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Thread: dallmeyer 3b front separation

  1. #1

    Join Date
    Jun 2012
    Posts
    12

    dallmeyer 3b front separation

    Hi everyone. This may have been discussed elsewhere, but I couldn't find what I was looking for. In any case, I just recently bought a Dallmeyer 3b, and there were a few things I'd just like to get advice about from you more knowledgeable photographers. The 3B I bought has a serial #68207 and has a barrel sleeve with rack and pinion. It appears to have a thread for a hood with a small lip (almost like a mini hood), but no hood was included. I guess my first question is how come I always see 3B's that are simply a straight barrel with the aperture adjustment lever only and a turn to focus engraving? Mine seems like a slightly different design and has aperture markings that stop at f3.5 rather than f3.

    Also, the front element couplet is showing a bit of edge separation, as well as a 3-4mm spot towards the edge of the glass that appears to be a separation. I figure this lens is just fine to shoot with, but since I've been pursuing this lens for quite some time, I am hoping that maybe I could get the elements separated, cleaned, and recemented. However, I am nervous about having this attempted as I know there might be a possible risk of cracking, etc. due to the heat used in softening the original cement. I just don't know if it'd be worth the risk, but maybe you guys can appease my concerns. I've emailed John over at FocalPoint to see what he thought, but some of you might have suggestions or experience in recementing one of these older lenses. Sorry, no photos of the separation yet as I just picked this up from the post today.

    Any help or advice is much appreciated!

    Thanks very much,

    Jordan

  2. #2

    Join Date
    Jan 2009
    Location
    Denmark
    Posts
    5,274

    Re: dallmeyer 3b front separation

    The sleeve 3B always has a brass lens, except when it has been lost!

    The basis process used to separate the 3B achromat is soaking in a solvent - not heat softening. Gentle warming to under 100 deg C does help/speed-up the separation process when the edge of the visable dissolved balsam/old balsam boundary is near the centre (an inch).

    If you can get the glass out of the brass mounting cell, this is amateur work. The only real danger is droping the sticky lenses on a hard surface! I don't think you will be able to get a 100% garantee from any commercial repairers - as there can be hidden defects and surface damage. I haven't found any in my work with about 20 lenses, though . The worst job is removing the insoluable deposits which form on the yellow/opaque sections.

    The spot you mention is undoubtably separation too. May be OK for use as it is.
    Does yours have the lever iris system? This could explain the loss of speed.

    Photos please. And you need to check the soft adjust and how the glass is mounted in the front cell. You find recent info on home balsaming in the DIY thread.

  3. #3
    Alex Timmermans
    Join Date
    May 2008
    Location
    Holland
    Posts
    561

    Re: dallmeyer 3b front separation

    Problem with a 3b is that the front lens is difficult to take apart.
    It has a bend rim to enclose the glass in the front brass part.
    At least mine has.
    "You dont take a picture, it's given to you"

    www.alextimmermans.com
    www.collodion-art.blogspot.com
    email : collodion-art dot onsmail dot nl

  4. #4

    Join Date
    Jan 2009
    Location
    Denmark
    Posts
    5,274

    Re: dallmeyer 3b front separation

    Mine isn't available at the moment, but I think you are right for all 3B versions, Alex.
    In the new year I am going to build a "Potters wheel" type lathe to cut through these darn burnished edges so that I extend my domestic rebalsaming experiments! Remounting must rely on packing with balsam or modern removable glue. The edges I have seen that been opened and closed again look very nasty.

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