Jump to content

Has anyone tried Lab-Box, a daylight film developer tank?


terrymc

Recommended Posts

Green is the safelight (#3) for develop by inspection for black and white film.

 

The idea is that enough of the sensitizing dye has washed out, at halfway though,

and that the eye is most sensitive to green.

 

Color negative papers and Panalure have a sensitivity minimum near 600nm,

allowing for a dim safelight near that point:

 

http://wwwru.kodak.com/global/en/professional/support/techPubs/ti0845/ti0845m.gif

 

they call this amber, though the filter looks closer to brown, or black if you

look at the glass without light behind it. Minimum density is about 2.5.

 

Color negative paper only needs to respond to the light coming through a color negative.

 

For some reason I don't know, Ektachrome paper doesn't have this property.

-- glen

Link to comment
Share on other sites

  • Replies 62
  • Created
  • Last Reply

Top Posters In This Topic

Gary Naka, "It [the darkroom] was white and light green (no idea why the light green)."

 

Green is the color of safelights used with color processing. That may have been part of the answer.

 

What had/has me confused was that the bottom half of the wall was light green, the top half was off-white.

I never thought to ask the staff or yearbook advisor if they knew why the paint color scheme.

 

I don't know if they ever did color processing in the darkroom. I think it was B&W only. But again another question that I did not ask. But I do not recall if the enlargers had a color head. I really should have taken a pic of the darkroom.

Link to comment
Share on other sites

  • 2 years later...
You do have a point about the difficulties of loading film onto a reel--I teach a beginning B&W film class at a community college and the thing my students have the hardest time with is learning how to load film onto reels. With our budget we're not about to invest in the number of Lab-Boxes we would need along with the additional chemistry we would use with them, though, particularly since virtually all of our students learn how to successfully load steel reels and tanks.

 

I wish I was near, so I could take that beginning B&W film class just to learn darkroom basics. And I'd accept you as an instructor. Anyone around Knoxville, TN is welcome to teach me some basics. I want to learn this. And meeting another Photo.net member icing on the cake.

Link to comment
Share on other sites

' date=' post: 5919858, member: 10999298"']I wish I was near, so I could take that beginning B&W film class just to learn darkroom basics. And I'd accept you as an instructor. Anyone around Knoxville, TN is welcome to teach me some basics. I want to learn this. And meeting another Photo.net member icing on the cake.

I'd be happy to teach you, but I live in upstate NY so the commute might be a bit much...

  • Like 1
Link to comment
Share on other sites

' date=' post: 5919858, member: 10999298"']I wish I was near, so I could take that beginning B&W film class just to learn darkroom basics. And I'd accept you as an instructor. Anyone around Knoxville, TN is welcome to teach me some basics. I want to learn this. And meeting another Photo.net member icing on the cake.

Lesson #1

Ignore any 'instructional' film-processing videos on YouTube. I've yet to see a single one made by someone that actually knows what they're doing or talking about!

Buy an old book on the subject, written in the days when film was the only way to take a photograph.

Lesson #2

Your best tool for learning how to use film is a digital camera. Because apart from all the chemical slopping about, the camera skills are all directly transferable between digital and film... Except it takes a fraction of the time to see the result of your triumphs and mistakes with a digital camera.

  • Like 1
Link to comment
Share on other sites

All totally irrelevant since the invention of LEDs I'm afraid Glen.

 

I suppose so, but there are still a lot of the old kind around.

And besides, our house came with four of them.

 

The #13 has a very narrow transmission, where most color negative papers are

less sensitive, and, as I knew some years ago, where some LED also worked,

but also cost a lot more. But also at about 590nm, amazingly close to the line

for low pressure sodium lamps. But how hard is it to find a yellow LED right

at that line?

 

Reminds me, in some other group, someone asked why spectrophotometers are so expensive.

But it seems that you can find a used one for about $100. There are a lot of them out there,

in case anyone wants one.

-- glen

Link to comment
Share on other sites

Reminds me, in some other group, someone asked why spectrophotometers are so expensive.

