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Louis D

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Everything posted by Louis D

  1. I just double checked my cheap 45 and 90 degree Amici prism diagonals, and the OP is correct. They are vastly stopped down. I only use the 45 degree ones for terrestrial observing and the 90 degree one in a 60mm RACI finder, so the vignetting has never bothered me. I've never experienced blackout with either, even with widest field eyepieces; but that was always with refractors. Perhaps there is some interaction with the Mak's central obstruction going on as well here?
  2. Another widest field option in a 1.25" barrel is the 24mm APM UFF. It does quite well up to the last few degrees of field where it gets a bit indistinct. The rest of the field is quite sharp. I measured mine to have a 27.5mm effective field stop diameter, which probably accounts for the slight fuzziness at the edge since that is pushing what is possible in a 1.25" barrel. By comparison, my 26mm Plossls have 22.3mm and 22.6mm field stop diameters. I measured my 25mm AT Paradigm (BST Starguider) to have a 26.7mm field stop diameter, so it comes close to maxing out the available field of view in a 1.25" barrel. The 24mm ES-68 at 27.2mm FS diameter has greater distortion to get to 68 degrees apparent field (AFOV), but not that much more true field (TFOV). A 0.5mm difference in FS diameter isn't all that much. If you already have 2" eyepieces and are comfortable with them, I would steer you toward the 22mm Omegon Redline (TS-Optics Expanse, Technosky Superwide HD, etc.). They are better corrected than any of the above to the edge (just slightly behind the 22mm NT4), have excellent eye relief (once the eye cup is unscrewed) for eyeglass wearers, have a 28.4mm FS diameter (thus the 2" barrel), have a true 70 degree AFOV with very low distortion, and are lower priced than the APM or ES alternatives.
  3. The only thing known to correct achromats for color is the long discontinued Aries Chromacor.
  4. I tend to use 1200mm and shorter focal length scopes. I do have a 15" f/5 Dob that might make those closely spaced eyepieces useful, but I haven't used it in years since my back got messed up in an auto accident.
  5. I've got a similar lineup in my A-team case except that I don't have the Delos 6mm and 8mm eyepieces, or really anything in either focal length range aside from my 5-8mm SW zoom which has too little eye relief for me. I've thought I might want something in those slots, but I find myself happily skipping from my 9mm Morpheus to my 7mm XW to my 5.2mm XL to my 3.5mm XW without feeling like I've jumped too much in any one step, except perhaps with the 3.5mm XW. My question is, do you make much use of those those single digit Delos eyepieces? Or do you prefer them and skip the XWs? I'm thinking a 4.5mm Morpheus or Delos might get more use than either a 6mm or 8mm Delos.
  6. Yes, Skywatcher prices, along with most astronomy gear prices, have gone up quite a bit. Those of us in the US are now getting hit with a special 25% tariff on Chinese made items on top of those price increases, so consider yourself fortunate you're not having to deal with it as well.
  7. If you can rig up a way to attach the camera in place of the scope, of course you can use the mount sans telescope. It would definitely resist wind much better with a camera only due to not having a large sail of a scope tube attached to it. Would the mount track more accurately? Barely. It will still have uncorrected periodic error (stars track small orbits) among other issues. Again, keep the exposures short for later selection and stacking, and it would probably work well enough to learn basic astrophotography on.
  8. SN 00007 makes it one of the first 10 produced. That's a bit of a collectors item. Enjoy! Clear skies to you.
  9. Mathematically, yes. Reducing image scale reduces the visibility of tracking imperfections. I would avoid the cheap 0.5x focal reducers unless you're using a really small sensor. They introduce all sorts of outer field aberrations like field curvature and spherical aberration.
  10. Yes, I bought a dielectric 1.25" diagonal with a rigid case to safely hold the BV weight while minimizing the optical path length. I normally use a 2" diagonal for mono viewing because I have so many 2" eyepieces.
  11. It's not that it won't track properly, it just won't do it accurately enough for long exposures. You'll start to see stars wandering around a bit due to inaccurate tracking. The mount also won't be able to resist gusts of wind, so you'll need to shelter it from wind somehow. It would be fine for short exposures for later stacking.
  12. Goto mounts will have field rotation which limits how long individual frames can be. Off the shelf cameras won't be as sensitive to the far red where H-alpha resides as a dedicated astro camera would be. It is an important nebula emission line for DSO imaging. Here's a mega-thread on DSO imaging without an EQ mount:
  13. Agree with @Highburymark about merging high power eyepieces in a BV. The problem is that they expose even the slightest miscollimation of the BV. I just use a pair of Celestron Regal 8-24mm zoom eyepieces with a 2x Barlow nose piece that yields 3x in the BV. That way, I'm operating the zooms at 2.7mm to 8mm. Absolutely no problems merging the images at any focal length, although I rarely go much higher than about 12mm natively (4mm Barlowed) on the zooms in this mode due to viewing conditions and exit pupil issues. I also have no problems matching zoom focal lengths. I zoom both roughly to where I want to be power-wise, tweak focus using my dominant eye if needed, and then fine tune the focal length of the zoom for my non-dominant eye until the images exactly merge. It's actually easier to figure out best merge than best focus in my experience.
  14. Small DSOs like globular clusters look really poor in ~75mm scopes. There's simply not enough resolution to resolve them at 200x and above in my experience.
  15. Then I would invest in a binoviewer. Even the entry level units are quite good. I saw far more detail on Mars during this latest opposition with my Arcturus binoviewer and two 50 year old B&L microscope eyepieces than with any of my XL, XW, Delos, or Morpheus eyepieces in mono mode. There's no substitute for using two eyes to pick out low contrast, fine detail.
  16. Not seeing it. I just pull the 1.25" diagonal and 2" to 1.25" adapter and binoviewer with associated OCS/GPC bits for reaching focus out of the focuser and replace it with a 2" diagonal and eyepiece to switch between modes. On my Dob, I just pull the binoviewer and OCS/GPC bits out of the focuser and put an eyepiece in its place. On my Mak without OCS/GPC focus help, it takes forever to move the mirror enough to reach focus with just a diagonal and eyepiece after pulling out the binoviewer. Thus, I don't switch modes on it during an observing session. I don't see how the quick changer would help unless it has an extension tube incorporated in it to match the backfocus of the binoviewer. Am I missing something here?
  17. It depends on the magnification used. At low powers, you're not likely to see any difference except perhaps on the brightest objects. Where you will see it is at high powers where there will be a slight violet violet fringe around bright objects with FPL-51 that is much more subdued with FPL-53, especially in triplet form. However, even the most APO refractor still has some fringing compared to a Newtonian at high powers. If you've always used pure reflectors as I have, it's a bit of a surprise that the term APO doesn't equate to absolutely false color free, especially on either side of best focus as you find that best focus. I would equate APO to very well tamed false color. In a reflector, a white star is always white no matter which side of focus you're on by comparison.
  18. I find 8x binos to be right at the limit for me to hand hold. I need to be sitting with my elbows braced for 10x and above to get decent views. If you're going to be standing, I would go with 8x42 bins. Sitting, 10x50s will work.
  19. Yep, I did the same thing several years ago, except in reverse. First, the 17mm ES-92 replaced my 17mm Nagler T4. The next year, the 12mm ES-92 replaced my 12mm NT4. Now if only ES would make a ~22mm version to replace my 22mm NT4. 😉 I don't think I'll hold my breath on that one happening any time soon, though. I bought the 26mm Meade MWA to see if it could fit the bill, but it actually worked out to be closer to a 25mm Morpheus. 🙄 It's actually grown on me in that role once I'd adjusted my expectations for it. If you like the 12mm ES-92, you'll love the 17mm version. It's actually a bit better corrected at the edge, and a bit easier to hold the view in.
  20. Have you tried contacting Tele Vue in NY by phone? I've read they can supply replacement caps, so they might also do eyeguards.
  21. My old 14mm Pentax XL has worse field curvature than the 14mm Morpheus, and a narrower field to boot. However, it is pin sharp and astigmatism free to the field stop once refocused. The wider field and lesser field curvature of the Morpheus ousted my venerable XL from the spot it had held in my A-team case for 15+ years. I decided I could live with the edge astigmatism since it was in a part of the field that doesn't even exist in the XL. In all other ways, the two eyepieces were basically equivalent.
  22. This is a great topic along the lines of the famous Meade 4000 Plossl threads. How to distinguish early Japanese made from later Chinese made Celestron FRs.
  23. Working as designed. Never mind that the design (or implementation) is flawed.
  24. Not astro related, but it reminds me of my wife's workplace where the batteries in a UPS caught fire, destroying an entire server room. She and a coworker actually fought down the flames using fire extinguishers brought to them from all around the building. They managed to save the office building by keeping it out of the drop ceiling (the fire department arrived 15 minutes after the fire was out), but my wife was hacking up black soot for days. The room was nearly an entire loss except for some backup tapes that somehow survived in their tape drives. As a result of this fire, we will not use battery based UPSs inside our house. There are flywheel based ones, but they are only made in enterprise class sizes ($100,000+ units).
  25. If you're buying used, avoid the Meade FR unless you really know what to look for. In the past, there was time when their FRs had optical issues. The Celestron is a solid bet in the used market. I've never read of any issues with them. The Antares will be similar to the Celestron from what I've read. The Starizona corrector is the one to get if you're very picky about image quality.
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