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Thread: Swapping lenses in a Petzval

  1. #1

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    Swapping lenses in a Petzval

    About the only project I completed this Summer was one involving an 8x10 Petzval lens that I picked up from Eddie. I made some adapters for it so that I could mount the lenses in a shutter in various configurations. I thought you'd like to see the results.

    I took two sets of photos, one close and the other at a distance. I didn't get around to doing any at portrait distance, however.

    I started with the cemented doublet in front, and the flint & crown pair in the back. The first photos are with the original Petzval design, i.e., flint forward, crown in the rear. The second are with the flint and crown reversed in the rear (the Dallmeyer flip).

    Next I removed the doublet from the front, and used only the flint/crown pair in the rear, reversing the order of the two lenses.

    Lastly, I mounted the flint and crown lenses separately, at barrel-length from one another, reversing their order also.

    I'll put the photos in separate posts, so that I can mark them appropriately. My apologies for the differing exposures - most were guesses.

    Charley

  2. #2

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    Re: Swapping lenses in a Petzval

    This is with the cemented doublet in the front, and the flint/crown pair at abrrel-length away, in the rear.

    The first set are with the original Petzval formula, i.e., flint forward of crown.
    The second set are with the Dallmeyer formula, i.e., crown forward of flint.

  3. #3

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    Re: Swapping lenses in a Petzval

    In these photos, the doublet is removed from the front, and the flint & crown pair remains in the rear of the barrel.

    In the first set, the crown is forward of the flint lens; in the second, the flint is forward of the crown.

  4. #4

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    Re: Swapping lenses in a Petzval

    In these photos, the flint and crown lenses are mounted separately - one in the front of the barrel, the other in the rear.

    In the first set, the flint lens is forward of the crown, in the second, the crown lens is forward.

  5. #5

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    Re: Swapping lenses in a Petzval

    Bonus pix!

    Here's a photo taken with the crown in front, flint in back (at barrel-length), and with a red (090) filter.

    And one with the original Petzval formula, doublet with flint in front of crown, but with a 1/2 inch extension put into the barrel.

  6. #6

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    Re: Swapping lenses in a Petzval

    I'd like to know more about how you adapted the lenses to a shutter. Did you take the lens out of the originial brass (assuming) barrel and then mount them in a homemade barrel on both sides of the shutter?

  7. #7
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    Re: Swapping lenses in a Petzval

    Neat experimenting, Charley! I'm playing with a half-Petzval right now (crown and flint only). Too much fun.

  8. #8

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    Re: Swapping lenses in a Petzval

    Charley--Interesting post! I'm curious as to the focal length and maker of the lens. It looks more like a half plate lens from the coverage on your film. Also, the very first comparison with flipping the rear group (ala Dallmeyer) is curious. Is the first (traditional) configuration the native configuration of the lens? That would be odd because it looks like that configuration is incorrect by the results. Reversing the rear group clearly makes a huge difference in the sharp coverage of the lens and yields the traditional swirly highlights around the edges of the field.

  9. #9

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    Re: Swapping lenses in a Petzval

    Quote Originally Posted by domaz View Post
    I'd like to know more about how you adapted the lenses to a shutter. Did you take the lens out of the originial brass (assuming) barrel and then mount them in a homemade barrel on both sides of the shutter?
    Short answer: yes. The glass is still sitting in the original brass mount, but that mount has been unscrewed from the barrel. The size of the adapters, of course, is important.

    Here's a picture of the lenses in the original barrel, and one of them mounted in a shutter. The knurled brass piece on the front lens is an adapter to allow 77mm filters to be used.

    Charley

  10. #10

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    Re: Swapping lenses in a Petzval

    Quote Originally Posted by BarryS View Post
    Charley--Interesting post! I'm curious as to the focal length and maker of the lens. It looks more like a half plate lens from the coverage on your film. Also, the very first comparison with flipping the rear group (ala Dallmeyer) is curious. Is the first (traditional) configuration the native configuration of the lens? That would be odd because it looks like that configuration is incorrect by the results. Reversing the rear group clearly makes a huge difference in the sharp coverage of the lens and yields the traditional swirly highlights around the edges of the field.
    Yep, the whole project is interesting and the results are all curious - lots of fun.

    I haven't measured the focal length; it's fairly short, probably less than 6 inches. The focal length using the Dallmeyer arrangement is somewhat longer than the Petzval arrangement. Calling it an 8x10, of course, is a sleazy lens-seller tactic

    There are no markings on it, so I have no idea about maker, and there's no way of knowing in what configuration the lens left the factory.

    Charley

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