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AliMac

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Posts posted by AliMac

  1. If you're aiming at something for the kids to enjoy as well, you can't go far wrong with a Dob. The eyepiece would be at just the right height for them and it's a really simple setup procedure. That is to say, you just need to take it outside! A skywatcher 150 would fit comfortably inside your budget and give you about £150 left to buy an adaptor for your SLR as well as a collimating eyepiece.

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  2. Well, first light. The images seemed just as sharp as with my refractor, and I couldn't make out any visual problems caused by the blemish on the mirror. I'll see how I get on with it over the winter, and I'll probably try to get a recoat next summer. I think it probably needs collimating as well, but I think I'll get by for a while at least.

    I didn't have much time tonight, but got nice views of M13 and M31. With the former I feel sure I could make out some speckliness with averted vision, which is definitely a step up from my 90mm. I really need to look into getting a right-angled finder though; my neck is killing me....

    So, sigh of relief, I'm reasonably satisfied that I've not wasted £122.

    Thank you all again for your replies. I'm constantly amazed at just how helpful everyone is on this board.

    Cheers,

    Ali

  3. think they strip it in a chemical bath [so it peels the aliminium of the mirror blank then they re aliminum it and seal it with an overcoat [think its quartz ] they may ask for a picture of the mirror and the scratch may still be there but the alumium will likely cover it [takes about 3-4 weeks £69 plus postage

    Thanks for that. I hope it won't be necessary, but it's good to know that the nuclear option is likely to have the desired effect!

    Assuming the collimation is reasonably on song the scope will probably perform OK. It's amazing how bad the coatings have to be before the views start to suffer noticeably. The condition of the mirror will probably play on your mind though so getting it re-coated might be worth considering in due course to give you peace of mind that you are getting the full performance a decent 8" mirror can give.

    I'm also very reassured to read the above! Is it a question of the amount of light reaching the eyepiece being diminished by a mucky/scratched primary, or should I expect visual effects as well?

  4. Having spent the last couple of hours looking at it, I think you're both right about it being scouring marks. Also, from what John said above, and from other info gleaned from Google, it seems that the coatings on this model are prone to deteriorating. I guess someone saw the black dots, thought they were dirt, and had at them with a cloth causing a bit of scratching to the surface of the mirror. If it turns out that the scratches are too severe, will recoating the mirror solve the problem? I presume the process involves removing the reflective layer. Are telescope mirrors coated from the front or the back? What I'm getting at is whether the scratches to the mirror surface would be removed by recoating.

    I've just had another try on a more distant chimney pot and the view seems fine. I'll give it a try on stars as soon as any deign to appear. I imagine that'll be in a week or two.

    Thanks again for all your replies.

  5. Thanks for all your replies! I now have the scope safely in my possession. I've had a quick look through it at a neighbour's chimney pot, and the view seems ok. However, the mirror has quite a large blemish on it, as you'll see below. I have no experience of mirrors, so could anyone tell me if this is sufficiently dreadful as to warrant a clean, or even, heaven help us, a recoat?

    I suspect I won't get a chance to test it properly for a while yet, given the clouds that are rolling in even now...

    Ali

    post-12001-0-76861900-1345131928_thumb.j

  6. Hello all.

    I wonder if anybody has any experience/knowledge of the above. I just bought one on ebay for £120, and at the moment I'm feeling like it was a good buy. That said I havent seen it in the flesh, as I'm picking it up tomorrow.

    I've been thinking of getting a Skyliner 200p, and I really wanted to know how the two compare. Does the Revelation have a parabolic mirror for example?

    Also, apologies to anyone I pipped at the post for it...

    Ali

  7. Maybe try this instead, courtesy of Phil Plait's Bad Astronomy blog;

    Canadian Telescopes - MIRA 80mm Alt Az Telescope - (Astronomers Without Borders Program Edition) - Telescopes.net from Woodland Hills Telescopes: Sky and Telescope, Astronomy Telescope, Binoculars

    The setup looks pretty good (nice tripod, at least), and if you donate $20 they'll give a telescope to a group in the developing world.

    Don't know if it's worth doing from the UK though.

  8. Ignore all of your eyepieces and barlows, except for the 20mm. That's your wide angle lens, and will give you your best chance of finding it in the first place. Then it's a question of focus. The white blur indicates you're in the right place, so you need to wind your focusing knob all the way in, and slowly wind it out while looking through the eyepiece until you resolve an image. Apologies if this sounds a bit patronising, but it's best to try the basics first!

  9. I'm pretty much a back garden man, but I imagine you'd find some decent dark out towards Southwell. Maybe around Kelham. The problem is you need to get a good ten or fifteen miles away from the conurbation, and with my measly 90mm of aperture it seems a bit of a waste of petrol...

  10. Lovely sight, and absolutely perfect timing. I was showing some friends the lovely line of moon-venus-jupiter, and pointing out the Earthshine on the moon, when it sailed past. We were looking down St Peter's Gate towards the square, so it was beautifully framed by the townscape.

  11. No such thing as a daft question! :D

    The 51 degrees bit is to set the mount to your current latitude. Basically, you set that and forget about it, apart from checking it's still in the right place occasionally!

    You're limited in what you can see to what's above the horizon at your time and location, but within those parameters your scope can be moved to point in any direction. Sometimes the motion needed to point your scope at what you want to see can be somewhat counter-intuitive, and you can end up with your eyepiece the wrong way up. Depending on what type of scope you're using, if it's attached to the mount by rings, you can loosen those to rotate the scope until the eyepiece is where you want it. Otherwise, just loosen the star diagonal and rotate that.

    What scope are you using, by the way?

  12. I take it you've managed to align it roughly with Polaris (the North Star) using the little white line on the RA axis? if so, that should allow you to track an object manually just using the RA control knob. Try it on something bright like jupiter or venus at a high magnification. That should let you check if you can track with any accuracy. I don't have the motorised version myself, but I think you should probably only fit that once you've made sure you're properly aligned.

    Unfortunately, the EQ2 is never going to be 100% accurate as you can't align it with any real accuracy, and I think you'll probably experience quite a lot of drift within a few tens of minutes, unless you've been very fortunate in your alignment.

    If you can save the pennies, a slightly more advanced mount, such as the EQ3-2, would allow you to fit a polarscope so you can get a much more accurate alignment to Polaris. I've been trying to scrape the cash together for just such an upgrade myself, but something always seems to get in the way!:D

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