Exposure to light during during processing

[Michael Ting]

Doing 4x5 processing in trays, when is the earliest that you can turn on your darkroom light? I hate working in the darkness!

After out the developer tray? After out the stop tray? After 1 min in fixer??

I should do some experimentation on this, but want to know if anybody have actual experience with similar situations.

Would it be different, if you're developing an ISO100 film, versus ISO3200 film?

[Henry Friedman]

You must not expose to light until well into the fixing stage. I've read that one must wait until 1/2 the fix time is complete. But why not stick it out for the last 2 minutes? You've already invested a lot of time in your negatives; why take a chance on mucking them up?

[Michael Kadillak]

Purchase a relatively inexpensive infrared monocle with a headset and it will appear that the lights are on throughout the film developing process. The subject has been discussed extensively at michaelandpaula.com and here as well.

Cheers!

[Bruce Watson]

I thought that was what daylight processing tanks were for. I process in a Jobo 3010 drum partly for this very reason.

[Brian Ellis]

"You must not expose to light until well into the fixing stage. I've read that one must wait until 1/2 the fix time is complete. But why not stick it out for the last 2 minutes? "

Sorry but this is incorrect. Development stops after the stop. Fix is for permanence (it removes the undeveloped silver halides that, if left on the film for any length of time, would eventually discolor and ruin the negative). You could look at the negatives straight from the stop if you wanted to though you might not be able to see the image very well. I put mine in the fix and wait about 20 seconds before turning on the lights so that the negative will have cleared enough to see the image. You might follow Henry's suggestion about sticking it out for the full 4-5 minutes for the reason he gives, there's certainly nothing wrong with doing it, but personally I don't like to stand in the dark inhaling chemical fumes for any longer than I have to.

[Ole Tjugen]

According to the advice here, developing by inspection is impossible.

You can actually have a very weak (very, very, very weak!) light on beginning the last 1/4 of the developing without hurting the film. Just enough to get a glimpse of what you're doing, and maybe even see how development is coming along.

Remember that eyes adapt to the dark, film does not. It is amazing how much light does not fog film at all!

[Brian Ellis]

Michael - Sorry, I missed the last sentence of your question. No, it doesn't matter what the film speed is as long as it's been in the stop bath. However, if you dislike standing in the dark that much (as I do too) why not investigate tube processing via BTZS or home-made tubes or Jobo or daylight tanks?

Ole - I think most of us know about development by inspection. But there's no indication in the question that Michael is doing that.

[Doremus Scudder]

Brian,

Yes, stop bath arrests development, but, 30 seconds in the solution does not wash out residual developer. The residual developer can become active again under the right conditions. This is even more pronounced with an all alkaline process. With carried-over developer and an alkaline fix, turning on the lights before fixing is completely finished invites disaster. The unfixed halides are exposed to light and the carried-over developer, now active again since the environment is alkaline, begins to reduce silver again. This results in fogging and streaking. I have also seen this problem when a traditional acid-fix is close to exhaustion and the lights are turned on early.

I use acid stop, acid rapid fix and don't turn on the lights till the time for fixing (3x clearing time) is up.

Michael,

If you really hate working in darkness, do find a daylight tank or get a Jobo-type rotary processor. Turning on the lights early in the fix only saves a minute or so anyway.

Best,

[Brian Ellis]

"Yes, stop bath arrests development, but, 30 seconds in the solution does not wash out residual developer. The residual developer can become active again under the right conditions. This is even more pronounced with an all alkaline process. With carried-over developer and an alkaline fix, turning on the lights before fixing is completely finished invites disaster."

Actually neither the stop bath nor the fix "wash out" residual developer. The stop bath neutralizes any developer remaining in the emulsion, thus "immediately arresting development" (Adams, "The Negative," p. 191). "Carried-over developer" is of no importance from a light standpoint because it was neutralized by the stop bath. Once neutralized light in the darkroom can't cause it to somehow become unneutralized. The fix also doesn't "wash out" developer. The purpose of fixing is to remove unprocessed silver halides (i.e. those not converted to metallic silver in the developing process). Otherwise those halides will eventually discolor and ruin the negative. But even that doesn't happen in a matter of minutes under a light in a darkroom, it's a gradual process over a period of time.

I've been using the BTZS tubes for about ten years. Standard operating procedure when using tubes is to have lights on throughout the entire processing time, development, stop, and fix. During development while the lights are on the tubes are capped, then with the light still on the caps are removed, the tubes are placed in a container of stop bath (yes, even having light on when going from developer to stop isn't a problem if it's done quickly), then with the light still on the film is removed from the tubes and placed in a tray of fix. This is the way Phil Davis recommends the tubes be used and it's how I've been doing it for many years through thousands of negatives.

If you feel more comfortable fixing in darkness for the entire time by all means do so. But the original question was about the earliest possible time lights could go on and that's well before fix is complete.