Astronomy and Birding in one - with a Mak?

[rusirius]

Further to my original thread on the subject ( see http://stargazerslounge.com/beginners-help-advice/94083-astronomy-birding-one.html ), I came across this scope at FLO:

Celestron - Celestron C90 Mak

I was initially after a grab-n-go scope that I could use for astronomy, but also as a spotting scope for nature. For astronomical purposes, I'm not expecting much but I was hoping to get a good view of the moon and a reasonably good view of planets and a few doubles and brighter objects. I understand that any scope of this size would be limited for DSO's.

One drawback that was pointed out to me with refractors of this type is their relatively short focal length which is usually around 500mm which means that one could not really attain the maginfication required for planetary observation. The Mak on the other hand is 1200mm. Am I right in thinking that this should allow it to be pushed to higher magnifications? In theory, a 5mm eyepiece should give 240x but what is likely to be attained in practice?

I would, of course, expect that this kind of magnification might be difficult to manage on a photo tripod, so I'm presuming that for astronomy purposes I might be better off with a motorised equatorial mount. But can they also be used in practice for terrestrial viewing or would I still need a photo tripod as well? For visual use only, what is the most compact and lightweight mount I could get, and, how do you convert from photo tripod screw to EQ mount rail?

Also, would a a Mak of this size give reasonably good detail on a planet? I used to have an 8in SCT and the loss of contrast caused by the central obstruction had a severe impact on the amount of detail that could be seen with a 5in refractor performing significantly better. This is less than 4in so what should I expect?

[John]

The max (useful) magnfication on that scope would be around 150x I would think. 90mm won't rival a 5" refactor or get anywhere near an 8" SCT unless its (the SCT) badly collimated - I had my best ever views of Saturn through an 8" SCT a couple of years ago.

Personally I reckon that scope would be better for birding than it is for astronomy - it will work for the latter but I feel you could soon exhaust it's potential. If I was looking for a scope to do both I'd probably be thinking of a 5" SCT and change the diagonals depending on the use I was putting it to.

[ringz]

Just make sure that the minimum focus distance of the Mak is close enough for you.

--

Martyn.

[Ibbo!]

Not at all what you are thinking but.....

I have used my Baby Tak 60 mm refractor for a bit of bird watching

What hapened was I was working in Keswick and needed something to do other than go to the pub and I have a passing interest in birds you know the thing put food and watch them from the window etc

Anyway discovered about the ospreys and went for a look using the kit from the view point ( a zoom scope of 60mm dia allegedly) it was baffled and quite dim I was disappointed

The next year I went with my own binos and scopes

I went to the view point and had the chat about optics and that my 60mm astro scope was no good for looking at birds

quality counts

it blew the birding stuff out of the water

Ok you would need eyepieces, a diagonal and a good tripod

but with a T ring and a DSLR you would have a great birding lens plus a great widefield astroscope which does give good views of the moon Ok its not brill at planets (but lets be honest what is unless you have light gathering and long focal length) and does give quite good views of the brighter DSO's

As an aside I also took the Tak 102 (now thats a birding scope if the little blighters stay still for 1/2 hour )