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  1. #1
    ChrisC's Avatar
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    Very short enlarging times.

    Today I finally got my Homrich 4x5 enarger mounted to my benchtop, and while giving it it's first use, I found the exposures to be way too short when enlarging to 8x10.

    I had to stop the lens down to f22 to get a time remotly usable, and even then I wasn't getting anything longer than 5 seconds without filters, making dodging almost impossible, along with fine tuning the time to any real degree.

    The previous owner fitted a dimmer switch to the baseboard, which I'm not using because it won't fit in my darkroom, but I was wondering if adding a dimmer stitch between the timer and the enlarger would be problem free. The enlarger's a condensor, and really nothing to it but a bulb and cord.

    I'm no wavelength wizz, so would a dimmer change things around too drastically to get consistant results? I'd rig the dimmer up to a slightly larger knob, with notches around as to keep track of the settings, but would contrast etc be consistant throughout the degrees of brightness?

  2. #2
    Mick Fagan's Avatar
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    I don't know what a Homrich enlarger looks like, but I assume it's a straight B&W enlarger with a filter drawer.

    When having this problem with colour enlargers I dial in neutral density to give me more time.

    It works like this:- dial in 30 units of cyan, yellow and magenta and you approximately have dialed in one stop of neutral density. Meaning that if you were exposing at 5.6 for 5 seconds, you would need 10 seconds at 5.6 with one stop of ND filtration added.

    What you could do is use three equal colour filters, if you have them, by doing this you are just adding grey, which is identical to adding ND filters to the end of your lens on a camera.

    Maybe a variation of this, with what you have in your darkroom may help.

    Mick.

  3. #3
    ChrisC's Avatar
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    I had thought of doing something similar, but it's going to require a heck of alot of filters to get my times longer. My 5 second times were at f22. Here's what the enlarger looks like for what it's worth.

    http://www.apug.org/forums/attachmen...achmentid=2766

  4. #4

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    Chris

    can you change the lamp to a lower wattage?

    Clayton

  5. #5
    Mick Fagan's Avatar
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    Is that a filter drawer there, or an entrance to the condensor(s) set up?

    If it is possible you may be able to insert some ND around there, as long as it's above the negative. A downside may be that you will/may slightly turn the enlarger into a diffused type, with ND directly above the negative.

    I would try and get a smaller wattage globe.

    Running a dimmer changes the colour output and thinking about it, it would go to the red part of the frequency and therefore I assume, change the speed of the paper, if you are using a multigrade paper.

    If you have a filter drawer, the easiest solution would be a ND gel filter. We used to use ND gel filters blue tacked behind the lens in the 4x5 & 8x10 repro cameras in the lab. When DOF was paramount, we stopped down by using the ND filter without having to change the lighting intensity and therefore not change the colour output.

    Mick.

  6. #6
    ChrisC's Avatar
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    Clayton: It's just a normal screw fitting, and what looks like a normal 250W bulb with a white coating on it. I'll have to see if the light bulb man in town has anyhting that'll fit the bill.

    Mick: I think a dimmer bulb would be the best place to start. I'll see if I can find something suitable, and if not start looking into filters. The bulb would be a logical place to start, and most wallet friendly too.

  7. #7

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    Chris

    sounds like you need to go down 4 stops which would give you 20s at f11.........4 stops would be a 15w bulb...........all that sounds mighty strange to me.......I think you may have some very thin negs. Can you remember what your shutter speed/f stop/film combo is and what the light was like when you shot it? Also your developer and dev times?


    Clayton

  8. #8
    MikeS's Avatar
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    5 seconds at f22 sounds about right to me for going from 4x5 to 8x10. Those are close to the times I get as well. I've used a dimmer in the past, and it does work, but depending on the type, it can shorten the life of the bulb greatly (why I stopped using the one I had).

    -Mike

  9. #9
    ChrisC's Avatar
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    Quote Originally Posted by claytume
    Chris

    sounds like you need to go down 4 stops which would give you 20s at f11.........4 stops would be a 15w bulb...........all that sounds mighty strange to me.......I think you may have some very thin negs. Can you remember what your shutter speed/f stop/film combo is and what the light was like when you shot it? Also your developer and dev times?


    Clayton
    It sounded very strange to me, too. My negatives look very similar to the 6x6 negs I've shot and enlarged on a different enlarger with no troubles. I made a mistake with the bulb, too. It's 150W.

    I'm using Ilford FP4+, and Rodinal 1:50 to develop for 12 minutes, much the same as I've been doing on MF negs for a year or so. The negative in question is a semi-close-up rock face down at Makara just after 4pm on the 9th of this month. It was bright sunlight shining onto the rock face, and I used 1/60 @ f22. I spot metered off a grey card I keep in my backpack.

  10. #10
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    You would need something like the GE PH 211 bulb like the Beseler 45 series enlargers use. There's an auction on ebay going on here: http://cgi.ebay.com/PH-211-GE-ENLARG...QQcmdZViewItem so you can look at one. You can probably get a better price at a reputable camera and darkroom supply.
    Gary Beasley

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