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Piero

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Everything posted by Piero

  1. Interesting. Hopefully it will work well on fast telescopes too.
  2. Excellent review, Neil! The VIP is a great piece of equipment. In my opinion, the 2" modded version is even more useful than the standard version as it is sold. As the former configuration does not extend inside the focuser, it does not have all the focus issues of the latter. Just to balance things, as far as I know, the finding of the tak adapter to get rid of the 1.25" nosepiece is credited to @YKSE (Yong). I only started using the pushfix adapter with the docter because a) I like 2" nosepieces in medium large eyepieces, and b) it allowed me to screw the VIP Barlow into it in
  3. Good set! I have the same diagonal as well as the 2" prism model. Both are very fine.
  4. A 24mm 82 is a nice low power ep using that f-ratio. . Again, choosing eyepieces is really a personal matter. Personally, I would prefer a bigger "jump" and go from 24mm to 10mm. Then, I would choose a 6mm for a "zoom-in". Later on, something like a 4.7mm-4mm for close-up (e.g. moons, planetary nebulae, small galaxies). Said this, those 3 eyepieces (24mm, 10mm, and 6mm) would stay in the focuser most of the time. Few eyepieces means less swapping and less financial drain. Ethos, Pentax, Delos, APM XWA will all be fine. I find that that is more about loyalty to a certain brand, ergonomic
  5. It can be hard to advice and choose because the existing set should also be considered. I was not aware that you had an 8.8mm ep. If you plan to keep it and use it with this dobson, a 10mm can be redundant. Another option is to use the 8.8mm ep with another scope (e.g. refractor?). A third option is to sell it. These decisions are rather personal though. Coming back to your reply, again, people can have different observing styles. At 1200mm focal length, to me the 10-14mm does not give a proper boost in magnification for observing small details. I still feel my docter 12.5mm like a panora
  6. If I were in the market for a medium power eyepiece for a F4.7 dobson, I would look for something around 10mm focal length, rather than 13-14mm. That would be closer to a 2mm exit pupil. With this in mind, options could be 10mm Pentax XW (<<== what I would get, but I prefer ~70 to 100 deg AFOV), 10mm Delos, 10mm Ethos, and 9mm APM UWA 100 deg. If you add a TV paracorr2, the resulting exit pupil will be around ~1.7mm which is still nice and very usable for a medium power eyepiece.
  7. I happily stay away from orion optics. Bresser has nice offers for small dobsonians. For medium size, one is better off to build his/her own telescope in my opinion.. a) it is a great experience, and b) one does not have to compromise with other builders' design / crazy ideas.. you just make what you want.
  8. Personally, I wouldn't buy an OO telescope for the following reasons: - quite shocking reported experience with customer service - I know that here in the UK a lot of people have a solid tube (due to the fact that OO uses solid tubes for nearly all their VX series...), but to me a solid tube for anything above 10" (with exception for a 12" F4) is an obsolete design. - their mirror cell does not seem particularly impressive to me either. I wonder how many have the same issues experienced by Gerry and don't even know. That would explain the lack of care for coma correctors, therm
  9. Thanks Stu, that's a very interesting article. I wasn't aware of it.
  10. Yes, that is the one. See: https://www.firstlightoptics.com/howie-glatter-collimation-tools/howie-glatter-single-beam-2-inch-laser.html There are other attachments for more exotic collimations, but the 1mm is the one you need really. I have the 650nm version which is fine for collimation in the night. You can use the 635nm which is fine for day time collimation, or night time using a brightness reducer.
  11. The HG's a great laser collimator. Congratulations! I use mine with the 1mm attachment. I also have the tublug but only use it when feeling lazy.
  12. After 3 pages, it seems to me that this thread hasn't gone anywhere.. It is a shame because it would have been interesting to read about a star testing-based quantitative comparison between these two instruments. Oh well..
  13. I would recommend a 8" f6 Dobson as an all-around telescope. The skywatcher version is good and rather cheap, but if you can stretch it a bit, the Bresser version is mechanically much better. Orion optics UK... I would only consider it in the second hand market. Even then, I would probably go for something else.
