Louis D

The complete line includes 10mm, 15mm, 20mm, 26mm, 32mm, and 38mm focal lengths. They are also sold as Apertura and Omegon Super Wide Angle (SWA or SWAN) among other names.

The more you know. Just an American meme associated with NBC PSAs.

So you went on Amazon and ordered them and had them the next day with Prime delivery. A few years later, the local hardware store closed up. Who's laughing now.

You're lucky it wasn't confiscated the moment you said it was a torch. They're prohibited on flights because you could start a fire in the cabin with them.

Back in the 70s, we were pitched decimeters as the natural replacement for feet. Apparently, it never caught on anywhere. I always hear people's height described as centimeters in SI units.

You have no idea have unintelligent TSA agents can be. It's what you get when you offer super low pay and terrible working conditions.

Since Weed Wacker and Weed Eater are both registered trademarks, retailers have to use the generic term for them on web pages. Do retailers in the UK list vacuums as Hoovers on their web pages despite that being the most common term for them over there? Probably not since it's trademarked.

Nope. However, I added enough spacing in front of my TSFLAT2 in my AT72ED to flatten its field once as an experiment. Once I did that, it actually has only mild astigmatism to the edge. That eyepiece design holds great promise if the designers would simply add a field flattening group ahead of the field stop. I did the same with my Pentax XL 14mm and found it to be perfectly corrected edge to edge. Again, I wish the designers had added a field flattening group to it.

I'm guessing you jest in earnest, but that is exactly the phrase in American English. A spanner in the works sounds wrong, wrong, wrong. We may even embellish it as "throw a monkey wrench in the works". Do y'all ever use the term "monkey spanner"?

Well, to make it fully American, it would be wrench, not spanner. Spanner has at least one specific usage for spanner wrenches with pins on the ends for rotating round retaining rings with holes in them. No one in the States ever says spanner by itself, though. It just sounds incomplete without wrench. Just like no one here calls flashlights torches. Torches have actual flames coming out of the end. I have no idea what Brits call the latter.

Maybe in that case (like the 14mm and 20mm Pentax XWs) it would be. In my experience, the 10mm Delos, 9mm Morpheus, 30mm ES-82, both ES-92, and 9mm Vixen LV all appear flat to my eye. The 27mm Panoptic might have a bit as do some of the Nagler T4s (17mm springs to mind). The 14mm Morpheus has a bit as well, although Don P. doesn't see any in his copy. The worst are the 80 degree, 30mm WideScan III clones. They have several millimeters of curvature center to edge.

No. It just means it won't add or subtract any OTA field curvature. Get a TSFLAT2 and put it ahead of your 2" diagonal if you want to flatten your Zenithstar 66's field.

You might be right after all that it could be a very mild case of exit pupil aberration. It just doesn't manifest itself as kidney beaning (SAEP), though. I see a much more severe version of it in the Meade MWA 26mm where the outer 2 degrees is completely black until you get close enough to see the field stop. At that distance, kidney beans start dancing around the mid-distance part of the view. At no point could I induce similar kidney bean shadows in the APM. I'd try the Baader eye cup in your case. It is 1mm shorter and quite flexible compared to the OEM eye cup. It's not that expensive to experiment with.

It was generally accepted on astro forums back in the early 2010s that the Celestron Axiom LX, original Meade 5000 UWA, and original Explore Scientific 82 series with the mushroom top were all the same optically and differed only in cloak style and claimed focal lengths. Perhaps this wasn't actually the case?

