Louis D

Certainly not the best if you need to transport them any significant distance, especially if walking or biking. In that case, a suitcase/travel Dob would be more appropriate, but you have to build them yourself as Reiner Vogel has done many times over. I don't understand why no manufacturer has stepped up to make these commercially. They would make recommending Dobs even easier.

I wasn't a fan of the Radians' SAEP on bright objects (lunar and solar), so I went with Pentax XLs back in the late 90s. The XLs also seemed to have more eye relief than their LVW counterparts, which was important to me as an astigmatic eyeglasses wearer.

That is nice and dark by suburban standards. I'm in Bortle 7 or worse in most directions. I would think either a 30mm or 40mm would work well under your skies. I actually use both regularly, so it's not an either/or situation. The 40mm (Lacerta ED, Pentax XW, ES-68) is best for really big objects or groups of objects and for centering smaller, but brighter ones before swapping to a higher power. The 30mm UFF is nice for framing slightly smaller objects or groups of objects at a higher contrast level, higher power, and rendering them more sharply while using a smaller, lighter eyepiece that typically balances better when swapping with higher powered eyepieces.

If you want a widest field view without breaking the bank, or dealing with a lot of weight, the 40mm Lacerta ED is very good. I've found it to be just a bit less sharp at the edges than my 40mm Pentax XW. The Lacerta appears to still be available from this dealer where I bought mine. Here's my review of it: Keep in mind, if you live in light polluted skies, the sky background will be very washed out at that power/exit pupil. However, the Pleiades and other large star clusters will look very nice in it.

Since many early rockets used RP-1 (a highly refined kerosene) just as SpaceX's Merlin and Kestrel engines, I don't see how it's all that much worse now than then. Also, consider all of the burned kerosene in the form of jet fuel, also highly refined, in airliners every day. SpaceX is migrating over to methane fueled engines for their future rockets. I have no idea how it compares to RP-1 as a pollutant, though.

I've really been enjoying my GSO 5" f/5 Newtonian with Linear Bearing 2" focuser for quick outings. It's low cost, relatively light, holds collimation very well, has no cool down issues, has sharp optics, puts the eyepiece up nice and high so I can keep the tripod low for stability, goes from wide field to high power views with merely an eyepiece change, and has a usable two speed focuser. You might need a pier extension for your mount to use one without hitting a tripod leg at high elevations. If you're picky about edge to edge sharpness at low to mid powers, you might want to pickup a GSO coma corrector for it. If you concentrate mainly on high power viewing, you'd want to remove it anyway because it introduces spherical aberration at high powers.

Maybe by sheer luck, it's that weird thread size on Arcturus (and other entry level) binoviewers' nosepiece upper end. It's somewhere around 26mm from what I've read and been able to figure out.

Seriously Steampunk looking. I love it! I'm picturing the astronomers of the day like this:

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.