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About timwetherell

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  1. timwetherell

    DIY 10mm Eyepiece and Performance Comparison

    Great to see someone experimenting with optics! It's a lot of fun and can yield some surprisingly good results I have an old Erfle 20mm scavenged from something like a gun sight? Back when I had my little 60mm refractor with it's nasty eyepieces I'd always wanted an Erfle because Patrick Moore raved about them. I guess back in the long long ago before things like Naglers were common, that was about the best one could do. My Erfle isn't particularly brilliant optically compared to modern offerings but it has a high nostalgia value!
  2. timwetherell

    What is in your "Do not sell" case?

    Depends what technology delivers in the future, but I think my least probable sell is my TMB 40mm orthoscopic. It's only used in my WO66 finderscope but has a nice crisp flat field and for a 2" 40mm, it's very light (compared to something like a TV 41 panoptic) Gives me a pretty well corrected 7 degree FoV which is great as a finder but also good for ridiculously big objects like the North America nebula
  3. timwetherell

    The struggle with M 101

    This was my impression of M101 with a 7" refractor last night under good sky conditions - very much better than my previous viewing where there was a very slight haze and crescent moon. that time it was a barely discernible smudge! M101 does seem to be an object for which sky quality is critically important. I guess back in Messier's day apertures were small but light pollution was non existent!
  4. timwetherell

    Observing from indoors?

    I sometimes use my solar scope through the patio doors too - at least to establish if anything interesting is happening on the sun and if it's worth setting up outside. Interestingly one door introduces far more distortions than the other. Luck of the draw with the glass I guess.
  5. timwetherell

    The struggle with M 101

    I've been able to see it with a 7" refractor from the UK under 20.5 skies down here in the south west. It's little more than a very faint stain in the sky! One thing that I find helps is to wiggle the scope from side to side. One's peripheral vision is very sensitive to movement so a big dim wiggling thing is a lot more visible than a big dim still thing
  6. timwetherell

    Celestron 10mm plossl

    Chinese Celestron 10mm plossl. bought a 10 and a 15 for a spectroscope I'm developing and the 15 was better suited to that isntrument than the 10, so the 10 is now surplus to requirements. Essentially new condition, comes with case. Asking £7.50 including UK postage or a fiver if you can pick up in Somerset
  7. timwetherell

    Monocular as a finder

    Personally I find straight through finders rather difficult to use - bit of a strain on the neck near zenith. I'd be inclined to seek out a very light weight 5 x 30 right angle finder perhaps?
  8. No never made binoculars. I did renovate some old Russian 10x70s once though - just dismantle clean and repaint. I got them for a song back in the early 90s when big binos were a real rarity There seem to be quite a lot of big binocular telescopes on the market today but to be honest, I think it would be better and cheaper to just buy a single scope with 1.4x the aperture and fit it with a binoviewer. I imagine keeping two big OTAs perfectly aligned would be a pig of a job and it's not like one has any depth perception at astronomical distances anyway? Single bigger scope gives you 40% better resolution and you have the option to use one eye and go half a magnitude deeper as Olly says.
  9. timwetherell

    New location - new opportunity

    Definitely a good idea to have a scope permanently set up if you can. it really changes the way you observe and I personally find it about doubles my observing time! I do share your concern about the particle board and dampness! Though many big dobs are housed in garages which probably offer no better protection than a good cover would. I'd pay special attention to the base it's on. If that's a piece of damp concrete water will most likely work its way up into the particle board but if that's waterproof and the cover hangs over the sides so rain runs away from the base, it'll probably be OK.
  10. Yeah, I had a clever idea to store some smaller eyepieces in the pier for my scope in my observatory. But in the English climate they were getting a hammering. Not so much from fungus but from a daily dew cycle "gluing" muck to the lenses. Fortunately they cleaned up perfectly but I don't store them in the obsy anymore. As for ventilation, I have an air gap round the rotating roof with a flange that keeps the rain out perfectly. However in our recent blizzards that fine powdery snow blew right under it and I ended up with 1/2" of snow on the observatory floor!
  11. timwetherell

    cement mix pier base?

    I used a 6" auger to drill 1m deep piles into clay which seems to have done a god job. The polar alignment hasn't drifted at all in two years. Reading Miguel's post above, If I was doing it again i'd probably protect the ends of the rebar in some way rather than just poking them into the clay!
  12. I had a chance to compare a 6" f8 Celestron achromat against a TEC 140 once, and at low powers with a 31 Nagler it was very similar. So in a way yes, if you're looking at big dim things in wide fields such as M31, to my eyes it was 95% of the performance for 10% of the cost. At higher magnifications the difference was more obvious though, stars not just quite such tight pinpoints in the achromat and chromatic aberration around the brighter ones. Small deep sky objects were still pretty good in the achromat, but didn't just quite have the edge of the apo. Likewise, Jupiter was quite well resolved in the achromat but again, there's the purple halo which does detract a bit. The achromat was still a pretty good telescope especially considering it only cost about £300! If you happened to have a couple of grand sitting in your pocket a 6" apo would definitely be noticeably better as an all rounder, but for many people there are other priorities like feeding your family! In which case the achromat would still give a lot of enjoyment
  13. timwetherell

    Evostar 72ED early impressions

    LOL - love it! But of course now they'll say "WOW it was so much brighter in the big dob" Enjoy the new scope - ED refractors do give a lovely view of double stars!
  14. Yes Sirius B is a very challenging target in the UK with Sirius so low in the sky! I finally managed it visually a couple of nights ago with my 7" refractor but I've tried many times before to no avail. It all comes down to seeing. In moments of very steady air it's right there and relatively obvious but most of the time it's lost in a sea of scattered and dispersed light from Sirius. For some reason the atmospheric dispersion and turbulence tend to smear the light into a flame or fan shape like a peacock tail, which would be very pretty if it's wasn't masking what you were looking at!
  15. All of the above is absolutely true, but remember that the human eye is very non-linear in its perception of brightness. My own general rule of thumb is that you have to double the apperture to get a sense of "Oh wow, that's much better". Going from 60 to 150 would definitely qualify for the "oh wow"

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