Zermelo

M31 is (from our perspective) oval shaped. In a modest scope, especially in a light sky, you're essentially seeing the nucleus, which is also oval shaped. It's easy to imagine that you're seeing more of it than you are. With a larger scope/better skies/better dark adapted eyes, you see more of the outer regions, though it still looks oval. One thing that will change is the apparent distance to the satellite galaxies, M32 and M110. When I first looked at M31, I was surprised at the gap between it and M110 in particular, having previously seen the photos from Hubble, etc.

I bought mine for less than that!

Don has previously linked to this bench review of zooms by Ernest Maratovich. The Svbony 7-21mm comes out particularly well. I have this, and the 9-27mm, and the (identical, OVL version of) the 7.2-21.5mm, and I find all three perform very well. The AFOV does vary a lot with magnification though, which is where the APM wins out. Svbony also do a 8-24mm, but I've not seen any reviews of that one. The Baader mk IV is widely liked.

"The darkness of the Horsehead is caused mostly by thick dust blocking the light of stars behind it.The lower part of the Horsehead's neck casts a shadow to the left. The visible dark nebula emerging from the gaseous complex is an active site of the formation of "low-mass" stars. Bright spots in the Horsehead Nebula's base are young stars just in the process of forming." Wikipedia

(i) There is inevitably some subjectivity in deciding whether or not there is a "black" dividing line. As already mentioned, as you move away from the centre of the Airy disc, the brightness tails off over a finite distance, it isn't immediate. So, for pairs that are on the cusp of being split, it will be a judgement as to whether or not the point half way between the stars is at the same level of blackness as the rest of the field. Obviously some observers will be more optimistic than others in making this call. I remember a previous thread where someone posted a graphic showing the light curve dimming and brightening between the stars; possibly @vlaiv (but then I always think it was him). (ii) on the seeing: yes, I'm sure this can affect decisions too. When operating at high magnifications in less than perfect conditions, the stars can be jumping about quite a bit. In a very brief moment of stillness, I think the eye can be tricked into seeing a gap where there was none. I've also experienced observations where a star has appeared briefly to be - at the very least - resolved, but I suspect that it was another artefact of the seeing - the image of the star has been "flicked" very quickly to one side, and back again, and the persistence of vision suggests two adjacent discs. I expect the actual effects of imperfect seeing depend on the size and motion of the cells in the air column, and probably also the size of the instrument objective.

@John may know a few, he's North Somerset.

It shows some very nice colour variations.

We are temporarily staying in Ashburton, South Devon, and all that I could manage to bring was a pair of 10x50 binoculars. We walked to a pub for a meal tonight, and came back across the fields, with most of the streetlights hidden, and the sky was very impressive. Naked eye, I could just see the double cluster and the clusters in Auriga. These were decent in the bins, as were M42, M45 and M35. To my eye, the seeing looked quite good, so I hope some of you out there have more powerful kit out.

Does this feature in those lists of "Top 100 dream jobs" that crop up from time to time?

After a purchase like that, baked beans are all that we would be eating.

That is superb, especially with the lighthouse.

Of the various UFF brandings, the Celestron versions are at the pricier end. Compare the 10mm: Celestron £149; Svbony is currently a little under £50, but I bought mine for less than half of that, in one of their frequent sales. Now, if only they offered the 24mm or 30mm...

I've replaced the mounts on my two Bresser with generic Synta-style versions from eBay, you can pick them up for as little as £8. To re-use the original screw holes, you need to open up the mount's slots slightly with a needle file, as they're not quite long enough.

The performance of the Nirvana 16mm has been discussed in several previous threads. Some people find it to be poor, but I have really liked mine, even in faster scopes. I wonder if there has been some QC variation in production over time. On the OP's question, I'd agree with the previous recommendations. I still use my BCO 10mm a fair bit, despite the narrower view; it is very sharp and contrasty. I find the eye relief on the 6mm to be a bit too tight. The Svbony 3-8mm is a no-brainier, and the sale on Ali expressway may still be on - get it for under £100 shipped. The NPL 30mm is also excellent for widefield.

Yes. Though I have read that it can shift the focus position and consequently reduce the image quality a little. Catadioptric scopes have a large range of focus, but they are designed to focus close to the optimum distance between the mirror and corrector for their particular design. Introducing the focuser throws that off a bit. I've not done it myself, others may have experience.

The blurb on FLO says 45 degrees for those four FLs. https://www.firstlightoptics.com/vixen-eyepieces/vixen-slv-eyepieces.html

Co-incidences... while @Stuwas out observing last night, one of the questions on BBC2's Only Connect was about how the wrestling body had to change their name because of the clash with the conservation organization.

Welcome to SGL, and yes, this is a perfectly good question. I presume you are planning just to hold up the phone to the eyepiece. Many people have obtained decent results this way, though usually on brighter objects like the moon. Fainter objects need a different setup. The cameras on modern smartphones are increasingly good for simple astrophotography. Look for a photo mode specifically catering for low light or night scenes (it might even mention astro uses). You can get reasonable results holding the phone by hand, but it is a bit hit and miss. A more repeatable approach uses a device that grips the phone and eyepiece, and holds them in relative position. There are several models at a range of price points, but this one gets good reviews here: https://www.moveshootmove.com/collections/move-shoot-move-rotator/products/3-axis-smartphone-adapter-for-digiscoping-telescope-spotting-scope-adapters

For buying my next house.

Some nice DIY work here:

It's sometimes also more historically correct, but we've had that argument before 😊

I've also thought that would make sense. You may be right, it could be that it's only possible to control visibility of that forum, and not the type of access. Another thought: is it possible to reset someone's access to the buy/sell section if their account hasn't been used for, say, a couple of years? Then they would need to meet the newbie criteria from the date of their first post after the hiatus. That might cut out some of the cases where dormant accounts have been hijacked, but it might need changes to count the number of posts starting from the date of "reincarnation".

This "feature" of the Synta 127 Maks has been discussed before here. Clearly you will be losing some light grasp, and hence the limiting magnitude of the faintest objects will be the poorer for it. I'm not sure how much that would make a noticeable difference to the view of brighter objects like Jupiter. There is also the question of the effect on resolving power of the undersized mirror. With a refractor, it's a simple function of the size of the objective lens, but for a catadioptric with mis-matched elements? I asked the question here, but didn't get an answer. Logic suggests that the smallest aperture in the system will be the limiting factor, yet I've split doubles down to the theoretical limits for 127mm several times, so I'm not sure that any such effect is noticeable. @SwiMatt, have you tried splitting tighter doubles with yours? Or doing a star test? With Jupiter, seeing detail is as much about teasing out the subtle contrast between adjacent regions. I suspect that, most of the time, (i) observing conditions, (ii) prior observer experience and (iii) the loss of contrast caused by the Mak's central obstruction may swamp any difference in the effective aperture loss of the undersized mirror. And a sub-optimal diagonal may outweigh all of those.

https://www.firstlightoptics.com/diagonals/stellamira-1-25-90-di-electric-diagonal.html

I think quite a few physicists agree with this. For example, when GR predicts an infinite density for a black hole singularity, it's an indication that the theory has broken down, and not that there really is a point with infinite density. In my mind I distinguish between, for example, (a) the universe may in principle have infinite extent, and (b) some physical quantity may take on an infinite value at a specific point. I'm comfortable with (a), but not (b). Perhaps in the same way that mathematicians (at least, before Cantor!) were careful to distinguish between the "potential" infinite and the "completed" infinite. The latter was considered beyond the pale: division by zero does not give "infinity" as an answer, it is undefined.