View Full Version : Tri-x & scanning

6-Oct-2007, 04:43
Just moved from the city to the country and now have a septic tank. So now I send
4x5 Tri-x out to a lab for processing, then scan using Epson 4990 and then on to
phoshop. My question is do I need the lab to process N- & N+ or can I have them all
at normal devopment. It can be quite expensive. Also any thoughts on processing
with a septic tank.


Jim Jones
6-Oct-2007, 05:39
The small amount of chemicals necessary to develop film shouldn't hurt a septic tank. However, there may be local laws to consider.

Joseph O'Neil
6-Oct-2007, 06:17
The real danger, if you call it that, to your septic system is the silver in your fix. You see, silver is a natural anti-biotic, and if it kills off the bacteria in your septic system, that's how and when you have problems.

so what you do is this - before disposing of your developer, add a tiny bit of stop bath - or even plain old white vinegar - before disposing of your developer as the acid will help chemically neutralize it a bit.

Secondly, look at using a more dilute developer solution coupled with longer developing times. The less actual concentrate you pour down the drain the better, and i find that using a more dilute developing solution gives you more control over N- and N+.

Last, get a large pail with a lid, and pour your used fix into it. Look into previous threads about silver recovery that you can do yourself- the simplest is throwing a steel wool pad into the exhausted fix, but there are other methods, One you remove the silver or most of it you can dump your used fix into your system.

Ah - I think I've said this before, but if you do kill the bacteria in your septic tank somehow, our old family "cure" for a septic system gone dead was to get a stinky road kill off the highway and throw it in the tank - I'm told that always worked the best. Your mileage may vary. :)


Bruce Watson
6-Oct-2007, 08:12
My question is do I need the lab to process N- & N+ or can I have them all at normal development.

If you are sure you'll never print the film in question in the darkroom, then you can skip the push/pull dance. Actually, if you can get the lab to agree, your "normal" can be their N-1. This is just an extension of the idea that you want your film to be just dense enough to allow you to make the prints you want and no denser. With a scanner-only workflow, this level is typically less dense than with a darkroom workflow. Has to do with Callier Effect, local contrast in the more dense regions, all that. It's been discussed before and is floating around the archives for your searching pleasure.

For the record, that's what I'm doing myself. I develop my 5x4 Tri-X to what would normally be an N-1 (I aim for a Zone VIII density of around 1.0 instead of the more conventional 1.2-1.3). I do this with all my film. I call this "expose for the shadows and let the highlights fall where they may" processing. I stress that this is an optimization for scanning. Don't do this if you are *ever* going to print in the darkroom.

Brian Ellis
6-Oct-2007, 08:17
I've found that negatives a little flatter than I used to make seem to work best for scanning. So I almost never use plus times any more and have reduced my normal time by 10%. I do still occasionally minus develop but less often than I used to because of the controls available in Photoshop for dealing with very bright highlights. I don't use Tri-X, I use HP5+, but I think my experience is fairly typical across the board.

6-Oct-2007, 12:57
I'm in the habbit of under developing most of my negatives. With a full exposure (or sometimes a bit of over exposure) I develop with about 75% time length of what would probably be considered 'normal'. So this has become my 'normal', which I use on most of my negatives. I don't do any traditional printing, I scan in my Tri-X with a 4990, same setup as you.

If the scene is very low on contrast (only a few stops of latitude), I'll do a full normal (plus, for me) or even over development to spread out the values a bit. This is rare for me, as I usually end up shooting scenes with a good amount of contrast.