100 shot at 400

Arthurwg · May 22, 2023

I made a foolish mistake, inadvertently shooting a roll of T-Max 100 at ISO 400. As these pictures are important to me, how should I process them? They were shot in strong light if that makes a difference. My guess is to push it two stops. What do you think?

MattKing · May 22, 2023

1) Choose a speed enhancing developer like Microphen or T-Max developer;
2) If they exist, follow the manufacturer's recommendations for that film and developer combination, with the film exposed that way.
You say "shot in strong light". Does that mean contrasty light?
How important to your images are the details in the shadows?
How did you meter the scene?

albada · May 22, 2023

If you don't mind mixing your own developer, my tests show that with T-Max 400, Crawley's FX-37 diluted 1+5 gains one stop of true speed compared to D-76. FX-37 was designed for t-grain films, so it should perform well with T-Max 100 as well.
Among commercial developers, I suspect Microphen diluted 1+1 would provide a significant speed-boost, but I haven't tested it.

Mark

Paul Howell · May 22, 2023

With most developers from 100 to 400 is a 2 stop push, with Acufine Tmax 100 is exposed at EI of 200, so that is a one stop push, at 200 recommend development time is 4.5 m, add 30% for 1.34 m for one stop push and develop at 4.8 so round up to 5 mints at 68 degree, would be my best guess.

RalphLambrecht · May 22, 2023

Arthurwg said:
I made a foolish mistake, inadvertently shooting a roll of T-Max 100 at ISO 400. As these pictures are important to me, how should I process them? They were shot in strong light if that makes a difference. My guess is to push it two stops. What do you think?

a two-stop underexposure is deadly for the shadows. Pushing will not recover them but it may give you at least an image. Don't expect high-quality images. Sorry for your loss!

Alex Benjamin · May 22, 2023

MattKing said:
Choose a speed enhancing developer like Microphen or T-Max developer;

Agreed. My choice is Ilfotec DD-X in such cases. MDV has 11.5 mn for T-Max 100 at 400.

Arthurwg · May 23, 2023

All very helpful. Thanks.

mtnbkr · May 23, 2023

FWIW, I did the same thing last year due to a meter miscalibration (3rd party meter was wrong from the factory) and was able to salvage the 2nd roll of 2 by push processing 2 stops in Cinestill DF96 (the only developer I use at the moment). The images were usable, but not great.

Chris

pentaxuser · May 23, 2023

I bow to those who have greater knowledge but I have seen some very OK shots of HP5+ at 1600 which is 2 stops under so is there any reason to think that T100 at 400 especially in a speed enhancing developer will fare any worse?

I remain fairly optimistic for you, Arthur

pentaxuser

Paul Howell · May 23, 2023

I would need to compare the data sheets, but HP5 might have a straighter curve and less contrast than Tmax 100? I get really good push process results with Tmax 400, no increase in time to 800, at 1600 more like a +1 or 1.5 push then 2. I have experimented with Tmax 100 and a push, there is noticeable loss of shadow details at +1 and +2 no shadow details to speak of. That's why I would use a speed enhanced developer, Aucfine would be my choice only because I have experience with it. Tmax 100 has such fine grain that I don't grain will be noticeable in Acufine, or another such as Tmax developer, DDX, or Rodinal for that matter.

Agulliver · May 24, 2023

I would think you'd have best results developing in Microphen or another speed enhancing developer. I regularly push B&W film a couple of stops, though more commonly film with box speed of 400. There might be issues with shadow detail but that's where good darkroom/software use comes in. T-MAX 100 should have published times for various developers at 400, but I'd specifically recommend Microphen.

Arthurwg · May 25, 2023

Fortunately shadow detail won't be an important part of these pictures.

pentaxuser · May 25, 2023

Arthurwg said:
Fortunately shadow detail won't be an important part of these pictures.

It'll be nice to see them Arthur as long as you feel able to show us as it will give us a feel of what TMax100 at 400 is like

Thanks

pentaxuser

titrisol · May 25, 2023

Arthurwg said:
I made a foolish mistake, inadvertently shooting a roll of T-Max 100 at ISO 400. As these pictures are important to me, how should I process them? They were shot in strong light if that makes a difference. My guess is to push it two stops. What do you think?

TMAX100 with 2stop pushing?
Since shadows are not important to you, use a fresh developer and give it a conservative 2+ development.
It will give you an image.

Agulliver · May 26, 2023

Just FYI, the phone app "film developer pro" that I use (which I think taps into the MDC) suggests 11 minutes at 20C in Microphen for T-MAX 100 at 400. Plenty of other developer options are available, but I'd choose Microphen for this if possible. It's just designed for pushing.

I don't predict any significant problems if you're not specifically looking for shadow detail. Negs may come out quite contrasty but that can be tamed in the darkroom or on the computer. Or maybe that's what OP is looking for anyway.

100 shot at 400

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