Loading ...
Sorry, an error occurred while loading the content.

10540Re: Final squareness/lens test. Problem found

Expand Messages
  • digidodi
    Aug 1, 2003
    • 0 Attachment
      Unless as I suspect the error is lateral in the lens or cell. Then
      you would still have good on axis performance, but as all
      photographers know, if you move the camera laterally away from the
      axis for one reason or another, you get uneven aberation because you
      are putting part of the image zone outside the aberation free image
      circle. I think this is what's happening.

      Anyway, for the record, Markus accepted to have me send the refractor
      to him and he will test it. I have also had a new tube send to him by
      the tube manufacturer. We'll see, and I'll post the outcome here.

      We bet for a bottle of Champagne that the error is in the lens (my
      bet) or tube (Markus). If I am wrong, I will admit it without problem.

      But Thomas, could you comment if lateral error is a potential problem
      in lens or cell assembly and could explain what I see?

      Dodi


      --- In tmboptical@yahoogroups.com, "Markus Ludes"
      <apm_telescopes@w...> wrote:
      > Hey I installed many lenses in such tubes and all have play . If
      your lens show on axis at high power zero coma, that it is for shure
      not the lens
      >
      > best wishes
      > Markus
      > ----- Original Message -----
      > From: digidodi
      > To: tmboptical@yahoogroups.com
      > Sent: Friday, August 01, 2003 10:11 AM
      > Subject: [tmboptical] Re: Final squareness/lens test. Problem
      found
      >
      >
      > Markus
      >
      > You are wrong. With a 90 degree rotation in thread, there is
      still
      > absolutely no play with the lens cell in the tube, and no tilt. I
      > tried but cannot move the lenscell in any other direction but
      turning
      > it.
      >
      > Rotating the lens by 90 degrees produces exactly the same error
      star
      > for star, aberration per aberration.
      >
      > I am sorry, it *is* the lens or the cell, or - very unlikely -
      > potentially the top end machining of the tube of course.
      >
      > Dodi
      >
      >
      > --- In tmboptical@yahoogroups.com, "Markus Ludes"
      > <apm_telescopes@w...> wrote:
      > > Domique, as I just told you in privat mail, forget the idea you
      > have had. If you rotate the lens cell, you can do it only if you
      > unlock it from the thread, than you get play in the threadsa
      between
      > cell and tube and you have a working tilt. Do what I told you,
      make a
      > laser alignment test to find out if focuser and tube is really
      square
      > >
      > > best wishes
      > >
      > > Markus
      > > ----- Original Message -----
      > > From: digidodi
      > > To: tmboptical@yahoogroups.com
      > > Sent: Friday, August 01, 2003 1:49 AM
      > > Subject: [tmboptical] Final squareness/lens test. Problem
      found
      > >
      > >
      > > Well, I did one more test. I rotated the lenscell 90 degrees
      and
      > the
      > > error rotates with it.
      > >
      > > So the error is in the lens itself. Although it is
      spectacularly
      > good
      > > in the center for Mars, I intended to use the scope for deep-
      sky
      > > photography, so I will probably need to swap lenses. Too bad,
      it
      > had
      > > lambda 1/11.
      > >
      > > A slight problem of quality control in lens cell or mounting
      of
      > > elements?
      > >
      > > What do you suspect Thomas? The lens or the cell. Can I do
      > something
      > > myself or better send it back?
      > >
      > > Dodi
      > >
      > >
      > > Yahoo! Groups Sponsor
      > > ADVERTISEMENT
      > >
      > >
      > >
      > >
      > > To unsubscribe from this group, send an email to:
      > > tmboptical-unsubscribe@egroups.com
      > >
      > >
      > >
      > > Your use of Yahoo! Groups is subject to the Yahoo! Terms of
      > Service.
      > >
      > >
      > >
      > > [Non-text portions of this message have been removed]
      >
      >
      > Yahoo! Groups Sponsor
      > ADVERTISEMENT
      >
      >
      >
      >
      > To unsubscribe from this group, send an email to:
      > tmboptical-unsubscribe@egroups.com
      >
      >
      >
      > Your use of Yahoo! Groups is subject to the Yahoo! Terms of
      Service.
      >
      >
      >
      > [Non-text portions of this message have been removed]
    • Show all 18 messages in this topic