Exposure Times with LPL Enlarger

Discussion in 'Enlarging' started by Richard D. Markel, Jun 16, 2006.

  1. Richard D. Markel

    Richard D. Markel Member

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    I have posted this question several times in the distant past but never really got a satisfactory answer if, in fact, there is one.

    I am currently using an LPL 4by5 enlarger with the VCCE head. Unlike the color head the VCCE head does NOT have a light attenuator. I am using a 150mm Rodagon N lens for 4by5.

    I test my films using the zone system and develop for a diffuser light source. In other words the negatives are denser than I would develop for a condenser system. I use a densitometer to check my zones and usually test for zone 1 and zone VII.

    I am more than satisfied with the results. The prints are great, but here's my problem. My exposure times are too short. I use both Ilford and Agfa (RIP) MC fiber. For an 11/14 print my times are about eight seconds at f 11!!! This wether I am printing 4by5 negatives with the 150 mm or 6by7 negatives with a Rodagon N 90 mm. I would have hoped that they would have been about 12 seconds at f8. No time to burn and dodge and, although f11 seems fine on these APO lenses, I would rather use f8. And little chance I can use graded with these times and the filters switched out.

    I have the XLG model which has a 250 watt halogen bulb. You CAN NOT REPLACE THE BULB WITH THE 200 WATT USED IN THE SMALLER MODEL. It will not work, has a different footing an will blow the lamp.

    The reason for the caps is that some have suggested a different bulb or that in fact there is an attenuator in the head. I can assure you that neither solution is possible.

    I have printed some of the same negatives in the school darkroom where they have Omega condenser enlargers and I get normal times, i.e. 12-14 seconds at f8.

    So, any suggestions? One very knowledgeable individual has told me that the light transfer from the APO Schneider and Rodenstock lenses is much greater than with the Nikkors. He has measured same.

    I could go with neutral density filters but will only use that as a last resort.

    I keep getting the feeling that I am missing something. I’m stumped. HELP!
     
  2. Muihlinn

    Muihlinn Member

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    the atenuators built-in color heads used to be ND filters...
    What about a light intensity control circuit?
     
  3. firecracker

    firecracker Member

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    I don't print 4x5 negs, but when I run into the same problem, I just have to close down the F stop to cut down the amount of light and/or use a longer lens to get more height on the enlarger.

    What are the maximum F stop numbers on your lenses? Don't close all the way, though.
     
  4. Donald Miller

    Donald Miller Member

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    The short answer is expose your negatives by another stop. This will build your overall density. Recheck your density range after doing this to see if your development times are still proper.

    This should increase your enlargement exposure times with no need to use ND filters in the enlarger light path.

    Don't be anal about what Adams wrote on Zone densities. You might try for a 1.00 density range (high densities minus low densities....not minus FB +fog) That will get you into the ball park.
     
  5. raucousimages

    raucousimages Member

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    I have the same enlarger without your problem. The only thing I can think of is that the Focus/Print lever is not kicking the filter in front of the light. You should cee a notiable drop in light when you switch from Focus to Print. Or is your bulb bad? I have had bulbs get very bright just befoe they go out. Other than that I dont know what to tell you.
     
  6. raucousimages

    raucousimages Member

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    One more Idea. Do you have the correct mixing chamber? I think there were different chambers for smaller formats, this might change somthing.
     
  7. Lopaka

    Lopaka Member

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    Here is what the inside of the color mod looks like when the brightness attenuator is switched on. It is thin metal plate with uniform holes across the opening to reduce the light evenly across the entire opening - so as not to bias any filtering inside the module. Hope this helps.

    Bob
     

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  8. Richard D. Markel

    Richard D. Markel Member

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    Thanks for all the suggestions

    1. Yes, the focussing lever is working and I notice a significant decrease in light when it is thrown before making exposure.

    2. I don't want to develop for even more density because my high zones will blow out.

    3. Thanks for the picture of the metal attenuator used on the color head. This is certainly one solution, taping such a piece of metal over the hole into the diffusion chamger.

    4. I could go to f 16 but I just wonder if this is a compromise that is not justified if one has a good lens to begin with. And what happend when I try to print graded paper? Way too much light.

    At any rate, I will never buy an enlarger again that does not have some sort of attenuation possibilities so that one can stay at critical f stop while just adjusting the time. At this time I am looking for an 8 by 10 (ugh!) enlarger anyway so I may make the change then. I have no other fault with the LPL but I do think that the b&w head could have been designed better.

    So my next thread will be your thoughts on a two enlarger darkroom!

    Thanks again fellows

    dick
     
  9. david b

    david b Member

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    Do you really think you can see a difference going from f11 to f16? Have you done a side by side comparison yet?
     
  10. Richard D. Markel

    Richard D. Markel Member

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    Probably not, but I really like the prints I am getting and don't really like the idea of being forced to use a particular f stop.
     
  11. tim elder

    tim elder Member

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    You don't mention if your enlarger column is mounted on the base board or not, but if it is, maybe you could build a sturdy shelf about six to eight inches higher than the base board and mount the enlarger column to that? This would increase your exposure times.

    Tim
     
  12. firecracker

    firecracker Member

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    But you're already thinking about using a different enlarger, right?

    You sound a bit like a whining kid in front of a candy store. :smile:
     
  13. david b

    david b Member

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    I am with firecracker (what the hell is your real name?) on this one.

    Suck it up and change the aperture or just buy an new enlarger that will work for your negs.

    This is a bit ridiculous.
     
  14. firecracker

    firecracker Member

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    One more thought: Enlarger lamps get darker as they age. If you use your enlarger with the same lamp long enough, maybe you may be able to stick to F8 with twice as much time as you like to get the kind of result you want.
     
  15. Richard D. Markel

    Richard D. Markel Member

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    End of thread.

    End of membership.
     
  16. jovo

    jovo Membership Council Council

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    At first I thought: "You sound a bit like a whining kid in front of a candy store." was a bit harsh despite the smiley face emoticon, but now it seems rather appropriate. Don't let the door hit you in the ass on your way out.
     
  17. firecracker

    firecracker Member

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    He seemed to have other choices (enlargers), which is a good thing.