Louis D

April 29th is the latest APM delivery date according to this most recent post in the CN Vendor Forum.

And don't forget that some Maks use undersized primary mirrors, so they don't actually operate at the aperture of their corrector which diverges the incoming rays and requires an oversized primary to collect all of them. For instance, the Synta 127mm Maks actually operate at about 118mm from what I've read. The JOC 127mm Maks do actually operate at 127mm from what I've read.

Now that I think about it, I retired my 12mm and 17mm NT4s after buying the 12mm and 17mm ES-92s. Huge improvements in eye relief, usable field of view, and SAEP control going to the latter. Also, a minor improvement in field flatness with the ES-92s.

I already pointed out that the 8" EdgeHD displays stunning planetary views. To reiterate, in my experience, it's standard 8" SCTs that always seem to show mushy, low contrast views of planets in comparison to 8" Dobs with hand figured mirrors and 20% or smaller secondary obstructions.

I have actually been surprised they've kept them in the line up for this long. I have a feeling they finally ran out of new old stock at corporate warehouses to supply dealers rather than stopping production recently. I think this was the case as well for Tele Vue's recent product discontinuations like the 12mm and 17mm NT4s. Once NOS ran out, it was probably determined to be uneconomical to order a new batch to be produced, especially given the 13mm NT6 and 16mm NT5 being so closely spaced with them. They can just point buyers to the 12mm and 17.3mm Delos if they want long eye relief.

I only use zooms in my binoviewer where changing a pair of eyepieces is a pain and when traveling light, as to 2017's solar eclipse. I use the discontinued Celestron Regal 8-24mm zooms to good effect. They were also sold with Olivon spotting scopes. They're pretty decent, but I much prefer fixed focal length premium eyepieces for general usage due to their longer eye relief, better polish and coatings, wider field of view, and better edge to edge correction.

Long eye relief at high power (<1mm exit pupil) isn't a must for an eyeglass wearer unless you've got really strong astigmatism (>2.0 diopters). As an f/13 scope, it is going to be pretty gentle on eyepieces. Also, you probably won't want to go much below an 8mm eyepiece to keep the exit pupil above 0.6mm which is already pretty tiny and prone to exposing floaters in the eye.

12mm usable thanks to 4mm of eye lens recession for all but the 25mm which has 17mm of usable eye relief.

Crazily enough, on that webpage, TV says their 1.25" PMs are parfocal in ALL (their caps) 1.25" diagonals and prisms. I would expect them to be parfocal in Newtonian focusers as well. @ninjageezer Double check that your truss poles are extended all the way and locked. However, if the eyepiece focuses without the PM, it should focus with it based on my reading of the above TV PM webpage.

Yes, GCs are very disappointing in a 90mm APO compared to an 8" Dob, let alone a 15" or larger Dob.

Have the primary refigured to 1/10th wave or better if it isn't already, decrease the size of the secondary to no more than 20% obstruction by diameter, and replace the focuser with a low profile focuser. My best planetary views have been through 8" to 12", well collimated Dobs with custom mirrors like Zambuto and an undersized secondary. The low profile focuser gets the eyepiece closer to the secondary to grab as much of the reduced cone of light as possible. Of course, it might be cheaper to just start over and look for a used custom made Dob with full goto.

I'd probably start with a Celestron 0.63x reducer/corrector if you already have the 8SE. I can't find an SCT corrector that isn't also a focal reducer. However, these don't play well with short focal length eyepieces. From what I've read over the years, you don't want the R/C present at high powers. I see something similar with the GSO CC in my Dob and the TSFLAT2 in my fracs. Both contribute spherical aberrations at high powers that overshadow any intended correction. The Starizona R/C is much more expensive, but probably achieves better correction. I'm not sure how applicable it would be to visual work, though. The difficulty of trying to get absolute sharpness with SCTs is probably why other designs are more popular for high power visual work.

Both

Read this Celestron whitepaper on the EdgeHD. Even in the center, the spot sizes are tighter than a typical SCT: It might also be possible to get similar results with a Starizona flattener/corrector: My point is, even on axis, SCTs need some optical corrector help at the rear baffle tube/port.

