Louis D

To get widest true field of view, you'll either need the reducer/corrector for 1.25" eyepieces or a 2" visual back and 2" diagonal and 2" eyepieces with widest possible true field of view such as a 40mm Pentax XW or 41mm Panoptic. Either way, you're working against a 2000mm native focal length that only grows longer with 2" accessories because of the additional back focus required. At best, you're looking at well less than 2 degree of true field of view either way. If you want wide fields of view, get either a short focal length Newtonian or ED refractor. Either scope will complement the SCT very well.

The 20mm reticle is sharp in the center but miserable in the outer 50%. It's probably a König design variant if I had to guess. I've got the Orion version. See below for a comparison image through it:

A plain Barlow would probably work well for imaging and would give you the ability to vary magnification by varying the distance between it and the imager. I'm not aware that they add any focal image curvature. Most eyepieces don't work well for projection because they project a curved image plane. This isn't an issue for afocal projection where the taking lens has ample depth of field to handle it. I'm assuming you're attempting projection imaging and not afocal projection.

Here in Texas, we've got "shoulda could" meaning "should have been able to". We also have "usta could" meaning "used to be able to". There are many more Texas colloquialisms that sound just plain ignorant to someone born and raised in the upper Midwest where Johnny Carson and many others learned to speak correct and clear American English that sets the national standard.

Let us know if the 17.5mm is actually a 74 degree field instead of 76 degrees as I have heard from at least one report. I measured my 9mm and 14mm Morpheus(es) to have 78 and 77 degree fields, respectively, so I know there is some variability. This is way less variance than the variability in the Starguider/Paradigm and HD-60 lines (57 to 65 degrees instead of 60 degrees):

Same here. 😁 At least we can agree on some things. The manual ones are referred to as hedge clippers or hedge shears over here, depending on the region. Hedge trimmers are always electric or gas (petrol) powered, so no confusion here. This is all the more ironic since most Americans refer to the plants they trim with them as bushes rather than hedges. Hedges are more of a British thing. We'd just call a hedge a row of bushes more generally. Very few properties are separated by hedges or hedgerows instead of fences over here. Bushes are generally planted along fences to make them less ugly, not as a separator in their own right. They can also be planted around houses as a landscape feature, but I think that's done pretty much everywhere. Then there's grass shears with a 90 degree offset for trimming grass manually. Lastly, there are the powered grass trimmers or string trimmers that most Americans refer to weed whackers or weed eaters (the original brand name). We'll generally say we're weed whacking the yard with one (really, no joke). This just goes to prove how quickly one comment about yard work can derail a thread. Apologies to the OP. Uh, good luck with your RDF to bring it back on topic? ☺️

It's rare I get hit with a word I've never heard before, but today was such a day. I had to look up secateurs, what we Americans would call pruning shears. Do Brits prune unwanted growth with secateurs or is there a verb version of secateurs as well?

If you stay far enough back, the RDF window will subtend a very small angle on the sky limiting any parallax error due to your head bobbing about. However, it can become more difficult to find the dot in the first place when at a distance. If this becomes a problem for you, get up close to the RDF, locate the dot, and then carefully back off holding the dot in your vision.

I wouldn't have any experience with that. The last class I took was for my Master's program in December 1992. Definitely no cameras in the room that I can recall. They would have almost had to have been film cameras at the time. Back during my undergraduate days in the mid-80s, I did work on campus recording classes for distance learning onto 3/4" VCR tapes that were then sent to various companies where they would be viewed by a class made up entirely of employees. After a period of time, they were returned, and the tapes were erased via Deguassing coil for reuse and to prevent anyone from viewing a class for free. I would guess distance learning has changed considerably in the last 40 years as well. 😉

Make that x50 for inches. I'm sure just a typo on your end. In my personal experience, I find x30/inch more realistic for most nights and objects. The moon's terminator and double stars are the notable exceptions for going higher (high contrast subjects) and planets for going lower (low contrast subjects). As for the OP's original question, I like to look at exit pupils. I tend to favor 0.7mm at the high end, and 7mm at the low end. Given the f/12.7 focal ratio, that would equate to 9mm and 90mm. You can forget about the 90mm end of things. It is simply unrealistic to get a large exit pupil in an f/12.7 Mak. Let's stick with a 32mm Plossl then for a 2.5mm exit pupil and budget for a fast ED refractor or Newtonian for wide field views down the road. At 9mm, the 8mm BST comes close with a still usable 0.6mm exit pupil. Your 20mm yields a 1.6mm exit pupil while your 10mm yields a 0.8mm exit pupil. That 10mm, if it were a decent eyepiece, might indeed be your maximum magnification eyepiece on most nights. A 15mm BST would indeed split exit pupil sizes at 1.2mm between the 10mm and 20mm. The more I think about it, the more I think you might be better off with an 8-24mm zoom plus a 32mm Plossl to get you started. The Celestron/Meade/SW/Astromania/etc. would be a good choice for the zoom and the SW/Astro Essentials/Revelation 32mm Plossl at the long end. Once you have a better idea of the magnifications and exit pupils that work well for your observing style, you can pick up some wide and better corrected fixed focal length eyepieces.

