Page 1 of 2 12 LastLast
Results 1 to 10 of 16

Thread: Spacers of Sinaron W 90/4.5 DB mount, for the same lens in Copal#1 ?

  1. #1
    Thalmees's Avatar
    Join Date
    Jun 2006
    Posts
    342

    Spacers of Sinaron W 90/4.5 DB mount, for the same lens in Copal#1 ?

    Spacers of Sinaron W 90/4.5 DB mount, for the same lens in Copal#1 ?
    Hello everyone,
    Used Sinaron W 90/4.5 in DB mount for the past 12 years.
    It has tow(2) spacers for the front element, between the front cell and the DB mount.
    Sinaron W 90/4.5 is the equivalent of Rodenstock Grandagon-N 90/4.5, BTW.
    My query:
    Does the lenses in Copal comes with front cell spacers? as DB mount lenses do?
    Is the same spacers necessary for the same lens came in(or converted to) Copal 1 shutter ?
    I do not know if the lenses in Copal1 comes from the factory with spacers or not?
    If you have the lens in Copal shutter(Sinaron W or Grandagon-N), please find if there is any spacers?
    That may provide the ultimate unswer, I think.
    Spacers fit exactly on the shutter, are the same size of external circumference of the lip(mount) of the Copal#1 shutter mount.
    Appreciate any input.
    Regards.

    The generosity of spirit in this forum is great, its warmly appreciated.
    ------------------------------

  2. #2

    Join Date
    Jul 2016
    Posts
    4,566

    Re: Spacers of Sinaron W 90/4.5 DB mount, for the same lens in Copal#1 ?

    I guess this is about the shims adjusting the distance between cells in Rodenstock lenses.

    Those shims are a factory adjustment to provide the particular optimal distance between cells in each unit. If you vary that distance with different shims then you can optimize the lens to work better for near or distant subjects, or to work better in the center or in the corner. For each particular lens, and after optical measurements, Rodenstock could add a shim of a particular thickness, more than one or none, to make each unit perform as better as possible.

    If the lens had those shims when DB mounted then you have to move those shims to the copal it is replacing the DB. The shims are a component of the lens, not of the shutter. ...so when you replace the shutter (or the mount) the shims have go with the glass.

    If you buy a used lens it can happen that the shims are lost, or because ignorance somebody placed there shims that are not the right ones when a shutter or DB was replaced, this would make the lens to not work with the same performance than when delivered by the manufacturer.

  3. #3

    Join Date
    Sep 1998
    Location
    Loganville , GA
    Posts
    14,409

    Re: Spacers of Sinaron W 90/4.5 DB mount, for the same lens in Copal#1 ?

    Quote Originally Posted by Pere Casals View Post
    I guess this is about the shims adjusting the distance between cells in Rodenstock lenses.

    Those shims are a factory adjustment to provide the particular optimal distance between cells in each unit. If you vary that distance with different shims then you can optimize the lens to work better for near or distant subjects, or to work better in the center or in the corner. For each particular lens, and after optical measurements, Rodenstock could add a shim of a particular thickness, more than one or none, to make each unit perform as better as possible.

    If the lens had those shims when DB mounted then you have to move those shims to the copal it is replacing the DB. The shims are a component of the lens, not of the shutter. ...so when you replace the shutter (or the mount) the shims have go with the glass.

    If you buy a used lens it can happen that the shims are lost, or because ignorance somebody placed there shims that are not the right ones when a shutter or DB was replaced, this would make the lens to not work with the same performance than when delivered by the manufacturer.
    Sorry, shutters have mechanical tolerances as do DB systems. The shims are added by the factory after optical bench measurements after being mounted to the shutter it will be used on.

  4. #4

    Join Date
    Jul 2016
    Posts
    4,566

    Re: Spacers of Sinaron W 90/4.5 DB mount, for the same lens in Copal#1 ?

    Quote Originally Posted by Bob Salomon View Post
    Sorry, shutters have mechanical tolerances as do DB systems. The shims are added by the factory after optical bench measurements after being mounted to the shutter it will be used on.
    Bob, of course it is not a bad industrial practice deciding the shimming depending on the particular shutter's actual thickness, but (modern) shutter thickness tolerance are specified at +/-0.025mm, while it is very difficult to notice a performance loss with a change under 0.05mm, anyway some may see a difference in lab conditions with a 0.02mm change.

