Anyone Tried Using LED Replacement Bulbs vs. Incandescent for Contact Printing?

[analog65]

I was thinking and wondering how LED replacement light bulbs would work or not work, as a light source for making contact prints versus the normal incandescent bulbs?

Anyone tried this yet?

If so, what have you discovered?

 

[Fr. Mark]

I used daylight balanced t8 fluorescent bulbs with ancient Azo paper it works. I stuck an LED bulb also daylight balanced in an enlarger and had way too short printing times. I think printing paper may be too blue sensitive. Hopefully someone who really knows will answer.

 

[analog65]

Yes, it is an interesting question.. I am hopeful someone has already tried it and can comment, but if not, I will just go buy a bulb and try it.

I used daylight balanced t8 fluorescent bulbs with ancient Azo paper it works. I stuck an LED bulb also daylight balanced in an enlarger and had way too short printing times. I think printing paper may be too blue sensitive. Hopefully someone who really knows will answer.

 

[analog65]

contact prints via a LED light bulb (not installed in an enlarger)

I just found an article online where a guy tested it and verified that it works.

Question was answered. Now I will go find a bulb and dimmer to give it a try in my own darkroom.

Thanks

The OP has not said whether he’s using Contact Paper or Enlarging Paper and also has not said if he’s using an enlarger for exposures.

Have a look at Kodak's Tech. Bulletin G-10 (for AZO paper):
http://www.kodak.com/global/en/professional/support/techPubs/g10/g10.pdf
In particular this paragraph:

"Contact printers generally have a very high level of illumination. In order to keep exposure times within reason, contact printing papers, such as AZO Paper, are made with a relatively low speed. Therefore, it’s not practical to use contact papers with an enlarger as a light source." [Presumably because enlarger light sources are not considered bright enough for contact papers].

Contact papers are silver chloride graded emulsions and are very slow papers. Graded enlarging papers are silver chloro-bromide emulsions with much faster speeds. Graded papers respond to blue illumination, variable contrast papers to blue (for high contrast) and green (for low contrast).

Most of us use a simple incandescent bulb for contact papers and rig it so its distance from the paper can be varied to keep the exposures reasonable.

I’ve not tried LEDs with contact papers or graded papers, but I’d expect LEDs with lumen output comparable to incandescent should work as long as the spectral distribution contains sufficient blue.

 

[MartinP]

Just something to know - the Foma Fomalux silver-chloride contact-paper is about five stops slower than their normal papers, so it 'could' be usable for projection printing with an enlarger, depending on the size of the print, the power of the light-source, the stability of the enlarger and with good stray-light hygiene.

 

[DREW WILEY]

I've enlarged onto Azo papers using an ordinary colorhead no problem. Maybe if you have an old opal lamp condenser head and a slow enlarging lens, no. But LED is less bright than typical halogen. I know... I know....people argue with me all the time about that. They seem
real bright; but side-by-side, no. I do my homework.

 

[Tim Layton]

Yes, and it works good. Here is an article that I wrote about it at http://www.timlaytonfineart.com/blo...ght-bulb-for-contact-printing-in-the-darkroom

I was thinking and wondering how LED replacement light bulbs would work or not work, as a light source for making contact prints versus the normal incandescent bulbs?

Anyone tried this yet?

If so, what have you discovered?