TMax 400 Film Testing - ISO of 500
Hello! Recently, I decided to try developing TMax 400 in TMax RS at 1+9 dilution at 75 degrees rather than 1+3 at room temperature. For both setups I used continuous agitation with a Unicolor drum on a reversing motor base. Rather than going through extensive home testing, I used the BTZS kit. They sent five pre-exposed sheets of a calibrated step wedge which I developed and returned.
The rated film speed of TMax 400 was about 500 with the BTZS test. This ISO agrees with my own testing when I tested film speed using TMax 400 and 1+3 dilution of TMax RS. I measured the film density with a spotmeter. Though not terribly exact, there was a distinct increase in density between an ISO of 330 and 400, but minimal between ISO of 400 and 500. I called the ISO 400 since that agreed with Kodak.
Since I've read that most folks rate TMax 400 at an ISO of 320, I'm curious about these results that show TMax has an ISO of 500 with my setup. Have folks found TMax 400 faster than stated instead of slower? Looks like I should rate the film at ISO 500 for my setup instead of 400. Best regards.
Mike
Re: TMax 400 Film Testing - ISO of 500
I also develop Tmax 400 in Tmax RS at 1+9 and 75 deg. However I tray process with aggitation 10 s every minute instead of using the drum. I am one of those people that exposes it at ISO 320. I started using this technique several years ago after picking it up at a John Sexton workshop. I have gotten good results exposing for ISO 320, but have never formally tested it. I can say that with Tmax 400, underexposure is much more difficult to recover from than over exposure. If you want to consider making ISO 500 your standard I would make an extra exposure at ISO 320 for a while until I was sure ISO 500 was correct for your setup.
Re: TMax 400 Film Testing - ISO of 500
After testing, I rate Tmax-400 at EI 250 in ID-11 1+1. I have never tested a film to be faster than the box speed. Most are 1/3 or 2/3 f/stops slower.
Re: TMax 400 Film Testing - ISO of 500
I get the same EI 500 with TMY and 510-Pyro.
Jay
Re: TMax 400 Film Testing - ISO of 500
Perhaps, I'm mistaken here but isn't the true EI of a film a function of the film, your lens, your meter, and your method of development?
For example, a slow shutter speed will influence the EI differently than a shutter right on the money. As a result, the EI of the film can be all over the place depending on the factors mentioned above.
Please correct me if I'm mistaken here. :)
Thanks
Cheers
Re: TMax 400 Film Testing - ISO of 500
"Perhaps, I'm mistaken here but isn't the true EI of a film a function of the film, your lens, your meter, and your method of development?"
The View Camera Store uses the BTZS method of testing, which varies a little from traditional zone system testing and among other things doesn't rely on in-camera shutters for the testing (a good thing considering the number of shutters some of us own and the degree to which the various speeds may be off). It's been too many years since I used the BTZS method for me to remember enough about it to be able to explain why particular shutter speeds are unimportant with it but I know they aren't because the film isn't exposed in camera, it's exposed in an enlarger with a shuttered lens.
Re: TMax 400 Film Testing - ISO of 500
Quote:
Originally Posted by Brian Ellis
"Perhaps, I'm mistaken here but isn't the true EI of a film a function of the film, your lens, your meter, and your method of development?"
The View Camera Store uses the BTZS method of testing, which varies a little from traditional zone system testing and among other things doesn't rely on in-camera shutters for the testing (a good thing considering the number of shutters some of us own and the degree to which the various speeds may be off). It's been too many years since I used the BTZS method for me to remember enough about it to be able to explain why particular shutter speeds are unimportant with it but I know they aren't because the film isn't exposed in camera, it's exposed in an enlarger with a shuttered lens.
Hello Brian,
Thanks for the info. I'm afraid I'm a little confused as to how the process works. So, if The View Camera Store provides you with five pre-exposed sheets of a calibrated step wedge, which is developed and returned... there must be a step in between that I'm not familiar with. I'm not sure how this relates to a pack of TMax that you will be using.
I'll have to do some homework on this... :) Interesting!
Cheers
Re: TMax 400 Film Testing - ISO of 500
Denistometry is wonderful, but you might want to try shooting a "real" photo, and take it all the way to the final print.
Choose a subject in the sunshine, with shadows, flesh tones and other recognizable shades. See what happens when you shoot at 100, 200, 400, 500, etc. Some people like detail in the shadows, while others like a "snappier" look.
See which film speed gives the best results. It's your thermometer, your water, your agitation technique, etc.
Re: TMax 400 Film Testing - ISO of 500
Quote:
Originally Posted by Capocheny
Perhaps, I'm mistaken here but isn't the true EI of a film a function of the film, your lens, your meter, and your method of development?
For example, a slow shutter speed will influence the EI differently than a shutter right on the money. As a result, the EI of the film can be all over the place depending on the factors mentioned above.
Please correct me if I'm mistaken here. :)
Thanks
Cheers
I hope not, because with several meters, several cameras and many lens shutters, I would have about 150 slightly different Ei for every film. I consider film, developer and technique to be the significant variables. The others go along for the ride.
Re: TMax 400 Film Testing - ISO of 500
Quote:
Originally Posted by Ralph W. Lambrecht
I hope not, because with several meters, several cameras and many lens shutters, I would have about 150 slightly different Ei for every film. I consider film, developer and technique to be the significant variables. The others go along for the ride.
Hello Ralph,
I'm a bit intrigued by the BTZS process used by The View Camera Store and will have to look into it. But, I thought the "process" of determining the true EI tied "everything" together. Or, at least, under the Zone System it does.
But, Ken's method sounds like a logical one... and more fun! :)
Cheers