DIY safelight

[RalphLambrecht]

The problem with certain red safelights

The Herschel Effect

If a photographic emulsion is exposed to blue light and subsequently to red light before development, some of the effect of the original exposure are destroyed; this was discovered by Sir John Herschel in 1840.

While this can in theory affect all modern B&W paper emulsions it really only causes problems with VC papers when the wrong safelight is used (too close or at too high an intensity) while the red light may be insufficient to cause physical fogging, but enough to seriously affect the contrast grades achievable.

The early emulsions Herxchel worked with where of course all blue sensitive.

Ian

Ian

Wouldn't this be the opposite of fogging?

 

[Ian Grant]

Maybe, it's called latent image bleach, but it's a detrimental effect of the safelight and often gets overlooked when people wonder why they can't achieve a full range of Contrasts with some VC papers. Some safelight filters are worse than others.

It's fogging in the sense that it's unsafe exposure to too much red light of a harmful intensity.

Ian

 

[joe7]

thanks all for replying,very appreciate it.

 

[Mark Fisher]

Well, I'll have to pipe in.....consider simple screw in LED lights. I use the OptiLed red and amber 2.5W Festival series lamps. I've found that they are extremely bright and very safe. I use them for lith printing and keep them on the entire development cycle (10 minute range). My darkroom is about 10' x 6' and one lamp is adequate (2 better). I can't imagine using anything else.

 

[DeBone 75]

I use a DIY safe light made out of a 3 lb. coffee can with a red lid. I use a 15 watt bulb. Works for everything, paper and X-ray film. I have it about 4' from the enlarger and 9' from the dev trays.

 

[RalphLambrecht]

Well, I'll have to pipe in.....consider simple screw in LED lights. I use the OptiLed red and amber 2.5W Festival series lamps. I've found that they are extremely bright and very safe. I use them for lith printing and keep them on the entire development cycle (10 minute range). My darkroom is about 10' x 6' and one lamp is adequate (2 better). I can't imagine using anything else.

Are they different from what laphro suggested in post #20?

 

[joe7]

I use a DIY safe light made out of a 3 lb. coffee can with a red lid. I use a 15 watt bulb. Works for everything, paper and X-ray film. I have it about 4' from the enlarger and 9' from the dev trays.

it's a good idea to use the coffee can..never thought about it before,any other suggestions/ideas?just let me know,i'll consider it
thanks

 

[salihonba]

Or a 100 pc empty DVD cake box, a 15 watt bulb inside, orange/red plastic layer outside the cone.

 

[Mark Fisher]

Are they different from what laphro suggested in post #20?

They are different. The Philips are 1 W and the OptiLed are 2.5W so I suspect that the OptiLed are brighter. I don't know whether the color temp/wavelength would be similar or not.

 

[dancqu]

Visible Safe Light Levels.

Safelights which pass both the green and red portion
of the spectrum provide the darkroom worker with
a much higher level of visible room light. Yellow
to orange safelights do provide that lighting.
Their use does require Graded paper.
Graded paper is essentially
blue only sensitive. Dan

 

[domaz]

Get a 1W Luxeon Red LED and resistors from Sparkfun or an electronics house, also find a 5V wall wart power supply (1A or better) calulcate your resistor value to go between the wall wart and the LED, solder it up and you have a cheap and easy LED safelight.

 

[jeroldharter]

Someone here I think used to sell red LED safelights that consisted of an array of many low intensity red LEDS on a rotating head that could be plugged into a standard light socket. They we very reasonable at the time, I think <$10, and I bought a couple. They work well and are fairly bright. But they are red and I find the amber color a more pleasant work environment.

I really wish that LED's would come of age for DIY projects such as enlarger light sources. No reason those guys with 12x20 cameras should not be making some 24x40 prints.

 

[joe7]

Get a 1W Luxeon Red LED and resistors from Sparkfun or an electronics house, also find a 5V wall wart power supply (1A or better) calulcate your resistor value to go between the wall wart and the LED, solder it up and you have a cheap and easy LED safelight.

i found this on ebay:
http://cgi.ebay.com/1W-ULTRA-BRIGHT...al_Components_Supplies_ET?hash=item1c0725b12e

maybe i need to purchase a few units of light,but i'm still not sure about using the resistor..how to calculate the resistor for this light?i already have the 3v,5v and 12v power supply.

 

[rmolson]

I used CFl s in a safelight once, fogged the paper at twice the safe distance, never again They may say 25 watts but the output is more like 50.

 

[David Brown]

I used CFl s in a safelight once, fogged the paper at twice the safe distance, never again They may say 25 watts but the output is more like 50.

Yes, of course! If the CFL was actually 25 watts, then the equivelent output to a tungsten bulb was probably more than 50! CFLs put out more light for much less wattage. That's why they are considered to be an energy saver. If a safelight specifies a 25 watt bulb, you probably need something less than 10 in a CFL. Maybe someone else knows tha exact ratio, or it may be different by maker.

 

[Lee L]

From my post #4 to this thread:

Also keep the wattage at or below the equivalent incandescent wattage light output recommended for the safelight filter you're using.

Fluorescents commonly state their equivalent light output in Watts relative to an incandescent bulb. Since the commonly specified incandescent safelight lamps are in the 7.5 to 15 Watt range, you'll need a much smaller wattage fluorescent lamp to get output that low. I've seen 3 Watt fluorescent lamps rated equal in output to a 20 Watt incandescent, and a 2 Watt fluorescent lamp rated equal to a 15 Watt incandescent output. The lowest wattage fluorescent on the Home Depot web site is a candelabra base 7 Watt fluorescent equivalent in output to a 40 Watt incandescent, way too bright for common safelight fixtures.

