Variocontrastheads and condensors?

Discussion in 'Darkroom Equipment' started by naaldvoerder, Oct 28, 2004.

  1. naaldvoerder

    naaldvoerder Member

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    Hi forum,

    I am curious to know if there are enlargers, that can be equiped with a variocontrasthead/multigradehead and still use condensors. Or is diffused light in these heads a conditio sine qua non?

    Thanks Jaap Jan
     
  2. Donald Miller

    Donald Miller Member

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    You choose one or the other. Variable contrast enlargers are all diffusion to the best of my knowledge. It would seem that there could be a variable contrast head built with condensor light source...but to my knowledge no one has done so.
     
  3. roteague

    roteague Member

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    On the same vein, I have an old Saunder LPL 4500D - I think that is the model number, I'll take a look tonight. It has been in a box for the past 6 years, and I thought I would look to see if it is still usable after all this time to do some B&W printing. Additionally, the baseboard was stolen several years ago, that would need to be replaced.

    Your thoughts would be appreciated.
     
  4. Donald Miller

    Donald Miller Member

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    Is this the dichroic version (color head)? If so you should have no problems printing variable contrast materials. It could be that the 4550 LPL baseboard would replace the missing one. If so they are pretty expensive...something around $450.00 is what was quoted to me.
     
  5. wfwhitaker

    wfwhitaker Member

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    There's no law that says a variable contrast head can't also be a condenser head. However, there does not appear to be such a thing commercially available as a production item. I am assuming that by "variocontrasthead/multigradehead" you mean something more sophisticated than a filter drawer.

    I would venture to guess that with variable contrast heads as with color heads it is more economical to mix the different colors as diffuse light. A variable contrast head is, after all, just a color head with two colors instead of three. Mixing boxes have been the norm for years and everyone seems happy with the general design.

    It's interesting to note that Glenn Evans (glennview) has made a variable contrast source for the Durst 138 enlarger from an Ilford 400 Multigrade head. The lamps and filters are arranged in a special fixture which replaces the standard lamp socket in the Durst. The filtered light projects upon a diffusion plate which is then projected by the condenser system. In that way it's essentially a condenser variable contrast head. The diffusion plate is about the same size as the Durst bulb, so it should mimic the original optical system pretty closely.

    -Will


     
  6. martin@jangowski.de

    martin@jangowski.de Member

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    It is possible to mount nearly any head (color or multigrade) on top of the condensor drawers of a Durst Laborator 138. There is a thing called "LADANE" that mounts instead of the 45deg. mirror at the condensor head. Usually, the light comes horizontally from the bulb in the back of the head and gets directed downward through the two condensors. After removing the mirror, the head on top shines directly downward through the condensors.

    It is possible to mount the Ilford 500 Multigrade head in two manners on the L138, as a diffuse head (up to 4x5") directly over the negative carrier or as a light source used with condensors instead of the mirror. I had this combination for a few years, but after finding a inexpensive CLS1000 color head I switched and never looked back.

    Martin
     
  7. Donald Miller

    Donald Miller Member

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    The thing that does come into play with the 138S Durst and the possible conversion that has been mentioned is that as the size of the light source relative to the condensors is increased then one loses the benefits of an condensor enlarger. Condensors serve the purpose of collimating the light bundle.

    The ideal conversion, I would think, would be to use a point light source or even the high wattage and low voltage halogen conversion that Durst Pro has developed and then passing this light emission through a set of dichroic filters that would be incorporated in the area of the filter drawer. Shouldn't be too difficult to accomplish.

    I have three of these particular enlarger and this may be an idea for a conversion of one of them.
     
  8. edz

    edz Member

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    Yes there are multigrade enlargers with condensors just as their are colour heads with condensors--- a multigrade head is really little more, in theory, than a colour head with a few "pre-set" positions. Due to the higher cost of condensors and the fashion of diffuse illumination they are not the mainstream but were relatively "commonplace" into the 1970s--- the Agfa colour head not only used a condensor illumination system into the diffusor (which is technically needed to mix the coloured light to get uniformity) but typically uses in conjunction with, beyond the standard condensor of the Leitz and Agfa enlargers, an additional condensor. Because of the dyes in chromogenic films there are no real benefits to condensed light but a few downsides so, beyond the cost rationalization, the move too was driven by function... but its cost and production rationalization that has, in additional to fashion, applied this to B&W heads...
     
  9. hansbeckert

    hansbeckert Inactive

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    There have been some condensor models with dichroic light sources, but I cannot tell you with certainty what models.
     
  10. Adrian Twiss

    Adrian Twiss Member

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    The Kaiser VP series of enlarges (which go from 35mm up to 6x9) have condesers and will take a multigrade head. The light is passed through an opel glass then through a double condenser.
     
