John

I think it's not so much a case of landing as it is moving alongside and docking with an object as small as Bennu. It's gravitational pull is so low. They would have had to find a way to anchor the craft to the loose surface. Not easy I suspect.

Astonishing !!! Thanks for posting this Andrew

I collimated a mak-cass 90 recently. I used an artificial star. It was a bit of a fiddly process with very small adjustments needed but once you get it, it stays put. I then checked it at high power (180x) on Polaris at the 1st opportunity. I'm not sure that the cheshire can really help with a mak-cassegrain ?

I've never found filters really help with galaxies. Nebulae, yes, but not galaxies in general. Dark skies are the key for galaxies.

The black anodizing goes gold when exposed to strong sunlight for long periods. It may have been stood in a window or a conservatory for some time during it's life. I've seen this quite often with Skywatcher scopes and others. I have a "gold" Meade 26mm plossl

I'm not a fan of "floating" my eye over the top of an eyepiece personally. I like a nice eye cup to rest my eye socket against and also to keep stray light off the eye lens. I had that problem with the ES 92 12mm and the Tele Vue 32mm plossl before I fitted the eye cup extender to it. These are personal preferences though. Some folks seek out these characteristics. I nearly mentioned the Pentax XW28 in my earlier post but I'm aware that they are like hens teeth to find and do have some mild issues of their own. Probably better than an erfle though.

Yours is very similar indeed to the 90mm F/13 that @Lockie posted pics of in the thread I linked to earlier. This is the same view of the 90mm F/13 and you can see that small nut in the same position. @Lockie did manage to get the dew shield off though - I wonder if he could tell us how ?

I reckon that little nut and bolt are what is holding the cell / objective / dewshield assembly onto the tube. Sometimes there are three of those at evenly spaced intervals but perhaps they figure that one is enough for the relatively small aperture. With the dew shield glued into the objective cell it's not going to be possible to get at the other end of that bolt as far as I can see. It's not aimed at owner maintenance !

I had one for a while. It worked well in my slower scopes - F/8 and F/9. In faster ones it still worked of course but showed some edge of field astigmatism. Quite a nicely made eyepiece I thought. Similar in build quality to the Nirvana's and William Optics ranges. Might be worth a "wanted" advert if you are not in a hurry. You might be able to pick one up for quite a bit less than the retail price.

I used to like Saxon. Good solid British rock band

What scope will this be used in Jon ? The Erfle design is not generally known for being sharp right across the field in faster focal ratios, regardless of what the adverts say. There is the OVL 27mm flat field but again it's not too well corrected in fast scopes. Decent in F/10 ones though: https://www.harrisontelescopes.co.uk/acatalog/skywatcher-extraflat-27mm-eyepiece-1.25.html?gclid=EAIaIQobChMIrY-mtIfG7AIVFu3tCh12_wnPEAQYAiABEgJRUfD_BwE

Saxon is a brand name that you seem to come across more in the southern hemisphere: https://www.saxon.com.au/telescopes.html Their products certainly look mostly like Synta products.

There you go OP - a nicely kept Hyperflex zoom might be available shortly How does the AFoV across the range compare John ?

Another fan of the 7.2 - 21.5mm zoom here. I use mine a lot and often with a Baader 2.25x barlow to give a high power 9.5mm - 3.2mm zoom which is very useful in my scopes but perhaps not so much in a mak-cassegrain 180 ?

The longer 90mm Bressers use a slightly different objective cell design though: https://stargazerslounge.com/topic/291186-new-bresser-90mm-f133-unboxing-and-initial-thoughts/ Would the AR90 use the same ? I still think it is likely that the objective will be tilted with the cell having been knocked like that. With the 127L's the objective cell was metal but the counter cell was plastic as I recall. Same as the Meade AR5's.

I have also tried a few times to see Phobos and Deimos with my 12 inch scope. No luck as yet for me. I agree that Deimos is likely to be easier than Phobos despite being dimmer.

The effectiveness of these filters is influenced quite a lot by the diameter of the exit pupil that the scope / eyepiece combination generates so eyepiece choice is quite important.

Looks like the objective cell has been knocked so that it's no longer properly aligned with the tube. This may well have tilted the objective as well. If you have a cheshire eyepiece you can check this. If not then a star test will show it as non-concentric diffraction rings around a star (Polaris is a good one) either side of sharp focus. You could try unscrewing the objective cell / dew shield assembly from the top of the scope tube then screwing it carefully back on so that it is square with the top of the tube. Awful way to deliver a scope

When I was starting out I had a much less capable scope than yours - a 60mm refractor. Even with that I was able to find and observe a number of deep sky objects including the Orion Nebula, the lovely double cluster in Perseus, the great globular cluster in Hercules Messier 13, The Andromeda Galaxy (well it's core anyway). The first galaxies I managed to find with that scope were Messier 81 and 82 in Ursa Major. These are close together in the sky and with a low power eyepiece (the 25mm again in your case) you should be able to see both of them side by side in the view. So your scope can see lots of these objects but the trick is, as you have probably realised by now, is finding these targets in the sky and for a non-GOTO equipped scope this where star hopping comes into play. I provided a star hopping chart earlier for the Andromeda Galaxy. Here is one for the Messier 81 & 81 pair of galaxies. Do make sure that your finder scope is accurately aligned with your main scope - that is important for star hopping to be successful: There is a good book called "Turn Left at Orion" that shows you how to find lots of objects with a small scope. Worth getting if you can find it.

I've noticed this effect with stars when using a number of brands of UHC and O-III filters. It seems less obvious with Astronomik filters to me.

More from the same author !: https://binocularsky.com/binoc_choosing.php The porro prism design seems to have the edge for astronomical use. My most used binoculars for astronomy are a 8x56 porro prism design branded Opticron.

The Celestron O-III is the same item as the Baader O-III. Both have very narrow band pass widths. Too narrow for my taste even with the 12 inch dob. The band widths of the various brands are important and will impact the experience that the observer has. There are not a lot of choices that give really effective band pass widths IMHO.

When I'm observing supernovae it does occasionally cross my mind that while I'm having a good time finding and observing these immense and cataclysmic events, when they actually happened, if any nearby worlds were inhabited, those lifeforms were having a decidedly bad time

There is an e.bay vendor who claims to have 3 in stock but I've no idea if they really have

I think the above advice to try and find a low cost pair to try out is excellent I've tried binoviewers out a few times over the years in refractors and my dobsonian and have found that they are not for me. Others do find them very good I know so you need to find out if they are good for you