Louis D

Out of curiosity, I edited and upsampled your image in Photoshop Elements and Noiseware to see what it would look like, and I was surprised at how good it came out below: Those little Seestar S50 camera-scopes sure are nice.

Or, rather going for a bigger scope, invest in an image intensifying system. They're also really handy for observing diffuse nebula in real-time. The only problem is you generally have to adapt non-astro systems to astro use, which can result in a lot of trial and error.

True, but enough don't to still make it a useful feature.

I just wonder if the Baader Hyperion Aspheric 36mm is enough better than the TS Paragon ED 35mm to justify the additional cost. I have the latter, and it's pretty decent, but not great, at f/6.

Have they improved the focuser on it recently? 5 years ago, I was looking at buying a used one that had been upgraded to a MoonLite focuser because the stock focuser was not so great.

Same goes for harmonic mounts without counterweights. Not only that, they can track backwards just as accurately as forwards without backlash: Watch for when totality begins and it starts scanning around the solar/lunar limb. A direct drive could probably do the same thing as well.

I thought the Sky Watcher Freedom Find mounts use encoders to keep track of alignment regardless of the clutches.

In the case of GSO 2" to 1.25" adapters, it maintains parfocality between 2" and 1.25" eyepieces if both have their focal plane at the same distance relative to their shoulders. Notice below how the 1.25" adapter's opening is recessed exactly as much as the thickness of its lip so the shoulder of the 1.25" eyepiece will be at the same level as a 2" eyepiece's shoulder in the absence of the adapter: It actually works quite well to avoid lots of refocusing if your eyepiece collection is parfocal between 2" and 1.25" eyepieces.

To be clear, when using 2" eyepieces, just insert them into the big opening without the adapter. When using 1.25" eyepieces, insert the adapter into the big opening, and tighten the big opening's screw to hold the adapter firmly. Next, insert the 1.25" eyepiece into the adapter's smaller opening and tighten its screw to firmly hold the eyepiece. I hope that makes sense.

This image pretty clearly shows how much light in general the internal Canon cyan filter is cutting from 550nm to 700nm:

How about using a 1.25" Herschel wedge? It should have a shorter light path, but I'm not sure about its thermal dissipation capacity with a 120mm scope. I use mine with a 90mm refractor with zero noticeable heating.

For straight through correct image viewing, there used to be erecting porro prism units sold by Celestron in particular. Technically, you could substitute high reflectivity mirrors for each prism reflecting surface. IIRC, if you have enough back focus, you can use two right angle mirror diagonals in sequence and then view looking in from the side of the scope. Perhaps if you adjust the angles as with the Matsumoto unit, you could view from behind the scope. I haven't played with this concept in years, so my memory might be a bit faulty. About 25 years ago, I was trying to make a correct image, compact viewfinder scope using 2" clear aperture, surplus right angle prisms bonded at right angles to each other. It worked rather well, but it was insanely heavy due to all the glass.

Sounds like a new thread in the making. Ugly or Not Ugly for various eyepiece lines. The Delos have been likened to chicken drumsticks. Whether that is ugly or not could go either way depending on how you like the looks of drumsticks. 😁

@DaveG64 Are you asking about a field derotator? They're normally used with alt-az mounted scopes. If you're using a RA-Dec aligned mount, you shouldn't need one. The built-in rotator is there for framing purposes. If you're alt-az mounted, it could still be used for this purpose, with the derotator following it somewhere in the rest of the focuser chain.

Looks a lot like the GSO 1.25" 90-deg Erect Image Amici Prism Diagonal. You might search for reviews on it.

I was thinking the same thing. The Svbony 18mm UFF version, SV190, is only $81+tax here in the US. That's way cheaper than the 18.2mm DeLite ($269+tax). The spread in the UK is probably even wider.

You could probably only detect the vignetting of that combination by taking a photograph of an evenly lit sky or light colored wall through it and comparing it to one taken through a full 46mm or larger clear aperture diagonal.

I didn't think harmonic drives were all that picky about balance. Sure, when balanced, they have a higher load capacity, but it's not required at lighter loads.

Have you used the time to make a shroud and align the RDF? How about checking collimation? What about wrapping the focuser threads in Teflon tape? Just throwing out ways to constructively pass the time while waiting for clear skies.

Here's a composite image of the image through various telescopes of mine taken on the same night: They are all shown at the same resolution from my smartphone camera. I didn't both to 2x the ST152 achromat because the 1x image was so mushy. Ignore the brown coloration. It's an artifact of the eyepiece I was imaging with. Here's a composite showing various filters applied ahead of the camera when using the ST152: You can improve sharpness by filtering out more and more poorly focused wavelengths of light. Green is the sweet spot for achromats. Longer f-ratio achromats will have fewer issues, but then you'll have to deal with a really long tube. Think f/15 to f/25 to get closer to ED and APO performance out of an achromat.

I took a look at the list of the 50 objects in that book, and it's odd that its missing some obvious (or at least easy) crowd pleasers like M27 (Dumbbell Nebula), M17 (Omega Nebula), Epsilon Lyrae (Double Double), and any of the M34/M35/M36/M37/M38 open clusters. Many of the objects listed also require dark skies to make out, so not very good choices for the average suburban observer. If you really want endless observing possibilities, look for volumes 1 and 2 of The Night Sky Observer's Guide by Kepple and Sanner. Sky & Telescope's store has new copies of volume 2.

On axis sharpness sometimes is sacrificed for wider apparent field of view in budget wide fields. If you had compared the 32mm Plossl to a 24mm Panoptic and found the latter to have more bloated stars on axis in comparison to the former, then I would be concerned.

Check the far corners to see if the artificial star shape become more rounded at smaller f-stops.

Or even a negative profile adapter. Although I don't know if it would be wide enough to accommodate the knurled zoom collar, or if you could still grab enough of it to turn it..

To see the aberrations, you really need darkness. That means either testing at night or in a dark or near dark room of sufficient length. I would recommend a black nickel ball bearing. The chrome ones seem to reflect too much stray light from the light source, making it difficult to see aberrations. I've yet to perfect an indoor technique after trying clear Christmas tree light filaments, chrome and black ball bearings illuminated by a tactical LED flashlight (torch), or a backlit foil pinhole using various light sources. Good luck and let us know what works for you.