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About BillP

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    Star Forming

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    Astronomy, Photography, Computer Science, Health/Medicine.
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    Virginia, U.S.A.
  1. Thanks for noticing. I corrected my original post.
  2. I had the complete set for quite a while. They utilize single coatings, so no multicoatings. The narrow-angle scatter is related to all the layers in multicoatings. There are always some level of particulates and irregularities between the multilayer coatings, and those issues generate a small amount of scatter close to the star point. Comparing a ZAO to a Brandon to a TV Plossl for this type of scatter around a star point is fairly obvious to see for me, the ZAO and Brandons being very close and the TV Plossl (and others) showing the brighter halo close to the star point. Not a big overt thing but if you are atuned to the small differences you will see them. Overall the Brandons, like the ZAOs, show a bit of a richer black background FOV. So they give IMO a very refined view of open clusters and globs. Of the common current production eyepieces, their planetary performance is excellent. Unfortunately they do not have a lot of small focal lengths and the eye relief is really tight so uncomfortable in that role. The annoying thing about them for me is how poor the off-axis is relative to their price point. While they are advertised to be designed for as low as f/7, the off-axis is aberrated even at f/8, and even in an f/16.7 refractor I had the off-axis still did not fully clean up! So a really refined on-axis being low in scatter with highly contrasted black background views, but a really untamed off-axis. Their AFOVs are also not entirely consistent between the different focal lengths. The 24mm is larger. Given the very nice on-axis star point, a good doubles eyepiece. But still overly expensive IMO. An acquired taste. The Vernonscope 2.4x Dakin Barlow btw is quite excellent. Very clean and transparent and held its own against even the best Barlows I've tested. The little "Magic Dakin Barlows" they sell not so hot IMO and show lateral color that was just too much for me. But the original 2.4x Dakin is quite excellent...although again expensive. Their quartz silver 1/20th wave diagonals are to die for. Hands down best diagonal I have ever used. Would love to own one but at $795 USD way too expensive for me. But wow was it excellent being the brightest and lowest scatter diagonal I've come across!!!
  3. It's funny...the longer I'm in the hobby and the more I observe, I tend to use lower magnifications more. Before I was always pushing the limits. These days I enjoy DSO better in the context of a larger surrounding FOV so observe mostly between 50-150x and rarely more. Occasionally will venture up to 200-250x if a difficult double or planetary nebula or Moon/planet. The Moon is about the only object I enjoy at higher magnification regularly so am either very low to get the entire thing in the FOV or at 250x...one or the other and rarely anything in between.
  4. I'm not sure we'll be able to ever figure it out. Probably a combination of several factors all together (i.e., gestalt): - Long eye relief with a very comfortable and well behaved exit pupil behavior (i.e., eye placement and holding the view). So many long eye relief eyepieces have the design of their exit pupil such that head positioning is very sensitive and for some it just plain causes eye strain (Radians come to mind). - AFOV is engagingly wide, but not so wide that you need to roll your eye. So seems to be at an optimum usability point. - Eye lens is not concave, which robs eye relief and forces you to "dip" into the eyepice to see entire AFOV. - Housing was purposefully made as this as possible so when viewing through the eyepiece it has a very thin profile (trying to replicate the floating in space aspect of the view as much as possible like the 28 RKE). - Contrast and clarity are exceptional (IMO) and a cut above many others; Off axis well controlled as well. - Thank goodness no undercut!! (a biggie for me)
  5. The Baader Morpheus 6.5mm and 9mm are both quite fantastic and also have the long eye relief necessary for effective use with eyeglasses. Finding something in the 20-24mm range also with close to 20mm eye relief will be a bit more difficult. The 2" 24mm Explore Scientific 82deg is marketed as 17mm eye relief, but this is measured from the center of the eye lens, which I believe may be concave on that one (not sure). If it is then the usable eye relief from the top of the folded down eye guard may be insufficient for eyeglasses. I have not tried but it seems to get pretty good reviews, the APM 24mm Ultra Flat Field Eyepiece. This is marketed as having 65° AFOV with a 29mm eye relief, plus is a smaller 1.25" eyepiece that might fit your need well. Btw, I used to have the 28mm UWAN. It is monstrously large and heavy which made it a pain to use so sold it.
  6. If you are a planetary enthusiast, have a fairly refined and critically maintained optical train (scope and diagonal), use more comfortable focal ratios (not f/5 and faster), and use it with a Barlow to increased the FOV that is sharp. Yes, a lot of conditions. But this holds true for monocentrics in general. They are a specialized eyepiece for specialized circumstances. I'm now retired and on a fixed income so $100 purchase I need to sit and think about. For me though worth it as I really need something good in the 4mm range (using with my 2.5x Powermate) to tease out planetary details from my smaller bore scopes. This eyepiece did all that quite well so am adding it to my stall and finally putting to rest my 4mm search (which has been many years). IMO the "planetary" eyepiece is very specialized and not something everyone should quest after. Many wide fields put up excellent views of planets, like the Morpheus or the DeLites. I would not use planetary niche eyepieces in my Dob either because fast focal ratio they generally do not handle well and I do not clean my mirrors but once a year so dust build up on mirror adds enough scatter that overwhelms any advantage from the planetary eyepiece can add. But my 81mm, 102mm, and 152 Apos I keep in top operating condition and given their smaller bore for planets every ounce of extra contrast is a welcomed thing for planetary, particularly Jupiter and Mars. So if the circumstances match then worth getting a planetary niche eyepiece, and $100 is sure a lot less than $600 for a ZAO or $300 for an XO, especially when the on-axis results are competitive.
