How much white light is allowed?

ChristopherCoy

Subscriber
Joined
Aug 9, 2011
Messages
3,599
Location
On a boat.
Format
Multi Format
As it turns out, I have a built in safelight in my darkroom. Doubling as a half bath/laundry room, I found I can use these 25w bulbs from centuries past that I found in my camera junk box.

However there is a little bit of white light at the base of the bulbs. Do you think this will affect paper from 3' away?



 

Rick A

Subscriber
Joined
Mar 31, 2009
Messages
9,883
Location
Laurel Highlands
Format
8x10 Format
I'm sure they will affect the paper, but do a proper safe light test to verify.
 

pentaxuser

Member
Joined
May 9, 2005
Messages
19,764
Location
Daventry, No
Format
35mm
It's a good question to which Rick has given a good answer. However in the U.K. you can get what looks like a dark brown/black plastic open fez-like cover that screws on to the bottom of the bayonet attachment and effectively covers the bottom of the bulb where the white light is.

I know you use Edison screw bulbs but there may be something that does the same job?

pentaxuser
 

RobC

Member
Joined
Nov 5, 2007
Messages
3,880
Location
UK
Format
Multi Format
red safelights were used way back when papers were graded and only sensitive to blue light. Today VC paper is senstive to blue and green over a much wider part of the spectrum. And papers are not all equal. You must test your safe light as Rick A says. And 3 feet is much too close anyway.
 

bdial

Subscriber
Joined
Jan 2, 2005
Messages
7,451
Location
North East U.S.
Format
Multi Format
I'm with Rick on this, most likely won't work.

Aside from the band of white, 25 W is probably a bit too much. I tried a 25 W (white) in my filtered safelight and it fogged.
However, you could try wrapping the white part with some electrical tape, the bulb base will likely stay cool enough that it won't be a problem.
In any case, the only way to know is to do a proper test.
 

Gerald C Koch

Member
Joined
Jul 12, 2010
Messages
8,131
Location
Southern USA
Format
Multi Format
Take a bit of black paint and paint over the clear space above the base before you do any testing.
 

gone

Member
Joined
Jun 14, 2009
Messages
5,505
Location
gone
Format
Medium Format
As mentioned, tape or paint will work fine. In addition, the wattage won't be as issue if you screw them into a lamp w/ a shade and address the opening at the top. Or, angle the light to the ceiling and bounce it back to your work area. It isn't the wattage, it's how much of it is getting to your area.
 

Rick A

Subscriber
Joined
Mar 31, 2009
Messages
9,883
Location
Laurel Highlands
Format
8x10 Format
My safe light is 15 watts behind a dark red filter, slightly over one meter away from my work area. My tests show I can have paper open for nearly half an hour before any noticeable flashing.
 

Ken Nadvornick

Member
Joined
Mar 18, 2005
Messages
4,942
Location
Monroe, WA, USA
Format
Multi Format

Christopher, the red ones of these are the 635nm bulbs I use that I referred to earlier. Inexpensive and highly effective, these are an excellent choice. They are a favorite of the carnival companies to light their amusement rides super inexpensively, and so will be around for a good while.

I have six in-line in a homemade fixture that all sit underneath a half-cylinder "dome" of a single sheet of Rubylith. Naked they fail the CD/DVD test by showing tiny spikes of blue and green, and have subtly fogged paper that way in the past. However, under the Rubylith those spikes disappear completely and almost none of the red is blocked.

These are the guys I safely tested with Ilford MGIV FB/RC for at least 60 minutes pre-fogged. Don't know how long I could have continued as I terminated the test at that point. The DIY fixture clamps magnetically to the top of my Thomas Duplex. The six bulbs are 5+ feet from my easel, and illuminate that easel indirectly via a white ceiling tiles, as the Duplex housing itself blocks direct light.

The Duplex gets used for graded paper. These red LEDs for VC paper. (And Slavich graded, which specifies red only.)

I get zero fog and ridiculously long safe times...

Ken
 

BobMarvin

Member
Joined
Oct 22, 2012
Messages
65
Location
Brooklyn, NY
Format
Medium Format
I used red bulbs when I first started printing in the late '50s, but they were a really dark red, specifically sold as safelight bulbs. The ones in your picture look like decorative red bulbs that would NOT be safe.
 

M Carter

Member
Joined
Jan 23, 2013
Messages
2,147
Location
Dallas, TX
Format
Medium Format
wildbill said:
Why bother when you can get a suitable bulb for $4.29?
http://www.freestylephoto.biz/12622-Halco-11-Watt-S14-Red-Safelight-Bulb
I've had this bulb as my only safelight for about 10 years.
Click to expand...

I have a pile of those, retired since the LEDs mentioned above became available. For the same cost you can get a heck of a lot more light in your darkroom with the LEDs.

I do almost nothing but lith printing though, so seeing the development through a fog of brown liquid is critical (and that's an understatement)!

Here's the LED's spectrum overlaid on an Ilford RC sensitivity spectrum (the only paper spectrum I could find quickly when I made this graphic for the Facebook lith group). Pretty impressive.

 

Attachments

  • spectrum.jpg
    58.6 KB · Views: 165
OP
OP

ChristopherCoy

Subscriber
Joined
Aug 9, 2011
Messages
3,599
Location
On a boat.
Format
Multi Format

RalphLambrecht

Subscriber
Joined
Sep 19, 2003
Messages
14,627
Location
K,Germany
Format
Medium Format

I agree with others and recommend a proper safelight test.a dab of red nail polish may cover your white spot on the bulb.
 
You must log in or register to reply here.
Menu
Log in
Register
Cookies are required to use this site. You must accept them to continue using the site. Learn more…