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Louis D

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About Louis D

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    Brown Dwarf

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    Texas, USA
  1. No, you won't damage anything trying this experiment. What you're trying to achieve is a collimated beam. I don't know how well it would work. The reflector in most flashlights is an approximated parabola with the bulb filament at the focus. Newer Cree LED type flashlights use what appears to be a focusable PCX (Plano-Convex) lens in front of the LED to collimate the beam.
  2. Perhaps you're looking at Albireo. It's a blue/yellow double star system in Cygnus. It could be that the binoculars aren't providing enough magnification for a clean split, so you're seeing one component or the other dominate in color.
  3. Louis D

    Orion H-beta filter-advice

    The best guide to the usefulness of each filter type is this one from the Prairie Astronomy Club. The H-beta is listed as best for about 17% (16) of the 95 nebula compared. Thus, you have to make your own choice if it is worth dropping about $100 to get the best view possible of less than 20% of nebula. Diminishing returns.
  4. I have the 9mm Morpheus. It isn't quite sharp to the edge like my 10mm Delos, but it is very close. There's just a tiny bit of astigmatism and chromatic aberration at the edge with no discernable field curvature. Given the wider AFOV, it's a reasonable trade-off. The Morpheus is basically as sharp on axis as my vintage 9mm LV and newer 9mm HD-60. All are great on-axis. It comes down to budget and desired AFOV. Be aware that you'll have a long optical stack in the focuser with a 9mm Morpheus in a 2x barlow. Make sure your focuser is free of flexure. The 14mm Morpheus has much more astigmatism, chromatism, and field curvature in the last 5+ degrees near each edge than the 9mm Morpheus. For half the price of the Delos (when the Morpheus was on sale here), it's also a reasonable trade-off to get a slightly wider field with excellent eye relief. I've got the 12mm ES-92 as well which has a wider TFOV than either the 14mm Morpheus or Delos with excellent correction to the edge, so I think I'm good without the 14mm Delos for now.
  5. Looks like Astronomics (CN sponsor) will be offering the same scope under the Astro-Tech label: Astro-Tech AT152EDT f/8 Triplet APO Refractor OTA Hopefully, the price will come down because the TS-Optics version is priced quite a bit lower when converted to USD.
  6. If the focuser knob won't rotate, you've probably got a bent or otherwise jammed screw inside the tube that moves the primary mirror forwards and back for focusing. Did the focuser knob ever turn freely before the accident? There shouldn't be any significant resistance to motion in one of the two directions, assuming it's at one or the other end of its limit of travel. If the mirror is somewhere in the middle, it should rotate freely in both directions.
  7. Louis D

    a nagging Nagler dilemma

    Why not go for a different focal length first instead of duplicating a focal length you already have? Once you have all your focal length holes filled, go back and start upgrading things. That's what I've been doing over the past 20 years of observing. That's why I have so many duplicates at certain focal lengths. Since I don't need the money right now, I just keep them all for comparisons instead of trying to remember how things used to look in long gone eyepieces. I never understood the constant churn of buying and selling so many amateur astronomers go through unless it's because they're really short of cash or storage space.
  8. Louis D


    I'm pretty sure that if you have enough in/back focus, two normal diagonals placed at 90 degrees to each other will result in an erect, non-reversed image if you view from the side of the scope. Have the first diagonal send the image sideways to erect left to right and the second diagonal send the image upward, erecting top to bottom. You do need to look into the second diagonal as if the scope were pointed 90 degrees to the side of where it is pointing which can be a bit awkward to get used to initially. I'll have to dig it out, but I once made a super compact erect image finder using two 2" right angle surplus prisms cemented at right angles to each other along with a 62mm f/4 surplus objective. Since there was about 110mm of light path through the prisms, I had less than 140mm of optical distance left to mount the objective and eyepiece ends with some PVC plumbing bits. It worked stunningly well but weighed well over a pound due to all the glass involved. US military grade spare optics really rock! All were still sealed in moisture proof packaging. If you use two high quality dielectric, silver, or prism diagonals, the light losses should be minimal. You could try the concept first with two 1.25" diagonals to see if you like it if your refractor has enough in/back focus. It would certainly work with an SCT or Mak.
  9. No one has mentioned them, but the relatively close and large globular clusters like M13 and M22 really benefit from higher powers. Below a certain power, they just look like fuzzy balls. Get above a certain power, maybe 160x to 200x in an 8" Dob, and they suddenly resolve into tiny grains of diamonds on velvet. Of course, it takes steady skies, a well figured and collimated objective, and a well designed and polished eyepiece all working together to achieve this. I've found that doubling my aperture allows me to double my magnification under Texas skies, at least. While I top out around 200x of usable magnification in my 8" Dob, I can easily push to 350x in my 15" Dob. Folks with 20"+ Dobs around here regularly go above 500x with ease. This is especially true in the summer when a ridge of high pressure settles over us leading to dry and steady skies for weeks on end. I've seen multiple nights in a row where there is no perceptible twinkle to the stars. For our skies, it really is all about exit pupil. Keep it above 1mm and you're golden, even with very large mirrors.
  10. I have the 6.5mm Meade HD-60, and it hangs right in there with my 7mm Pentax XW.
  11. Just be aware there's a global dust storm raging on Mars, so it looks like a large orange-red disk now. It might be winding down, based on this thread's photos.
  12. Yikes!!! That's almost 80 pounds of counterweights! My back would never be able to hoist that sort of load onto a mount. One more reason I'm not a big fan of GEMs. Now, a split ring mount, that would be more appealing to me for an EQ mounted Newt.
  13. I figure if you've already dished out $1800 on the scope and mount, why go cheap on the eyepieces unless you're out of money. I've found poorly corrected eyepieces at f6 still look only slightly better f12, and going to f15 isn't going to change it that much. Perhaps at 50 degrees as in a Plossl, f15 would be great at the edge, but cheap 80 degree eyepieces don't suddenly become Naglers at f15. If they have field curvature at f/6, they'll still have field curvature at f/15. Astigmatism and lateral color will improve, but it will still be there to a lesser extent. An Erfle won't become a Delos just because you slow down the light cone.
  14. If you go to this light pollution map for your area, you'll see you're in red/yellow area which means you won't be able to see the Milky Way, but you should be able to see many brighter stars and use them to locate star clusters and brighter nebula via star hopping. You'll probably need a UHC or OIII nebula filter to bring out more detail in them once centered. Notice that if you go south and east just a little ways, your sky conditions will improve quite a bit.
  15. I double up my 127 Mak with my 72ED on either side of my alt-az grab and go mount. Stars are tighter in both than in my 8" Dob. The Dob shows more detail on just about everything, though.

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