If you've got enough aperture to resolve a GC at high enough power, light pollution isn't such a big issue. For instance, M22 is barely visible as a brighter fuzz patch near the Teapot asterism from my backyard at lower powers, but at over 200x in my 8" Dob, it breaks up nicely into teeny tiny pinpoints of light for the most part. Not all GCs will resolve with only 8" of aperture, though. In fact, only a few of the closest/largest ones resolve nicely for me. I need to get a bit further south and seek out a clear view of the southern horizon sometime to see if I can bag Omega Centauri. It should be just doable from southern Texas IIRC.

I'll try to remember to snap a pic the next time I have one of them set up.

I have a couple of these triple mounts for different scopes. They are quite robust and work very well. You have to be careful about where you put the various finders in the three shoes or you won't be able to get your eye in the proper position or get them all to fit next to each other. I put my RACI finder (the heaviest of the finders) as far over as possible to keep it more in line with the altitude axis so I get less backward tipping at high altitudes. Next goes my QuikFinder on an adapter from ScopeStuff in the middle position. Last goes my GLP sight because it ends up almost straight ahead of the eyepiece in the diagonal, which doesn't matter for it but would make using the QF in that position next to impossible without tipping the eyepiece out of the way.

Why is it that SCT planetary images look good, but every time I look at planets visually through SCTs at star parties, the views are always upstaged by nearby Newts with custom mirrors of similar aperture? The only time an SCT gave comparable visual planetary views for me was through an 8" EdgeHD. It was just as sharp as the views through the Dobs with custom mirrors.

🤔 And here I thought the Powermates weren't supposed to alter focus position of an eyepiece by much, if any. Try pulling the eyepiece upward out of the PM to see if that helps at all as well as pulling the PM up out of the focuser. Seems weird that focus position is so far off as with a long Barlow. At least with the latter, it has a 2" to 3" insertion tube, so you just insert it partway and lock it down once focus is reached.

As a college engineering intern for General Motors in 1986, I was paid $8/hour. Considering the US Federal minimum wage was $3.35/hour back then, it wasn't that much when you consider I had to pay for a room to live in near Detroit and buy my own food and pay for transportation out of that money. Since I was paying my way through college, it wasn't like I could just ask my parents for financial help. The US Federal minimum wage was $1/hour back in 1958, so you were really underpaid, and UK labor laws were pretty lax over there back then.

Off topic a bit, but don't y'all have outdoor public tennis courts that are free to play on? We have them at many city and county parks, middle and high school grounds, and even a few churches with large grounds have them. Then, all you need is a racquet and some tennis balls. With so many, it's not too difficult to know which are generally available and when. They are almost as common as outdoor half court basketball courts around here. If you had said squash, handball, or racquetball, I'd have agreed. Those courts are more difficult to find, generally being indoors. You have to have a rec center or other club membership to use them.

No, but plenty of countries deliberately make it difficult to sell into them. Tariffs, duties, taxes, inspections, quarantines, proof of origin, etc. For instance, lots of countries now insist on the seller collecting all taxes and tariffs due before shipping and remitting them to whatever country it was sold into instead of leaving it up to the buyer to pay them locally before receiving said items. That's a whole lot of extra paperwork to deal with as a retailer.

And no optometrist ever caught this during an eye exam? You have to look through a binoviewer-like device (a phoropter) that should have flagged this. I believe prism correction in eyeglasses would solve your problem based on your description.

I found that the only alignment problem I was having with my Arcturus BVs, which do have self centering holders, was due to eyepieces with undercuts tipping in the holder during the tightening process. I have to cram them down while tightening to prevent them from popping up at an angle. I should just fill the undercuts with pinstriping tape.

Same reason most Americans won't mail items outside the US. Too much hassle and higher risk on transactions. I think I recall @Don Pensack of Eyepieces Etc. mentioned that he won't be doing business with Europe anymore due to various new regulations that are onerous to deal with.