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SW 72ED refractor


tico

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Hello,
I have a SW 72ED within range, but I've never really seen one, I don't know if it can be considered a manageable refractor in reality...??
Has anyone used it for visual observation with a 2" diagonal star? Any problem with the Baader Hyperion IV zoom?
is that this is the material that I would like to use and the one that I have..
I also have a 2" amici prism at 45°, would I have focusing problems with this refractor for terrestrial observation?
Thanks for your comments.

Tico

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What do you mean by "manageable"? If you're talking about weight then it is a very lightweight instrument. I can easily pick up the scope and mount with one hand if I need to move it to a different location. 

With regards to focus there is just about enough in focus for a 2" diagonal with most eyepieces. With the BHZ you might have to use it in 2" mode so that you gain the extra height a 2"-1.25" adaptor takes up. However, a 72mm doublet objective is so light weight that the scope is very rear heavy. With a 2" diagonal you would have to invest in a much longer dovetail and risers so that you could push the telescope so far forward that the focuser is in line with the dovetail clamp on the mount. In practice I've found that I do not use 2" accessories and instead use a 1.25" diagonal and 24 Panoptic for my wildest field. If you want to use 2" accessories you would probably be better off buying at least an 80ED to help with balance. You could add weights to the front of the scope but if you're going to increase the weight I think you might as well do that with a bigger lens and get some extra light gathering capability in return. 

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I have the Astro-Tech 72ED (original version), and it easily comes to focus with 2" accessories.  However, the focuser slips under heavy 2" loads, so I wouldn't recommend it.  If you're going to use heavy 2" diagonals and eyepieces near zenith, makes sure to look for an R&P focuser to help control slip.

As @Ricochet says above, it takes a long dovetail bar to reach balance.  It just barely works with a 6" and is better with an 8".  However, the focuser knobs then need to be at an angle to avoid hitting the bar.

I doubt the 45 degree Amici prism would cause backfocus issues with most eyepieces with the Sky-Watcher version.  They don't require all that much more infocus relative to 90 degree mirror diagonals.

Edited by Louis D
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