Louis D

Reminds me a lot of Manfrotto photo gear. For some reason, they use castings than can crack apart under stress. They would be much stronger if they were machined from solid billets of metal.

Here's an article about making an off-axis aperture mask. It should give you the general idea of what is going on. You would just cover the mask opening with solar film for solar observing, and securely mount the mask to the tube opening.

I would recommend making an off-axis aperture mask out of stiff foam board with the circular opening between spider vanes and covered with solar film. That way, you'll have an unobstructed view, so there won't be any secondary shadow to fight while solar observing at larger exit pupils due to your scope's long focal length and fast f-ratio. With the off axis aperture mask, you'd end up with a roughly 135mm f/12.2 unobstructed solar scope. Yes, it will be a huge 5.3 inch APO. I see you already have a truss shroud which is extremely important during solar observing.

It can be a slippery slope if not treated properly. This poor chap named Mike Clements in Utah is reportedly suffering from the worst case of Bacillus Aperturtitis ever documented: https://archive.sltrib.com/story.php?ref=/sltrib/news/57034821-78/telescope-clements-mirror-inch.html.csp#gallery-carousel-446996 https://jaysastronomyobservingblog.blogspot.com/2013/02/mike-clements-70-inch-reflector.html Let us all pray he has a full recovery some day.

Why not? Is it just the roughly 3 foot circumference? I've daisy chained a dozen or more zip ties end to end to go around very large items successfully.

It could get you in a heap of trouble in some parts of the US. I'll take a pass and use a white towel if need be. It's also handy for wiping off the sweat while solar observing near noon here in Texas. I run a box fan at full tilt across my body to try to keep a bit cooler while solar observing from mid-April through mid-October. Heat stroke is a very real possibility, so I also drink plenty of fluids while outside.

Was he using a fresh microfiber cloth being careful to roll it upward while wiping to lift grunge away without dragging it across the surface?

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.