10540Re: Final squareness/lens test. Problem found
- Aug 1, 2003Unless 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?
--- In email@example.com, "Markus Ludes"
> Hey I installed many lenses in such tubes and all have play . Ifyour lens show on axis at high power zero coma, that it is for shure
not the lens
> best wishes
> ----- Original Message -----
> From: digidodi
> To: firstname.lastname@example.org
> Sent: Friday, August 01, 2003 10:11 AM
> Subject: [tmboptical] Re: Final squareness/lens test. Problem
> You are wrong. With a 90 degree rotation in thread, there is
> absolutely no play with the lens cell in the tube, and no tilt. Iturning
> tried but cannot move the lenscell in any other direction but
> Rotating the lens by 90 degrees produces exactly the same error
> for star, aberration per aberration.between
> I am sorry, it *is* the lens or the cell, or - very unlikely -
> potentially the top end machining of the tube of course.
> --- In email@example.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
> 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 reallysquare
> > best wishes
> > Markus
> > ----- Original Message -----
> > From: digidodi
> > To: firstname.lastname@example.org
> > Sent: Friday, August 01, 2003 1:49 AM
> > Subject: [tmboptical] Final squareness/lens test. Problem
> > Well, I did one more test. I rotated the lenscell 90 degrees
> > error rotates with it.
> > So the error is in the lens itself. Although it is
> > in the center for Mars, I intended to use the scope for deep-
> > photography, so I will probably need to swap lenses. Too bad,it
> > lambda 1/11.
> > A slight problem of quality control in lens cell or mounting
> > elements?Service.
> > What do you suspect Thomas? The lens or the cell. Can I do
> > myself or better send it back?
> > Dodi
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