Louis D

Generally, the more complex and expensive eyepieces do perform better in faster scopes, but not always. The Baader Hyperion Aspherics come to mind as a counter example. Despite their price, there are better options at their prices for fast scopes. Your best bet is to ask on here or CN first before plunking down big bucks on an eyepiece.

TBH, I'd just get the Astro Essentials 32mm Plossl for £29 and put the savings toward another eyepiece. I never use a 32mm Plossl for critical viewing. That, and the Celestron Omni line is nothing special to justify the upcharge for the brand name. The Vixen might be an improvement over either the AE or Celestron, but not enough to justify the price jump (double). Perhaps at a more frequently used focal length, but not at 32mm.

I have the 9mm Morpheus, and it views just about as crisply and contrastily (is that a word?) as my 10mm Delos, just a bit wider in AFOV. Definitely a no compromise choice there.

You'll want to target 50x to 90x maximum in my experience. If you can observe very early in the morning, you might be able to go higher before the seeing becomes too unstable.

I figured for under $150 shipped, I'd give it a try. Due to direct from China shipping, it may miss being a Christmas present. However, my birthday is 3 weeks later, so it should definitely be here by then for a birthday present.

I've always associated being near the coast with excellent seeing based on the reputation of the Winter Star Party in the Florida Keys for having really stable seeing conditions..

Search for "beginner telescope" in this forum and start reading the dozens of threads on this topic. You should start to get an idea of what to buy.

No, the Nirvanas are entirely different eyepieces made, IIRC, by KUO. All ES (and Bresser) eyepieces are made by JOC. Both are quality options. JOC used to sell their eyepieces under various Celestron and Meade brandings prior to 2013. Right now, the only bonafide rebranding of the ES-82s outside of China that I know of is the Opticstar line. There is some controversy surrounding these that they might be second quality, but that has never been conclusively proven one way or the other.

I just used the flashlight method to measure the distance from the top of the eyepiece to the point where the projected light cone was smallest. 12mm to 14mm is definitely how they view in practice. Geometry doesn't entirely define usable eye relief or all of the original Morpheus would have the same usable eye relief, but they don't. The shortest focal length ones have the tightest eye relief despite having the same eye lens diameter and AFOV as all the rest. I see a similar pattern with the HD-60s going from 9mm down to 4.5m in both measurements and in practice. In particular, the 4.5mm is quite difficult to use with eyeglasses. Conversely, the Paradigm/BST Starguiders view remarkably similarly across focal lengths in both eye relief and AFOV by comparison. This is more similar to the Pentax XL/XW lines which all view pretty much the same across focal lengths in both eye relief and AFOV. All I can surmise is that there are at least two schools of design for these types of long eye relief and wider AFOV eyepieces that leads to the differences or constancy in eye relief (and AFOV in the HD-60s). If I could ever get the upper assembly removed from the Paradigms, I would remeasure the usable eye relief. However, I can't get the upper casing to unscrew from the main barrel as others have done.

Forget the 25mm BST in a fast scope, it's not sharp in the outer field. You're just as well off to get a 32mm Plossl for widest field of view in a 1.25" barrel and save a few bucks. The 25mm BST also requires quite a bit of in focus, so it won't come to focus in my Dob with a low profile focuser and GSO coma corrector. The 12mm BST is much better corrected in the outer field than the 15mm, and yields a more usable power across more scopes. The 5mm is a good choice for highest power in the f/5 scope, but will be all but unusable in the f/10 scope due to the super high power and tiny exit pupil. The 8mm might be the better compromise choice if it will be used in both scopes. 8mm is about as short of a focal length you'd want to use in an f/10 scope. Despite owning 6 different 1.25" Barlows (with some duplicated for dedicated binoviewer usage to reach focus increasing that total even more), I've never been a fan of Barlows. They're clumsy to use in practice as compared to dedicated focal lengths and can cause vignetting, focus, or exit pupil issues. I have no experience with any current day 1.25" Barlows. Everyone one of them in my collection dates to the 1990s and was made in Japan. I've found they had better polish, coatings, and stray light control than today's crop of sub-$100 Barlows. You won't really need a Barlow in the SCT due to the long focal length. I consider them merely a stop-gap measure for shorter focal length scopes like your 130 while you accumulate more focal lengths. After which, you won't find yourself using one much at all.