So you need a really low wattage fluorescent lamp to have low enough output for the more common safelight fixtures, and fluorescent wattages that low aren't very common. It's also probably a good idea to get a fluorescent rated at lower color temperatures, something in the 2700K range, so that you're not wasting the blue-green output of daylight fluorescent lamps, which won't make it through the safelight fixture.

I now use amber or red LEDs from superbrightleds.com myself. They supply 12VDC models in several configurations that I wire up to a variable output DC power supply, so I can switch to whatever output level I like. I've tested them with the materials I use, and they work fine when used sensibly. superbrightleds.com also sells 120VAC models in standard Edison bases that work, but you may need to filter them down or bounce them off a ceiling. The AC models don't dim properly with an AC dimmer because of internal electronics. The red and amber models from superbrightleds.com with lower output should also work well inside a traditional safelight fixture.

Put these Dead Link Removed in amber or red in a safelight fixture or in an open reflector bounced off the ceiling and you'll be doing OK. Thats $4 / bulb + shipping.

Lee

 

[fschifano]

I'm not at all convinced that a CFL is safe in a safelight no matter how small it might be. The problem is that CFL's emit ultraviolet light. Tungsten lamps do not. Safelight filters were not designed to filter out UV light and they might not. We can't see UV, but photographic paper can. See the problem?

 

[wildbill]

Just keep it simple for Christ's sake. Like I said early on in this thread, Freestyle sells red bulbs as well, #12622. No safelight gadgetry, so cfl's, no filters. Just a frickin' red light bulb.

 

[paulie]

rear bike light is my light of choice, ive tested on pre flashed paper for 20 mins with no fogging, they take 2 AAA batteries and have three red leds under a red reflector

one lights my room up as much as a old philips red bulb 40w

hooray finally a great idea for an alternative to tungsten

 

[FRANOL]

Get a 1W Luxeon Red LED and resistors from Sparkfun or an electronics house, also find a 5V wall wart power supply (1A or better) calulcate your resistor value to go between the wall wart and the LED, solder it up and you have a cheap and easy LED safelight.

Led wizard http://led.linear1.org/led.wiz
Calculate everything to made LED light (Led, resistors,voltage) and scheme how to soldier.Just made darkroom light with 25 led (2800 mcd and 660nm).Just like Kodak safe specification

 

[FRANOL]

There is a old inkjet printer in your garage, inside is a AC-DC adaptor(plastic box inside) 220 or 110 V to 12 or 24 DC volt with 1.0A.One hundred led 0,20mA need only 0.4 A, so this is enough for darkroom with 2-3 enlargers.But there is a catch.Led have view angle and 30° it's what you can find(the best) with 2700-2800 louminuos intesity.Led with 100 louminus intesity take a same current like led with led with 2800 l.i. and price it is a same.
30° view angle from 1 m. or 3 feet high it's about 50 cm. or 20 inch. on table so 2 light source is min.If you folow scheme from Led wizard and put resistors nothing can go wrong if you put + or - in a wrong way.Wrong way-no light , right way-light. But remember that in circuit must be resistors .Here in Croatia I have found in RS Components(international company) Led with 660nM.Led with 660 nm(2800 mcd) was only 2.This led wavelenght start from 590 nm and peak is 660 nm and is a safe for all paper and many film.
If I can help.....

 

[CBG]

I've had good luck with these screw in LEDs: www.superbrightleds.com/cgi-bin/store/index.cgi?action=DispPage&Page2Disp=/specs/E27-W24.htm

The red LED bulbs are good for safelights. I just replaced the ordinary bulbs in my safelights with the red LEDs - the wide angle bulbs. It seems silly to have red LEDs shooting through red filters, but it's belt and suspenders - double safe.

I also use the green and blue/UV LED bulbs in concert to do split grade contact printing. I have separate timers attached to each to make settings easy.

 

[john_s]

I would be worried about the irregular spectral output of fluorescent light sources. Incandescent is more predictable and more towards the red end of the visible spectrum.

And a big advantage of the incandescent globe is that a standard dimmer can reduce the intensity and at the same time make it a bit redder (=safer) if necessary.

Whichever safelight system I am using, I like to have two different intensities: one low level for time consuming tasks that are easy to do in low light, and a brighter level for looking at developing prints for a short time. (No substitute for proper examination in white light, but adequate for testing and ordinary prints).

In my case the low level is red, and the high is yellow-orange (not really very safe for long with VC paper)

 

[2F/2F]

Safelights are free or near nothing. If you are given one without a filter, red bulbs are under five bucks at Freestyle. You can also just put a red bulb from Freestyle into any screw socket (including a lamp, of course, so you can move it around).

 

[fschifano]

Maybe a little more difficult to implement, but very safe would be to get some rubylith from a graphic arts supplier. I made a DIY safelight with it from a cast off safelight housing, and a sheet of glass cut to the right size. Tape a couple of layers onto the glass, and you're done. I use mine for cutting sheets of paper on a trimmer, so it's in pretty close. You can wire in a dimmer if you like. I cut down the light with a piece of Rosco .3 ND gel sandwiched in with the rubylith. It's just enough light to see the markings on the trimmer and to line up the paper accurately. I've tested it and it's safe with a 15 watt lamp