  11. L Gebhardt

    L Gebhardt Subscriber

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    How would you do this? The dicroic filters would need to be variable across the entire filter. In a color head they just move more and less of the filter into the light before it gets mixed in thr mixing box. The Ilford heads use two separate bulbs and adjust the intensity of each to vary intensity of each before the mixing box. It would be fairly easy to create a small mixing box to put above the condensers to act as a more point source.
     
  12. roteague

    roteague Member

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    I pulled it out last night, it is a LPL 4500II, and yes it does have a color head. The baseboard should expensive, but one of these enlargers new is over $2000. I noticed on Calumet that there was an optional wall mouting bracket for the LPL series, which I am going to see if I can find. If not, then I will look for a baseboard.

    Thanks for the feedback,
     
  13. Donald Miller

    Donald Miller Member

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    The way that I would do this would be to begin with what Durst Pro has done with their conversion using the 1200 watt halogen lamp. In fact, even though it is expensive at $865.00. I might buy their conversion kit. Next I would buy a set of the physically largest dichroic filters that Durst or even Omega use in their color enlargers in the Magenta and Yellow spectrum. I would design an individual adjustment for each of these colors from the 0 to 200 units that they provide. I would try not to use a mixing chamber of an appreciable size since to do so would eliminate the benefits of a point light source. I think that in using a point light source no mixing chamber would be required since the lamp arc is such small dimension that the light path through the filter and any possible inaccuracy of the filter value would be on no consequence.

    Why would one consider this type of a conversion? For myself, I think that the point light source would have definite benefits over a diffusion source enlarger. I have found that, even though I have three diffusion enlargers along with three condensor enlargers, that the condensor enlargers do provide enhanced local contrast over the diffusion enlargers. I have found, in my experience that the local contrast lost in the use of a diffusion light source enlarger is unrecoverable at some latter point through any printing manipulations.
     
  14. L Gebhardt

    L Gebhardt Subscriber

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    I still don't understand how if the filters are below the lightsorce how you will adjust them. In the only color enlarger I have played with, Omega D5, the filters partially move in front of the light source. If this happens without a mixing box you will see the filter with the condensers. Is there something I am missing?

    I agree, which is why I am curious. I currently own two D5XLs with three heads (condenser, Ilford, and Chromega). I haven't used the condenser head in a while, but I did notice a change in my prints when I stopped. I have not tested the diffusion against the condenser and seen if I could product the same look with each however.
     
  15. Donald Miller

    Donald Miller Member

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    In the Durst 138S enlarger the filter drawer is situated immediately in the front of the lamp. The light is then transmitted to a front surface mirror and reflected downward through the condensors. The color enlarger that I have used has dichroic filters that increase very linearly from a small value to a larger value. Thus they are configured more as a variable intensity color "wheel" then a single value that is adjusted in or out of the light path. My thoughts are based on this "variable wheel" model. It is this type of a dichroic filter the I would place into the light path.

    I stayed away from condensor sources for years because of all of the horror stories that AA and others promulgated. I am happy to relate that here has been no single thing that has contributed more to the improvement of my prints then the condensor light source. Of course all should choose their own direction in this regard.
     
  16. noseoil

    noseoil Member

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    Don, if I understand your post, are you saying that filters similar to a graduated neutral density filter exist in M&Y? If this is the case, it seems that a mechanism for adjustment and calibration would be easy enough to make in a home shop. Calibration would be the most difficult part to accomplish, but it would be a question of trial & error against a known standard which already exists from a diffusion enlarger with a color head.

    Second, it sounds as if you are comparing the prints from a variable head with mixing chamber to a condensor enlarger, as the different results found between films developed with PMK and ABC. The diffusion head is a softer image, while the condensor gives the true clarity and sharpness which is inherent in a good negative with high acutance.
     
  17. Donald Miller

    Donald Miller Member

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    Yes, that would be a good comparison. What I have found is that local contrast is evident on a print in which the light bundle is sharply collimated as in a condensor enlarger; that furthermore a diffusion light source compromises this local contrast because the light is scattered as it enters the negative interface. That when one fails to realize this local contrast and sharpness that it can not be captured at a latter step or even in increasing contrast (for instance) with a diffusion light source. This is evident to me today because diffusion light sources do not exhibit the need for print spotting to the degree that condensor sources do. I believe this is due to the diffusion light source light scatter "washing" the spots in the diffusion light source. This "washing" comes at a price...that price is reduced sharpness and local contrast. Of course the sharpest condensor light source would be the point light source.
     
  18. dschneller

    dschneller Member

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    Hi,

    I have a Beselar 23CII with a Dichro Head that has been added. This enlarger is normally a condensing enlarger. With the Dichro Head I have the option of using a diffuser (two pieces of white plastic) or the condensing lenses.

    Hope this helps,
    Dave