John

I think so. A 30mm 2 inch eyepiece is a good focal length for wide field observing with an 8 inch dobsonian.

Roger Vine thinks fluorite is good but he is a little more modest about it than Takahashi !: http://www.scopeviews.co.uk/Fluorite.htm My favourite bit from that is: "....In truth the optical materials that make up the lens in your telescope (or binoculars or camera) are just one part of several factors which affect the lens’ performance. The design, figure and assembly of the lens all count too...."

Agreed. Tele Vue eyepieces are expensive. No escaping that. I bought all but two of mine used otherwise I would not be able to afford the ones I have. Luckily there are some excellent and less expensive options available these days

I use a DIY counterweight on the bottom section of my dob because many of my eyepieces are heavy. My tube is aluminum so I use a magnetized kitchen knife rack and a couple of old iron weights for this purpose. If you have a steel tube you can put magnets directly onto the tube. Wrap them in something to stop them scratching the tube. My eyepieces go up to 1175g in weight. 285g might be OK using the tension handles on each side of the altitude axis. As the tube drops (ie: to observe things lower in the sky) the tendency for the nose of the scope to drop increases. Edit: I'll just add that the only benefit you get from 2 inch eyepieces is the larger field of view. They don't deliver better performance than 1.25" eyepieces. Most folks have one or two 2 inch eyepieces for low power / wide field observing and then 1.25" eyepieces in the medium to shorter focal lengths.

So why did Takahashi drop the TSA102 model ?

Apart from Canon Optron are there any other manufacturers of objectives that use CaF2 ?

Shocking though it is, this is rather old news. The FCC granted Space-X permission to launch over 12,000 satellites back in 2018. The condition with that permission was that they were all up there in operation by 2024.

The UAE have borrowed it for their Mars mission

I've owned the 31mm Nagler longer than any of my other eyepieces. Explore Scientific were not in the game when I bought it. I'm not very good at justifying the costs of quality equipment I'm afraid I don't use the Nagler 31mm very much since I got the 21mm Ethos, the cost of which would be even harder to justify with things like the APM 20mm / 100 around now. I did compare the Nagler 31mm with the Pentax XW 30mm and the Nirvana / UWAN 28mm quite a few years back: 3bigeps.pdf It is interesting to note that the Pentax XW 30mm is £100 less expensive today than it was back in 2009 when I compared them. The Nagler is £200 MORE expensive now than it was back then.

The other scope in that picture is my 130mm F/9 TMB/LZOS triplet. The SW ED120 is in this picture along with my Vixen ED102SS, the Tak and the TMB/LZOS: The Tak gets very close to the SW 120 in terms of resolution but the additional 20mm is noticed on really tight binary stars and in light grasp on deep sky objects. The TMB/LZOS performs very like the Tak in terms of pure image quality but with 30% more aperture. I guess similar to a Tak TOA 130 ?

Yep, me too. 100mm F/9 vs 130mm F/9. 4Kg vs 9.5kg: To be fair, a 150mm F/8 doublet is about the same size and weight as the 130mm triplet though.

I think they might vary a bit Mike. I used one which showed a touch more CA than my ED120 doublet did. I think this comparison involves a similar scope: https://astromart.com/reviews-and-articles/reviews/telescopes/refractors/show/orion-120ed-vs-astro-tech-127edt

I find a higher magnification darkens the background sky and helps to tease out the fainter DSO's but I want to maintain a large true field as well. Hence UWA and HWA eyepieces. More £'s as well of course

That is an eyepiece of a different design. It gets good reviews so a worthy contender if 30mm will suffice.

When it all hits the used market, at least it will be "low mileage"

Until recently I had a 40mm Aero ED. These were originally available in the USA under the Astro Tech branding as their Titan II range and I believe had the same optics in them as the TMB Paragons. The Paragon range was 40mm and 30mm. The Aero ED's included a 35mm as well. I had the 30mm and the 40mm. The 30mm was quite good but the 40mm was excellent. Very well corrected at the edge of field for it's price in my F/6.5 Vixen ED 102 refractor and even in my F/5.3 12 inch dobsonian although the exit pupil was not terribly effective in that latter scope. The Aero ED's (also available under other brandings) are also reasonably light for 2 inch eyepieces. Unfortunately I can't see the 40mm listed anywhere now but if you do come across one they are worthy of serious consideration for use in F/6 and slower scopes. I let mine go for a silly price a couple of months back simply because I find shorter focal length UWA's and Hyper-Wides more effective under my moderately light polluted skies. Probably should have hung onto it

Going a bit too far perhaps ? The scope is 67mm Borg. The eyepiece and diagonal are 3 inch format:

The Helios is the same instrument as the Skywatcher Evostar 120mm. The manufacturer (Synta) used the brand name Helios before moving to Skywatcher. I think the Soligor refractor is made by GSO, Guan Sheng Optical in Taiwan.

The Blue Snowball (NGC 7662) is in Andromeda. It's not all that far from Messier 31, the Andromeda Galaxy:

I've seen a greenish tinge around the "fishes mouth" part of the nebula fairly often with my 12 inch dob. Very occasionally, when I've used a UHC filter I felt that I might have detected traces of a pink tinge as well but that might be the effect of the filter.

The focal ratios of these long refractors are F/10.75 for the 93mm (although I think that might really be a 90mm) and F/8.3 for the 120mm. These are considered relatively "slow" focal ratios by todays standards so the light cone they produce is not as steep as a "faster" scope would produce and this means that the optics within the eyepiece do not have to be too sophisticated / complex to deal with it effectively, ie: without adding optical issues. Better quality accessories such as diagonals, barlows and eyepieces can improve things a bit but won't turn a poor scope into a good one. Having used both the types of scope that you have, they are not poor scopes anyway. They actually perform pretty well. You said in the earlier post that you learned a lesson that these scopes aren't that good - was that though your own experience of using them or from what you have read ? Why not try them at night on astro targets and see how they perform then ?

Both these refractors are good performers. Their focal ratios (focal length divided by the diameter of the objective lens) are not particularly demanding on eyepieces so you probably won't see much difference between using the 25mm plossl and the more expensive Celestron X-Cel LX 18mm, apart from the latter giving a bit more magnification. As has been said - get them out under the stars and they should both deliver some very satisfying views.

BBC report and images returned from the latest ESA mission to the red planet: https://www.bbc.co.uk/news/science-environment-55943374 NASA's latest martian rover is scheduled to arrive there in less than a week: https://mars.nasa.gov/mars2020/ It might be getting smaller in the eyepiece of our scopes but still lots to get excited about on Mars

I think Takahashi maintain very consistent standards. I've not heard of any poor LZOS objectives. I think APM has quite stringent minimum specs for LZOS to meet: https://www.apm-telescopes.de/media/files_public/uguxbbhkgbx/APMApo-Linsen-Spezifikationen.pdf There will of course be the odd one that slips through the net. I guess it is the level of quality control and consistency that one pays for with these premium priced items.

These threads should explain a bit about what is happening: https://stargazerslounge.com/topic/371781-sky-watcher-price-increases/ https://stargazerslounge.com/topic/363878-astronomy-sales-during-the-pandemic- update/