But it seems that you can find a used one for about $100. There are a lot of them out there,

in case anyone wants one.

The price of spectrophotometers dropped right after linear array CCD sensors made an appearance in flatbed scanners, and someone thought "Hang on a minute! Add a prism or diffraction grating to that, and I might be on to something..."

 

Also. Nothing magical about the Sodium D lines. A near-monochromatic amber LED - or several at pennies each - will serve just as well. It's only film photography for chrisake. Not anything important.

Edited by rodeo_joe|1
Link to comment
Share on other sites

The price of spectrophotometers dropped right after linear array CCD sensors made an appearance in flatbed scanners, and someone thought "Hang on a minute! Add a prism or diffraction grating to that, and I might be on to something..."

 

(snip)

 

It has been a while since I used a spectrophotometer, since before high resolution CCD arrays.

 

The usual ones have a sample and reference, usually liquid in cuvettes, but I do remember putting something non-liquid in one.

 

In the liquid case, it measures (the log of) the ratio between the beams through the two.

That is, the absorption of whatever is in the liquid solvent, but not of the solvent itself.

 

One that I found out learning about densitometers, (well, I might have already known this) is

that the current through a PMT is proportional to light intensity, and exponential with voltage.

 

In the case of densitometers (this is the one I didn't know), you run them at constant current,

and the voltage is proportional to the log of the intensity, and over a reasonably large range.

 

Well, log amplifiers are not that hard to make, but you want the system to work well over

a large range of intensity, which happens easily that way.

 

The thing I remember most about the spectrophotometer from so many years ago, is that

the manual was written in Japanese English. (I hope I don't have to explain that.)

In any case, you want accurately measure the light through the sample and reference

at the same wavelength.

 

Not so much later, I bought my first Epson printer. (Not so long after they came out.)

Epson figured out that they should not write the manuals in Japanese English.

However, I also bought the service manual for the printer, which is in Japanese

English.

 

But okay, if you measure the spectrum of the reference, store that, then measure

the sample, that avoids some complicated optics to measure both at the same time.

And the CCD doesn't remove the complication of a high quality diffraction grating.

 

As well as I know, good ones want to measure over four orders of magnitude

(absorption constant of 4), which is not so easy, and I think most scanners don't

do that. But for many cases, you might not need that much.

-- glen

Link to comment
Share on other sites

(snip)

Also. Nothing magical about the Sodium D lines. A near-monochromatic amber LED - or several at pennies each - will serve just as well. It's only film photography for chrisake. Not anything important.

 

As well as I know it, you want to be pretty close to 590nm.

 

I suspect grabbing a random amber LED might not be that good, but most do publish

the spectrum, so you could select a model that was close enough.

 

You can see the dip in the spectral response of photo paper, though they usually

don't put so accurate a scale on it as you might want.

 

https://asset.fujifilm.com/www/us/files/2020-02/58a3cafc83258dfc2560379e38fab76b/Fujicolor_Crystal_Archive_Paper_Type_DPII.pdf

  • Like 1

-- glen

Link to comment
Share on other sites

Who mentioned Crystal Archive colour paper?

For multigrade B&W paper you can use almost any old Red or Amber LEDs in your junk box. Or even a mixture of both.

 

And if you are printing Fuji CA paper, then there are LEDs specifically engineered to mimic LP sodium lighting.

Expensive, agreed, but if your budget doesn't run to that, there's this, specified as having an emission in the range of 590 to 595nm.

Link to comment
Share on other sites

Yes with black and white paper, even VC paper, there are a lot of choices.

 

For color paper, much less choice. I do have an actual #13 safelight, though.

I suspect you can't get away with the 240W for the one you show.

 

I mostly used my #13 with Panalure, but it has been used with some Kodak color paper.

In either case, it isn't very bright. It should be called a safe-dark, as that is closer to

what it does. I once dropped the paper on the floor, and couldn't find it.

 

And then there is (was) Ektachrome 1993 paper, with no safelight allowed.

-- glen

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now



×
×
  • Create New...