Turning a Condenser Enlarger into a Diffusion Enlarger?

Discussion in 'Enlarging' started by Eric Jones, Dec 30, 2004.

  1. Eric Jones

    Eric Jones Member

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    Hello All,

    Currently I work in a public darkroom facility which is outfitted with Omega D5 Condenser Enlargers. Has anyone tried diffusing a condenser enlarger by introducing white plexi or a Lee or Rosco diffusion gel into the condenser light path? Was the stop loss too much therefore introducing paper reciprocity problems or did the diffusion have any other negative consequences on the resulting image? Just wondering about others experience or thoughts before I go test myself.

    Thanks
     
  2. Tom Stanworth

    Tom Stanworth Member

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    Have a go. I tried using frosted glass once and it was not a clean enough peice to work. There was a big loss in light, but then again, it is just that the condenser had been really fast. It might make sense (if the inside of the condenser housing is light absorbing black) to make it white to increase the amount of light hitting the diffuser.

    Tom
     
  3. David A. Goldfarb

    David A. Goldfarb Moderator Staff Member Moderator

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    I've known people who have done that and said it works. It's certainly a cheap and easy experiment. If it were your own enlarger, you could add a cold light head at very reasonable cost. Aristo sells one for Omega for around $200-300.
     
  4. Donald Miller

    Donald Miller Member

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    Durst does offer this as an approach, for those who want diffusion, on their condensor enlargers. A great deal will depend on the bulb wattage. I would use 1/8 in opaque acrylic if I were going to attempt this. As others have related the light loss will be substantial. Another thought is to increase the bulb wattage to a 500 watt lamp. If the condensors are left in the light path then heat affect on the acrylic would appear to be manageable. My Durst 5X7 condensor does use that wattage (500 W.) lamp.
     
  5. Doug Bennett

    Doug Bennett Member

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    I did it with my first enlarger, an Omega B-22. I first tried some milk glass, but the reduction in light was severe. I then used a piece of Rosco 111 Tough Rolux under the bottom of the bottom condenser. The light output was still accecptable, and I was hoping to have "the best of both worlds." However, comparing prints with and without the diffusion, I was unable to see a difference.

    I've since moved to a Beseler 23C-XL enlarger, and have not repeated the experiment. I did borrow and try an old Aristo coldlight head, but was not impressed. Exposure times were way too long for my taste. Was the lamp on its last legs and growing dim? Maybe.

    I tend to produce a fairly contrasty negative, and did have problems with highlight rendition. I was commonly using a #2.5 or higher filter, thinking "more contrast, more contrast." One day, I pulled out the #1 and used it, and voila, my highlights were much better.

    Now, I tend to print my "normal" negs on a #1, then "kiss it" with the #5. Works for me. YMMV.
     
  6. Eric Jones

    Eric Jones Member

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    Thank you everybody for your thoughts. I guess I should have explained the "why" I wanted to do this in my original post. I own a Saunders 4550XLG diffusion enlarger but it will be a few more months until my darkroom is complete. I print my "fine art" prints on Begger Silver Supreme paper which only comes in Grade 2. I wanted to tailor my negs to that Grade 2 with diffusion enlargement. But, hey I'll throw a Step Wedge in the condenser and see empirically the difference with and without a form of diffusion in there and report back my thoughts.
     
  7. Paul Howell

    Paul Howell Member

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    Eric,

    It is my understanding that simply does make a diffusion enlarger. A true diffuson enlarger is sans condenser and uses a large mixing box to really diffuse the light. Does the dark room you work in have color heads? A color heads is a diffusion type, but most require different mixing chambers for different negative sizes.
     
  8. Eric Jones

    Eric Jones Member

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    Thanks Paul,

    Last time I looked they all had b&w condenser heads but I'm going to ask the owner if he has any other heads lying around that I can switch out, hopefully he will.
     
  9. Thilo Schmid

    Thilo Schmid Member

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    Eric,

    this should be possible, but you will likely face the following dilemma: if you place the diffusion material somewhere between the lamp and the condenser, it will not be very effective. If you place it between the condenser and your neg., you will not have many degrees of freedom and every texture, scratch or irregularity in the material will affect the print.

    It might be an option to place the diffusion material between the two condenser lenses. I have not yet tried this.
     
  10. Maine-iac

    Maine-iac Member

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    I tried "converting" my condenser head to a diffusion head by all the methods suggested in these posts many years ago. Gave up when I discovered that no matter what I did, the light was still being collimated by the condensers. That's when I got an Aristo cold light head that served me well for many years, until I started using VC papers almost exclusively and also wanted to print Ilfochromes; then I broke down and bought a colorhead for my Beseler 45 which I've used for everything very satisfactorily ever since.

    I have the 4X5 mixing box on mine, and theoretically, if you're printing smaller negs, you should get the smaller format mixing box, but I haven't felt any need to do that. I don't see the point. For medium format, which is what I use most, and using my split filter printing method, my exposure times under the enlarger are in the 8 seconds Magenta and 6 seconds Yellow range with the lens at f/11 for an 8X10 enlargement. That's perfectly acceptable to me.

    With 35mm negs, the times increase slightly by a couple of seconds, but for that, it's hardly worth the investment of money or time switching mixing boxes.

    Larry
     
  11. dancqu

    dancqu Member

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    I don't know what you mean by "degrees of freedom"
    Blemish free thin sheet diffusing are materials are plentiful.
    I think my Omega B8 has room directly on top of the
    negative carrier for some thin sheet. Dan
     
  12. Ronald Moravec

    Ronald Moravec Member

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    Rosco doesn`t work as the pattern shows if next to the negative. 1/16 plexiglass in the filter slot above a condenser set will get you somewhere between condenser and diffusion. Round plexiglas cut to a circle and put under the condensers of my Omega is pretty close to diffusion.

    All methods waste a lot of light