Contrast Control on Saunders LPL 6700

Discussion in 'Darkroom Equipment' started by hao922, May 9, 2010.

  1. hao922

    hao922 Member

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    It seems that I could not get any contrast control from the enlarger that I just acquired.
    Just to test the enlarger's contrast control. First, I tried with a low grade filter(M0, Y0), then I used a very high contrast (M170, Y0) just to try if I could get some contrast.
    The two prints were almost the same. There was no contrast added to the second print.

    Later on, I tested the enlarger's light source by placing a white paper under the lens while dialling the magenta filter, and I could actually see the color of the light change. If the filter is actually working, I could not think of any reason the contrast control did not work.

    I have another condenser enlarger which is very easy to adjust the contrast, just by inserting different filters. (same chemical, same negative, same paper)

    Could anyone help me with the issue? Thank you!
     
  2. archer

    archer Member

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    Are you sure that the paper you used was variable contrast? I ask because I made that mistake before when I grabbed a pack of fixed grade paper when in a hurry. It was good for a laugh.
    Denise Libby
     
  3. hao922

    hao922 Member

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    hi Archer, I am 100% sure. I used the same paper on a condenser enlarger, and I could change contrast by just using different filters in the filter drawer.
     
  4. 5stringdeath

    5stringdeath Member

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    If I remember right, there is a lever (on the left side of the head I believe) that toggles between the filters and "white light" which takes the filters out of play. I know you said you saw the color of the light changing, but it could be something to check out .... I had an LPL a couple years ago, not this exact model, so the lever may be in a different location ... or in fact your model may not have one at all, but its a thought.

    If indeed the magenta and yellow filters are in play, and the color of the light is changing ... and you've ruled out the paper ... I dunno, I guess the filters could be worn out. I know in some old dichronic heads this is the case, but I wouldn't think it applies here.

    edit: It does indeed have the lever somewhere. From google "White light lever for easy focusing"
     
  5. ic-racer

    ic-racer Member

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    Try comparing 170 Yellow (C0, M0) to 170 Magenta (C0, Y0) and see if you get a difference.
    Fresh developer?
     
  6. ozphoto

    ozphoto Subscriber

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    If the white light lever is in place - you'll know just by looking at the light colour.
    Dial in the maximum M - if the white light lever is engaged, you won't see any colour shift.

    And yes, it is on the LHS right at the top.
     
  7. hao922

    hao922 Member

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    I checked the enlarger. Yes I might have dailed the white level while printin.
    I will check again next time when I do my next printing, and I will let you guys know what the problem is.
    Thank you all for the input.
     
  8. hao922

    hao922 Member

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    I did a full test today and made sure that the dialled white level to the correct position in order to let the filters play (I tested on the extremes (170Y & 170M) to know that they indeed worked). CONSISTENT PAPER & CHEMISTRY
    This is what I found: on the diffusion condenser, the print made on a filter grade 3.5 (0Y60M) is just slightly more contrast than the one made on a filter grade 2 (0Y0M). The contrast gap between those two grades is much smaller than the ones produced on a condenser enlarger.
    Only when I used Grade 5 (170M) and doubled the exposure time at the time could I notice a very noticeable contrast boost for the same negative. But the contrast on Grade 5 still is about equivalent to what I could get from a Grade 3 filter on a condenser enlarger.


    I have heard that diffusion enlarger produces less contrast prints, but I never knew that the difference is this much based on my test, if my test is correct and my diffusion enlarger functions as expected.

    Could somebody please shed some light on the contrast control based on what I have done? ALso, on the web people say condenser's contrast is strong on highlight whereas diffusion's is good in shadow details? anybody has any experience on that?

    Thank you all for the input.
     
  9. ozphoto

    ozphoto Subscriber

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    Doesn't sound as if the filters are engaging properly - I have one of these enlargers, and the difference between G2 and G5 is very, very apparent.
    Again, can you see the light change to very obvious M colour when you dial in 170M?

    If not - it isn't engaging correctly. If it is, sounds as if they have faded really badly - surprised by this if they have. :O
     
  10. hao922

    hao922 Member

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    hi, ozphoto, I can see the light change from a somewhat white to a light red when I dial the Magenta filter from 0 to 170 while keeping the other two filters at 0.
     
  11. richard ide

    richard ide Member

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    I would check your filters for fading as a 170 magenta should look very red and/or can you remove the cover and see if the filters are moving in to position properly.
     
  12. hao922

    hao922 Member

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    http://www.flickr.com/photos/flickhao/4597566301/in/photostream/
    http://www.flickr.com/photos/flickhao/4597565531/in/photostream/
    http://www.flickr.com/photos/flickhao/4598181000/in/photostream/

    Hi Richard, I have posted the links for the pictures I have taken of the inside of the enlarger head (could not attach here did not know why). They show the position of the fully engaged magenta, and this is the highest position it can be levelled up using the dial. Should the filters fully levelled so that they can cover the hole through which the light comes? If the position is normal(filters fully engaged?), the only possible problem might be the fading of the color filters? that means I have to change one? anybody has done so before?

    Thanks again everybody. You guys have been really helpful here.
     
  13. Steve Smith

    Steve Smith Member

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    The LPL 6700 uses dichroic filters. These cannot fade as they are not filters in the traditional sense. They use interference patterns to create the colour rather than block the part of the colour spectrum not required.

    I have a 6700 and it works fine with variable contrast papers - as it should.


    Steve.
     
  14. perkeleellinen

    perkeleellinen Member

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    I have the LPL C7700 and I've found that M170/Y0, which is supposedly grade 4.5 on Multigrade paper is actually more like grade 3 or 3.5. There's noticeable contrast differences going downwards to grade 1 but it's not possible to go harder than around grade 3.5. For most people this isn't much of an issue as they print on the lower grades, for me it is as I like to print on grade 4.

    If you check the archives here, you'll notice this is a common issue. If you think the contrast is very low at M170/Y0, you could try changing the lamp.

    The two solutions appear to be to either change your processing to get more contrast into the neg or buy under the lens multigrade filters.
     
  15. ozphoto

    ozphoto Subscriber

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    Steve, your advice on changing the lamp was going to be my next suggestion as well. :smile:
     
  16. ic-racer

    ic-racer Member

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    All seems OK by those results.
    1) If not using combined Y/M settings, you will need more exposure with higher settings. Especially compared to white light.
    2) Condenser will print with more contrast.
     
  17. hao922

    hao922 Member

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    Thank you guys for the help. As for the suggestion of changing the lamp, do you guys mean that lamp is not powerful/bright enough? what is the watts of the lamp that people normally use for this type of enlarger? It seems there are two types 85W82V and 100W/12V.

    Thanks again
     
  18. perkeleellinen

    perkeleellinen Member

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    When the lamp gets old it tends to emit yellowish light which affects the contrast.

    I use a 12V/100W bulb. Make sure it's a Xenophot bulb made by Osram - they're much brighter. The Osram code on mine is 64627 HLX EFP
     
    Last edited by a moderator: May 11, 2010
  19. hao922

    hao922 Member

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    thank you so much Steve.
    I will check it out.
     
  20. hrst

    hrst Member

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    You might also want to try to dial all the filters to max (170C 170M 170Y). It should block (almost) all of the light, or be very, very dim when you look at it visually. If there is, for example, quite a strong green color cast left, it would indicate problems with magenta filter.