  7. FYI, I just updated the article in the 1st post yet again. Sorry for the inconvenience. I carried out one more test and the results were quite interesting so I decided it was worth adding. Basically the new version has the addition below. I changed the version date in the updated article to October 12, 2018 so it is not confused with the earlier version. Finally, the rectilinear distortion in the Modified Erfle is extremely low. When placed in a daytime spotter scope straight lines in the off-axis, even right up to the field stop, stayed straight. I then wondered how the true field of view (TFOV) might differ in this eyepiece compared to something like an Explore Scientific 24mm 68° or a Tele Vue 24mm Panoptic, both of which have a significant amount of rectilinear distortion. Having an Explore Scientific 24mm 68° on hand I compared it to the Burgess 24mm Modified Erfle and discovered that the TFOV of both the 61° Modified Erfle and the 68° Explore Scientific were almost exactly identical! So although the Modified Erfle visually shows a smaller AFOV, its TFOV is almost exactly the same as the wider Explore Scientific 68° with its added rectilinear distortion to maintain more controlled off-axis star points.
  8. I am so sorry! Uploaded an older version. Just corrected it. If anyone already downloaded please delete that and get the new version now attached at the top of this thread.
  9. Have been assessing these two relatively new eyepieces for the past few months. Attached is article I put together with my impressions. Burgess 24 Modified Erfle and 10mm UltraMono.pdf
  10. No I do not. But feel free to email Jerry Hubbell from Explore Scientific that is part of the MSRO. He's happy to answer questions - jrh@explorescientific.com.
  11. Perhaps this - https://www.researchgate.net/publication/324602855_KPS-1B_THE_FIRST_TRANSITING_EXOPLANET_DISCOVERED_USING_AN_AMATEUR_ASTRONOMER'S_WIDE-FIELD_CCD_DATA
  12. I recently came across a group near where I live that configured their imaging equipment to detect exoplanet transits. I had no idea this was feasible with consumer telescopes and gear. I took a short drive to look over their equipment and talk to them to put together this article. Enjoy! MSRO Exoplanet Hunters.pdf
  13. #1 - Price. If they are outlandishly priced, then I don't care how good they are. About $250 USD is the most I am willing to do for an eyepiece, and that amount hurts. #2 - AFOV (size & correction) - I don't divorce the off-axis correction from the AFOV size. They both go hand-in-hand IMO and if the off-axis is too terrible then the AFOV really is not as expansive as contended if the outer region is so bad as to look diseased. And of course, the off-axis correction is also tightly coupled to the focal ratio and design of the telescope. So if the eyepiece is destined for my f/4.7 Dob then it may lose on criteria #2, but if it is for my f/8 Apo then it may be just fine. So I need to evaluate the AFOV criteria in connection with the scope it is intended for. So I do not require the off-axis to be "perfect", just clean enough to not be distracting. Some mild aberrations are ok IMO since I tend to spend most of my observing in the center of the FOV and I do not usually "observe" something if it is too near the field stop and I just move it to the center for better scrutiny. So the off-axis just has to be clean enough so that I will take note of interesting stuff there to center and observe and I am mostly happy. #3 - Ergonomics - I am bothered by large and heavy eyepieces. So again, no matter how fantastic the eyepiece is optically, if it is a pain to use on the scope because of its weigh and overly large and cumbersome to handle, I generally will not want it. Now with ergonomics goes eyeball ergonomics as well. So if the eyepiece is very difficult to hold eye position easily (varies depending on the person), then I am likely not to want it. Longer eye relief is a plus for me, but I do not mind short eye relief either so that aspect is not so critical for me unless it feels like I need to be unnaturally close to see the entire AFOV peripherally -- often an issue if the eye lens is more strongly concave.
  14. I used to have that eyepiece. I liked it.
  15. The TV Patent shows it as a symmetrical and refers to it as "Plossl-like". I've taken many apart over the years and indeed they are simple symmetricals with two identical doublets with convex surfaces facing each other. The very first smooth sided ones were the more typical symmetrical prescription with plano outward facing surfaces, after those the next runs of the smoothies had the patent prescription with the concave outward facing surfaces. In the photo, the first run smoothies on the left had the plano instead of concave surfaces. These had a characteristic very pronounced bevel on the housing. I call them the Big-Bevels. The subsequent runs which had the infamous circle-NJ optical mark, were the patent prescription with the concave lens surfaces to better control astigmatism in the off-axis (at the cost of shortening the ER some I think).
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