatives will certainly able to still be printed at a higher or lower contrast than normal.

Best,

Doremus

[IanBarber]

with T-Max I don't worry about adjusting development down until total time is more than 4 minutes).

Is this because of the characteristics of T-Max compared to other films Doremus

[John Layton]

You've mentioned that you are doing "coastal" photographs with a strong ND filter - so I'll assume that this may involve ocean waves crashing over rocks. With this in mind, you may find that your "standard" equation of N- exposure and development will be modified to some degree...as you consider that your highlight detail, in this case represented as foaming surf, will be in constant motion, and thus tonalities may be constantly changing. Furthermore, you may find that the rocks which might underly some of this surf become intermittently exposed (perhaps for a significant portion of your total exposure) are actually quite dark, and thus the "net tonality" will likewise be rendered somewhat darker than a spot reading of an otherwise "white" area of foaming surf might indicate. This will work out in your favor, and allow you to "dial back" your overall adjustments to exposure and development, at least somewhat, and at least when compared to a situation, such as a waterfall, where the highlight densities don't exhibit such a great degree of relative movement. Something to keep in mind!

[Pere Casals]

Is this because of the characteristics of T-Max compared to other films Doremus

Of course there are films with more or less reciprocity failure. For example Neopan Acros never need developing adjustments because reciprocity failure, as it is very low. TXP may need adjustments sooner than T-Max.

This may be because tabular grains have more relative surface than cubic, and dye sensitization works stronger because more sensitizing dye is in contact with silver halide chrystalls, also I guess it depends on what sensitizing dyes are used. Today b/w films benefit (more o less, depending on film) from sensitizing dyes discovered for color film. Still somebody of the kind of Ron Mowrey is who can speak about all that.

Note that re-engineered today's TXP is semi-tabular, not a pure cubic grain film like in the past.

I'd like to point that, while what Doremus stated is more than enough in practice, you can also calibrate your film for reciprocity failure conditions.


Normally BTZS film calibration is made with an exposure of around 1s, but illumination power can be reduced to 1/100 while will be exposed during 100s,.

In this case you will get an alternative family of curves that are different from the case when exposure was 1s and illumination was 100 times stronger.

Then if you metter different spots of a scenes (to be exposed 100s) that alternative familly of curves will tell you what density will deliver on negative every spot of the scene, giving you absolute control of the process.

This long exposure calibration may be useful for photograpers that do a lot of long exposures, still with experience those photographers may simply guess the result, or better, they can use Neopan Acros that has very, very low reciprocity failure, so no need to correct development to control contrast.



Acros it also has another advantage, beyond contrast control... scene dinamyc range that can be captured do not decrease with long exposures. Other films compress shadows, and this is not corrected by development, as reciprocity failure acts as a toe cutter.


So for very long exposures simply consider Acros. In that case it is well worth.