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Louis D

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Everything posted by Louis D

  1. Too bad your scope didn't come with a removable section ahead of the focuser for binoviewer usage. Some of the newer Chinese ED scopes are coming equipped with them.
  2. How much weight can he lift if it is hugged close to his body? My back isn't the best, so about 40 pounds is my max. That's why I can't use my 15" Dob much any more because the mirror box weighs 65 pounds. I figure I'll use it more when I get a vacation/retirement home in the New Mexico mountains where I can leave it setup and wheel it out of the garage or shed for observing.
  3. The nm value is the passband width. The narrower the better because more non-emission light is rejected increasing contrast.
  4. Are you in a local low spot? I've noticed on my drive in to work that ground fog and frost form much more commonly in a low spot along a small creek, even when it is dry. I'm so glad my Dob has a Sonotube tube after following this thread. It also never gets cold to the touch in the depths of winter, either. It's just heavier than thin walled metal tubes.
  5. Don't be so harsh on yourself. That's actually pretty nicely done job of wrapping the tube. Too bad it didn't mitigate the dewing. You must live in a very damp region. Do you often get morning fog? Do you get any dewing on the guide scope's objective lens?
  6. 11mm is one of the rare focal lengths I own no fixed focal length eyepieces in and don't feel like I'm missing anything. It's just too close to 10mm and 12mm to matter in anything but a really long focal length scope. The 11mm Nagler T1 was also discontinued fairly early in the T1 life cycle (during the smoothie phase) and became quite the expensive collectible as a result.
  7. I used the Thousand Oaks Silver-Black eclipse glasses for the 2017 solar eclipse, and everyone agreed the image was much sharper than the view through typical Mylar eclipse glasses. I've been using Baader solar film for almost 20 years on telescopes, and it is definitely better than the view through a 90s era glass solar filter I once owned. However, I'll probably try the newer TO material for new home-made solar filters to see if it is any better. Has anyone in the UK tried it out?
  8. Sorry to hear this. Dewing is caused by the objective radiating energy to the clear sky and dropping in temperature below the local dewpoint. I think your only option left is to apply dew heaters directly to the back and/or edge of the mirror. A refractor is probably going to dew up just as quickly under these same conditions since the difference in thermal mass of the glass between a refractor objective and a mirror is going to be minor. A dew heater is definitely in your future.
  9. Yes, the 11mm NT6 and 12mm NT4 were both recently dropped, though I'm not sure in what order. The 2.5mm NT6 was also dropped a while back along with the 20mm and 26mm NT5s. The 2-4mm Nagler zoom was also discontinued in the not so distant past. Any others dropped in the last 5 years or so that I left out?
  10. I compared my 17mm and 12mm ES-92s accidentally to my 14mm Morpheus when I just working upward in power one night. I was shocked to find myself thinking the Morpheus felt like looking through a porthole compared to the two ES-92s. I went back and forth, and sure enough, just going from 92 degrees to 76 degrees was enough to induce the same feeling I get going from the 76 degree Morpheus to 60 degree Meade HD-60s and Paradigms/Starguiders. 16 degrees is 16 degrees even when its 92 to 76 rather than 76 to 60. Come to think of it, going from 60 degree eyepieces such as the HD-60s down 16 degrees to 44 degree eyepieces such as my Celestron Regal zoom at 24mm is also claustrophobia inducing as well. Yet, going from 92 degrees to 44 degrees (less than half as wide) just seems so entirely different that I don't get that same constrictive feeling. Sort of like going from a car to a bicycle. Two entirely different experiences that are not really directly comparable. Going from the ES-92 to the Morpheus is more like going from a high performance sports car to an above average performance sedan. Both are good performers, but after driving the high performance vehicle, the above average vehicle feels decidedly lacking in comparison. If I had never driven the sports car, that performance sedan would have seemed terrific based on my own limited experiences.
