Very short enlarging times.

Discussion in 'Enlarging' started by ChrisC, Sep 18, 2005.

  1. ChrisC

    ChrisC Member

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    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. Mick Fagan

    Mick Fagan Subscriber

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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. ChrisC

    ChrisC Member

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  4. claytume

    claytume Member

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    Chris

    can you change the lamp to a lower wattage?

    Clayton
     
  5. Mick Fagan

    Mick Fagan Subscriber

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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. ChrisC

    ChrisC Member

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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. claytume

    claytume Member

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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. MikeS

    MikeS Member

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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. ChrisC

    ChrisC Member

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    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. glbeas

    glbeas Member

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  11. dphphoto

    dphphoto Member

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    Chris: I've never heard of this enlarger before, but it looks 1st rate.
    I used to work at Meteor Photo (now owned by Photobition) outside Detroit back in the '70's. They had an analyser/translator system with a standard exposure time of 2.5 seconds for commercial color enlarging with Chromega 4X5 enlargers. Yes, that's custom printing, and you get pretty used to the short exposures.
    I'm used to the Beseler MX enlargers with the built-in dimmer, but I usually keep the voltage set close to 110. Maybe a smaller bulb is the answer.
    Mike S: I just moved to Knoxville within this past year. After living in S. Florida, it's a delightful change of pace, with real mountains, rivers, waterfalls and incredible scenery. All in all, a wonderful place to practice large format. Dean
     
  12. ann

    ann Subscriber

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    just as aside, lights64 listed on the ebay site, provide some one the cheapest bulbs prices around. they beat my dealer all the time, and my dealer provides a professional discount to our purchases and they can't beat the prices.
     
  13. claytume

    claytume Member

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    Chris

    all your numbers sound like you're in the right ball park so I would look back at the enlarger, try a lower wattage bulb.

    Incidently, next time you shoot something like this shoot some extra sheets. Add a stop more exposure to each one and reduce dev times 20-30 percent. You'll see shadow detail pick up and they'll be easier to print.

    Clayton
     
  14. Claire Senft

    Claire Senft Member

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    If it is a regular enlarging bulb then a inline bulb dimmer is around 12.00 USD. It works like magic. Very versatile.
     
  15. Donald Qualls

    Donald Qualls Member

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    The time of 5 seconds, f/22 under 250 W and concenser doesn't seem at all unreasonable. My 135 mm lens goes down to f/45 (and I'm not afraid to use that small a stop with only 2x enlargement); when I'm enlarging 9x12 cm to 8x10 under a Zone VI cold light, I'm finding f/28 times of about 15-20 seconds with each filter in split filtering; that'd be comparable to that same range of time (15-20 seconds) in a single exposure with a #2 or so filter. Changing to f/22 would give me times more like 15-20 seconds, and the cold light isn't anywhere near a 250 W tungsten equivalent; seeing a stop and a half difference based on the light source seems entirely reasonable.

    One thing I might suggest -- different papers differ considerably in speed. The Ilford MG/RC that gets rebranded a lot is in fact one of the fastest papers going, perhaps as much as three stops faster than other common multicontrast emulsions. Changing to a slower paper would lengthen your printing time without having to mess with filters...
     
  16. fschifano

    fschifano Member

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    I'd be a bit hesitant about using an inline resistor to limit the voltage going to the bulb. You describe a conventional tungstem bulb, so it worn't shorten its life. That can happen with a tungsten halogen bulb which needs to run at a certain temperature to perform well. I'd be more concerned with the change of color temperature and the way it will cause your paper to respond.

    You can get a very large piece of Rosco ND gel material for very cheap, cut some appropriately sized pieces from it and insert them into the filter drawer. The stuff comes in 1/2, 1, 2, and 3 stop densities. I use the 1 stop density when I need it and it works very well with a diffusion light source. If you need more density, you can stack them. There is no color temperature change and your paper will respond the way you've come to expect. It's easy and costs only about $6US. What's not to like? No guesswork involved.

    See here: http://www.adorama.com/RO3402.html
     
  17. Christopher D. Keth

    Christopher D. Keth Member

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    You'll need to be careful using a dimmer in your enlarger. When you dim (undervolt) a bulb you change its color temperature toward the warm (lower color temp) end of the spectrum which will also act to change contrast. You will probably want to find the spot in the dimming that gives you workable times and then leave it alone, since fiddling with it a lot will probably throw your print consistency out the window.
     
  18. Roger Hicks

    Roger Hicks Member

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    Yes, but you gotta be good. My wife Frances can handle this (just) but I'd prefer 10 seconds or so: I'm not as good as she is.

    Cheers,

    R.
     
  19. gchpaco

    gchpaco Member

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    This is definitely true, but there are even faster papers than MGIV out there--the Kentmere RC papers are particularly ridiculous. I've found that I like printing on Forte Polywarmtone mostly because of the lovely paper color, but it also is rather slower than MGIV, permitting easier controls.
     
  20. Jim Jones

    Jim Jones Subscriber

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    Soince consistancy, not absolute accuracy, is required if you use a neutral filter to extend exposure time, a properly exposed and developed sheet of film makes a serviceable ND filter.
     
  21. Donald Miller

    Donald Miller Member

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    I routinely print 4X5 negs at 6 seconds and F22 on my Durst with 1000 watt lamp. If the times become too short, I insert a three stop ND filter that I fashioned into the filter drawer ahead of the condensers.

    Burning and dodging can be a pain if the negatives are not optimal.