Louis D

I recommend using a cell phone holder to attach mobile phones to eyepieces if you want to do afocal photography. DSLRs don't work well in this application.

I couldn't figure out from the translated description if the black optics section is removable and 1.25" filter threaded. If so, it might work well with binoviewers to reach focus. Right now, I use the optics section of a Meade 140 APO Barlow for this purpose.

Artemis is also not a long term, viable option. Congress mandated they use the leftover, reusable Space Shuttle main engines that were sitting on the shelf since the end of that program. However, they're being thrown away with each flight. There are enough engines for 4 or 5 flights. After that, they'll either have to restart production of a very expensive engine, find an alternative engine and flight certify it, or redesign Artemis as a whole. Yet one more way that legacy defense contractors have one hand tied behind their backs when trying to design something "new".

Legacy space operators are under the gun to have flawless flights. This necessitates really long review processes and long inter-launch periods as more reviews are conducted. SpaceX by comparison, being a commercial space operator, can pretty much make their own rules, at least until the money runs out. I've worked in both realms, and generally, commercial operators get things done faster, but with more failures along the way.

Where did I say they don't? I simply said that if you're going to compare triplets based on price (which is what the OP seemed to do), make sure they are both using the same grade of glass. After that, price difference comes down to quality of the lens figuring/polish/coatings/etc., tube mechanicals (focuser, lens cell, baffling, etc.), labor costs, factory profit margins, middleman markups, dealer markups, differing import tariffs, etc.

You're comparing apples to oranges with the Esprit triplet comparison. It uses FPL-53 equivalent instead of FPL-51 equivalent glass as in the Askar. The former is considerably more expensive than the latter. That, and I find the Esprit line priced on the high side for a Chinese made product. Synta (SW) makes a good product, but so do JOC (ES/Bresser), Sharpstar (Askar and many house brands) and Taiwan's Long Perng (many house brands). Do your homework and choose the accordingly.

How so? I'd say the best way to break a 2" filter would be to screw it onto the bottom of a 2" to 1.25" eyepiece adapter and then insert a long barreled 1.25" eyepiece into the adapter.

Okay, but supposing you did want to directly use 2" filters with it, you could use this 1.25" to 2" Step Up Ring attached to the 1.25" filter thread.

I would add "at a given aperture under good seeing conditions". For example, years ago at a star party, on the same night that Jupiter looked featureless at 200x in 4" APOs and 8" SCTs, it looked rich in details in a 15" custom Dob at over 300x. That convinced me to buy a used 15" Tectron Dob. It did not disappoint. 300x felt like 100x in a small scope. Of course, I had very steady skies to observe from here in Texas.

For low power star hopping, I would stick to the lowest cost option available. The Baader would probably shine at high powers, but who star hops at high powers? Remember, though, the clear aperture on these lower cost Amici prisms is somewhat less than 27mm, so you will probably see vignetting with widest true field 1.25" eyepieces. Also, they're plastic bodied, so I wouldn't put a heavy, expensive 1.25" eyepiece in them.

The WSP location in the Florida Keys is at about 24.6° N, 81.3° W. It is more or less in the The Straits of Florida between mainland Florida, USA, and the island of Cuba. Its seeing is influenced by the Florida Current that eventually merges with the Atlantic Current to form the Gulf Stream. The Florida Keys are generally well south of the jet stream.

In a good way or bad way? The Winter Star Party in the Florida Keys is known for very steady seeing conditions.

My thoughts exactly. I went from an 8" tube Dob to a 15" truss Dob and found the improvement massive on DSOs and planetary detail (remember, steady Texas skies here). Of course, after a massive auto accident 23 years ago that ripped up my back, I have barely been able to lift the 15" out of the back of the hall closet because the mirror box weighs 60+ pounds. I figure I'll move it to a dark sky vacation/retirement home at some point and place it on a roll-out platform with jacks to keep it steady.

I was surprised by how claustrophobic the 14mm Morpheus felt when swapping it in between the 17mm ES-92 and 12mm ES-92. I wouldn't have ever thought a 76 degree AFOV would feel that way until I did the swap. However, if you never swap in a wider eyepiece, you'll never feel that way using a Morpheus.

I generally think in terms of percentage jump. Going from a 60mm to a 72mm is a 20% increase in aperture. Going from a 72mm to a 100mm is a whopping 39% increase in aperture. However, going from 100mm to 120mm is only a 20% increase once again. Going from 120mm to 150mm is 25% increase, so slightly larger, but not massively so. Certainly not enough in my mind to justify the cost, weight, and difficulty of mounting a 6" refractor (APO or not) over a 6" fast-ish Newtonian. A 150mm APO refractor is going to run you about 20x or more the price of an f/5 Newtonian which is APO by definition. By contrast, going from a 200mm reflector to a 240mm reflector would be a 20% increase. However, the increase in number of observable objects is not nearly as much as the jump from 60mm to 72mm. Increases in aperture are thus much more noticeable at the lower end in my experience than at the higher end. For instance, going up in 25% increments starting at 50mm rapidly opens up the number of objects the human eye can detect or resolve. However, once you get up around 10 to 12 inches, the jumps need to be larger in my experience to open up a significant number of new objects. Thus, I see mostly 16 inch and under Dobs at star parties because of this. You also need really dark skies to justify using 18 inch to 36 inch Dobs.

