Mount Suggestions Sought for Awkward Obsy Plan...

[eshy76]

Hi everyone...roll up...roll up....it's a "spend my money" thread!

I am embarking on an attic observatory build, which I won't go into details on here - there's a thread on that in the DIY Observatories section. Anyway - a key part of this is that there will be a 1.1m2 sliding roof window in a loft, through which will unfurl my imaging gear. I currently have a iOptron CEM25P and William Optics Z73 which would fit through this gap perfectly well but....

...I am thinking ahead to the inevitable mount and scope upgrades....the largest scope I would likely ever want for imaging is an Edge 9.25 HD, which is 55cms long and, I think, 26cms wide. And 9.5kgs in weight.

I would need a sturdier mount for this in future, so my question is - which mid-range to premium mount(s) would be enough to wield an Edge 9.25 HD + imaging gear, while being compact enough to fit through (and potentially rotate in) a hatch in a loft? Including counterweight bar...

So far, the mount I have found which seems to fit the bill is the Avalon M-Uno...the RA-axis being close to the OTA and a lack of counterweight bar makes it an early contender...

I am seriously considering using a Linak DL2 type rising column to lift the whole thing through the hatch as a possibility. However, if the mount in question has a "turning circle" that would fit in that hatch, then I wouldn't need to go down that route.

My Avalon thinking was inspired by the link below on critical rotating dimensions, kindly provided by @old_eyes in the obsy thread.

Thanks in advance! All suggestions welcome! (Please no comments on hot air currents and vibrations - those warnings have been heeded!)

https://www.blackwaterskies.co.uk/2013/12/observatory-planning-and-german-equatorial-mounts/#lightbox/2/

[Silent Running]

The Rainbow RST mounts are very interesting too. I have a Rainbow RST-135... very light and compact, no counterweight, yet with a large capacity. Can be used in equatorial or AZ configuration. The RST-135 costs a bit less than the M-Uno, while the larger (though still small and compact) RST-300 costs more than a 10-Micron GM1000. If you need a mount to go through a small opening this type of mount or the similar Hobym Crux mounts seem hard to beat.

[eshy76]

On 18/01/2021 at 22:08, Silent Running said:

The Rainbow RST mounts are very interesting too. I have a Rainbow RST-135... very light and compact, no counterweight, yet with a large capacity. Can be used in equatorial or AZ configuration. The RST-135 costs a bit less than the M-Uno, while the larger (though still small and compact) RST-300 costs more than a 10-Micron GM1000. If you need a mount to go through a small opening this type of mount or the similar Hobym Crux mounts seem hard to beat.

Hi there - I only saw this message today - sorry for the late reply. Unfortunately the roof obsy project has been mothballed - the builders have framed the ceiling of that room in case I want to go ahead with it in future...about 1.1m2 of clear aperture...

...what is ironic is that I recently picked up an RST-135 before seeing your post! But the motivation was very different - I'd resigned myself to having to set up and tear down in the garden every clear night for the foreseeable future...so the Rainbow Astro appealed by being very quick to set up and very light, while performing pretty well.

And, now that I think about it, and after reading your post, it could well end up being stationed in the "Observatory" (as the room is still called) and would be perfect for it in terms of compactness! I would probably keep the focal length to below 500mm if I were to go ahead with that...probably pair with a RASA 8 or something like that....

....but that's a few years away - thanks for the suggestion! Great minds, etc...