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Thread: A dim bulb

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    A dim bulb

    After 25 years of incandescence and collimation, a cold light bulb went off in my head, and I decided to get an Aristo Cold Light head for my D2.
    So far so good, except that my exposures are now 2 stops greater than previous prints of the same negatives, and the light looks very dim in the dark. Hardly enough to read the f stop on the lens.
    The installation was straightforward; the unit matches the enlarger; the diffusion panel is stock Aristo; it came with instructions (which I followed explicitly, thank you); and I am using the heater a full half hour prior to making art.
    Question: Have others noted that the cold light is dimmer than a 75W bulb?
    Is my unit underperforming or my bulb going south?
    Last edited by Deckled Edge; 03-01-2008 at 04:34 PM. Click to view previous post history. Reason: Bad math

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    Whiteymorange's Avatar
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    The Aristo head we use on a Beseler 45MX is MUCH dimmer than the 75 watt bulbs used in the surrounding 23C's of my school's group darkroom - and the exposure needed much longer, using Ultrafine VC RC paper. That said, the resulting image is certainly equal to or better than anything I can pull out of the condenser enlargers. The cold head enlarger was donated, and came with a sheet of yellow filter material under the lamp. We've left it there to aid in contrast control for VC papers, though using a grain scope on this enlarger can be a problem for these old eyes.

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    Yes, much dimmer even once it has warmed up - it takes a little getting used to but worth it.

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    I've got a Zone VI cold light and it is dimmer than the 75-watt incandescent. I also found through testing that I do need to develop the negatives for more contrast when using the cold light - provided, of course, that I want a similar contrast in the print.
    juan

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    The Aristo can (or could) be had with a tube for VC papers, or one with the same spectrum but higher output. Thinking that shorter exposures would minimize vibration issues, I went for the high-output version and find that an 8x10 print on VC paper, from a 4x5 negative, usually runs about ten seconds at f/11 or f/16. This is a bit more light than I would prefer, both from the stand point of lens diffraction and the difficulty of making small adjustments in exposure. Without the Metrolux compensating timer, I think that serious printing would be impossibly frustrating---prints smaller than 8x10 are tough enough as it is, since exposures run to five seconds or less down around f/22.

    The enlarger is a vintage D2, but where I live the line voltage tends to run on the high side (almost 125 volts) so that may have something to do with it.

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    Thanks,
    I queried the web and found at least two types of bulb supplied for the Aristo DII. There is no identification on my bulb to discern whether it is a W54 or the older, bluer type. With nothing to compare and no color temp. meter, I can't say that it is a "blue" light or a "bluish white" light.
    Greybeard, I do mostly contact printing, and my lenses stop down to at least f32. Additionally I use a Gralab digital timer, so I can nail 5.7 sec. repeatedly. What bulb do you have, and where might I get one?

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    I don't mean to hijack this thread, but I'm having a problem with my cold light head. Recently, my exposures have needed about a 50% increase, to get the same results (from the same negative) as prior printing sessions. I'm also having a much harder time focusing, when the print is 20x24. Is my lamp dying? Thanks.

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    Quote Originally Posted by eddie View Post
    I don't mean to hijack this thread, but I'm having a problem with my cold light head. Recently, my exposures have needed about a 50% increase, to get the same results (from the same negative) as prior printing sessions. I'm also having a much harder time focusing, when the print is 20x24. Is my lamp dying? Thanks.
    Possibly -- or you could have an obstruction (a spider's made a web in your enlarger, etc.), dirt, or some other problem. Try opening the enlarger's head and examining the light path, as well as the surface of the bulb.

    IIRC, tungsten bulbs do vary in brightness over their lifetimes, and I think the general trend is to get dimmer, but I don't recall the details, so I don't know if a 50% increase in exposure time is reasonable. What sort of bulb is it -- tungsten, halogen, cold-light, etc.?

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    It's a cold light, with a Zone VI stabilizer. There are no obstructions. My method for working around the problem has been to leave the bulb on, for about an hour, before printing. This lets me stabilize with a higher output. I don't really mind the longer exposures. The bigger problem is in focusing.

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    What bulb do you have, and where might I get one?

    What I have is a V54 High Output. I bought it from Calumet in about 2001, and it was one of two options at that time. The light is distinctly "green" to my eyes, since the V54 lamp phosphor is designed for use with variable contrast papers. It is on the Aristo Grid Lamp website at this URL http://www.aristogrid.com/D2.htm and is priced slightly higher than the "standard" output. Power consumption is about 60% higher per the specifications, but the ratio of optical powers may be more or less than that.

    It works just fine for contact printing, by the way; it is easy to compensate for the higher brightness by just raising the lamphouse.

    I hope that this helps.

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