Hacked Together Green Safelight - It actually works

[htmlguru4242]

I've been hearing / reading about using a green safelight for panchromatic materials for development by inspection.

I didn't want to go out and spend $20 - 50 on a safelight filter, so I figured I'd build my own. I had a really dark green plastic bottle (old vitamin bottle, I think) and some dark green translucent plastic banging around. I placed the green plastic over the bottom of the bottle, and wrapped the sides in black paper, so only the top would emit light. I cut a hole in the cap, placed a flashlight inside, and turned it on. Once in the dard, I placed the shaft of the flashlight in a paper towel roll, so it would stand straight up. This put green light onto the ceiling, which reflected it down to my work area. The area was bathed with a soft green light, which was more than sufficient to see what I was doing, and bright enough to see images on film. I thought that it would definetely be too bright, so, just for fun, I tested it with unexposed film. I placed a film holder on the counter (had Fortepan 200 in it), opened the dark slide and put some quarters on the film. After three minutes, I developed the film in the dark for half the time, with the green light for the other half.

There'd been SOO much light during everything that I figured that the film would be black. However, when I looked at the film under the green light, the area where the quarters had been was not much darker than base + fog, and the other areas were VERY slightly fogged.

I'll now see what happens when I do this with actual in-camera images ...

 

[Jadedoto]

That's actually exciting to hear. Just starting LF development (have a 4x5 and getting ready to build my 8x10), I've been thinking about how I dropped enough money on so many things that I just don't want to spend any more money. I've been thinking of starting the system out with green LED's (multipack, so I can have some more red ones for ortho work) and a filter...

Dont'cha love how everything can be hacked together so nicely (and cheaply!)

 

[john_s]

You're on the right track, but you might find that film that's already exposed in camera will be more sensitive to the green light because the threshold for minimal exposure will have been passed. Have a look at the Kodak pdf on safelight testing called, i think, "How safe is your safelight?" The testing procedure is perhaps more elaborate than most of us need, but it's worth a read.

 

[Jadedoto]

You're on the right track, but you might find that film that's already exposed in camera will be more sensitive to the green light because the threshold for minimal exposure will have been passed. Have a look at the Kodak pdf on safelight testing called, i think, "How safe is your safelight?" The testing procedure is perhaps more elaborate than most of us need, but it's worth a read.

(I totally revived an ancient post without noticing!)

Right, but the safelight would be used (in my case anyway) for DBI, so the exposure to the safelight would be quite minimal.

 

[kwmullet]

Also, you may see from time to time as people discuss DBI that some folks get all worked up about exactly what wavelength of green their safelight is. It has nothing to do with the spectral sensitivity of the film, your eyes are (probably) just more sensitive to green light than other colors, so green light ends up being more useful to inspect your film during development.

Another thing. My understanding is that the further into development you are, the less sensitive to light the film is, so a given amount of light is less likely to fog your film halfway through development than before development begins.

Typically, inspection starts about 3/4 of the way towards the anticipated end of development and only lasts for less than a second -- just long enough to assess if the highlights (darkest areas on the negatives) are well-established yet when viewing the base side, and deciding whether to develop further or stop. Exactly when you stop development depends on your taste in negative contrast.

The nicest thing about DBI is that once you use it, there are no surprises after you go light -- you've already seen your negatives develop, and you know what they look like before you finish your processing.

I use Kodak's dark green safelight filter, the appropriate wattage bulb (5 watt, I think) at about 3-4 feet. My best description of the amount of light it gives off is if you turn it on within a minute of going dark, you can only tell that it's on because you see very faint green highlights on objects where the safelight illuminates. After ten or so minutes of letting your eyes adjust, it casts enough light to see everything within 5-6 feet of the light, enough light to see the image on developed film, but not enough to read anything but the very largest printed type.

One of the most helpful resources I've found for DBI is reprint of a 1999 View Camera Magazine article by Michael Smith:
http://michaelandpaula.com/mp/devinsp.html

Good luck with the DBI,

-KwM-

 

[jim appleyard]

Glad it works! Back when I was a poor, starving photographer (not like I am today), I used to use red x-mas-tree lights in the darkroom. They work.

 

[htmlguru4242]

Wow, talking about reviving ancient posts! . I'd completely fogotten about this!

It does work though! And, Jim, I've used the red christmas light trick as well.

At this point, I'm also looking into LEDs to see if they can do anything useful. With their extremely low price, it's more than worth it to give them a try!