Louis D

There's also the 7mm Celestron Luminos in that rough price range.

Look for the GSO/TPO/Apertura/Zhumell/AstroTech/TSOptics/Revelation 2X ED 2" Barlow. It is really good for the money, is full aperture, has an excellent 1.25" adapter included, and the optical nosepiece is 2" filter threaded so it can be screwed directly onto 2" eyepieces for about 1.5x or onto the end of a 2" diagonal for about 3x. If you can locate a used Tele Vue Panoptic Barlow Interface (PBI), it works very well with this Barlow to make a poor man's Powermate because the GSO Barlow has almost exactly the same focal length as the TV Big Barlow the PBI was intended to work with.

With regards to eye astigmatism: Do you wear glasses? If you do, check your prescription for CYL or Cylinder correction. It will be quoted in diopters. The bigger the number, the more astigmatism you have in your eye. Check this chart from Tele Vue to get an idea at what exit pupils you can tolerate your astigmatism. Exit pupil is the eyepiece focal length divided by your telescope's focal ratio. Astigmatism less noticeable as power increases and exit pupil goes down.

Did you post a write-up somewhere? I recall your recent 30mm UFF write-up on CN. I would hope at $665 that the 31mm Nagler T5 is pin sharp from edge to edge with no field curvature, no chromatic aberration, and no astigmatism. My 30mm ES-82 has very noticeable chromatic aberration in the last 10%. However, I only paid $220 for it years ago, so I'm content to live with it. It's not apparent in the image below, but it is very noticeable if I let a planet drift from edge to edge during observing. It is way better than Kasai Super WideVue which looks like a prism starting at 20% out from center.

Actually, I want a 25mm ES-92 for under $600.

So you changed gears mid-thread. If price is no object, and you must wear eyeglasses due to astigmatism, the 17mm ES-92 is my favorite in that focal length range.

See if that bottom section unscrews and contains all the lenses. If it does, see if it will thread onto the end of your diagonal like a filter. You should be able to reach focus in this configuration, but at a higher magnification factor. I know the GSO 2" ED 2x Barlow can be used in this manner.

Of course, because the golf ones are surely "high precision". 😉

And someone who is probably aware of multiple rebrandings of the same thing with varying degrees of packaging ergonomics and attractiveness.

Aside from Televue, Brandon, Vixen, Takahashi, Masuyama, Pentax, Nikon, Olympus, Docter, Zeiss, Leica, Meopta, Swarovski, and a couple others I may be forgetting, pretty much all the rest are simply market brandings for readily available, Chinese or Taiwanese made eyepieces. Often, Vixen and Takahashi subcontract out their eyepiece manufacturing to other Japanese companies. Even Baader is suspect since their Hyperion line is basically the same as the Orion Stratus line. Most eyepieces are made by GSO, JOC, KUO, Synta, Long Perng, etc. If they're good, it doesn't really matter what the lettering on the eyepiece says.

Simply go around to the other side of your Newtonian and lean over it to reach the eyepiece. The image will appear upright when viewed this way. I have no idea how long you'll be able to hold this position, but it works. There's generally not enough focus travel to put any prisms in the light path of a Newtonian to flip the image the right way around, so you're pretty much stuck with the above workaround. If you really want a correct left-right and top-bottom imaging spotting scope because terrestrial use is most important to you, get either a refractor, an SCT, or a Mak telescope and put an Amici prism diagonal on the back. At night, it doesn't really matter if the sky is flipped or rotated unless you're trying to match an eyepiece view against finder charts.

Avoid ebay and other non-astro classifieds. Stick to dedicated astronomy classifieds associated with your home country. The folks who post on them are generally on the up and up. That, and you'll probably want to drive and meet face to face if buying a largish Dob. At that point, you can check it out, ask the seller to show you around it, aim it at terrestrial targets, etc.

My understanding is that ED glass was more common in eyepieces 15 to 25 years ago. Then China cornered the market on rare earths and starting jacking up the prices on them except to Chinese customers. As a result, most newer non-Chinese eyepiece designs dropped using ED glasses because they had become cost prohibitive. To get the same level of correction, eyepieces tended to get longer or fatter to make up for the loss of ED glass properties.

For widefields, I would recommend 10mm and below Pentax XW and the discontinued XL. The XWs give slightly darker backgrounds, while the XLs are easier to hold the view and are better corrected to the edge. I would also recommend most of the Delos. The perform equally as well as the XW and are much better at 12mm to 17.3mm. The only ES I would recommend would be the 12mm and 17mm ES-92s that view just like the Delos, only with a wider field of view. They are massive, weighty, and 2"-only. The Panoptics are sharp and provide a dark background, though they have a bit of field curvature. The Delites are supposed to be a step up in sharpness and contrast from the Delos, though a notch below the best narrower field planetary eyepieces. The Morpheus are a slight step behind the XW/Delos/Delite. I would avoid the 14mm because it has slight curvature and astigmatism at the edge. The 14mm Delos would be the better choice. The Nikon NAV-SW have fewer reports, but some folks swear by them. The NAV-HW are regarded as slightly better than the Ethos, but just a notch behind the 12.5mm Docter. The 12.5mm Docter is considered phenomenal in most respects, but it only comes in one focal length. The 30mm APM UFF is an excellent choice at that focal length. At high powers, the Tak TOEs and Vixen HRs are considered the best that are currently available.

