Dawes and Jupiter (from S&T 11/2015)

[Piero]

I just finished reading an article in Sky and Telescope Nov 2015 about the observations and sketches that Dawes (the guy who defined the resolution formula) did on Jupiter with 2.7", 6.3", and 8.25" refractors.

I was very impressed by the quality of the sketches as well as the details on the satellites he took at 460x using a 6.3" refractor. Even nowadays with high-end telescopes, I believe that it is quite difficult to reach 460x with a refractor even when the seeing is very good! 

Anyway, besides the note about magnification, I think it is a very interesting article to read if you have a chance. 

[michael.h.f.wilkinson]

Don't forget your cheapo 60mm toy-store refractor can reach 340x (well, it says so on the box and it is true, if not useful ). He might have been using 460x just to tease out that last bit of detail. Estimating relative positions of features might have been a bit easier at 460x

[Mike73]

Yes I read that article last night.

Its amazing just how accurate and detailed some of the early observations were!

[John]

It's an impressive figure, especially when Jupiter, most of the time, does not respond that well to really high magnifications, at least for discerning the surface contrast features. I've found using really high powers do help fine faint planetary moons, central stars in planetary nebuae and that sort of high contrast target though.

Herschel frequently seems to have used very high power - 700x-1000x according to some of the notes I was reading at the Herschel Museum in Bath.

[Mike73]

It's an impressive figure, especially when Jupiter, most of the time, does not respond that well to really high magnifications, at least for discerning the surface contrast features. I've found using really high powers do help fine faint planetary moons, central stars in planetary nebuae and that sort of high contrast target though.

Herschel frequently seems to have used very high power - 700x-1000x according to some of the notes I was reading at the Herschel Museum in Bath.

I think I've used x350 on Jupiter with my old 16" once but that was far out of town with perfect seeing conditions.

I find I usually use somewhere between x180 and x260 for Jupiter but some of the finest modern day sketches I've seen have all been over x300 or higher. 

[michael.h.f.wilkinson]

I like to look at Jupiter at 290x with the XW7 if seeing allows, I personally do not find Jupiter doesn't take magnification well. This may well be down to personal preferences.