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Stephen,
A Pronto would be fine without the barlow. The ST4 has sub-pixel
accuracy. Some folks use the STV with the efinder which is even shorter focal
length than the Pronto. Of course the STV has slightly greater sub-pixel
accuracy than the ST4. I would not use the barlow as it is unnecessary. The more
important matter is to make sure that the guidescope is mounted very firmly onto
the main scope to minimize flexure.
Loke
Dear Group,
As a relative newcomer to AP, I would be grateful
for any advice relating to the appropriate focal length of a guide scope
relative to the astrograph when using the ST4 autoguider. My main instrument
is an AP130 (focal length 780mm) and I also own a Televue Pronto (Fl 450mm).
Would guiding with the Pronto yield a satisfactory result or should I consider
a longer FL guidescope. I have tried the Pronto with a Televue 2.5* barlow but
I found that this greatly complicated finding a suitable guide star in my flip
mirror finder.
Any advice is greatly appreciated.
Thanks,
Stephen
Scott.
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