Blue light bulbs abd availability of lightbulbs

[LF2007]

I just received a second hand enlarger off e-Bay. It came with a blue 75 watt Philips- lightbulb (transparent). Why would anyone use a blue lightbulb? Does it have any advantages in printing?

 

[ic-racer]

A blue filter blocks the light the paper does not see.

What kind of enlarger is it? Perhaps someone can give a good suggestion on a bulb for that enlarger. Some enlargers have specific requirements.

 

[LF2007]

It's a Leitz Valloy II

Can I also use regular lightbulbs available in supermarkets?? Or does it have to be a special type of bulb?

I learned that in Europe regular lightbulbs will be banned by 2012. All lightbulbs will be replaced by energy saving lightbulbs. Not sure if you can use energy saving lightbulbs in an enlarger, as they need warm up time. Anyone have experience with them?

 

[alistair56]

I have a magnifying glass on an extendable arm that came with a tungsten blue bulb. I bought it from someone who did embroidery. According to the manual the blue bulb was to correct the colours of the embroidery thread - a bit like a tungsten filter I guess

 

[ic-racer]

It's a Leitz Valloy II

Can I also use regular lightbulbs available in supermarkets?? Or does it have to be a special type of bulb?

I learned that in Europe regular lightbulbs will be banned by 2012. All lightbulbs will be replaced by energy saving lightbulbs. Not sure if you can use energy saving lightbulbs in an enlarger, as they need warm up time. Anyone have experience with them?

Ok, so you have a great enlarger. Certainly worth fixing up right. You may be able to get by with a regular 75W bulb, but for best even illumination I'd look for the correct bulb.
Glennveiw has a correct Osram 75W bulb for $15, but I think its the same as the PH/211, here for $5:
Dead Link Removed

This picture from glennview.com shows the box for the Osram bulb.

I don't live in Europe, but I don't think those regulations apply to specialty lamps.

 

[srs5694]

Just speculation, but: A blue bulb, depending on its exact characteristics, might produce a higher-contrast print on variable contrast (VC) paper than would a white bulb. It's conceivable that the enlarger's original owner liked this and so used a blue bulb to get this effect. Of course, I have no way of knowing this is so; you'd have to run some tests to even verify that the bulb has this effect. If you know who the original owner was, you could ask.

 

[ic-racer]

Just speculation, but: A blue bulb, depending on its exact characteristics, might produce a higher-contrast print on variable contrast (VC) paper than would a white bulb. It's conceivable that the enlarger's original owner liked this and so used a blue bulb to get this effect. Of course, I have no way of knowing this is so; you'd have to run some tests to even verify that the bulb has this effect. If you know who the original owner was, you could ask.

Blue or cyan filters have no effect on VC or non-VC paper. They block light outside of the paper's sensitivity spectrum. The paper doesn't know or care

 

[Steve Smith]

Some grain focusers come with blue filters to allow better focussing as you are only seeing the light the paper sees. A blue bulb could have the same effect but this may not be the reason it was fitted.


Steve.

 

[Adrian Twiss]

It's a Leitz Valloy II

Can I also use regular lightbulbs available in supermarkets?? Or does it have to be a special type of bulb?

I learned that in Europe regular lightbulbs will be banned by 2012. All lightbulbs will be replaced by energy saving lightbulbs. Not sure if you can use energy saving lightbulbs in an enlarger, as they need warm up time. Anyone have experience with them?

The problem with regular bulbs is that they have the branding and wattage information on the top of the bulb. There is a danger it would be projected onto the print. Enlarger bulbs (apart from their very even coating) have the branding and wattage printed on the side.

 

[srs5694]

Blue or cyan filters have no effect on VC or non-VC paper. They block light outside of the paper's sensitivity spectrum. The paper doesn't know or care

Cyan, yes (in theory; in practice a cyan bulb, especially one made for non-photographic purposes, might not be pure cyan and so might have some effect). Blue, no. VC papers are sensitive to blue and green light, so if you use a blue filter (which blocks green and red light), you end up changing the contrast, since you'll be reducing the amount of green light that hits the paper.

The OP identified the bulb as blue. If that's accurate, I'd expect it would have some effect. Of course, people often misidentify cyan as blue; or the color might be light enough or impure enough or affect only certain frequencies and so have little or no real effect. Testing is the only way to be sure.

 

[srs5694]

Some grain focusers come with blue filters to allow better focussing as you are only seeing the light the paper sees. A blue bulb could have the same effect but this may not be the reason it was fitted.

Patrick Gainer did some tests that were published in Photo Techniques a while back. I believe the article was titled "Hazards of the Grain Focuser" or something similar. He found that using blue light is not the best choice for focusing; using either green light or white light works best. Using blue or red light results in misfocusing. This isn't about what the paper sees; it's about what our eyes see; the lenses in the human eye are really pretty bad in many respects, and in particular they focus different wavelengths differently, resulting in focus errors when you focus using light of certain colors.

 

[ic-racer]

Cyan, yes (in theory; in practice a cyan bulb, especially one made for non-photographic purposes, might not be pure cyan and so might have some effect). Blue, no.

Yes, good point, I was mistaken. A proper blue will add some contrast to each filter grade in a filter set. Its just the non-MG papers that won't care.