Quote:
Originally Posted by Waqas
Hi everyone. A beginner to this hobby, I have owned a 5" skywatcher dab for a month only, enjoyed moon, Saturn, Jupiter with it, and have passed it on as a gift. Now hoping to get a 12" Collapsible Dab, just like the one under discussion here. (I know it is a big jump for a novice like me, but I am not only an amateur but also an immature hobbyist. I want to go biggest aperture I can afford to buy.)
Now my question. If I wish to extend its use to astro-photography sometime in future, can I simply buy a plain 12 inch collapsible dab, and convert it into a tracking scope in future? or buy a Goto and covert it into tracking one(which could follow the object of interest and let me take decent photos)? is it possible? would it be costlier, than buying a Synscan now? Synscan and Goto are going beyond my affordability.
thanks is advance
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Hi Wagas,
A member of the local astro club has a 12" Skywatcher goto dob, and about two months ago he was kind enough to let me put a videocamera at the eyepiece end of the scope to see how well its tracking was, for occultation recordings. Such recordings use fairly high frame rate (less than 5 seconds maximum exposure length, and mostly four frames per second to 15 frames per second).
The tracking was not good for images with less than 1 frame per second. Mostly it was OK, but every few seconds there was a bigger jump in the track which meant that one image would get blurred.
I would say that 4 frames per second would be OK, but most astro photography would need exposures a hundred times longer than this, and as it stands, the goto dob is not quite good enough.
By contrast, the club has access to a 30" dob with ArgoNavis/StellarCat tracking, installed by Peter Read of SDM Telescopes. This dob has a native focal length of about 3.5 metres. When we put the camera at the eyepiece end of this scope, the tracking is much better. Eight second exposures are well-tolerated. Wind (as you would expect) is a bit of a killer with such a huge optical tube assembly, but that is not the fault of the tracking.
Again, this is not really the kind of exposures that astro-photography people commonly think about. It is perfectly good for occultation recordings, but would begin to show field rotation after twenty to thirty seconds.
Regards,
Tony Barry