Louis D

I see now. The thin wall tubing was too thin around the focuser. Sonotube may be heavier, but it is stiffer and never dews up or gets cold to the touch in winter.

Based on the price, it's most likely the 24mm ES-82 and the OP is probably seeing the "ring of fire" common in the Televue Type 5 Naglers and their clones, like the longer focal length ES-82s. Unfortunately, it's perfectly normal for these eyepieces.

To confirm it's the secondary shadow, put the moon in the center and pull back from the eyepiece. The black fuzzy patch should become a sharp, black circle. If you move your head around relative to the eyepiece, the black shadow will move around the face of the moon following your head's motion.

I do work with a guy in his 60s who keeps a flashlight, his phone, and a Leatherman tool in pouches on his belt. He's always having to fix things at unexpected times in unexpected places. I kid him he has the beginnings of being Batman.

First off, who would keep their eyepieces in those belt holsters while observing? It just seems like a really bad idea. Maybe a pack large enough to hold several at once, but individually?

I bought two used 127mm Maks for $200 each, one for me and one for my daughter. That's basically the same price as a new 90mm Mak. The latest 127 versions come fitted with a 2" visual back, so you can use 2" eyepieces for a wider true field of view with some vignetting and weird reflections from bright objects. For planetary, my 8" Dob blows it out of the water, but the 127 Mak is so much more compact and easily pack-able for car trips. The views through 90mm Maks seem much dimmer than through the 127 Maks despite only being just over an inch smaller. However, I find the views through my 90mm APO much brighter than either because it operates at a much shorter focal length. If you need absolute compactness, then the 90mm Mak is the way to go.

Point it at a distant object and remove all the adapters from the focuser. Hold a low power eyepiece in the focuser opening and move it in and out by hand while looking through it like a loupe. See if you can get a focused image at any distance. If you can get a focus, note the distance. Infinity focus will be noticeably closer in to the main tube, but it's a starting point. At least you will get a rough idea of where focus lies.

😲 That's wild. I've never heard of a solid tube Newt flexing. If you're that picky, you might want to look into a Clement focuser. No flex, no slippage, and virtually no backlash.

Search for Meade OR Celestron Schmidt Cassegrain telescopes. That should get you more hits.

I've never heard of heavy eyepieces causing secondary decollimation in large Dobs. Are they twisting the truss poles somehow?

I'll believe the 4.5mm being heavy. My 14mm Pentax XL is 352g, my 10mm Delos is 398g, my 7mm Pentax XW is 389g, my 5.2mm Pentax XL is 435g, and my 3.5mm Pentax XW is 423g. Thus, the shortest focal lengths are actually the heaviest. It doesn't help they have long metal barrels between the negative and positive sections. The Morpheus appear to use an engineered plastic like Delrin which probably helps to keep weight down as the barrel gets longer. That 17.5mm sounds even more tempting at that weight. My 17mm AT AF70 is 441g, my 17mm NT4 is 727g, and my 17mm ES-92 is a whopping 1153g! Impressive achievement for Baader.

It probably throws up good images similar to many other 10" mass produced Newtonians. However, the images will probably be the same as in a Skywatcher Skyliner 250PX Flex Tube SynScan GOTO Dobsonian Telescope minus the two speed focuser. The mirrors are probably identical. The Dob would track, just in alt-az instead of equatorial mode, so there would be image rotation ruling out DSO astrophotography. You could still do planetary AP. The OTA weighs 19kg and the rocker box weighs 25kg for a combined 44kg, or just about the same, but much less top heavy. Actually, "closer" only with a given eyepiece. The 10" Dob would be able to go to higher power owing to the larger aperture. It would just require a shorter focal length eyepiece or a Barlow. But you're right, it's way more compact. It's just that you can't get much above about a 1 degree true field of view with it. I think the OP has to decide what weight is comfortable to carry around. I know my limit is about 50 pounds. I've got a 15" Dob that doesn't get used because the mirror box is 65 pounds and kills my back to get it out of storage and up onto the rocker box.

