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Restored Darkstar 10" Dob - First light


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Last night it was wet with cloud, but around 11:00 I noticed there were some decent clear patches so I had a short session with the Darkstar Dob.

I didn't have time to bodge together a finder (the one I had lined up has been repurposed as a guidescope and I haven't had time to sort out a skywatcher foot) so I was mostly using 'point and hope' and just looking for relatively rich starfields and trying different eyepieces.

I tried nearly all my EPs from 40mm down to 5mm, and they all came to focus. The 5mm UWA wasn't giving tight stars when pointed in the vague direction of Altair, but as I could see Altair twinkling with my naked eye I think that was a pointless exercise! I didn't try my 4mm plossl or 2.5mm UWA eps.

The 40mm, 32mm and 25mm plossls showed lovely star fields. I tried a cheap 8-24mm zoom but only long enough to prove it works. I tried a start test with a 10mm plossl but I coudln't make out any detail in the defocused stars. In contrast the 18mm ortho, when pointed straight up, did let me see a small ring of sorts, although was not a very steady shape, it was definitely a ring and appeared to be symmetrical.

Without a finder I could (just) find a very low down mars with the 25mm EP at x66 to see an orange globe. I optimistcally tried the 5mm UWA but I couldn't get the planet in view, although I did manage to get it focused and see some better looking stars despite being much lower down than when I tried it before. The heavy(ish) EP kept making the tube drop so I think I need to add a counterweight.

 

All in all, it was really just an exercise in proving the scope works, including that the focuser travel was spot on (it is) and my collimation was OK (it was, helped no doubt by being f8 f6.2).

I'm looking forward to a proper session with a finder and time to get my eyes fully dark adapted.

 

Edited by Stub Mandrel
Corrected f-ratio
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5 hours ago, Peter Drew said:

Dark Star used either what mirrors were available at the time or ones specified by a purchaser. 10" F8 is relatively unusual, any idea of the maker?      ?

Sorry Peter,  I worked it out in millimetres and used 200 instead of 250mm. The mirror is marked DS 63".3 (my estimate was 64") and is 10.2" diameter, so a slightly over length version of their standard 10 x 60 scope. I'll edit my post above. Also the stickers on base and mirror cell have an 01 phone number so 1995 or later, quite a late one? I assume the 'DS is just Dark Star, some suggest they were making their own mirrors by then.

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