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It has been torture trying to arrive at a solution where I can use my DSLR with both 16-35mm and 70-200mm with a ZWO mini guide scope and colour camera for guiding. I finally arrived at the solution below that balances perfectly. I think it will take some care to properly align the lens with guide cam but do the more experienced users think this could work?
just waiting on my ZWO ASIAIR Pro now to get it working.
Wow, First time I've seen the Moon through a telescope and what a sight. We had a good look at the Moon last night. It was also a chance to play around with the different eyepieces and what a difference that made. The red dot pointer was spot on after I found the little cardboard trick on you tube. Only using the 6SE in manual mode at the moment. Hopefully the cables for the firmware updates will be here today and the sky will be clear tonight. I fear that tonight will be cloudy, seems to be building up now, even looks like we may have a little rain. Looking at the moon was a little bit emotional. I am so happy we have the telescope. One question someone may be able to help with, is there a way to make the focusing on the Celestron 6SE a little less coarse.. It's almost like we need some kind of fine focus. Don't get me wrong, the focus is great , it's just a little bit sensitive, It's almost as if it needed something with a larger circumference.
We were looking at the moon with mouths wide open in awe of the beauty of something ordinarily we take for granted. I think we are hooked into astronomy, although there is so much to learn, at least now we have the time. We are finding that we now have the urge to take pictures, and also record our observing. Do people just use notebooks for observing notes or is there some kind of correct way of doing things
Thanks for all the words of encouragement
This is my third report, the first time having had a bit of good fortune, the second time out having had a reverse and found very little of what I was looking for. Armed with a few tips from members of this forum and some learning points of my own, I start setting up at 22.30.
It’s still far from dark, but some patterns now showing above. A little low cloud on the horizon, forecast is for some high cloud moving in from 23.00. I’ve planned a target list in two parts for tonight. First part is objects I’ve seen before but my other half hasn’t (she has to be in work tomorrow and will be staying out for the first act only). I need to be able to find these quickly. The rest of the list is objects I’ve yet to find, which I can take my time over after she’s retired.
By 11 I’m aligned and I can see enough to find the first target by eye – nu Draconis. While the contrasting doubles get the plaudits, there’s something to be said for such a perfectly symmetrical pair, in brightness and colour.
Next I switch to beta Lyrae, again an easy enough find by eye (though my partner remarks kindly at the speed of operation). A nice contrast to the Draco pair, obviously different mags, and we argue about the colours for a while.
Then on to Albireo, which she has heard much about, and seems impressed by, even in the twilight. Again we discuss colours.
I’ve left the fuzzies until later, and I now pick out M13 surprisingly quickly. In our 70mm at x27 it’s only a smudge, though as on previous evenings, averted vision does suggest some speckling. I try adding a 2x barlow, which I’ve not done before, and am surprised to see now some differentiation – a slightly denser core. Partner’s eyes are a bit astigmatic, but she does see it too.
Pushing it now, I head back to Lyra for M57. The sky isn’t as dark as when I (just barely) saw it before, but we try. I can just get beta and gamma into view in my widest EP, so somewhere in the middle. I flick my eye about as I did last time, and catch it again. I try to describe the procedure to my other half, and after a few minutes, she says she does too. I would have bet against that one, but the last item on list A is one I haven’t even found myself before – the Dumbbell – and it will take some finding.
Learning from last time, I’ve ditched the Mag-7 Star Atlas Project maps - pretty though they were, I just couldn’t read them in the dark. Instead, I have printed a selection from the Michael Vlasov atlas (also plugged on this forum) which are larger on each A4 page. The other thing I have realized is that my hopping technique was flawed (or non-existent). I was either just finding a known starting point and then sweeping in the direction indicated by the chart, and hoping to spot the target in the EP, or else I was trying to use the finder but “giving up” too soon and switching to EP view when I thought I was in the general vicinity of the target. The problem with approach 1 is that for a faint target, with a small scope in polluted skies, you could pass right over it and not spot it. The problem with approach 2 is that a refractor pointing upwards (hence with star diagonal) reflects up-down and left-right so if you switch to your EP before you have your target in field, a beginner is going to struggle making that last hop from the chart. Whereas my finder gives a true view. This makes good sense now, but I needed to spend a cold, fruitless evening at the EP to realize it.
So for M27, softly softly – there’s nothing especially close and naked eye that I can use. So I start at Albireo, nudge a little down and northwards with the slow-mos, then check in the finder against the chart. I’m just looking to match a pattern of the new stars now in view, and I can see one. I repeat the process. It still works, this is great. I’m amazed that this tiny, plastic 6x30 is delivering the goods. I can now see a star in my finder that I can see on the chart is right next to the Dumbbell. I adjust the scope a last time to centre on where the chart says it should be (and I know that actually M27 is pretty big). And only now do I switch to the low-power eyepiece. OK, I must have knocked my finder alignment out slightly during the evening, but a slight correction and there it is, in all its glorious smudginess. Extra mag doesn’t make much difference; I can see structure alright, but I can’t honestly say I can see the apple core, certainly not as good as the (full colour!) sample illustration in my Bresser instruction manual. But I don’t care, it’s M27, it’s another first, and I found it the proper way. It’s gone midnight now and my other half wishes me luck and heads off to bed.
