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Thread: CLS 301 Bulb Question

  1. #1

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    CLS 301 Bulb Question

    Contrary to popular belief, my CLS 301 is a tad too bright for me. Does anyone know if the ENH 250W bulbs can be used instead of the ELH 300W bulbs; both at 120V? The ENH also have a much longer life than the ELH, 175 hrs vs 50 hrs. I would think as long as the wattage is less, it should work for B&W printing. I realize the color temperature is slightly lower, but that should make no significant difference in B&W. I've also ordered some 10x10" ND gels to use in the filter drawer. Comments?
    Thanks, L

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    ic-racer's Avatar
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    Re: CLS 301 Bulb Question

    Ten dollar lamps for that head...good reason to keep using it! Based on specs it looks like the ELH would work fine, but I have no first-hand experience.

    How far does you lens stop down? My 300mm Rodagon only goes to f45, but usually that is enough to tame my 2000W head. No ill effects on the image at magnifications less than 2x with f45 in my experience.

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    Re: CLS 301 Bulb Question

    The ELH is the standard 300 watt bulb for the head. I want to use the ENH bulb instead which is 250 watts. Both can be bought well under $10.00 (usually around $4-6 on the Bay). I'm just assuming that lowering the wattage from 300 to 250 should work just fine, the head should run cooler and put out less light. All my enlarging lenses can be stopped down to at least f/45, but to print around f/11-16, it's putting out too much light, hence the ND filters. I'd rather put an ND filter in the drawer and use a better f/stop for the lens. In the old days, I would just dim the cold light head, but the Dichroic can't be dimmed as far as I know. L

  4. #4

    Re: CLS 301 Bulb Question

    You can dim the dichroic by adding neutral density. Say 50M50Y50C becomes the new 0.

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    ic-racer's Avatar
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    Re: CLS 301 Bulb Question

    You are printing 8x10 negatives at f11? I only use wide apertures like that when printing times are too long, not when they are too short.

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    Re: CLS 301 Bulb Question

    300 to 250W is a 20% difference, that is, one third stop. Probably nothing that would help you - any blank sheet of black and white film popped into the filter tray would attenuate the light by more. The directional characteristics of the lamp will be different, and if you are lucky, the 250W bulb will lose more light than it should by mere numbers. But that might also cause uneven illumination - particularly undesirable on a two lamp head like the CLS301, where the result will be double hot spots which can't be mistaken for vignetting.

  7. #7

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    Re: CLS 301 Bulb Question

    You're best off using Lee ND gel - .9 will give you a three stop reduction.

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    Re: CLS 301 Bulb Question

    Quote Originally Posted by frotog View Post
    You're best off using Lee ND gel - .9 will give you a three stop reduction.
    Yup, that's what I'm doing, just ordered a Norman 3 pack 10x10 ND filter gels for 1, 2, & 3 stops that I will cut down and put in the 160mm x 160mm drawer. I ordred a piece of 1/16" glass for the drawer so the ND filter can sit on top of it, otherwise the fan pressure will deflect the filter. Frotog, do you know if it makes any difference not having the UV filter in the drawer? None seems to make UV absorption glass any more, Focal Point doesn't know of any, so I'm trying in Germany. For the time being I'm using plain glass.

    Also IC, I'm enlarging 4x5 & 5x7 negs to 8x10 or 11x14. I like to use f11/16 because that is the sharpest f stop for the lens, yes I can stop more, but then diffraction starts to take over and you can see that even in an 8x10 print. Thanks to all for all the suggestions. L

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    Re: CLS 301 Bulb Question

    Quote Originally Posted by Sevo View Post
    300 to 250W is a 20% difference, that is, one third stop.... The directional characteristics of the lamp will be different, and if you are lucky, the 250W bulb will lose more light than it should by mere numbers. But that might also cause uneven illumination - particularly undesirable on a two lamp head like the CLS301, where the result will be double hot spots which can't be mistaken for vignetting.
    I agree, it's not much change, but I figured that the head will also run cooler at 500 w vs 600 w. The bulb shape specs and reflectors are the same, so the illumination characteristics should be as even just slightly less bright. The only difference is a slight decrease in the color temperature from 3350K for the ELH to 3250K for the ENH which for B&W should not make much of a difference. There is also a bulb life increase from 50 hours to 175 hours so 3x the bulb life. For most printers making large prints you would want as much light output as possible, but since I make small prints, it should work for my needs-particularly in conjunction with ND filters.

    Anyhow, I ordered some to give it a try and will post if there are any issues. L

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    Re: CLS 301 Bulb Question

    Quote Originally Posted by Chauncey Walden View Post
    You can dim the dichroic by adding neutral density. Say 50M50Y50C becomes the new 0.
    True! forgot that, Thanks! L

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