RE: [Losmandy_users] PE specs: Was Question about Titan mount

Oct 23, 2003



#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.


Pedro Pastor

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