    ...but actual (measured) variability of shutters' thickness are much smaller than specs, so IMHO that variability should have no impact in the performance. And for sure that moving the shims with the lens to a new shutter is the best bet we can do, doesn't it? ...because if a shimmig adds 0.30 mm for example... this would be noticed !!

    Well, ideally we should measure the original and the replacement shutters (with a 0.01 precission tool) and modifiying the shimming if a difference is found, true. If not doing that then the next best choice is reusing the shims...

  5. #5

    Join Date
    Sep 1998
    Location
    Loganville , GA
    Posts
    14,409

    Re: Spacers of Sinaron W 90/4.5 DB mount, for the same lens in Copal#1 ?

    Quote Originally Posted by Pere Casals View Post
    Bob, of course it is not a bad industrial practice deciding the shimming depending on the particular shutter's actual thickness, but (modern) shutter thickness tolerance are specified at +/-0.025mm, while it is very difficult to notice a performance loss with a change under 0.05mm, anyway some may see a difference in lab conditions with a 0.02mm change.

    ...but actual (measured) variability of shutters' thickness are much smaller than specs, so IMHO that variability should have no impact in the performance. And for sure that moving the shims with the lens to a new shutter is the best bet we can do, doesn't it? ...because if a shimmig adds 0.30 mm for example... this would be noticed !!

    Well, ideally we should measure the original and the replacement shutters (with a 0.01 precission tool) and modifiying the shimming if a difference is found, true. If not doing that then the next best choice is reusing the shims...
    Having spent 29 years as Product Manager for Rodenstock in the US I have seen everything from no shims in a 90mm 4.5 to one shim to multiple shims. It depends on the specific lens/shutter combination. Lenses have tolerances as do shutters!

    I’m sure that you have also seen that many lenses as well!

  6. #6

    Join Date
    Jul 2016
    Posts
    4,566

    Re: Spacers of Sinaron W 90/4.5 DB mount, for the same lens in Copal#1 ?

    Quote Originally Posted by Bob Salomon View Post
    I’m sure that you have also seen that many lenses as well!
    Yes... but for example fujinons as less prone to include shims, even for the wides.

    I was thinking that perhaps some designs were relying in shimming for optimization. My guess was that the designer could make the lens to have little effects when changing the spacing, or the counter... the design could seek an effect for example to allow to optimize one factor or a set of correlated factors...

    Just guessing....

  7. #7
    Thalmees's Avatar
    Join Date
    Jun 2006
    Posts
    342

    Re: Spacers of Sinaron W 90/4.5 DB mount, for the same lens in Copal#1 ?

    Quote Originally Posted by Pere Casals View Post
    I guess this is about the shims adjusting the distance between cells in Rodenstock lenses.
    Those shims are a factory adjustment to provide the particular optimal distance between cells in each unit. If you vary that distance with different shims then you can optimize the lens to work better for near or distant subjects, or to work better in the center or in the corner. For each particular lens, and after optical measurements, Rodenstock could add a shim of a particular thickness, more than one or none, to make each unit perform as better as possible.
    If the lens had those shims when DB mounted then you have to move those shims to the copal it is replacing the DB. The shims are a component of the lens, not of the shutter. ...so when you replace the shutter (or the mount) the shims have go with the glass.
    If you buy a used lens it can happen that the shims are lost, or because ignorance somebody placed there shims that are not the right ones when a shutter or DB was replaced, this would make the lens to not work with the same performance than when delivered by the manufacturer.
    Hello Pere,
    Appreciate highly your post. All details in one post, thanks so much.
    Your guess is 100% accurate hitting the two possible scenarios.
    My case scenario is the second one(purchased a used lens), but I also have the same lens in a DB mount.
    Now, I have a problem!
    Is the focussing screen(with fresnel or without) is able to show the difference in image quality(sharpness mainly) between the lens with shims and without? though I used a high quality focusable 10X loupe!
    Had hard time to discriminate any difference. I used one of Norman Koren targets, enlarged, on my iPad screen at max brightness to simulate high contrast, indoor. Distances was roughly 70X and 22X focal lengths from the film plane.
    Or should the test be performed outdoor on real film and real infinity(plus a distance closer than 10X focal length), then testing films under 10X loupe?
    Can not go out in the next couple days.
    Am I correct in analyzing the problem?
    Which way you will go?
    Any other method? Simple and practical?
    Any input from anybody is highly welcomed also.
    Thanks soooooo much Pere.