Good point. 👍 Mathematically, it should have about 5mm more eye relief (16mm vs 11mm) at 45° rather than 60° due to its 13mm eye lens diameter and 60° AFOV. Of course, I measured closer to 8mm usable eye relief or slightly less at the short end of the zoom range, so figure on 11mm to 13mm of usable eye relief at a 45° AFOV. Most folks find 12mm usable eye relief without eyeglasses to work well for them, so this makes it a comfortable replacement for short focal length Plossls and Orthos for non-eyeglass wearers willing to live with a 40° to 45° AFOV, which is reasonable for most high power observing situations. Even folks like me with strong astigmatism can often get good enough results at tiny exit pupils without eyeglasses.

It really depends on how much tension you have set in the altitude axis. I'm pretty sure that mount has adjustable tension. If you crank it up, you may be able to avoid any balance issues. The bigger problem you're going to run into if you run with light tension for a smoother altitude motion is the tendency for the tube to swing upward when you remove the eyepiece for an eyepiece change no matter how well balanced your tube is. There are no clutches on Dob mounts to lock it during eyepiece changes. You'll need to become adept at keeping the scope from swinging upward during eyepiece changes if you aren't keeping a high level of tension in that axis.

Why not just buy an Astronomik OWB Type 3 Clip-Filter EOS APS-C? It seems like the most reasonable solution for you. Here's the tech info:

@HollyHound Do you observe with eyeglasses at those focal lengths? I have such strong astigmatism in my eyes that I need a minimum of 17mm of usable eye relief to comfortably see the entire field of view of an eyepiece. My 12mm and 17mm ES-92s exactly tick that box, so I have no incentive to get the 16.5mm XW. My XL, XW, Hi-FW, Delos, and Morpheus eyepieces all provide at least 18mm of usable eye relief, so are also quite comfortable to observe with. I've held off purchasing the 23mm XW to replace my 22mm NT4 because I've read that the eye relief is marginal for eyeglass wearers.

I use a GSO 6" f/5 on a DSV-2B alt-az mount without any major issues. However, anything bigger, and I would prefer a Dob mount. One issue I have with my alt-az mount is that if I move my rig to a different spot in the yard to dodge sky obstructions, any bit of being out of perfectly level and the azimuth axis swings around to the low side. This pretty much does not happen with Dobsonian mounts unless you've got a really heavy load in the focuser. Having to relevel a mount in the dark is a pain, so there's a win for the Dob.

In head to head comparisons with the 30mm APM UFF, 27mm Panoptic, and 35mm Baader Scopos Extreme at f/6 and faster, I found the ES-82 30mm to have slightly bloated stars across the entire field of view at best focus. Enough so that I found it annoying. If the bloat were confined to the field outside the TFOV of these other eyepieces, I'd be totally good with that, but it's there even in the central region. I suppose if I had no frame of reference from never having tried those other eyepieces, I might not have ever noticed the central bloat. I was in this situation for years before getting a coma corrector. Once I knew what the field could look like with a CC, I could never go back to not having a CC in my Newts. Why pay big bucks for an APO to have pinpoint stars only for those same stars to be bloated by your eyepiece? That's why I have other eyepieces in this range, because no one eyepiece does it all (ultrawide field and pinpoint stars center to edge) in my experience at f/6 and faster. Due to its prohibitive price, I haven't yet tried a Nagler T5 31mm to see if it manages to have pinpoint stars center to edge like the UFF, Panoptic, and BSE.

Are these OO Newts intended for imaging? Otherwise, why suffer the consequences of a large enough secondary to illuminate a focus point well outside the tube?

Your best budget bet for visual is a GSO coma corrector that is sold under numerous brands around the world. I have two, each with a 25mm spacer ring added between the optical section and the eyepiece holder for best correction with my eyepieces that focus near their shoulders. They're really good except at high powers when the spherical aberration they introduce degrades the view. I remove it at high powers as a result. I've found they require 11mm of additional in-focus as I have them configured.

I have the original ES-82 30mm decloaked, and the APM UFF 30mm is sharper across the field, especially toward the edges. The ES-82 splits red from blue, giving two images of planets in the last 15% as they drift across the field of view. Point is, give the APM UFF 30mm a try if you were looking to improve the image quality over the Axiom 31mm at the expense of a bit of field of view. It's much lighter and more compact as well.