First Light for my Orion/Helmerichs 8" OH200 - 26th April 2022

[Captain Scarlet]

Those of you who’ve been following the DIY Thread et al may have noticed that I’ve spent the last 2-3 months re-tubing a 2017 Orion Optics VX8 1/10 Newtonian into a Klaus Helmerichs carbon tube. It had a lot of problems, and with most of them addressed I assembled and rough-collimated it a couple of days ago. Last night clouds dutifully disappeared, as of course they always do when a scope is good and ready, so Lady Luck decreed that clear skies were the order of the, er, night.

I took it out to cool quite early and noticed during the evening that dew was forming, which has been unusually absent from all my previous sessions this year as far as I remember. This would be interesting, as one of the features of the tube I ordered was a 1025mm length, i.e. very long for a 200mm f/4.3. In other words, a large built-in dew shield! We would see during the evening if that worked (it did!).

Another design feature I’d built in was an aggressively short out-focus distance of only 70mm. The height of my Baader Diamond Steeltrack outside the tube is 63mm at minimum, so not much to spare! In the event, not quite enough (with the Paracorr2) for some of my eyepieces, predictably the longer ones and especially the Nagler 31. I had to confine myself to Delos 10mm (100x) and shorter for the session. There was very little in it, though, I reckoned a few millimetres extra height would do it. I spent today, the day after, calibrating my relative focal distances for all my eyepieces and it turns out I need only 4mm more to accommodate my whole set, including N31. There’s more than that left in the quite long collimation-bolts on the OO cell so I can use them to push the primary further up the tube to push my focal plane a smidgin further out. Though I might also drill an extra set of cell-holding holes 20mm further up to give me lots of options.

Anyway, to the session itself. I’d cobbled together a not-very-exotic list just before it got dark enough, and rattled through them. In the event, there was a milky sheen of high cloud throughout the night, mostly transparent enough to see through but occasionally forcing me to find another part of the sky. By about 1am, it had clouded over completely. Apparently around 11pm there was a huge fireball over Cork: I was certainly outside and in full flow but I must have been looking West. I missed it.

Earlier, just after 9pm I finally this year got around to looking for Mercury, and found it easily enough, through my Kowa TSN-883 spotting scope at 60x. The 45% phase was obvious. Always a treat to see that planet.

Back to the OH200, as I’ve named the scope formerly known as VX8. In-the-field collimation required no further adjustments to anything after what I’d done inside, so in went the Nagler 31. And out it came again straight away, for reasons described above, and I stayed with 100x or higher for the session. The overall impression, compared to when I last looked through this scope as a necessarily-grossly-miscollimated VX8, was one of joy and beauty, no more nasty coma! I’m very happy with it now, with only a few tweaks left to do.

First up was the Leo Triplet, only because I’d written it down first. All three, M66, M65 and NGC 3628 were easily on show. I was surprised, actually. I last observed these a month or so ago with my 300mm and in my dark skies they were of course impressive. I was expecting them, especially NGC 3628, to be visible but spoiled by my experience at 300mm. Not so, they were very satisfying to look at. I couldn’t get all three in one view, of course, but next time with the extra out-focus, I shall!

Anticipating a wide-field experience with the relatively short focal length of this scope I had M44, Praesepe or Beehive on my list. 100x magnification notwithstanding, it was still a very nice view, the trio of triplet stars at the centre all in view. Beautiful pinpoints.

I haven’t looked at M13 since last year, and knowing that globular clusters respond very well to larger aperture, I was expecting an underwhelming sight even here in an 8”. M13 was pretty much the first thing I looked at when I got my very first scope a few years ago in mag 21.8 country. That scope was my Skymax 180, i.e. 7” scope also with c. 33% obstruction, and I recall I was, if truth be told, a little disappointed then. I’d previously seen M13 through a friend’s Mak 127 from London as a dim homogeneous smudge and had been expecting Wow through the 180 in dark skies. I recall it was merely a brighter homogeneous smudge. So I was expecting similar last night, and was very pleasantly surprised to see a dense cluster of actual stars all the way to the centre. It was impressive, and I was extremely pleased. I’m starting to really like this 8” newt.

Next on my list I had the Cat’s Eye Nebula. I typed in NGC 6543 to my Nexus DSC handset, pushed-to to the region, and saw nothing. I looked at the Nexus’ information on NGC 6543 and it told me it was the Snail Nebula. I assumed I’d typed the numbers wrong and the Snail Nebula was some indistinct AP object far beyond visual, and moved on. In fact they are one and the same. I’d only roughly aligned to start with and should have slewed around to find the Cat’s Eye: I’m familiar with it and it should have been easy. It was obviously just out of my FoV.

Iota Cancri, a competitor to Albireo by all accounts as a blue/yellow double, was next. I found it easily enough, but was barely able to detect the colours, but really nothing special, certainly no competition to Albireo or its superior, Almach. A little puzzled, I looked up to see I was looking through cloud! No wonder. And it didn’t seem to be about to disappear. Next!

I went to M52, also cloud-underwhelming. Next!

Nearly finally, I chose what seemed the only unobscured patch of sky remaining, near Vega, and chose Epsilon Lyrae again, which looked so amazing recently through my 4” LZOS. This view was similarly crisp and clean, even at only 100x. But it was NE-windy by now and I only got brief still spells between gusts.

Finally of all, I went to Izar and confirmed that this scope performs well. Easily split.

It would have been nice to try to see some of the Ursa Major objects, M51, M81/2 and the other more difficult ones all of which I’ve had incredible views of with my 300mm, but they were all basically straight up, in the dob “alt-az hole”

So, all in all, I’m very happy with this scope, with a good few improvements to come. Not least replacing the 63mm secondary (CO 31.5%) with a 50mm one (CO 25%) which ought to make a noticeable difference. And as you can see from the final “put-away” pic, dew happened! But no effect on anything inside the tube.

Cheers, Magnus

 

Edited April 27, 2022 by Captain Scarlet

[Geoff Barnes]

Great report Magnus. 

I'm jealous of your vantage point, I am surrounded on three sides by 200 foot tall trees! 

[cajen2]

That sounds great, Magnus. It must be really satisfying knowing that all your hard work is rewarded. Can you make me one next? 😆