Page 3 of 3 FirstFirst 123
Results 21 to 29 of 29

Thread: Ross Xpres 300mm f4.5 design

  1. #21

    Join Date
    Dec 2011
    Location
    Aust
    Posts
    159

    Re: Ross Xpres 300mm f4.5 design

    Ok, there are only two cells with cemented elements, so I might try unscrewing the rear cell to see what that does. Unscrewing the front cell didn't appear to make any discernable difference.

  2. #22

    Join Date
    Nov 2004
    Location
    Slovenia
    Posts
    234

    Re: Ross Xpres 300mm f4.5 design

    Collin, are you sure that the front cell is cemented? From the picture on first page, one would think that theat is a two lens air spaced cell. The problem might be unscrewing the front element. Just depends on the barell construction. If your front cell unscrew together, that doesn't mean you would not be abble to separate the front two elements. You might need special tool to do so.

  3. #23

    Join Date
    Apr 2013
    Location
    Millom, Cumbria, England
    Posts
    393

    Re: Ross Xpres 300mm f4.5 design

    The front definitely won't have a cemented element, it will be two air-spaced elements. Most likely there is a retaining ring to remove from the back of the front cell in order to be able to get at the elements.

  4. #24
    loujon
    Join Date
    Feb 2007
    Location
    Western, PA.
    Posts
    1,087

    Re: Ross Xpres 300mm f4.5 design

    Quote Originally Posted by Colin D View Post
    Ok, there are only two cells with cemented elements, so I might try unscrewing the rear cell to see what that does. Unscrewing the front cell didn't appear to make any discernible difference.
    Hey Colin

    I don't believe that your front cell is a glued group. Sometimes the rear element of the front group is the element that separates from the front element of the front air spaced group. Particularly if the Tessar design is not originally built to add diffusion. Yours was NOT made in this way and many Tessar designs that are not meant to be separated for diffusion have the design like yours. Where the rear element of the front air spaced group is the one that unscrews from the front element .

    If you look at the arrow that I drew on the front group of your posted photo. Check and see if the is the sign of a smallest gap between the painted black cell (inner cell of the front the group) and then the brass threads which are part of the (front element) cell to the outer element of the air gap front group.

    See if you can get the black painted (Inner element) cell to break free from the (front element) brass cell. There should be a inner set of threads that the inner cell (black painted) attaches to the front cell (brass).

    If you think what I said may be true you may want to get a pair of rubber pads and a little lubricant . add a tiny bit of lubricant to this tiny gap & not a lot. Add a little more lube & let it sit a few more minutes. Wipe the access lube off the the front cell so you can get a grip on both sections with the rubber pads. Now try and break the threads free and you should be able to break them apart. Let's hope.

    BTW- from the looks of it you defiantly have the correct front cell (Air spaced) and NOT two glued groups. Let us know if this works out.
    Attached Thumbnails Attached Thumbnails Colins 300 Tessar Ic Ross.PNG  

  5. #25

    Join Date
    Dec 2011
    Location
    Aust
    Posts
    159

    Re: Ross Xpres 300mm f4.5 design

    Now I understand, my ignorance is showing :P, I'll give that a try.

  6. #26

    Join Date
    Apr 2013
    Location
    Millom, Cumbria, England
    Posts
    393

    Re: Ross Xpres 300mm f4.5 design

    I agree with Louis. I checked my 8 inch Xpres and it looks the same inside as yours, there is no slotted retaining ring, so I reckon it is the piece that Louis arrowed that unscrews. I can't see another way of doing it on mine, no little grub screws, no rings, nada.

  7. #27

    Join Date
    Dec 2011
    Location
    Aust
    Posts
    159

    Re: Ross Xpres 300mm f4.5 design

    I've put some lubricant around the join but it is stuck fast even after a few hours. The lens is in good condition making me reluctant to use any excessive force to loosen the thread, I'll see how it is in the morning.

  8. #28

    Join Date
    Dec 2011
    Location
    Aust
    Posts
    159

    Re: Ross Xpres 300mm f4.5 design

    It still won't budge. The gap between the first element and the front element is minimal so I wonder if the lubricant is even reaching the thread. On the weekend I might try mor mechanical methods to loosen it. Apart from the softer focus thing, I'd like to clean the interior glass which has a very small smudge in the middle of one of the elements that shouldn't affect images but still it annoys me.

  9. #29

    Join Date
    Dec 2011
    Location
    Aust
    Posts
    159

    Re: Ross Xpres 300mm f4.5 design

    The latest development on this saga. Today I had another fling at working this out and think I might have succeeded. If I have got this right, the front element actually unscrewed at the very front. If you look at Louis's diagram, the thread for the front element is where the botton of the arrow starts, that is at the opposite end to the pointy bit, you can make it out on the photo. However, the cell that Louis points to still exists and appears to have two air spaced elements to it, this I have not been able to move.

    To see if I had discovered how to make this a soft focus lens ala Jim Galli style I unwound the front element to the last couple of threads; on the ground glass it appears to have a soft focus quality, with a very narrow point of sharp focus. Tomorrow morning I am takng a still life shot of two lens elements in low light to see how it looks.

    And I was able to clean out a small faint blemish that bugged me even though it was not matrial enough to really worry about.

Similar Threads

  1. Ross APO Process Xpres f:10/241mm
    By Bill_1856 in forum Lenses & Lens Accessories
    Replies: 3
    Last Post: 15-Nov-2011, 07:15
  2. ross wide angle xpres
    By Marco Ferrarini in forum Cameras & Camera Accessories
    Replies: 7
    Last Post: 1-May-2006, 18:09
  3. Ross Wide Angle XPres coverage?
    By DE Carney in forum Lenses & Lens Accessories
    Replies: 1
    Last Post: 7-Nov-2001, 05:35
  4. Ross Wide-Angle Xpres
    By neil poulsen in forum Lenses & Lens Accessories
    Replies: 2
    Last Post: 28-Sep-2001, 23:35

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •