Binoviewer with 60 mm Guide Scope?

[etsatlo]

Hi all,

I'd like to complement my 102 Skymax Mak with a wider field scope. I also love using my binoviewer.

I considered a StartTravel 80 but various reports I found said that it didn't have enough back focus without using a Barlow to work with a binoviewer so that slightly defeated the point!

I found a 60 mm guide scope which, having been designed for use with a camera, may have the required focus travel to work.

However I'd like to know if anyone has had any luck with something similar or experience of a guide scope as a widefield grab-and-go affair.

Cheers

[etsatlo]

Well, to answer my own question the result is: no.

Turns out using an eyepiece straight-through produces about 30mm of back focus room meaning the circa 110mm of most binoviewers (mine included) weren't anywhere near. Putting another 2x Barlow ahead of the binoviewer put it was far too zoomed in and image poor.

Having found the same scope as my OP on Amazon under another distributor for £40 I thought it may be worth keeping for the tube rings and dovetail if nothing else (now gone up to £120).

Plan B, trying to use as a secondary scope using a regular, single eyepiece meant using a star diagonal.

This required circa 50mm focus distance so meant I had to screw a 2x Barlow into the nosepiece of the diagonal. The binoviewer was still nowhere near focus.

Whilst brought to focus this did mean it was a bit more zoomed in than planned at (2x240mm) / 25 mm = 19.2x rather than the planned 9.6x at the native 240mm focal length of the guide scope.

Well last night was the first clear night to try it under the stars and see how it performed. I wasn't confident given how milky and struck with chromatic aberation the daytime views were.

Needless to say I was fairly blown away. The 3/4 waxing gibbous moon (with 0.9 moon filter) was a sharp as I've seen it with craters well defined and the mare showing beautiful contrast. The chromatic aberation was now almost absent (only slight yellow tinge oddly).

Jupiter wasn't great with chromatic aberation very strong on the planet itself but with the moons sharp as tacks. It is worth noting that this is my first view through a refractor (save binoculars) so the performance may not be absolutely, objectively good but to my eyes it was lovely.

Saturn was a lot better (less CA) but still not a patch on the Skymax 102 Mak however the rings were visible and sharp. Titan was also just visible.

After a brief sweep over the summer triangle I thought I'd try hunting down something elusive to me. I've been trying to find M13 using my trusty 6x30 RA finder and copy of Turn Left at Orion but having seen it briefly in the Mak I wasn't particularly blown away (that's saying something for some other globular clusters!).

So I tried my luck starting from Arcturus up to the SW corner fo the Keystone of Hercules. A couple of hops further and bam, there it was. Clear and bright (relatively) as day sat between the 2 neighbouring stars as shown in the book.

So overall, as a single-eyepiece, wide field scope riding shotgun on my main scope it is a very welcome addition and looking forward to more views!

I highly recommend something like this for mounting red dot finder (broadly in the right region), 6x30 RA finder (star hopping) and the shotgun scope (for wow). Mine was same price but from a UK distributor so not sure what duties would be. The machined aluminium is very solid.

All the best.

[happy-kat]

Sounds like you had success with your new scope addition and getting the wider view you were after.