  14. By the way, here is the 3" big paracorr "beast".
  15. My minimalistic 2" set. As I am moving fast, a paracorr2 was added a few months ago. Flo sent me the 3" version (that's a beast!) by mistake, but then all was sorted. It might be that I will let go the tublug at some point as I collimate with the laser only. Thoughts for the future. Left to right: Zeiss zoom, APM UFF 30mm, Docter, 2" HG laser 650nm + tublug. The VIP barlow is above the Docter. I use it with 0mm, 15mm, or 40mm spacers. The two boxes include 2" Lumicon OIII and 2" NPB filters
  16. @johninderby Are you still interested in this product? If so, we could split the cost. Let me know. Piero
  17. Coma is an aberration present in telescopes using paraboloid mirrors. It is not present in modern / half decent eyepieces. An F4 Newtonian has a coma free linear radius of 0.022*4^3 = 1.408mm . This defines the area in which the Strehl of a perfect mirror is 0.80 or better.. Also, variations of the mentioned formula generally use a more stringent factor than 0.022. Considering a field stop of 27mm for the 24mm TV Panoptic, coma is expected to be present and easily detectable in an F4 newtonian telescope. Also, the fact that Televue eyepieces are highly corrected to the edge, will make the dete
  18. In `Observational Astronomy for Amateurs` Sidgwick mentioned magnifications of at least 400x for critical lunar observing. Assuming crisps views, his comment can offer an idea of what kind of minimal aperture he meant! Again, I think we all have different tastes on this. At mags over 400x, one can seriously study the moon for years, due to the small image scale. Said this, some of the very best views of the moon I had were when it was full, slightly above the horizon, and using my TV-60 at 15x. In particular, the Moon was coming up from bushes and tree branches with a bird or two crossing
  19. Binoviewing with two docters is a rather expensive experience.. I don't binoview though. I compared my docter against a Delos 12mm and I preferred the former one. You can find that thread on CN forum. So, for me it does justify the cost. Besides, I bought mine in the second hand market from a member of this forum. Anyway, I don't have many eyepieces as a large set doesn't fit with my way of observing. For others, it is the opposite and owning an eyepiece between two magnifications (or FOVs) is important. For others, 100 deg afov eyepieces are cool, for me they are a dis
  20. My favourite eyepiece is the 12.5mm Docter UWA. Combined with my modified Baader VIP barlow I get an equivalent ~7mm or ~5mm, depending on target and mood. Another eyepiece I love and use quite a lot is the 30mm APM UFF.
  21. I think it all depends on the kind of objects one wants to observe. With my TV-60, I've spotted/observed about 250-300 targets. I intentionally wrote spotted/observed, because a few of those targets can only be spotted on that telescope given the limited aperture. Said this, it has been a great learning curve. In contrast to a larger telescope, a small wide field refractor can let one find many objects, which means the knowledge of the sky increases considerably. There are so many classes of objects that that telescope doesn't / cannot show well though. My 100mm Tak is a bit better
  22. Indoor, I enjoy using Interstellarium and Bright Star Atlas 2000.0 . Outdoor, I generally use SkySafari Pro or Stellarium apps on a tablet. The only "paper" tool I use in the field are the Herschel 400 guides by Alvin Huey (see: http://www.faintfuzzies.com/DownloadableObservingGuides2.html, but a printed copy can be purchased and delivered at home) . When using these guides, I focus on one single constellation for the whole session.
  23. Sure and sorry for the delay Heather Teeter's light shrouds are excellent in my opinion. Mine improved the telescope a lot!
  24. The main reason for detecting astigmatism at high magnification (e.g. <=1mm exit pupil) is because any potential astigmatism present in the eye is minimised or even absent. An observer's astigmatism must be really severe to show effects at high power. In general, most of the eye imperfections are off axis of the pupil. Reducing the exit pupil, reduces the use of that part of the pupil. On the other hand, any astigmatism in the telescope is still present, whether at high or low magnification. Of course, one could also discriminate eye astigmatism against telescope astigmatism at low ma
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