#17619 Oct 23, 2003
Your question seems to have started a bit of a debate on the meaning
of PE specifications. Some have said that the G-11 and Titan mounts
both specify a PE of +/- 5 arcseconds or better. I can't find such a
specification for the G-11 on the Losmandy web site. My 1996 vintage
CG-11 manual has such a specification in it, but I think it was
dropped from more recent publications. My G-11 mount did not perform
to the spec as delivered, and I sent it back to Scott. When I got it
back it tested at +/- 4 arcseconds of PE. Over time the PE got
worse, and I had to disassemble, lubricate, and adjust the worm mesh
to regain the original performance. The PE of the mount depends on a
lot of factors including loading, lubrication, and adjustment.
Perhaps this is why the specification is no longer published for the
G-11 and why it is so conservative for the Titan.
#17665 Oct 27, 2003
Thank you, Allen,
Yes, I can see it. I do not complain. I think my original question about the
Titan-G11 purchase on a budget has no definite answer.
On the other hand, talking about PE specs (or any other kind of specs),
maybe giving the expected error of the spec measure could help giving you an
idea of the behaviour you could expect.
For example, an PE of, let's say, +/- 5 arcsec PE (+/- 1 arcsec of measure
error) it is not the same as +/- 5 arcsec PE (+/- 0,1 arcsec measure error).
Telling things the other way round, maybe the difference between G-11 and
Titan (and Paramount) is that you could find more homogeneous PE, according
to the specified, without much change, on very different scenarios (load,
temperature, etc.) on higher quality mounts, and from mount to mount of the
same model !! (.quality control?). I am just guessing.
I am not expert on this topic, but I am sure there should be some objective
data to tell much of the truth.
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