Short tube refractor as View finder.

[Astrodread]

Been thinking for some time about getting a short tube refractor to mount on my Dob. mainly to act as a finder scope but i like things to have multiple uses. So somting like this would make a nice backpack scope. Ive the normal straight through 50mm finderscope that comes with the skywatcher 250pds. I dont get on with it at all. Talk about a pain in the neck. I love my RDF (baader skysurfer 3)

Ive been looking at the ST80 for about a year wondering if i wonna spend £70 - £100. then probably boulbe that for mounting bits etc. Another issue is weight. An ST80 with 90 degree diagnal, eyepiece and guide rings is gonna add some to the scope.. so im thinking of other options Ive seen that Telescope service sell some nice guide scopes but i think there out of my price range.

Thanks for reading

[Moonshane]

hi Pete

a wide field refractor like this would make a great finder scope. personally, I might use a 45 degree diagonal (I think it may come with one?) as this will make it a corrected image. alternatively use a 90 degree but this might get confusing as the image is correct in terms of up and down but reversed left right - one reason I sold my refractor as it got very confusing when using both that and a dob.

my choice is a combo of Telrad and a right angled finder - I have a 6x30 on my planetary dob and a 9x50 on my big dob.

as you say though a small frac would make a good travel scope.

maybe you could create a bracket to allow the frac to be fixed across two of your trusses? if you do it as low down as you can get away with this will not affect balance as much and may even help it.

[Astrodread]

Cheers for the info Shane. Ive never looked through a refractor so i didnt know about the diagonal. i wanted to get the eyepiece as close to my dob eyepiece as possible. do they do 90 degree erected diagonals?

[Mark at Beaufort]

I had the same view on this and tried to fix my William Optics SD66 frac to the top of my 10" Dob. I had great difficulty trying to balance the system so in the end gave up.

I have used a 9x50 right angled correct view finderscope which I believe in very good. However, sometimes you need a bit extra and I was fortunate to buy a Stellarvue 80mm finder (on eBay) - see attached photo. This finder in total only weighs about 2lb and fits nicely on top of the Dob. Yes I need some extra weight to balance but not too bad.

The other night it had its first outing and I could easily see M51 whilst looking for the super nova.

Mark

[Moonshane]

possibly but not sure. I suspect the quality would degrade a bit as it would go through a prism. I agree that close to the eyepiece is the most convenient position but this adds most weight where you really don't want it.

then again you seem pretty good at finding solutions to engineering issues