View Full Version : Wattage of darkroom light

16-Jan-2017, 06:33
I have a Johnsons of Hendon 5"x7" 'Always' darkroom light.
Does anyone know the correct/recommended wattage of lamp to use in it?


Len Middleton
16-Jan-2017, 08:18

Just to be clear, the fixture itself should have a MAXIMUM wattage rating, related to the heat dissipation capability of the fixture. That of course is NOT the one to use!

The actual maximum wattage that should be used will be dependent upon the effectiveness of the safe light filters and the distance the safe light is from unexposed light sensitive material.

You could do a test by putting a coin on a sheet of photo paper, leave it for a short while, then develop and fix to see if there is fogging of the paper by comparing it to where the coin was.

I use small low wattage appliance bulbs in my 5x7 Ilford and 10x12 Kodak safe lights.

Hope that helps,


Ted R
16-Jan-2017, 08:40
For my similarly sized Ilford safelight Ilford recommends about 15W

Doremus Scudder
16-Jan-2017, 09:45
I've used 15W bulbs in my 5x7 safelights. A 25W bulb heat-damaged the filter on one, so be careful!


16-Jan-2017, 12:13
So, the consensus it 15w or lower.
Thank you all, unfortunately there is no nor ever was any rating sticker label on the item


Jan Pietrzak
16-Jan-2017, 13:40

Along time ago, I was told to cut the wattage of safelights bulbs in half your eyes will adjust to the lower level of light.....the higher the wattage of the bulb the more chance of fogging your paper.....lower wattage saves the safelight filters....jan

22-Jan-2017, 21:51
I used the small 7.5w bulbs in my safelight. That was the smallest standard socket bulb that I could find.
But I had white walls and counters to reflect the light, so I did not need as much light as the BLACK painted darkroom at school.

Until I visited another high school's yearbook darkroom I did not realized how poor our high school's yearbook darkroom was setup. They had light paint on the walls, which reflected the safelight, and that made the darkroom sooooo much more pleasant to use.