Center a bright star (Venus might even work) and defocus it pretty far. You should be able to see the atmospheric (or telescope tube) turbulence as bubbling in the defocused image. You can sort of judge the quality of the seeing in this manner. Stick your hand in front of the objective/end of tube to see more cool thermal effects. It reminds of the view through a thermal imager.

If you get a clear night, let stars of different magnitudes drift to the edge and note if they change shape indicating edge aberrations. Also, try refocusing a star at or near the edge to see if that improves its sharpness. Racking a star near the edge inside and outside of best focus can easily reveal if the eyepiece has edge astigmatism because the star will stretch radially on one side and tangentially on the other. If it is minor, it will appear nearly pinpoint at best focus. If it's bad, it will appear spiky at best focus. If you keep objects centered with a driven mount, edge astigmatism does not matter very much, but if you use an undriven mount, especially at high powers, you really want edge to edge sharpness to extend "dwell" time to observe an object before nudging the scope again.

Closest for me was my 32mm GSO Plossl and 8-24mm Celestron Regal zoom I took with me to Nebraska for the eclipse. Everyone at the viewing site thought the views looked fine through each when used in my ST80 travel scope. Eye relief was sufficient in both even for eyeglass wearers.

See these previous discussions on SGL, CN, and elsewhere: https://www.cloudynights.com/topic/653616-eyepiece-turret/ https://www.cloudynights.com/topic/442049-does-anyone-use-an-eyepiece-turret/ https://www.cloudynights.com/topic/628144-turrets-and-what-4-eyepieces-you-use/ https://www.cloudynights.com/topic/576353-eye-piece-turrets-takahashi-tec/ https://www.cloudynights.com/topic/668439-geoptik-eyepiece-turret-any-experience/ https://www.cloudynights.com/articles/cat/user-reviews/review-of-the-tec-eyepiece-turret-r2598 https://www.cloudynights.com/topic/645543-npae-turret-nice-if-you-can-afford-it/ https://www.skyatnightmagazine.com/how-to/build-a-rotating-eyepiece-turret/

Ground floor is synonymous with first floor in the US. You'll often see elevators buttons marked G-2-3-4-... instead of 1-2-3-4-... here in the states to make it clearer. That must get confusing to Americans trying to get back to ground floor in an office building to see the buttons marked G-1-2-3-4-... Which button to I press, G or 1, to get back to street level? You'll also typically see a ⭐ next to whatever button gets you to street level to reassure users. I wonder if UK elevators do the same. Question is, what do y'all call the level in the ground? We call it a basement. Perhaps you call it the underground floor in keeping with the ground floor nomenclature or perhaps lower level as in an office building?

I store my Dobs in the back of coat closets on my first floor. One has end caps and the other one collapses into a box (truss style). No mirror coating degradation in 20+ years this way. Everything in my shed gets a coating of mildew due to the high humidity of summers in Texas (swamp level dew points). The garage simply doesn't have the spare space for a telescope with two cars, water softener, water heater, and power tool storage. The main house A/C keeps the humidity at bay during our cooling season from mid-March to mid-November.

I've read that they're pretty decent. Sorry I don't have any first hand experience with it. Have you ever see or picked up a 10" Dob in person? They're not exactly small or compact. As long as you're aware of that, it can be a very good choice giving years of astro enjoyment. Have you read through @johninderby's thread on his 10" Bresser Dob? (Apparently, we simulposted.)

As that is the only BST focal length I don't have, I'm quite interested in hearing your thoughts on it. Clear skies!

I would just pick up a pair of cheap 8x40 porro prism binoculars off Amazon with Prime. If they aren't well collimated or are unsharp, send them back and try again.

An 8" Dob is a lot sharper to my eye than a 5" Mak if we're comparing in the £400 range (don't forget to budget for a decent mount and tripod for the Mak). The Dob is just a single parabolicly curved primary mirror and a flat secondary mirror. The Mak has two spherical curves on the corrector, a spherically curved primary mirror, a spherically curved secondary mirror, and a flat in the diagonal. It's a lot harder to get 4 matching, well figured spherical curves than to make a single, well figured parabolic curve and a decent flat for £400. Once you pump up the power, Bortle 6 skies become a lot less milky. I should know, I observe under them in my backyard. As long as you can block the light from the street lamp getting to your telescope and eyepiece, it doesn't impact your views all that much. I had to put my recycle bin on top of my garbage bin last night to block my ******** neighbor's unshielded back porch light that shines like a beacon into my backyard. Talk about light trespass. Even in twilight, you can observe solar system objects and star clusters; although you're so far north, the planets must be really low for you, so it might not matter how dark the skies are if they're on the horizon. As long you have nearby dark skies, you should be able to observe in those directions to good effect. My nearby cities lie to my west, so I can't observe that way at all. Smaller towns lie north and south, so the skies are a bit better in those directions. However, it's just farmland to east, so I can get nice views in that direction. The Bresser/ES Dobs have really good trunnions for the altitude bearings, so balance is less of an issue for them. I've read they are better in other ways than the Skywatcher/Synta Dobs, such as the anti-reflection coating in the tube. If you've got the time to observe, why wait? The summer has many good objects to observe.

Makes me glad I have no electronics on my telescopes save for a 1990s era Skycommander DSC box.