  11. You more than likely found M31's core. As can be seen below, if you can see M32 and/or M110, you can see M31 as much brighter and bigger than either in the same field of view. From my own observing from my light polluted backyard, all I can see is the core of M31 (the pure white part below) and the cores of M32 and M110 as slightly larger than stellar light patches. If you don't know what to look for and where to look for them, M32 and M110 can be easily overlooked in light polluted skies at lower powers. Try increasing the power on that faint galaxy you found to see if you can resolve its companions as non-stellar.
  12. According to Ricoh, Pentax's parent company: Model: XW20 XW14 XW10 XW7 XW5 XW3.5 Focal Length: 20mm 14mm 10mm 7mm 5mm 3.5mm Lens Construction [Elements/Groups]: 6/4 7/6 7/6 8/6 8/5 8/5 Apparent Angle of View: 70° 70° 70° 70° 70° 70° Eye Relief: 20mm 20mm 20mm 20mm 20mm 20mm Sleeve Size: 31.7mm 31.7mm 31.7mm 31.7mm 31.7mm 31.7mm Length & Diameter [mm]: 86 x 61 97 x 61 110 x 61 120 x 61 127 x 61 137 x 61 Weight [g]: 355g 365g 390g 390g 395g 405g So, it's 10g heavier and 10mm taller. And here's a Ricoh/Pentax corporate group shot: Here's a group shot of my 3.5mm Pentax XW with the 5.2mm Pentax XL which is about the same height as the 5mm Pentax XW.
  13. The most comfortable views of the full moon are with binoviewers because both eyes see the same brightness. The discomfort you're feeling isn't because the moon is bright, it's actually as dark as asphalt at noon. However, one eye sees noon-lit asphalt and the other eye sees blackness. Your brain goes into overdrive trying to combine these two vastly different views and leads to all sorts of weird artifacts. With two eyes, I can see details quite clearly across the face of the moon that elude me entirely with one eye no matter what sort of filtering I try. For cheap, you can get a "moon" filter that has about a 13% transmittance to cut down on the brightness imbalance for starters. If that's not enough, stack a second one for 2% transmittance. Or, you could get a variable polarizer filter or both and combine them to really knock down the transmittance. Check ebay for the cheapest prices on basic filters like these.
  14. Just spitballing ideas here, you could also try wrapping the tube with ribbon heaters used to keep pipes from freezing underneath the foam mat insulation. That should warm things enough to prevent dewing without causing tube currents.
  15. Be sure to let us know your thoughts on your purchases. Every equipment report helps fine tune everyone's understanding of the pros and cons of each item.
  16. How about a photo of your assembled setup? If it's an AZ mount, can you mount the scope reversed and use in on the other side of the azimuth axis? That would put the finder scope on top. I had to do that with my DSV-1 mount and 127mm Mak. It means using the scope on the "left" instead of "right" side of the mount. I did have to loosen the handle mount and rotate it 180 degrees to avoid it being on the front side of the mount.
  17. I'm not really sure what you mean by upper limit in this context. The 30mm Aero ED is a 2" eyepiece and has about a 35.5mm field stop, so it is 10.5mm smaller than the 2" maximum field stop of 46mm as found in the 40mm Aero ED (which is no longer in production and sold out worldwide). The 35mm Aero ED has a 44.5mm field stop, so it is much closer to the upper limit for 2" eyepieces. If you meant upper limit for exit pupil, that would be 7mm*6=42mm for most dark adapted observers, so no issues with even a 40mm eyepiece. The 30mm is slightly better corrected than the 35mm, but it is narrower in field of view at 68 degrees versus 73 degrees for the 35mm. If you were to compare well corrected true fields of view, the 35mm would probably slightly win out, just showing it at a slightly lower power. I don't think you can wrong with either one as long as you concentrate on the central view and allow the edges to remain in your peripheral vision.
  18. Here's a comparison between the 30mm/35mm Aero EDs and the 31mm/36mm Hyperions.
  19. I wouldn't have spent days captured and compositing images if I thought it wasn't representative of the reality I was seeing with my own eyes. Until the advent of the most recent generations of phone cameras, I had neither the field width nor resolution nor edge correction to do this well. I'll bet the latest generation of phone cameras are even better than what I was using.