Given my neck injuries, I can no longer use an RDF/Telrad/QuikFinder above about 30 degrees nowadays on a regular basis. To work around this, I fitted a green laser sight to each scope which is by far the quickest and easiest way yet that I've found to put the scope on bright targets. I then center the object in the main scope and do a Skeye app alignment on my cellphone attached to the scope at about 60 degrees to the sky so I can see the screen. After aligning on several bright stars or solar system objects, I can use the app to locate objects objects close enough that they show up in my widest field eyepiece. I can't star hop most nights because my skies have gotten so washed out that only alignment stars are still visible naked eye. I know that laser sights are not popular outside the US for various legal reasons, but they have been catching on quite a bit here among advanced amateurs. I don't recommend using them at outreach events because they attract little kids like flies who are then completely distracted by their presence. As far as lasing an aircraft, I just keep my ears open for their distinctive sound and scan the sky before lighting up the laser. Back to the OP's question, you generally want your finder or sighting device up high enough to be able to get behind it or off the the side of it as with right angle finders. Put it at the back, and you'll be on the ground trying to use it. If you're having trouble getting aligned with it because of the tube, put it on a 2" to 4" riser or stalk to get enough clearance for your head. As far as Telrad vs QuikFinder, the former has zero parallax issues as your head bobs about while the latter shifts a bit relative to the sky. I've read the QF circles are actually projected at about 6 feet instead of infinity. The circles are also way easier to find in the Telrad than in the QF. They're thicker, larger, and for some reason I've never understood, just plain easier to acquire. Thus, I've been using the Telrad more than the QF, when not using the laser for various reasons, because I can only tolerate the pain of torquing my neck around to look through them for a few seconds at most. Spending that time trying to locate the circles in the QF is a complete waste of precious neck torquing time for me. In the Telrad, I can consistently find them almost instantly. Still, both pale in comparison to the ease of use of a laser, though trying to torque my neck above 60 degrees can be painful in its own right to sight on a high object. That's where Skeye comes in handy. Align on lower stars/objects and use the app to navigate to higher objects. It's not as accurate as my digital setting circles, but the user interface is way more intuitive. I just need to get in the general vicinity, and I'm good to go from there.

To stay cheap, you could pick up a pair of 23mm 62 degree aspheric eyepieces from ebay. Once you pull off the rubber eye cups, there's plenty of eye relief for eyeglasses, and almost enough with them in place. I've found they work really well from f/10 and up. Unless you have a CAT scope, you'll probably need either a Barlow or GPC/OCS to reach focus, increasing your focal length and focal ratio in the process. This allows the 23mm eyepieces to perform much better and at a decently high power for planetary and lunar observing.

On the bright side, the Chinese stepped up a few years back and built an even bigger radio telescope of similar design. Still, sad to see a famous old radio telescope go in such a horrible fashion.

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Since it came with a 9mm eyepiece of unknown quality yielding 650/9=72x, that should be enough to easily resolve Saturn's rings and some of its moons. However, if you want to push up the power some, I would recommend getting a 5mm BST Starguider, Dual ED, or AT Paradigm (they're all the same) for 650/5=130x. It's a very good eyepiece with comfortable eye relief and generous 60 degree apparent field of view. At 130x, you might start to resolve the Cassini division in the rings.

Do you have a 2" diagonal and 2" visual back? If so, there are multiple 56mm Plossls (Meade, Astromania, Astro Essentials at FLO in UK) which would maximize your true field of view, greatly enlarge your exit pupil, maintain decent correction, and be reasonably priced. Otherwise, stick with a 32mm Plossl from GSO (Agena Astro has them). It's as wide as you can go with 1.25 eyepieces for under $35. I have one, and it is an excellent eyepiece.

You might as well ask for a car that is sporty, good for hauling cargo, gets great mileage, fits in your garage, and is inexpensive. There are too many conflicting requirements to all be met at once in both cases. I would recommend you get a SW Heritage 130 or 150 when they come back in stock as it would meet many of your needs as a good starter scope. It's sort of the equivalent to an entry level, compact hatchback.

Meade filed for bankruptcy protection to try and shield itself from the Orion USA's antitrust jury award. I have no idea if they can use this approach to shed themselves of the court ordered payment. If so, it guts our antitrust laws. For now, I wouldn't buy their stuff on principle. Their owner, Ningbo Sunny has acted in bad faith repeatedly before, during, and after the court case.

Totally aware of all that, but it's still a startling effect when seeing it for the first time of the season on the horizon.

They're a little hard to use with a 6 foot tall truss Dob unless you could mount a camera where your eye goes. I can get the primary quickly on target with the laser by watching the return beam coincide with the outbound beam on the secondary while adjusting the primary knobs from the rear of the scope. After that, a cheshire is handy for tweaking the alignment in small increments, but with lots of back and forth motions between the focuser and rear of the scope. I have a 20+ year old AstroSystems laser which doesn't have the handy side cutout invented later. It is dual fit, 1.25"/2" though, unlike the current version.

The Revelation/GSO Astro 2.5x Barlow tends to get good reviews here and on CN. I've not used one since I'm quite satisfied with my vintage TV 2x, Meade 140, and Orion Deluxe Barlows.

I'm younger than you, but even in my youth during the late 60s to early 80s I thought those fashions were hideous.

I was thinking that the OP could get a bigger Dob for visual at first and then add a dual axis equatorial platform later for some basic imaging like Bob Brunck on CN in this thread has done. It seems quite doable.

I totally agree with @John. GCs begin resolving around 200x in an 8" as well. At 150x, they still look like fuzz patches. Smaller PNs also do well at 200x. In my 15" Dob, 300x or more is quite usable on these targets given reasonably steady skies.

Alright, you can forget about the 40mm eyepiece then. I was thinking more of an f/7 TV-85. I take it you're getting the Tak FSQ-85EDX. At 450mm FL, the 31mm Nagler will yield 14.5x and a 5.65 degree TFOV, so not much need to go lower or wider.