I'd like to build a cold light head for my Omega D2.

I understand that the light source in the Omega "Omegalite" is an ordinary household circular fluorescent light tube. I presume that there is a frosted or opal glass diffusion plate in the Omegalite as well.

A couple of questions if I may.

1) Has anyone built their own cold light source? What did you use and what was the internal construction that you found to be sucessful? The Aristo units seem to be little more than a tightly coiled lamp tube mounted quite close tot he diffusion plate.

2) For anyone who uses an Omegalite, what is inside the housing besides the fluorescent tube and diffusion plate? The external shape of the Omeglite suggests that domed top might be coated with white material internally to serve as a form of integrating sphere to level the light distribution. It would seem to be simple to improvise from a metal kitchen bowl painted with plat white paint.

Thanks in advance.

-- Ed Balko (veggie@monmouth.com), December 13, 2001

Answers

Hey, I'm sure there's somebody out there who knows about the actual construction of a coldlight...but there's more to an Aristo coldlight than that...the old omega lights are pretty primitive compared to an Aristo, even the most basic head....just buy one...they're cheap new, even cheaper used, very little can go wrong with them, and the tubes themselves last for a very long time....of course, you could try to make one, but it just seems like alot of work in a way.....

-- DK Thompson (kthompson@moh.dcr.state.nc.us), December 13, 2001.

Yes, I think there is more to the modern coldlights. Basically, I'm guessing the phosphors emit a more balanced light output i.e., in wavelengths enlarging papers are sensitive to. The older Aristos and Omegalites, in fact, are a little quirky to use with variable contrast papers because the light they emit is a little blue-heavy. Aristo V54, for instance, emits blue and green light to better work with variable contrast papers. I guess it could be jury-rigged with a regular fluoroscent light but given the fact that Aristo tubes are not that expensive to begin with, it might not be worth the time and hassle. Check out www.aristogrid.com. Cheers, DJ

-- N Dhananjay (dhananjay-nayakankuppam@uiowa.edu), December 13, 2001.

Ed: you can get a cold light used for $100-150 dollars (try Midwest Photo Exchange), and it is worth it. It fits your enlarger as it should. To build one, you will need to have the light tubes custom bent, then you will need a power transformer to make the lights work, and then you still end up with a cobbled up mess. Also, the Aristos have heaters built in to help keep the light output more under control. The heater is important. Mine came unplugged, and I like to have gone nuts because I couldn't duplicate an exposure. Incidentally, the Aristo grids have an expected life span of about 10,000 hours. That is a lot of 8x10s. I like to build my own stuff when I can, but this is one case where it is much better and about as cheap to buy used or even new.

Regards,

-- Doug Paramore (Dougmary@alaweb.com), December 13, 2001.

To answer your second question, the inside is coated white. Mine uses an ordinary circular fluorescent tube, and there is a diffusion plate. That's all there is, except for a housing on top for the ballast etc. for the fluorescent tube. It works all right for me. I intend to replace it with a modern cold light someday, but for now I'm saving my pennies for camera lenses.

-- Mark Severson (mws@ouchem.chem.oakland.edu), December 14, 2001.

ed - if you buy an aristo cold light head, find out what phosphor is in it. the older ones have the w45 coating and the newer ones have the v54 coating. the v54 is a newer formulation that is a better "match" for variable contrast and graded paper. aristo will "upgrade" an older unit with the newer tube for about $105.00.

good luck john

-- john nanian (jak@gis.net), December 14, 2001.

I used, well reall still use, an omega color head for black and white printing and in comparing it to the cold light heads I found no discerable difference, There was a considerable difference to the conder head I used prior. So get an old analogue color head and screw it on and try it, It is alot easier than building and you can spend the saved time on the dark, alone.

-- ED (zeke@idirect.com), December 14, 2001.