Re: [APML] 500mm mirror lens as a guidescope?

[Stuart Heggie <stuart.j.heggie@sympatico.ca>]

George, I'll go out on a limb here and say that for 50mm and shorter 
focal length, I polar align my SuperPolaris mount and I do not guide at 
all. My stars come out as pinpoints (to me anyway).
I agree with all the replies you got but in my work (aka real) life, I 
have found that we frequently set out to solve problems we don't really 
have. Even for my 105mm lens, at f2.5 I can go 15 min unguided if I 
polar align carefully (using only the polar bore scope).
Once I get up to my 180mm lens at f2.8, well then I use a 1000mm focal 
length refractor on the SP mount - guiding options are personal. For 
20min I guide manually because it takes longer to get the autoguider set 
up than to take the picture. For the big lens at f4.0 running multiple 
exposures of 40min each, I use my autoguider.

Now all this of course assumes your mount is reliable - my little SP 
mount is a dream - not sure what mount you have, maybe it needs guiding 
at all focal lengths.

Stuart

George Anderson wrote:

>While messing around with getting my B&W quickcam autoguider working and
>starting to worry about focuser flexure on my el-cheepo guidescope I
>started wondering (dangerous habit)...
>For widefield shots with a 35mm camera (50mm lens or less) would a
>guidescope with a 500mm focal length be sufficient?
>The 500mm f/8 mirror lens I have is very lightweight and has no
>detectable barrel flexure. The effective aperture is only 62mm but that
>is only a touch smaller than my 70mm f/10 scope that I use for manual
>guiding.
>Any thoughts from those in the know?
>
>George Anderson
>Montreal Canada
>
>Clear skies and good health
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>


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