I'd also recommend the Pentax XWs. The 1.25" ones are $30 cheaper than the Morpheus right now in the US.

Due to a couple of different eye lens sizes and 3mm to 4mm eye lens recession due to the eye cup design, I measured the usable eye reliefs as below: The AstroTech Paradigm is the same as the BST Starguider. The discontinued Meade HD-60 line is much more eyeglass friendly across the line. My thoughts on the two lines are in the following thread:

While the image loaded, I thought you were going with this to explain the planet-wide smog of Venus:

If we assume the eyepiece has a 46.5mm field stop and the scope has a 303mm focal length, the TFOV = 46.5/303*57.2958 = 8.79 degrees. The actual AFOV is irrelevant and highly dependent on various distortions. It only affects the presentation of the TFOV to the eye.

You might look into the new Svbony 3-8mm zoom. It's been getting good initial reviews on CN, has a 60 degree AFOV, and comfortable eye relief.

Avoid the Panorama II and Meade MWA lines. Both closer to 80 to 90 degrees in AFOV and suffer from significant SAEP (kidney-beaning). Don't overlook the other 100 degree variants on the APM XWA line. Astronomics has their Astro-Tech 100° line in the US, and then there's the Stellarvue Optimus line in the UK. There are more brandings out there, but I can't remember their names offhand. Eye relief in the shorter focal lengths will be much better than in your 6mm.

I've owned a Short Tube 80 as they used to be known for over 20 years. It rarely gets any use due to spherical aberration decreasing contrast and sharpness. My sharpest views with it are with a light green filter to cut out the red and blue ends of the spectrum where the light isn't focused very well. It turned me off to refractors for years. Then, about a decade ago, I bought a 72mm ED refractor and absolutely love it. Very sharp optics and practically no false color. While stars aren't as crisp in a parabolic mirror Newtonian as in an APO refractor, they're definitely better than in an unfiltered ST80. You can also resolve DSOs more easily in a 130mm Newtonian. I bring the ST80 on road trips as for the 2017 solar eclipse because I don't really care if it gets stolen from my car. That's how little I think of it.

Avoid fungus. It can spread to other optics once in your home. The problem only gets worse as the fungus spreads within the lens. Minor scratches at the edge might not affect the image. Avoid them across the center. Avoid the lens if it looks to have been sandblasted (used near beaches, waterfalls, etc.). A basic, manual 50mm f/1.4 to f/1.8 lens from years ago can be a good starting point for very little outlay. Autofocus doesn't buy you much if anything in astrophotography.

I was referring to kit #2: 2) Kit with OTA only (1-speed focuser) $328 That seems high by 2005 standards for a fast achromat with a single speed 2" focuser. Generic ST80s were going for about $100 or so with a 1.25" single speed focuser. I can't imagine a 2" single speed focuser added $228 to the price. When I started reading the review, I had assumed it had ED glass to account for that price increase.

Wow, that scope seems to have been massively overpriced for an 80mm f/6 achromat with single speed 2" focuser by 2019 pricing standards. I would have thought it would have had ED glass for that price.

Sounds a bit like the Tele Vue Bizarro, except that it was an 85mm scope.

The best page for comparing eyepiece types on TelescopeOptics.net is 12.4. TELESCOPE EYEPIECES: COMPARATIVE RAYTRACING. Two other eyepiece diagram charts floating around the web for years are below: You can see that the Achromatic Ramsden is indeed very similar to the Kellner in design.

The definitive optics book for amateur astronomers is Telescope Optics : A Comprehensive Manual for Amateur Astronomers by Harrie G. J. Rutten and Martin A. M. Van Venrooij. I find myself going back to my copy every so often to reread certain sections.

Actually, it helps if you don't wear eyeglasses at the eyepiece. It twists upward to reduce usable eye relief to place the eye at the correct distance to avoid blackouts. I've always presumed the LE of LET stands for Long Eye (relief). Maybe relief starts with a T in some other language? There are multiple long eye relief eyepiece lines labelled as or with LER, but this is the only one using LET.

Which end do you look in? 😁