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Peter Drew

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Everything posted by Peter Drew

  1. You probably couldn't afford my consultant advice 40 years ago!
  2. Couldn't agree more, you would have thought that someone at the point of manufacture would have tried one out!
  3. My only recommendation is that you experiment via used equipment, buying new and selling repeatably to reach your final goal will lose you money.
  4. The Moon can be projected but it will be very faint unless it's close to the eyepiece and low power. The Sun is unbelievably brighter than the full Moon, mag-26 compared to mag -12, mentally compare this to the difference between a mag +12 star and one of mag +26 star. We project the Moon on a 72" monitor by using a DSLR connected to the telescope and the monitor for outreach.
  5. The "finder" description" was a bit of a tongue in cheek comment although the SCT did previously have a 150mm F5 Skywatcher finder for several years. In truth, the SCT is mounted on a massive professional standard equatorial that easily handles both. Many years ago, when my 30" Dobsonian was installed in the main dome it piggy backed a 220mm F12.5 achromat, both now have their own observatories.
  6. One extra layer of felt and the grip issue is solved.
  7. My 150ED is mounted on my 16" SCT as a finder/general purpose refractor. I made my own rear adjustable ring for its alignment so no slippage issue.
  8. I think the "best case" scenario is that each of the damage elements will be no more than cosmetic and shouldn't overall affect the performance. The defect on the mirror is known as an "oyster" or "clam chip". Being as it's on the rear of the mirror, hopefully it won't impact on its quality. As others have said, the cast material of the cell could be difficult to weld, I would suggest a plate screwed and bonded to either side of the crack to restore its integrity. It's difficult to tell from the closeup, the extent of the dent in the tube, if it's just the central area then leaving it as i
  9. There aren't many 12x60 binoculars available. I have a 12x60 model with garish ruby coatings, my recommendation would be to NOT buy one of these!
  10. I would say that it is borderline between a "sundog" and a small part of a parhelial arc. It's in the right position for a sundog but they do tend to be a little more defined. Nice photo and observation anyway.
  11. For anyone about to use Baader solar film for the first time, apart from the usual safety recommendations, be aware that the film has an additional protective film attached to it and not particularly obvious. It needs to be removed before use otherwise it will spoil the image quality.
  12. According to their current website a 300mm diameter mirror costs £124 + £24 carriage + VAT, a 301mm costs £142 +£30 carriage + VAT so measure the mirror carefully!
  13. Excellent images for a 4" but they show the Alpine Valley, not the Rille which is a very fine feature running along its centre. Unless of course my computer resolution or my eyesight still fail to show it!
  14. I've not seen the Alpine Valley Rille in anything smaller than a 16", a 4" anything is of no use to me other than a finder or occasional solar telescope. It's my problem, not the telescope's. "A man needs to know his limitations" (CE)
  15. I certainly don't think it will have any effect now or later on the performance. Sometimes blanks do not completely "clean up" when ground to a diameter leaving a cosmetic "defect". As long as it's not on the active optical surface the manufacturer would deem it acceptable. Had there been glass chips inside the telescope that would be a cause for concern.. However, If I was the manufacturer of an optical component that is intended to be removed as necessary, I would choose a better looking item. If the telescope works well it's not worth risking an inferior replacement IMO.
  16. Hello Bill, welcome to SGL. I have an apartment in Tenerife with a few telescopes. I visited regularly before the pandemic and look forward to another visit when possible.
  17. Probably one made by the little known Don Jobson.
  18. Difficult to see another source of a 10" F2 mirror suitable for any telescope at that price.
  19. !0" reflector at 20" focus means it's operating at F2. My guess is that someone had a 10" SCT with a broken corrector and has used the primary to make a very fast Dob mounted Newtonian. If so, the results should be "interesting". I think the included Moon shot sums it up.
  20. Not worth it to me. I have the highly regarded Vixen 102mm FL, reckoned to be comparable with a Tak optically, (objectives made by the same company, Canon). Apart from very occasional white light solar it's one of my least used telescopes, a Tak, for me, would not be worth the outlay.
  21. Good read!. I think it highlights that relatively small increments of aperture result in small increments in detail. The greatest differences are usually the observer, the conditions and the accessories in use.
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