That would seem reasonable for it to weigh in between the 9mm and 14mm.

As I recall, the caps might weigh 1g or 2g taken together. Some don't even register, so must be less than 1g.

According to APM's website, the tube weighs 14kg and the mount weighs 34kg, so the scope isn't particularly heavy, but the mount is getting up there. Taken together, 48kg is quite a bit to move around if you have to dodge obstructions like trees and houses to see various parts of the sky as I do from my backyard. That, and it's extremely top heavy and awkward to carry as a unit.

Having looked through long tube Newts on low cost EQs, I can't imagine anyone wanting one. The biggest issue is that the vibrations take quite a long time to settle down after touching them to move them or focus them. Dob versions dampen those same vibrations very quickly in comparison.

According to my scale, my 9mm Morpheus weighs 327g without caps, and my 14mm Morpheus weighs 361g without caps.

Mirrors can be very expensive when hand figured to the highest standards. Teeter's 8" solid tube telescope pricing starts at $2300 with no mirror, $2625 with a GSO mirror, $3350 with a Lightholder Optics mirror, $3650 with a Zambuto Optical mirror in glass, and $3940 with a Zambuto Optical 20mm fused silica mirror. So, that simple 8" mirror can cost anywhere from $325 for a commercial grade mirror in plate glass to $1640 for a premium hand figured mirror in fused silica. Having compared GSO and Synta mirrors to Pegasus, Nova, Raycraft, and Zambuto mirrors on views of Jupiter, it's no contest. The views are significantly sharper and low contrast details are easier to discern in the 1/16th to 1/20th wave mirrors compared to 1/4th to 1/6th wave mirrors. For typical deep space objects, there isn't that much of a difference. I don't know how much fused silica substrates help outside of extreme temperature conditions.

Toric lenses to correct astigmatism depend on gravity to pull them into the proper orientation (the bottom edge is weighted). Guess what, if you don't look straight ahead into an eyepiece, the lens will tend to start rotating out of the proper orientation. Some people report having had good luck with them, but many more report having had enough issues with them that they quit using them for astronomy. If you've got them anyway for daily wear, it's certainly worth a try.

I use Delos, Morpheus, XL, XW, AF70, ES-92 and others all with long eye relief with eyeglasses without issues. However, I could understand folks having issues when not wearing glasses. I have a hard time holding the exit pupil on eyepieces with 30mm+ eye relief even with eyeglasses because I'm so far away that nothing on my face touches the eyepiece to help anchor my viewing position. As long as part of my eyeglasses, nose, cheek, or eyebrow lightly touches some part of the eyepiece, it helps with maintaining a solid view. I also can't observe standing because I wobble all over the place. Sitting helps immensely.

The only safe method I know of for sprays is using CO2 as in some fire extinguishers. Professional observatories do "snow" cleanings on a regular basis between long term washes. Even then, they have to have filters in place to prevent wayward oil from contaminating the mirror.

I admire you folks who can come home from a long day at work and then turn around and image the stars all night. I suppose if you get it automated enough with a permanent observatory, it's not so bad.

And the Takahashi TOE 2.5mm, 3.3mm, and 4.0mm eyepieces which have been getting rave reviews as well.

I would consider the 35mm Aero ED for a widest field eyepiece. It does pretty well at f/6 and nearly maxes out the true field of view possible in a 2" barrel. The Maxvisions are now sold out, so you'll be looking for used ones. The Meade 5000 SWAs are the same thing. The Morpheus eyepieces are nearly as wide as the 82 class eyepieces, are better corrected to the edge, and easier to take in the entire field at once. They've also added an optional eye cup spacer ring to make it easier to maintain the proper distance from the eyepiece to avoid blackouts for non-eyeglass wearers.

Do NOT use canned air on mirrors. It will spew impurities all over it. Take a read of that thread. It has some good information on cleaning mirrors. Personally, it takes a lot of dust on a mirror to have any visible effect on the contrast being provided by the mirror. It won't degrade light gathering or resolution to any measurable extent.