Jump to content

Stargazers Lounge Uses Cookies

Like most websites, SGL uses cookies in order to deliver a secure, personalised service, to provide social media functions and to analyse our traffic. Continued use of SGL indicates your acceptance of our cookie policy.

NGC 1502

  • Content Count

  • Joined

  • Last visited

  • Days Won


NGC 1502 last won the day on October 25 2013

NGC 1502 had the most liked content!

Community Reputation

1,327 Excellent


About NGC 1502

  • Rank
    White Dwarf

Profile Information

  • Gender
  • Location
    Essex U.K.
  1. Thank you Sunshine for your ‘tongue in cheek’ comments......but please remember that there’s sometimes a very fine line between success and failure...... I’m contacting Walkers Crisps to suggest “mirror flavour” could be the next big seller and you heard that here first.... Ed.
  2. Hi everyone. PLEASE READ THE FOLLOWING WITH CAUTION !! What’s described is a last resort if all else fails, and should only be attempted at your risk. Aggressive cleaning of optical surfaces could destroy it and be an expensive mistake. Lets start by saying that aggressive does not mean attacking with an abrasive substance or heavy rubbing - DON’T DO THAT !! Yesterday as I walked past my local branch of a well known second hand trader, I spotted a Skywatcher Heritage 130p complete with mount priced at £49.99. I pondered for a moment, went in and asked to see it. All looked fine except for two issues. The first was that the single stalk secondary holder was obviously bent causing the collimation to be wildly off. I thought that would be easy to fix and it was. The main problem was that the primary mirror was very grubby indeed. It looked like the scope had been stored mirror facing up without being capped. There was no signs of it being rubbed in a attempt to clean, I wouldn’t have bought it if that was the case. The secondary mirror looked fine, presumably because that faces downwards. On reaching home, the first job was to remove the primary cell complete with mirror. Easy, four tube to cell screws, plus another that also secures the lower end of the dovetail. Simple to remove mirror from cell. In the time honoured way I left the mirror to soak in luke warm soapy water while I had a cuppa. On returning to the job, I changed the water and using fresh top quality lint free wipes gently stroked the mirror surface underwater with frequent change of wipes. It made no difference.....mirror looked just as grubby.......repeated that process......no joy at all. I decided that the very even looking coat of “grubbiness” could be some sort of airborne contamination from unprotected storage. Maybe it wasn’t such a bargain after all. I tried leaving the dry mirror face up on a level surface and filling the very shallow curve of the optical surface with 99% isopropyl alcohol. Then a repeat of the previously mentioned soapy water clean. The mirror looked a bit better but not much... Repeated all of the above, with some improvement. Then I recalled a post I’d read from Roland Christan of AstroPhysics fame, thats the low volume top quality manufacturer of triplet apochromatic refractors in the USA. He mentioned that human saliva was great for cleaning optical surfaces, although in that case he’s talking about lenses, not mirrors. So I tried gently licking the mirror surface, that definitely started to help. Not altogether hygienic but I’ve survived to tell the tale ! Repeated the licking, washed with soapy water then a thorough rinse.......BINGO !! A pristine mirror that looks great even under harsh lighting. Reassembled, collimated, awaiting first light. I now own more telescopes than clear nights in a year Cheers, Ed.
  3. Hi everyone. Just heard of the passing this morning of Heather Couper, great lady who did so much for the world of astronomy over very many years. Sadly missed by us all. Ed.
  4. FWIW.......I’d stick with your 10x30 i.s. I have 10x50 & 7x50 non i.s. I see more with the 7x because the view is noticeably steadier. Binos with a monopod is inconvenient for quick looks, perhaps ok for extended viewing. YMMV.......Ed.
  5. That’s interesting. We know that a large exit pupil can give a bright background and low contrast view. But I’ve heard previous reports of a large exit pupil combined with a nebula filter giving success. If you can, your further comments would be helpful please...... Ed.
  6. Indeed, I’ve read in more than one place that the California nebula is an impossible visual object. But low power, wide field, a moonless transparent sky, away from the dreaded light pollution, with a nebula filter can do the trick.... Ed.
  7. Absolutely great to hear of the California nebula with large binoculars. Several years back I bagged it with my 70mm Pronto on a transparent night at Kelling star party. I didn’t expect to see it, but as I scanned the area at 18x, there it was. The filter I used was my only 2” filter an Orion Ultrablock, not usually recommended for this object and another reason I didn’t expect success. But there it was Ed.
  8. Welcome to SGL. Both of the binoculars you mention are Celestrons. The higher price will be better build quality and probably better materials. If you’re buying for long term use then the more expensive binos may be cheaper in the long run. I learnt this with eyepieces - started with entry level, “upgraded” to cheap widefield, became dissatisfied, paid top money to upgrade those. It would have been less expensive in the long run to have got good ones sooner. Please take notice of previous posters regarding what you can effectively hand hold. I have 7x50 and 10x50 bins. Now I’m older the 7x are used much more as the view is noticeably steadier, and the large exit pupil easier to view through. If you can, try before you buy, and don’t rush to decide. All the best with your choice, Ed.
  9. Welcome to SGL. My commercially available mounts are Dobsonians from Orion Optics UK. If I want to rotate the mount to the opposite side of the sky it only takes a couple of seconds. That’s 90 deg / sec. HTH Ed.
  10. Hi Baz.. Tough call making decisions, balancing pros & cons..... 8” to 12” is a big difference in light grasp as well as - bulk / weight / cooldown / cost...... Big factors for me are will the tube fit across the back seat of my car, do my back in, especially when I lift the whole thing - tube and mount - to avoid obstructions...... or will I see what I want but it’s in Scotland or Cornwall... Ed.
  11. Ultimate no hassle / ultra reliable / best fun / lowest cost / simple / freedom at last / actually see stuff directly not second hand - Get a Dob A few good eyepieces Decent star chart Sell all your other kit
  12. As above, but I’d like to add... You can do a quick and adequate check.......just view a brightish star at medium to high power. Centre it within the field of view. Defocus, you’ll see a set of diffraction rings with a large black dot, that’s the shadow of the secondary mirror. If that shadow is central within the diffraction rings, not skewed to one side, you’re fine. With patience a lot can be seen with a 76mm scope. It would take a long while to exhaust the possibilities. Ed.
  13. Good to check the focuser as above. When you’re ok with that, definitely sort the secondary FIRST, then the primary. If the secondary is off, then you could fiddle with the primary adjustments forever and not get it right. Ed.
  14. Tough to know what’s happening..... One reason that your collimation doesn’t hold is if something is loose - Although mirrors should never be held tightly, if they’re allowed too much slack the they can shift and alter the collimation. For the primary mirror the clips just need very tiny clearance from the optical surface. Check mirror cell to tube is secure. Also check the spider vanes are not too slack, secondary holder is not loose. Or - if you check collimation with your laser, then check later with the laser, is it slack where it fits the focuser ? Could be what’s causing the problem. You could try collimation with a basic collimation cap, then fine tune with a star test, in other words - ditch the laser.....some regard laser collimators as an expensive way to stuff your telescope Hope you sort it, Ed.
  15. I have the 2.5mm Vixen LV, one of the original versions. It gives 480x on both my 8” & 10” Dobs. That sort of magnification sounds ridiculous, and most nights it is But just occasionally it does the trick on very tight double stars. Even if the view is fuzzy, it can confirm the presence of secondary star in a close binary system. It’s certainly not used very often, but on rare occasions it’s useful. Of course manual tracking is tough, but my 8” OO has very smooth buttery movements, so with care not too difficult. Ed.
  • Create New...

Important Information

By using this site, you agree to our Terms of Use.