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Thread: Modifying a Petzval projection lens for Waterhouse stops

  1. #1
    IanG's Avatar
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    Modifying a Petzval projection lens for Waterhouse stops

    Has anyone modified a Petzval projection lens to add Waterhouse stops ? It's a cheap lens I picked up at a Flea market and has no focus knob/gear (it's missing).

    Ian

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    Mark Sawyer's Avatar
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    Re: Modifying a Petzval projection lens for Waterhouse stops

    No, but I've seen a few modified by others, including some very nice early Voightlanders, CC Harrisons, and the like. Sadly, it's often done with a hacksaw or grinder, leaving an ugly, butchered lens. I'd recommend having a machine shop do it, if you don't have the right tools.
    "I love my Verito lens, but I always have to sharpen everything in Photoshop..."

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    Drew Bedo's Avatar
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    Re: Modifying a Petzval projection lens for Waterhouse stops

    IanG:

    Don't do this. These lenses are becoming less and less plentiful each day. There are other antique lenses either manufactured for use with waterhouse stops, or modified some time in the past. While this lens may not be a desirable collector item, it is still an antique thast will not be made again. If you need a Petzval lens with waterhouse stops, get one that is already set up that way; they are out there.

    Please consider yourself to be the steward of this piece rather than its owner. I have a "vintage" Zone VI (mid 1980s) and a much older, perhaps antique, Kodak 2D from the mid 1930s. I feel that I am only holding these cameras for whoever will have them next. Both can be solid working LF cameras well into this century—and I hope the next.
    Drew Bedo
    www.quietlightphoto.com
    http://www.artsyhome.com/author/drew-bedo




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    Re: Modifying a Petzval projection lens for Waterhouse stops

    Hi Ian,
    If you want to do it yourself use a piercing saw for the slot. Clean the inside of the barrel below the slot that you've cut so that you're back to the brass and soft solder a couple of pieces of rounded sheet brass into the barrel to accept the base of your WH stops. If you use a thin piercing saw it will allow you to use card stops instead of metal pieces.
    See ya soon,
    Pete.

  5. #5

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    Re: Modifying a Petzval projection lens for Waterhouse stops

    Ian,
    I've just seen Drews post, old (1880's) magic lantern petzvals are plentiful in the UK. Personally I wouldn't pay more than £30 UKP for one of these lenses, and that's peanuts. It's your lens and it you want to modify the lens do it. However if you think that the lens is historically important consult those millions more knowledgeable than me and consider their advice.
    Pete.

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    Mark Sawyer's Avatar
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    Re: Modifying a Petzval projection lens for Waterhouse stops

    BTW, the more you stop down a Petzval, the more its images look like those from other more conventional lenses...
    "I love my Verito lens, but I always have to sharpen everything in Photoshop..."

  7. #7
    Jac@stafford.net's Avatar
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    Re: Modifying a Petzval projection lens for Waterhouse stops

    If the focusing knob is missing, but the shaft is still there and the track is good, then replacing the knob would be easy. Can elaborate if you wish.

    Regarding the Waterhouse stops, you can place an aperture in front of the lens for similar control, but I would try to find an ND filter first to maintain the rendering of the lens.

  8. #8
    IanG's Avatar
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    Re: Modifying a Petzval projection lens for Waterhouse stops

    Quote Originally Posted by Jac@stafford.net View Post
    If the focusing knob is missing, but the shaft is still there and the track is good, then replacing the knob would be easy. Can elaborate if you wish.

    Regarding the Waterhouse stops, you can place an aperture in front of the lens for similar control, but I would try to find an ND filter first to maintain the rendering of the lens.
    The shaft and bit that holds it all in in place is missing as well.

    These lenses are very easy to find in the UK and Pete Watkins was I think with me when I paid very little for it if someone wants to buy it and save me modifying they are quite welcome.

    I wolud have just remounted the front/rear cells in a homemade barrel but the lens isn't made that way, the elements fit the barrel itself.

    Ian

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    Re: Modifying a Petzval projection lens for Waterhouse stops

    Quote Originally Posted by Jac@stafford.net View Post
    you can place an aperture in front of the lens
    Quite true. More so, the earlier Petzvals were actually made for the stops to be in front of the first element, and any Waterhouse or iris inside the barrel would just be wrong for those.

    So for an unknown lens, try putting stops in front and inside first and compare the results obtained before you reach for that saw.

  10. #10

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    Re: Modifying a Petzval projection lens for Waterhouse stops

    I agree that front stops are a quick and non-destructive way of introducing stops. An internal split brass ring to hold the stops is quite easy for most designs. However, there must have been a reason why WHS became almost universal from around 1860.
    Some of the pre-WHS petzvals which have been modified to take central stops have their own special charm! Sometimes with the engraved section cut away and moved to another part of the brass sleeve and others where the slot could just be fitted with side entry and with tantalising loss of part of the engraving!

    Anyway, I can't see the historical/cultural legacy problem of installing them on projection Petzvals. I would advise "undercutting" of the square hole in the sleeve and getting the final "square" with a set of key files. If you get the slot 0.5mm off perpendicular it won't matter and the thickness of a hacksaw is about right!
    The two internal ring forming the edge light seal are easily made from split rings and can be soldered into position. But you will have to relacquer.

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