Roy Challen

Well, I use a zygo all the time at work. However, we analyse surface roughness (not the same as wavefront error but probably related) of metals, step heights, form etc. The line across the top left image is being analysed in the plot below it. However, I don't know what the analysis is looking for, so can't tell you what the numbers mean. No units either. This is from an old zygo, maybe Newview 7000, has a resolution of about 0.1 nm (for roughness). Comparing the images to our old zygo, it certainly seems that the mirror is smooth. But we'd expect that - it's easy to make glass smooth. Sorry I can't be of more help!

I think the general consensus is that the four digit number is the serial number, and the two digit number is the year.

I'm quite surprised that these aren't used more for astro, I use them on my air rifles/pistols but haven't needed to on my scopes. If I did, that's what I'd use. As you say, they're much more solidly made (they need to be).

BST means more solar observing. Winter is for lunar😊

That's not bad at all!

I met someone who did this 'semi-professionally' on a geological survey I volunteered for a few years ago. He identified something I found as being a stone age tool. It was the only thing found during that survey. Back to the subject though. Is the ED element the inner lens? And would it be softer than the outer? If so, then an over-tightened retainer ring might also do that kind of damage. Perhaps the ring was cross-threaded (might explain the gap in damage) and the previous owner kept on trying to tighten? Knapping of stone doesn't always require sharp impacts, so the pressure caused by over-tightening the ring, plus a relatively soft impact might do this too, although the fracture near the middle is a bit puzzling. It's similar to what I do at work, except we deal with metal fractures.

Superb! Definitely a hint of the rille in Vallis Alpes.

Nice report John. The seeing has supported some very high magnification recently, hope it lasts!

Great report Stu, thanks.

I had the same experience on Friday night, x375 in a Tal 100 is nearly x100 per inch - amazing for an achro! Just goes to show that given the right conditions, any telescope can shine! I used the RA drive for the first time ever on this mount too (5 years after buying it), no more twiddling 😉

Cheers Stu, I take it that's an iPhone app? I'm using Moon Atlas 3D for Android, it's a bit basic but does the job.

I think what you have is fine. Getting the most from your scopes isn't just about maximum magnification.

That M82/81 is impressive.

They do make a pretty sound, but it really isn't any louder than Concorde taking off. The loudest single aircraft I've heard was an F/A 18 going straight into a vertical climb on afterburner, mmmm that was noisy. But for sound that you can feel...top fuel drag race beats everything. But, you are much closer to the action than when watching aircraft. It's still a dream of mine to watch a rocket launch, Mrs.C is from Kazakhstan, so Baikonur is probably my best chance.

Yep, last night was great. Had the best seeing I've ever had, spent an hour on the moon.

Got the Tal RS out last evening for a lunar session. Oh wow, what a session! For starters the seeing was the best it has ever been in my garden. I pushed the magnification to x375 (6mm + 2.25x barlow = f/22.5, CA? What CA?) and the view wasn’t just acceptable - it was sharp. Not as sharp as without the barlow, but not mushy or blurred or in any way soft. I’ve never had the mag so high, in any telescope I’ve ever used, and it felt like it could take more. However, that was as high as my eyepiece selection would go. I don't think any smaller details were being resolved, but what was resolved was bigger, therefore easier to see. I was actually impressed with the Skywatcher 66⁰ 6mm. This series of budget wide angles doesn’t have a great reputation in fast scopes, but in the Tal, they are genuinely good eyepieces. I need to use them more, I think. There was a little bit of kidney-beaning with the barlow, but it wasn’t bad, and I quickly got used to the correct eye placement. At this magnification, it’s a bit pointless trying to take a tour so I concentrated on the Lacus Mortis region, located between Mare Frigoris and Lacus Somniorum. Lacus Mortis is a small lunar lake dominated by a central crater, Burg, with a cleft (that's how it appeared to me) central peak. Burg is nicely terraced, and this was very obvious due to the angle of sunlight. On the plain, there are two very obvious rilles and a couple of much fainter ones. Small craters dot the smooth areas. The ejecta surrounding Burg gives a nice texture. Surrounding the lake are low hills to the west, north and south. The southern rim is broken by several craters of different sizes, the two largest of these are called Plana and Mason. The level of detail was astounding. I spent about an hour in this area. It was made considerably easier by the fact that, for the first time since I’ve owned this mount, I was using the motor drive for the RA axis. It’s really easy, just plug it in and turn it on. All it does is track, although you can speed it up or down for centring. It is silent in operation, and seems to be accurate, certainly good enough for visual use. It is a bit more faff to get the extension cable, plug it in in the bathroom, pass it through the window and run it up the garden, but it really is worth it. I don’t know why I’ve never used it before… I had a quick look at Mars, but there were no details visible, even at x375. Maybe the nearby moon washed out any details. I also had a go at resolving the E and F stars of the Trapezium in M42. This was at a lower altitude than the moon and the seeing wasn’t as good here so couldn’t see those elusive stars. It felt as though the subtlest hints were being made of their presence though, so if the seeing were better, there may have been a chance. Watching A-D dance around was quite hypnotic 🤩. What a great session!

The beauty of portability.

Seems to me that the safest place for the glass is where it is now, fully assembled. Easy enough to remove the dovetail bar, by why do you want to remove the focus knobs? It's already a small scope suitable for airline travel.

For me, bins, definitely. My observing requirements are different when I'm away from home, so don't need a telescope. Also useful for terrestrial viewing when hiking or sightseeing.

Can you put one part in the diagonal and the other in the eyepiece, and just turn the eyepiece to adjust?

Amazing detail, in both posts, well done!

Great images, Michael. Reading the title, I thought some optical fault had developed after a year of use...glad to hear that's not the case.

Super images!

Nice, might be worth trying without the filter too.

Never tried any of them but the Celestron NeXYZ looks pretty good, at least, that's the one I'd buy if it were my money.