Okay, I dug out my 9mm Morpheus eye cup and its extension ring and tried them on the APM UFF 24. Everything easily threads together. The Baader eye cup alone is 1mm shorter than the APM's OEM eye cup. Without eyeglasses, I preferred the view with the OEM eye cup, but I was just barely touching the eye cup, so stray light could be an issue, but jostling the scope would be minimized. The Baader alone was just too short. The Baader eye cup plus extension is 7mm taller than the OEM eye cup (8mm taller than the Baader eye cup alone). I found I had to mash the eye cup into my eye socket to see the entire field without eyeglasses. It's pliable enough that this works well. It sealed pretty well around the perimeter, so stray light would likely not be an issue; however, scope jostling could be. I did notice in daytime usage that just as the field stop comes into view, a shadow ring appears just inside it if you continue to look on axis. If you pull back enough to get rid of the shadow, you lose the field stop. If you look at the field stop and tilt your head properly, the shadow goes away. Perhaps this is what the OP is seeing? Here are the comparison images. The Baader eye cup alone looks almost like the OEM one. It's much less stiff, though. I suppose the Baader could be unscrewed a bit to raise it up since the APM only has about 2 eye cup threads to grab onto anyway. Left to right are the OEM, Baader, and Baader+extension eye cups:

Interesting that the Axiom is heavier than the ES-82 version. 1483g vs 1369g and 1082g vs 973g. The Axiom cloak is only 5g heavier, while the main eyepiece body is 109g heavier. I wonder what accounts for the ~10% difference in weight?

Growing up with both systems firmly entrenched here in the States, it doesn't bother me until I'm trying figure out what socket wrench will fit a particular nut or bolt head while working on a car or bike. Then it can be quite infuriating. It's typical that both units are used for different fittings based on tradition. For instance, when changing a battery, the electrical posts are metric (10mm typically) while the hold-down bolt at the bottom is US Customary (USC) (1/2 inch typically). I just shake my head each time I swap out a battery. In day to day parlance, I can't imagine what the SI equivalent would be for considering a person tall. In the US, you're generally considered tall if you're 6 feet tall or taller. That would be ~1.83 meters which seems a bit awkward to use in daily speech. If a basketball player is 7 feet tall or taller, that person is considered extraordinarily tall. That would be ~2.13 meters. Again, awkward to use in daily speech. I suppose you could round down to 2 meters, but now you're only talking about a ~6 foot 7 inch player which is fairly common in both college and pro basketball (and even for many high school teams). My point is, USC units often align better with day to day, fuzzy measures than do SI units. Thus, they happily live side by side most of the time. In engineering, pretty much everything is expressed in SI units except for unwashed masses, customer facing descriptions, like the linear and cargo dimensions of a car. They're always expressed in inches and cubic feet, respectively. Liters have come to replace cubic inches for engine displacement, though, over the past 50 years. That one still perplexes me how it was generally accepted when horsepower continues to be used for engine power.

Why haven't time units gone decimal?

I have a GSO 2" diagonal with a TSFLAT2 field flattener attached to the front of the diagonal via an SCT to M48 thread adapter in place of the included diagonal nose. This gives me a nice, field flattened view from edge to edge without changing the magnification. Of course, you'd also need some nice eyepieces as well.

The only issue I've had with the early morning is that the temperature typically approaches the dew point and dew starts condensing on everything very easily.

You might look into converting a collapsible rubber lens hood into an oversized volcano style eyecup by inverting it and putting the wide end around the eyepiece and look through the lens attachment end. You might have to visit a well stocked brick & mortar camera store to try out various ones until finding one the fits well.

A little off topic, but how do you mount another saddle on the other side so you don't need to utilize a counterweight by leaving the top mount empty?

I'm sure you'll enjoy it. I have the TS Optics 90mm FPL-53 f/6.6 Triplet which is quite similar and like it a lot for visual observing. Just be patient while waiting for it to acclimate.

I guess they thought it made them more distinctive to put gargantuan eye cups on them? It was an early 2010s thing to go overboard on eyepiece cladding. For instance, the Celestron Ultima-LX had bulbous rubber grips that were oversized: They were the same optically as the Omegon Redline which I think are far more attractive and svelt:

I've compared my 9mm Morph to my 10mm Delos, and at f/6, they are almost indistinguishable except for field of view. The Delos might be a hair sharper or contrastier, but it is a subtle difference if it exists. I'm happy with both.