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  1. #11
    Two23's Avatar
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    My thinking is it's a Petzval that someone tried to clean and put it back together out of order.


    Kent in SD

  2. #12

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    Quote Originally Posted by Raphael View Post
    Hi all,



    Hello Mr Fromm,

    Glad to see you in this thread !

    That's the first name which came in my mind when seeing the handwriting, however, IMHO (and I also asked to the Lady-to-my-side as second opinion), it's Berthier, or maybe Berthiès :
    Attachment 69917

    BTW, I just read your articles series about "Unlikely lenses on Speed Graphics" with great interest


    @John : Yes, it's look a little a Tessar, but reversed, as the cemented doublet is in front

    Trying to make things clearer, if I can make a crude chart with ASCII art, it would likes this :

    ------------> (|| ))I|)

    Incoming rays, Front group, rear group

    Front group : cemented doublet (not sure if the last surface is actually plan)
    Rear group : Concave-Convex thick lens, a spacer ring (symbolized by the I) about 5mm thick, and thin plan-convex lens (not sure again if it's really plan).

    @shutterfinger : thanks for your reply, it's hard to tell, but maybe it's effectively a "B". Do you know if Lacour-Berthiot ever used this kind of monogram with the star ?


    Thanks again to you all !

    Cheers,

    Raphael
    maybe it is a reversed tessar because light travels through the lens
    opposite with a camera than when projected ?

    looks like a fun objectif

    john
    silver magnets, trickle tanks sold
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  3. #13
    Whiteymorange's Avatar
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    I'd vote for it being a modified Petzval. As this page from the 1890 Ben. French Catalogue (found here, thanks to Dan Colucci) clearly states, photographers have pernicious habits of taking lenses apart and screwing them up! There were many variations on the design tried by lens-makers during the 19th century. http://www.antiquecameras.net/petzvallens.html has extensive material if you're interested.

  4. #14

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    Quote Originally Posted by jnanian View Post
    maybe it is a reversed tessar because light travels through the lens
    opposite with a camera than when projected ?

    looks like a fun objectif

    john
    Hi John,

    Your question is an interesting one, and maybe any optics pundits around can answer it ?
    As the Tessar is not a symmetrical design, should it be reversed if the lens is used as a projection lens ? Logicaly I would think the answer is yes, but is this sure ?

    @Whiteymorange, thanks for your reply.

    I discovered recently the antiquecamera.net website, it's a goldmine !
    The design of my lens looks like a little the Dallmeyer portrait lens, as described on the petzvallens page. However i am inclining too for a mistakenly remounted Petzval. The fact that this lens was very clean for its age when I found it is aiming me this way.

    A check procedure will be to mount it on a camera and see what I get on the groundglass, but I haven't the appropriate lens board for now.

    Best regards,

    Raphael

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