  20. So this aberration doesn't scale linearly with magnification like coma in a Newtonian?
  21. Try it yourself. I keep an old Olympus C4000 with adapter tube that couples nicely with my 22mm AT AF70 for digiscoping. No camera lens for my Canon DSLRs will couple with any of my eyepieces (except maybe the ES-92s with their 43mm eye lenses and the two Meade 40mm eyepieces). Part of the problem might also be that the entrance pupils for most DSLR lenses are buried deep within the lens, so you can never get it to correspond to the exit pupil of most eyepieces to capture all the rays because the eyepiece would have to be inside the camera lens. Perhaps those with 30mm+ eye relief might work. I'm speaking from real world experience, not theory. I would have loved to have used my high resolution DSLRs for this experiment, but it just isn't possible for 90%+ of eyepieces.
  22. However, focusing out distance issues with your eye can move the image plane away from the field stop as I stated above, thus I focused wearing distance corrected eyeglasses. I know about the shoulder issue. I face the same issue with my GSO CC. Luckily most of my eyepieces focus within 5mm of the shoulder. To test your theory, check my image below of my 12mm Nagler T4 which focuses 19mm from the shoulder in two inch mode.
  23. It's not possible to use DSLR lenses for digiscoping with most eyepieces because you'll get severe vignetting due to the huge mismatch in diameters between the eyepiece eye lens and the camera lens's objective lens. You have to use cameras with tiny lenses. Today phone cameras are perfect for this task. They are surprisingly well corrected and high in resolution compared to what was available in digital P&S cameras 15 to 20 years ago. That other camera is 135 degrees on the diagonal (LG G5). Unfortunately, it's only 5 megapixels. It also has a weird white balance that is consistently yellowed. You can't use eyepiece projection directly onto the sensor, either, because most eyepieces don't project a flat field. You really need a lens on the camera to emulate the human eye's interaction with the eyepiece's exit pupil. In my case, the depth of field of the camera lens actually makes eyepieces with field curvature look better than they do to my presbyopic eyes. Your other two questions are answered in my earlier post I was composing when you responded.
  24. They were taken through my f/6 AstroTech 72mm ED with a TSFLAT2 field flattener ahead of the 2" GSO 99% dielectric diagonal spaced at 15mm with an SCT to M48 thread adapter (original diagonal nosepiece removed) with about 35 feet of separation indoors between the target and the scope's objective. As I said above, it's clear that certain camera/eyepiece combinations will yield sharp images to the diagonal limits of the camera (a Galaxy S7 phone camera). Check both edges for sharpness because I sometimes ended up with one or the other being slightly sharper due to camera tipping or centering issues. There's very little residual field curvature or edge aberrations from the objective itself. It's also unobstructed, so that's one less variable when it comes to evaluating eyepieces. The images I captured pretty closely resemble what I saw through each eyepiece with my eyes while wearing eyeglasses to correct for my strong astigmatism. Each eyepiece was focused for infinity corrected vision to hopefully show the field stop sharpness at its best since focusing for near or far sightedness can move the image plane ahead of or behind the field stop location causing it to look fuzzy.
  25. Nope, not the camera, it's the eyepiece. Notice how sharp the 40mm Meade SWA is right almost to the edge with nearly the same apparent field of view. You can also see that the 30mm ES-82 is fairly sharp nearly to the edge. I tilted the camera to get the edge in sharpest focus possible to show the field stop sharpness in that little extra bit of image to the right of the main image since my camera only goes to about 75 degrees on the diagonal. I bought a second super wide field camera to capture the entire field in one go in the "full width" images. However, it is a lower resolution camera and I had to up-sample the images to match the image scale of the 75 degree camera, so the utility of those images isn't all that great. There just is no free lunch when it comes to wide field and good image correction across that field. If you want both at the same time, it means getting a big, heavy eyepiece. Notice how nicely corrected the Baader Scopos Extreme is. However, it's weight slots it between my 12mm and 17mm ES-92 eyepieces, which is to say very heavy. Your best bet for well corrected and lighter weight is the 30mm APM UFF. However, it is fairly expensive, though still cheaper than TV Panoptics.
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