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Louis D

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About Louis D

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    White Dwarf

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    Texas, USA
  1. Louis D

    What Diagonal?..

    Non-dielectric include aluminum, enhanced aluminum, and silver mirrored surfaces. Then there are the prism based diagonals which don't use a mirror at all.
  2. Louis D

    What Diagonal?..

    I like the GSO (Revelation) dielectric 2" diagonal so much, I have two of them.
  3. Louis D

    which manual Alt-Az mount

    Most quality dual alt-az mounts don't really care if they are completely unloaded on one side. Just make sure your tripod legs are spread wide enough keep the center of gravity well within their footprint to avoid tippiness of the whole rig.
  4. You can generally assume FPL-51 or equivalent if the glass type is not stated. Pretty much every company trumpets when they use FPL-53 or equivalent, so the lack of any commotion generally points to FPL-51.
  5. That's really weird. I thought the Meade 2080 was a 1980s 8" SCT:
  6. Louis D

    which manual Alt-Az mount

    I have the DSV-2B for my AT72ED and 127 Mak: However, for what you want to mount, I would recommend the DSV-3. Be aware that wait times for Raul's mounts can be lengthy, but they are highly customizeable. Make sure your heavy duty tripod is rated for at least 45 pounds since the DSV-3 mount itself weighs 12 1/2 pounds unloaded. Add two 10 to 20 pound telescopes, 2" diagonals, and heavy eyepieces or binoviewers, and you're up to 40+ pounds in a hurry.
  7. Louis D

    Aero ED's impress

    Finally measured the usable eye relief on the 35mm Aero ED, and I get 14mm from the retracted rubber eye cup. Since the eye lens is recessed 7mm (I agree with Ernest on this point), it could have 19mm to 20mm of eye relief if the eye lens were flush mounted to the top of the housing. I'm not sure where Ernest got 8mm usable eye relief from. I measured the eye relief both outside of a scope and when used in the AT72ED. The two measurements agreed very well. 14mm also agrees well with the feels-like ER. It feels very similar to the 27mm Panoptic in use. It's tight, but still usable, with eyeglasses pressed into the eye cup. It has a 73° AFOV and effective-AFOV, so it has practically no distortion at the edge either way. Visually, I couldn't detect any stretching or squashing as objects approached the edge. It was a bit difficult to measure the projected image circle because of the vignetting at the field stop. The edge gradually fades away, so Ernest's 70 AFOV might only include the non-vignetted image circle. It was striking the difference between the fading edge of the 35mm ED and the sharp edge with no fading of the 40mm Meade 5000 Plossl. I'm guessing the field lens or the intermediate lens group is undersized on the 35mm ED and is losing edge light rays. The 35ED's barrel is noticeably narrower than the Meade, which doesn't show any edge vignetting. The effective field stop measures 44.4mm, so very nearly a maximum field eyepiece. It is barely wider than the 40mm Meade 5000 Plossl when used in the 127mm Mak. It is noticeably wider when used in the AT72ED. When scaling for the difference in magnification between the two, there is definitely some lost potential field of view with the Mak. Something is restricting the field of view in one but not the other. The 40mm Meade 5000 SWA did not show any unexpected restriction in the Mak as a third data point. As a result, I probably won't be using the 35mm ED in the Mak since the usable eye relief is so much tighter than the 40mm Meade 5000 Plossl (14mm vs 29mm) and any additional field in the ED is fading away to the edge anyway.
  8. Louis D

    Antares Speers Waler series 3

    Awww, come on. Someone's got to be the first to buy these and report on them, so it might as well be you.
  9. I went back and measured the magnification in my AT72ED through the binoviewer with the Meade 140 nose piece screwed onto the front of it. It gives exactly 3x magnification with the 14mm Pentax XL and a sharp, focused field edge to edge. I then measured it with the 140 nose piece screwed onto the front of the 1.25" diagonal and the 0.5x reducer screwed onto the front of the binoviewer. That gave 0.7x with severe vignetting in the outer 25% of the field and probably field curvature if I could see the darkened edge. Next, I used my home-brew Dobsonian OCS to reach focus. That's the 140 nose piece screwed onto the front of 45mm of 1.25" spacer tubes with the 0.5x reducer screwed onto the back and then the whole thing screwed into the front of the binoviewer. That gave exactly 1.0x magnification with no vignetting and lots of field curvature, but the edges remained sharp when refocused. Now I just need to figure out how to flatten the field. I could play with the spacing of the TSFLAT2 if I can come to focus in the 2" diagonal instead of the 1.25".
  10. Louis D

    Explore Scientific 26 mm, 62 degree

    Here are several CN reports about the 26mm ES62 by russell23: https://www.cloudynights.com/topic/579467-26mm-es62-observations/ https://www.cloudynights.com/topic/609691-explore-scientific-62°-series/?p=8428260 https://www.cloudynights.com/topic/584925-explore-scientific-62-degree-series/?p=8003115
  11. Louis D


    And I still remember the American politicians going nuts that the Europeans were beating us in the airline industry with the A380's introduction. Boeing calmly replied that their 787 would be competitive. At least the 747 has remained in production for over 50 years and has delivered over 1500 planes compared to just over a decade for the A380 and 254 planes. Had to look up the Brabazon. Such a cool concept. A flying ocean liner. Too bad the economics didn't work out for it. Some of the Emirates A380s have similar sleepers and lounges today.
  12. Louis D

    Antares Speers Waler series 3

    Talk about eye relief being all over the place. I'm not sure how the last four columns compare to other eyepieces since this data is rarely published for eyepieces:
  13. Louis D

    Messier 81 and 82 panorama

    At first, I was like, how did you get such stable seeing in the UK? Then I saw that you have a remote Spanish observatory. I'm guessing Spain's seeing is similar to the US's desert Southwest. Regardless, spectacular image.
  14. Louis D

    Aero ED's impress

    Let me know how it does in the Mak. What's the diameter of your Mak's rear port? I'm thinking the ~27mm rear port of the 127 Mak might be causing the issues I'm seeing with the 35mm ED since it behaves nicely in the 72ED and Dob which have wide open eyepiece ports. The narrow Mak port doesn't bother my other widest field eyepieces. I'm going to do some controlled daytime experiments this weekend with the 35mm ED and multiple scopes to characterize what is going on better.
  15. Louis D

    Aero ED's impress

    I was out with the 8" Dob just now, and the 35mm was behaving much better in it than in the Mak. With the coma corrector, it was well corrected across about 75% of the field, with the outer region not as objectionable as the 30mm WS III before refocusing. The last 5% of the field shows a bit of vignetting, but the field stop is sharp on a bright object like the moon. It really does seem to have a flat field, so all you see is astigmatism, which is about as strong as the 40mm Meade 5000 Plossl. There's also no chromatism at the edge that I could see, which is admirable. The center of the field is incredibly sharp in this combination. I could also take in the view with eyeglasses with just a slight bit of pressure pushing in. There was no blacking out of the field at any time. Barlowed with a telecentric magnifier, it sharpens up at the edge immensely, much better than the 40mm Meade 5000 Plossl. The Trap could be discerned at the edge in this mode. Overall, this eyepiece really needs matched up with a telescope before any conclusions about it can be drawn. I haven't encountered any other eyepiece quite like this before. I'll have to have another go with it in the Mak before passing judgement on it with that scope. In the Dob, it's a real keeper.

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