Before I look at the second half of the list, I take a breather and have a look at the sky. It’s actually not that bad, considering we’ve now officially lost astro dark. It looks perhaps better than last time I was out – I could see the milky way behind Cygnus then, but now I see it extending across the eastern sky well into Ophiuchus, and I can see bands of light and dark structure. It’s going to be interesting to see if this is maintained when lockdown is over.
Back to the list, and I yet again try to split delta Herculis, without success. This will definitely be the last time until I get a bigger scope.
Then to another double, kappa Bootis. I’ve found iota previously, and looked for kappa twice, but failed. That was before I used my finder properly though. So let’s start from lambda, work up to theta, then I recognize the field from the chart. Again, the finder’s slightly off, but there’s certainly a double in the EP, with a companion noticeably fainter. To be sure I haven’t found iota again by mistake, I quickly slew to compare with Mizar (which I know has almost the same separation). Tick.
Another previous escapee, psi1 Draconis. This one is a bit trickier and I end up doing three or four separate hops, having to start again at one point. But I do find it, a nice pair at 30”, the brighter one seems slightly whiter to me.
The tail end of the list has some clusters: M10/M12 in Ophiuchus, M92 in Hercules and M4 in Scorpius. A bit frustratingly, I realize that these are either now behind houses, or else dead vertical, and after a few minutes trying the starhopping procedure in a painful crouched position (BUY THAT NEWT) I decide I’m far enough in credit now to call it a night. It's nearly two.
By Michele Scotti
Hi everybody - I'm humbled that some of you are following the thread on the 800mm telescope. I thought it was worth starting a sub-topic specifically related to the mirror making.
So as the works on the mount got halted by the lockdown we had some time to virtually meet-up and discuss the optics for this project.
The onset was pretty straightforward with an 'if we are doing this we are making the mirror'. And that sorts out the make vs buy, I suppose.
As of now, the only two things decided so far are the diameter -at 800mm- and the f/3.3 - of course we can accommodate some variance.
Some aspects of the making are pretty unchartered territories for our club so I'd like to seek some good advice from anybody in terms of direct experience or rather point us at some resources/threads.
Back-ground: to make it short, our senior member had three 500mm f/5 done years ago. He did of course faster optics up to f/3 among many other mirrors - I actually never asked him how many, uh! He has always worked with full tool and has no experience with slumped glass. Btw we do have some experience in slumping glass but -weirdly enough- not in machining.
During our initial discussions we boiled the scenarios down to 3:
float glass, 35/40mm thickness considering 15mm of sagitta. This is a thermal challenge with its big outward mass, it's going to make the machining more of a challenge and the stabilization time longer float glass, 25mm (which seems more of a commercially available), slumped. Trading the thermal challenge with the slumping borosilicate, 25mm, slumped. Tbh this is just a better version of the previous point at a cost that is not prohibitive
What are the sources of glass in Europe for thickness over the bog standard 25mm?
Disclaimer: this is surely an ambitious endeavor and by no means we are underestimating that. Not only the bigger diameter is a step-up; the fast optics is a challenge too.
To start with we have some questions about slumped glass. It looks like an attractive, modern approach to mirrors that exceed a given diameter. I think I saw already some threads specifically about the slumping itself - that's golden.
However it's the grinding/finishing/parabolizing that is puzzling us. Are there specific techniques or is it the same as the flat back glass?
Also, how do you support the mirror? Would a support that replicates the telescope mirror cage be appropriate - a 27-point in our case? Or is it a matter to build a concave support that holds the back of the mirror? How accurate/solid should that support be?
Any experience out there??
I reckon that's enough as a start - thanks everybody in advance for your contribution.
Stay safe! Michele
I had a finely balanced decision to make yesterday about whether to stay up and attempt a post-midnight astro dark session, factors including:
- BBC/Met Office forecast was "clear all night"
- BBC/Met Office forecasts have been woefully innaccurate, both day and night
- Clearoutside was forecasting clear early evening, but later on it had "0% low cloud" and "75% high cloud" cover
- Lack of moon
- My other half is somewhat keen, but I didn't want to keep her up that long for a potential damp squib
- It's very late, and not dark for that long
- There look to be one, perhaps two more clear nights forecast in the coming week
- I have a new eyepiece and filter arriving soon 😀
I decided not to wait up, and instead charged my batteries for a possible session this coming week. I see in the observing reports this morning that at least some UK people did have clear skies, so I am a bit regretful. I've only started observing in the last couple of months, so I may have been spoiled by the number of good evenings we have been having? Looking back at some of the older comments, I see people wishing they'd never bought their scopes, after fifty or sixty days without sight of a star!
Anyway, to my question. Was I unwise to be put off by the Clearoutside prediction of "75% high cloud"? I mean, leaving aside the obvious possibility that they might be wrong anyway, Is there any difference in the effect on observation between low, medium and high cloud? Would you take one more seriously than another? I noticed that the "visibility" line was still saying 10 miles (the highest it ever seems to say) even when cloud cover was 75%. Is that significant?
Tonight is looking very similar!