Louis D

All I can do is comparative analysis on this, and both the 12mm and 17mm ES-92s require no refocusing center to edge in the same scopes, and at a wider AFOV. Neither does the 9mm Morpheus require refocusing for best edge image.

At f/6, the 9mm Morpheus is all but indistinguishable from the 10mm Delos as far as aberrations. The Delos is maybe a hair contrastier and more pinpoint, but it is ever so slight and might just be me wanting to justify the higher price. The 14mm Morpheus has detectable field curvature and chromatic aberration at the edge at f/6 with my fixed focus eyes. Younger eyes probably won't see it. My 14mm Pentax XL has much more field curvature, but refocuses to pinpoint perfection at the edge, unlike the Morpheus which has a bit of residual astigmatism at the edge. 20+ years ago, my 14mm Pentax looked flat field to my accommodating eyes. When it came time to choose one to keep in the A-team case, those extra 13 degrees (I've measured the Morpheus at 78 degrees AFOV vs 65 for the XL) of field more than make up for this slight issue.

Long eye relief relative to a positive-only designs (Kellner, Plossl, Ortho, etc.) at short focal lengths, not long enough eye relief for eyeglass wearers, though.

Probably a bad idea because you'll be looking in the direction of the sun to align it. If you use a 6 inch or larger section to dim the whole region around the sun, that might work.

Belt of Venus shows up most clearly in the opposite sky from sunset/sunrise. The OP states it was in the NW sky, which would be in the direction of sunset.

There should be a black screw for attaching a finder foot to the left of the focuser rotation lock thumbscrew according to these instructions. I assume you'll need to find an appropriate screw to replace the black screw once it's removed to attach the finder foot if it's similar to my AT72ED. On it, the black screw equivalent is just a set/grub screw to keep dust out of the threaded hole.

It depends on your aperture. You want about an extra inch or so all around for secure mounting. Add 50mm to your aperture diameter and that's the minimum size you need.

Missing orange. How about a vintage orange Celestron finder scope? 😉

Sounds like some of the big fracs that work their way around our local club.

I suppose it's safe with just the ND3, but it's insanely uncomfortable for more than a quick glance. I've used some of my Optica b/c color notch filters with my wedge and agree that they sufficiently knock down the brightness such than no additional ND filters are necessary beyond the built-in ND3. My Hercules wedge came with a variable polarizing filter. It works well to set a base brightness. I can then spin the eyepiece in the holder to adjust it further thanks to the polarized light coming from the wedge. The variable iris, though, seems useless. I don't know why the designer wasted money adding it. It's incredibly nice with lots of curved blades and a smooth action, but still unnecessary.

Probably not an issue because the light cone will spread out again on the other side of the image circle.

Not true. It actually reflects about 4.6% of the light impinging on it. You still need about an ND5 filter equivalent in the upper part of the wedge to bring the light down to a safe level visually. An ND3 is sufficient for astrophotography, though. As such, most wedges are sold with an ND3 permanently mounted in the upper section to allow for photography and require you to use either a polarizing filter or ND2 filter to bring the light level down for visual use. I've found an ND3 is too much and cannot locate a low cost ~ND2 filter. If anyone knows of one, let me know. I only know of the Baader ND1.8 for $49. At that price, I'll just keep using my variable polarizing filter which is more flexible anyway.

I had a Thousand Oaks glass solar filter years ago, but because the coating is just on the surface, not throughout the glass, it's super susceptible to pinhole damage. I eventually trashed it and went with BSF. I can't say that the image was any better with the BSF, just white instead of orange as with the TO filter.

Even with a refractor, I'd be concerned about not keeping the sun centered as with an unattended alt-az mount. As such, I always cap my frac when walking away from it with a wedge in place. I have no idea what all that solar energy would do to the side of the interior of the focuser, and I'm not about to find out.

I have a 90s era Lumicon UHC that I rarely use. I use my 90s era Lumicon OIII quite often. Do you already have a premium OIII filter? If not, I'd get one before a premium UHC.

Agreed, but the original posting I responded to said EQs are essential to AP. This is an absolute statement which is simply not true. Perhaps if it had said NEARLY essential, I wouldn't have bothered replying.

For me, I have a feeling eye relief will be the deal breaker. As I've stated earlier in this thread, the spec'ed 26mm eye lens diameter will limit absolute eye relief to 17mm if the AFOV is 75 degrees and the lens is flush mounted to the top. That is barely enough with eyeglasses. More likely, it will be a few millimeters less, so the actual AFOV visible with glasses will be somewhat less than 75 degrees.

I had to look up Jubilee clips. We just call them hose clamps here in the US since no one brand dominated the market. Apparently, the Jubilee brand name became genericized in the UK over time, sort of like Kleenex over here for facial tissue.

If the OP can keep the object exactly centered at high power, that's probably the best use case for a spherical mirror. It's still not great, but it's better than trying to use it for wide field views.

I took a hard pass on one of these tripods when I checked it out in person and noticed one of the leg clamps had broken. It appeared to be made of plastic of all things. When you say clamps, I'm assuming radiator hose clamps: They're great for holding things tightly together.

Not necessarily. A lot of good work has been done with alt-az mounts and field derotators. In fact, many professional observatories have been going this route lately.

I use one in conjunction with a 2x Barlow nosepiece and 45mm of extension between them to create a home brew OCS/GPC to reach focus at about 1x power in my Dob. However, the 0.5x adds loads of field curvature, so only the central region is sharp. They are mostly intended for use with cameras with small imaging chips to fit large objects onto them or to reduce exposure time. They don't see the blurry edges due to their small coverage area. The Celestron 0.63x R/C not only reduces the focal length, it also flattens the field. However, it also adds a bit of spherical aberration at high powers that is not visible at low powers. Thus, you shouldn't use one at high powers to get the best views.

Amazing what you can get from ebay. I buy a lot of new old stock (NOS) stuff from there as well as new and used items.

Probably because those OEMs can purchase those throwaway diagonals for even cheaper in bulk increasing their profit margins further.

The focal reducer is doing its job, reducing the focal length and thus the magnification. This is why everything looked smaller (super zoomed out). You really only need it for observing objects too large to fit in your lowest power 1.25" eyepiece. The double image is most likely caused by one or both eyepieces sitting tipped in the eyepiece holders. This is usually caused by the eyepiece undercut. Try holding the eyepiece firmly down in the eyepiece holder while tightening the locking collet. If it still tips, you may need to fill the undercut with narrow tape (auto pin-striping tape works well for this purpose). The eyepiece "focus knobs" are actually diopter adjusters to allow for different focus positions for each eye if you're not wearing eyeglasses. If you have the same diopter power in each eye or are wearing eyeglasses, both should be all the way down. The reason they merged the images for you was because by spinning the eyepiece, you were able to rotate one tipped eyepiece's optical axis to match the other eyepiece's optical axis. I have no idea what could be causing the bright spot in the center of the FOV. Perhaps you're actually seeing massive edge vignetting. It might also be stray light from somewhere in the optical train.