Enlarging bulb

Daniel_OB · Jul 27, 2007

there are on the market new energy saving bulbs for home use. They are in spiral shape and consume around 4 times less energy for the same output?

What is of interest to me is they are 4100K and do not warmup noticable.
I found 'em very nice for studio work.

Now I have intention to put one into my beseler enlarger (with matte tracing paper below the bulb to eliminate tube projection) for they have a lot of blue. Can anyone make a comment on their use in enlarging.

Thanks
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Nick Zentena · Jul 27, 2007

Check if it's rated for an enclosure. Many aren't. The 4100k is the wrong temp for enlargers. Enlargers bulbs are 2800k IIRC. You might be able to deal with this with more soft filters.

Personally I wouldn't for a normal enlarger. I can't see what you gain. An enlarger is on so little the power saving isn't an isssue really. The bulbs won't like the on/off cycle so won't last for their rated life.

AgX · Jul 27, 2007

The main objection would be that fluorescent lamps need some start up time. To compensate for that you would need to work with with a shutter.

The colour temperature issue is an issue of efficiency.

Daniel_OB · Jul 27, 2007

But isnot paper actually sensitive on blue part of the spectrum, so how then 2800K is better bulb. Exposure time should be longer with a bulb of 2800K. Might I am wrong? On/off is not a problem for I turn it on for the whole session (have red glass below the lens).

Thomas Bertilsson · Jul 27, 2007

Besides the light temperature, they also don't provide for even lighting. I tried it. The only bulbs I found that can possibly substitute for a real enlarger bulb are the completely round decorative ones. They are designed to work without a shade, and therefore have thick glass in them. They have even lighting, but only comes up to the 100W level. I normally use a 150W bulb for normal contrast negs. Sometimes a 200W.
- Thomas

Monophoto · Jul 27, 2007

As AqX noted, the principle objection to using compact fluorescent bulbs in enlargers is that they have a pronounced "warm up" characteristic. Warm-up in this context refers to the gradual increase in light output versus time after they are turned on. Typically, a CFL will take 3-4 minutes to achieve full light output.

For more information than you really care to know, there is an excellent research document on the RPI Lighting Technology Institute web site, Dead Link Removed

Daniel_OB · Jul 27, 2007

Thomas B
If you put transparent mat tracing paper (it is something like ground glass on view camera) below the bulb you will get even light, I think. Did you try that trick?

juan · Jul 27, 2007

Somewhere on this site Sandy King gave us the results of tests he performed. He found a gradual rise in bulb output over the first minute or so, then the output was rather stable. The context was alternative prints - the conclusion was that over the long exposure times for alternative prints, the bulbs light output variation was acceptable, but for the short exposures required for regular silver papers, the variation was too great for reliability.
juan

Nick Zentena · Jul 27, 2007

You could use a lens with a shutter. Clarons are obvious choices. Maybe even a red filter under the lens.

Monophoto · Jul 27, 2007

juan said:
Somewhere on this site Sandy King gave us the results of tests he performed. He found a gradual rise in bulb output over the first minute or so, then the output was rather stable. The context was alternative prints - the conclusion was that over the long exposure times for alternative prints, the bulbs light output variation was acceptable, but for the short exposures required for regular silver papers, the variation was too great for reliability.
juan

Exactly. Alternative printers commonly use fluorescent black light bulbs, either of the more common tube variety or screw-in spirals. If the exposure is 10 minutes, the fact that the light output is not uniform during the first couple of minutes is not important. And also, to quote Tillman Crane, "every palladium print is a monoprint", meaning that alternative printers have to cope with inconsistency between prints anyway.

And the fact that the bulbs don't generate a lot of heat, and don't use a lot of electricity means that it is also common for alternative printers to simply leave their light source on continuously during a session.

kram · Jul 27, 2007

I have tested a philips 100watt 'light bulb' shaped low wattage bulb. Problems when using multigrade paper. With a grade 0 filter in I was getting a contrast of 3-3.5. With a grade 3 filter it's grade 6+. Also times vary with the filter grade you use. 20 secs with a grade 3 (equivalent to normal grade 6?), with a grade 0 (normal grade 3) needed 55 seconds. It can be done but if you want anything softer than grade 3, you will need to use 1) a specialised bulb (not one from your local DIY) or 2) graded paper.

Daniel_OB · Jul 30, 2007

Kram
What color temperature was your spiral bulb?
I used 4100K spiral bulb with ilford #1 filter which is like orange. The bulb 4100K has a lot of blue which are stoped by that an orange filter and it is why I also got 2 min exposure time on variable-grade paper.
Now I got spiral silvania 3500K and it should be better. There is also silvania spiral bulb 3000K.
But what is the bulb color temperature that will make ilford filters to work?

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Thomas Bertilsson · Jul 31, 2007

2800-3000 degrees Kelvin is ideal for the Ilford Multigrade filters. The 75 and 150W large bulbs from Freestyle (among others, that's where I buy them) matches it perfectly with a 2950-3000*K range.
- Thomas

Enlarging bulb

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