    The generosity of spirit in this forum is great, its warmly appreciated.
    ------------------------------

  8. #8

    Join Date
    Jul 2016
    Posts
    4,566

    Re: Spacers of Sinaron W 90/4.5 DB mount, for the same lens in Copal#1 ?

    Quote Originally Posted by Thalmees View Post
    Is the focussing screen(with fresnel or without) is able to show the difference in image quality(sharpness mainly) between the lens with shims and without?
    The ground glass has "grain" and this does not allow to see all the resolving power a lens has, anyway some screens have finer grain that other.

    There is a procedure described here (http://www.largeformatphotography.in...l=1#post369572) that instructs to use a powerful magnifier to check the shimming directly in the ground glass.

    A better way would be using an eyepiece (from a telescope or microscope) attached to the camera back, and finally you may attach a DSLR (Nikon D3400, for example) to the camera back, you can DIY attach a DSLR extrension ring for macro, that has an F mount, to a plating that will fit in the film holder spring back, with the ground glass removed. A DX DSLR has around 250 pix per mm, so it can record very well if the LF lens is performing better or worse, if you have the DSLR attached to a computer (tethering) you would see it with perfect convenience in a big monitor !

  9. #9
    Thalmees's Avatar
    Join Date
    Jun 2006
    Posts
    342

    Re: Spacers of Sinaron W 90/4.5 DB mount, for the same lens in Copal#1 ?

    Quote Originally Posted by Bob Salomon View Post
    Having spent 29 years as Product Manager for Rodenstock in the US I have seen everything from no shims in a 90mm 4.5 to one shim to multiple shims. It depends on the specific lens/shutter combination. Lenses have tolerances as do shutters!
    I’m sure that you have also seen that many lenses as well!
    Thanks Bob for your input.
    That's only true if you are talking about a new batch of lenses just departed the factory.
    Assuming that 50% of all new lenses made during a period of past time, distributed with shims, regardless of number of shims. And 50% did not need.
    By the current time, in used market, I do not think we will find 5-10% of the same batch of lenses having shims, for obvious reasons of handling, maintenance and just being easily missed plus scarce availability and knowledge about them.
    But hopefully, testing for the effect of shims on a particular lens that came without one, is not extremely difficult, of course not of lab precision but with reasonable accuracy.
    At the same time, if a lens needed a shim of certain thickness, it's near impossible to find it today.
    Thanks so much again Bob.

    The generosity of spirit in this forum is great, its warmly appreciated.
    ------------------------------

  10. #10
    Thalmees's Avatar
    Join Date
    Jun 2006
    Posts
    342

    Re: Spacers of Sinaron W 90/4.5 DB mount, for the same lens in Copal#1 ?

    Quote Originally Posted by Pere Casals View Post
    The ground glass has "grain" and this does not allow to see all the resolving power a lens has, anyway some screens have finer grain that other.
    There is a procedure described here (http://www.largeformatphotography.in...l=1#post369572) that instructs to use a powerful magnifier to check the shimming directly in the ground glass.
    A better way would be using an eyepiece (from a telescope or microscope) attached to the camera back, and finally you may attach a DSLR (Nikon D3400, for example) to the camera back, you can DIY attach a DSLR extrension ring for macro, that has an F mount, to a plating that will fit in the film holder spring back, with the ground glass removed. A DX DSLR has around 250 pix per mm, so it can record very well if the LF lens is performing better or worse, if you have the DSLR attached to a computer (tethering) you would see it with perfect convenience in a big monitor !
    Appreciate your follow up Pere and the link provided.
    I read it and performed the test.
    I think it can be tested on GG with only longer focal length lenses, where target size become enlarged on the GG.
    At 90mm focal length, subjects/targets sizes are almost half(1/2) the sizes perceived by individual eyes.
    With a 10X loupe, the grain of GG are large enough to interfere with the very small details as you mentioned.
    It should be performed on film I think.
    I tested on latest GG from Sinar P2/F2 era, BTW.
    Thanks so much.

    The generosity of spirit in this forum is great, its warmly appreciated.
    ------------------------------

Similar Threads

  1. Need help with a Sinaron Lens (DB Mount)
    By Vincepad in forum Lenses & Lens Accessories
    Replies: 3
    Last Post: 1-Dec-2014, 19:45
  2. 150mm Sinaron SE DB mount to copal 0 shim?
    By Sven Schroder in forum Lenses & Lens Accessories
    Replies: 2
    Last Post: 16-Nov-2010, 02:14

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
  •