Hi Dave,
Quote:
Originally Posted by Astro78
50% brighter images on the 10" would be the clincher - but. If you consider the time spent tracking an object under high power with the dob vs. an object that will stay in field with a cheap motor on an eq5. Your likely to see more i reckon with the EQ and slightly smaller scope.
Just being able to sit there and study a centred object, to me is really valuable
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True, it is quite valuable to have a drive but 50% brighter?
Try 4x brighter in the 10"! In rough terms we're comparing a 5" and a 10" yes? The light-gathering power is proportional to the square of the diameter of the aperture.
5 x 5 = 25
10 x 10 = 100.
130 mm is not a "slightly smaller 'scope" than 254mm -- not today, not tomorrow, not until the laws of physics change.
If you are interested in visual observing of DSOs, the view you will get with 130mm aperture will certainly be disappointing after looking through a 12". The view will be a little more than 1/6th as bright -- 130mm -v- 305mm. Yes with the 130 you will get goto which is very nice and a drive also but the number of DSO's visible will be
dramatically smaller than the 10" will show and much less detail and brightness.
In the end it boils down to what you value. A brighter much more detailed image or the convenience of GOTO and a drive. But beware, 1/2 the aperture does not equate to 1/2 the light -- it's 1/4 the light
If you are going to observe deep sky, aperture rules! But also bear in mind portability. The 10" will take a fair bit more lugging around and storage space.
Best,
Les D