Louis D

Those 76mm/300mm scopes are insanely difficult to sight onto a target due to their diminutive size and table top use. I messed around with one at a star party that a fellow astro enthusiast had set out for the public to play with on a long, folding table. He'd picked up a couple of them from thrift stores over the years for about $20 each. I ended up lining it up on Jupiter by shooting from the hip since I couldn't get behind the scope to properly sight long the tube. I wouldn't expect a newbie to be able to do that. Once on Jupiter, I could see at least one band on it and the Galilean moons, but the view wasn't all that sharp even on axis. I think it had a decent Plossl in the focuser, but I don't recall noting what it was. The outer 50% of the field was noticeably blurry thanks to the f/4 spherical mirror and massive coma. They're really intended as gifts for little kids who have low expectations.

Typical zoom eyepiece designs have two moving groups of lenses, one at the bottom and one in the middle. The upper, final image forming lens group generally is more similar to one of Konig's designs than to a Plossl.

With the amount of astigmatism in the outer field, why would field curvature even matter? I've got a Galileo 15x70 that is great in the inner 50% of its 65 degree AFOV, but if I purposefully look at the edge, it's blurry due to astigmatism that no amount of edge refocusing will help. However, that's all in peripheral vision. I just swing the binoculars to center whatever was at the edge to the center, and all is well again. Are you going to be using these binos handheld or mounted? How much power are you looking to use? What are your intended use cases for them? For all around use, I really like my 8x42 porro prism binos from the 90s. They have a 65 degree field with 18mm of usable eye relief just like the 15x70s. I think they employ the exact same eyepiece design. I don't have to take off my eyeglasses to use either. This is a good thing because I have 2.0 and 1.75 diopters of astigmatism in my eyes; so at these low powers, everything is blurry even in focus to my eyes. You never did say if you have eye astigmatism and need to wear eyeglasses for sharp vision even with binoculars.

That's right, but imagine seeing red and blue/green star images stacked on top of each other. They don't blend to magenta, or any other color, to my eye. It doesn't hurt like the stripes image, but the effect still "trips out" your eyes. Sometimes, you can't avoid bright stars in nebula because bright nebula often contain young open star clusters. The eye tripping out is because the human eye can't perfectly focus the far ends of the visible spectrum simultaneously on the retina as exaggerated below:

To answer the second question, it depends on your budget and eyepiece case size. If I'm going to use a Barlow during an observing session, I'll just leave it in the focuser while switching eyepieces because fumbling with a third item in the dark is not fun when you only have two hands. In general, the matched Smyth lens in long eye relief, high power eyepieces works better than trying to Barlow a lower power eyepiece to the same power. However, it costs more to have a bunch of high quality eyepieces in your eyepiece case.

You could also put an elastic band of some sort around the lower threads to screw the extension/eyecup down onto. The friction should resist unscrewing upward.

If your eye is sensitive to far red, it can be useful to pick up Hα emissions. However, based on my experience with my 1990s Lumicon UHC filter, bright stars are both blue-green and red at the same time, so they are incredibly weird looking and difficult to focus simultaneously onto your retina: The improved DGM NPB looks the part below: You should be able to pick up all of the useful emission bands except for the C2 Swan bands (mainly from comets).

I've never actually used it. I keep forgetting I bought it. I'm getting worse ...lol. Squirrel!!!!

Do you know if APM is successfully skirting that tariff by mislabeling eyepieces as Germany?

In case you missed it, the OP led off with a link to that page.

At what exit pupil(s) are you observing? I've used my 1990s Lumicon OIII down to 2mm EP on brighter nebula to good effect in my 8" Dob. Yes the view dims, but if you study the image for a few minutes, fine edge details will tend to pop out that weren't obvious without it. It's also indispensable to reveal the Veil nebula under Bortle 5 skies.

Generally pot metal is majority zinc. That's what we're dealing with here. Metals alloyed with it can include lead, tin, aluminium, and copper. There is no standard for it. In all cases, it has a low melting point and a porous, brittle structure. Based on the images below of a broken SkyTee-2 mount, they're also cast from pot metal: I'm sticking with mounts machined from solid billets of aluminum like my DSV-1 and DSV-2B mounts for my scopes.

It could simply be old stock in new packaging. Did the box say Ricoh anywhere? My XWs are similarly marked as "Made in Japan", so it might come down to origin of part percentages under US law. It could also be they're not concerned with US labeling laws. Clearly APM isn't. There's no way their eyepieces qualify as "Made in Germany", but many are marked Germany rather than China. Perhaps by leaving out "Made in" they can skirt these country of origin laws?

Good point. Trouble for me is that I can't wear my eyeglasses with most of them to correct out my 2.0 diopters of eye astigmatism. Although, you could try these: or these: to block the sunlight.

Check the Orion version for price as well. Meade UHD is another branding. AliExpress sells them under the KUO factory brand Sky Rover.

At those focal ratios, give the SVBONY 68° Ultra Wide Angle 20mm a chance. I was surprised at how good they are Barlowed and binoviewed: They handily beat my widefield, long eye relief vintage B&L 15x microscope pair that I've used as my benchmark for years. Both pairs are terrible below f/12. I like the wide field, long eye relief, and sharp/contrasty optics of the Svbony. The price is nice as well. They're only $30 each from the Svbony store here in the US.

I hate to tell you I told you so, but...

Barsta appeared to be an aggregator/wholesaler of stuff made by a multitude of unnamed companies. I never got the impression they had their own factories like KUO, JOC, Ningbo Sunny, GSO, Long Perng, etc. Barsta seemed more similar to today's Svbony except that Barsta didn't seem to sell directly to the public.

True this. And, the University of Texas (at Austin) fires off a cannon on the field after every (American) football touchdown made by their team.

Sounds about right. You can see that the horizon has swapped corners with the eyepiece inserted vs. the camera view, but is still slanted 45 degrees.

When I first got my 8" Dob and used it in my front yard, passersby would ask if it was some sort of cannon. 🙄

I've also seen them sold as just Dual ED along with the aforementioned Paradigm branding.

Not like this one. You'd definitely NOT want to shine this GLP at the sky.

I was mistaking the eyepiece's 180 rotation for the scope.

Me too. More often than not, it works fine.