John

With a 180mm mak-cassegrain I would try and store the scope tube somewhere that is close to the outside temperature.

Personally I would go for the Nirvana over the ES 82's and save some money. The limitation with the Nirvana range is that there are only 3 focal lengths in the 1.25" size - 16mm, 7mm and 4mm. 6mm/7mm is quite a high power for DSO observing. It's OK for the small ones such as planetary nebulae but for galaxies, clusters and larger nebulae I would usually use lower magnifications. The 16mm Nirvana might be a more useful all round DSO eyepiece.

I use the 9x50 right angle corrected image (RACI) finders with my larger scopes including on my 12 inch dob. I have 6x30 RACI finders on my smaller aperture refractors. Mine are either Skywatcher or Orion (USA) branded but made by the same manufacturer. Like this: https://www.firstlightoptics.com/finders/astro-essentials-9x50-right-angled-erecting-finderscope.html Some people like larger aperture finders (eg: 60mm, 70mm etc) but I find 50mm does the job well for me and the star fields shown match those in my favourite star atlas - the Sky & Telescope Pocket Sky Atlas. With my dob I use the optical finder alongside a Rigel Quikfinder zero magnification illuminated reticule finder. I find having both very useful. This is the top end of my 12 inch dob:

What does astigmatism from the eye look like in the eyepiece Don ?

I think the Bresser dobs are Chinese ?

If you are considering the ES 6.7 82 then you probably out to at least have a glance at the Nirvana 7mm. Also an 82 degree eyepiece and really rather good for it's price: https://www.firstlightoptics.com/ovl-eyepieces/ovl-nirvana-es-uwa-82-ultrawide-eyepieces.html I used to have a Nirvana 4mm and it was a really nice very high power eyepiece

For £199 that is a very nice refractor ! I can remember when the 120mm F/8.3's first came out. A "big" refractor at a a relatively affordable price and it caused a lot of excitement. Even more so when the first of the 150mm F/8's made it here from China a year or so later. A 6 inch refractor that an ordinary person could buy off the shelf was practically unheard of back then. The Russian company Aries even designed the CA and SA correctors, the Chromacors, especially for these instruments. I had some fun with those a few years back !

I have owned a couple of Bressers but not the dobsonians. My first was back in the 1980's - made by Vixen in Japan and a top quality refractor

Apart from yours recently..... .....but you had a special reason I think

If / when you upgrade the finder, you will want Right Angled Correct Image (RACI). Much easier to use in my opinion.

Optically they will perform the same I think. If the additional features of the Bresser are worth the additional cost to you then go for it. The Skywatcher works fine out of the box though. I've owned a couple of them. The Bresser finder is rather poor so that might need upgrading.

I understand that the William Optics 2.5x 2 inch barlow lens requires quite a lot of additional inwards focuser movement to allow it to reach focus. Adding extension tubes won't help - that just makes matter worse. I have read about other people having issues getting this barlow to focus with their refractors. Not sure there is an easy solution

With the FC's (real and imaginary) we are talking about doublets using a Fluorite element. The TOA's are triplets. I think the markets for these are slightly different.

These are not my scopes, very much alas, but I think it is interesting to compare the original 1981 Tak FC-100 with the modern FC-100 DZ that Mike has just acquired. Strikingly similar and Tak seem to have settled happilly back to F/8 again now. The original FC-100 is regarded as highly desirable as I'm sure the DZ will be in years to come: And the FC-125 from 1981: And finally in this parade of Tak "porn", the majestic FC-150 from 1991 - F/11.3:

Yep - that is a very good point.

In terms of capability they are both about the same. In answer to James's question in comparison to the Baader Genuine Orthos (which have been out of production for sometime) the Baader Classic Orthos are as good if not a touch better for deep sky objects but the Genuine Orthos have the edge for planetary and lunar observing, in my opinion. Do bear in mind that these designs are orthos though so have relatively narrow fields of view and eye relief that declines as the focal length gets shorter. If you are after wide vistas and / or wear glasses when observing, other eyepieces will be a better choice.

I did originally post suggesting the 21mm Ethos but then re-read the requirements regarding weight / bulk so I withdrew that suggestion. Its new price also blows the price of the 26mm Nagler quoted above out of the water somewhat ! Fab eyepiece though. Mine (pre-owned) cost about what 22mm T4 costs new so I was fortunate there. I know that the APM / LUNT 20mm / 100 is also a very fine eyepiece and a lot less £'s of course. The slightly odd thing is that I rarely use my Ethos / Nager 31 behemoths with my refractors, even the 130mm triplet. The work excellently with them of course but I seem to find 1.25 inch eyepieces (eg: Delos and XW's) my tools of choice with the fracs, mostly

Bristol AS are having one on Friday. Our scheduled speaker has agreed to present "live" using Zoom. This will be the 3rd virtual meeting we will have had. The other 2 (also using zoom) comprised of a short period of chat followed by pre-recorded presentations which we all watched "together" as it were. Lowell Observatory have been putting out some good presentations under their "Cosmic Coffee" programme: https://lowell.edu/event/streaming-cosmic-coffee-houston-weve-got-a-breccia-apollo-13-in-northern-arizona/ I've particularly enjoyed those because I was lucky enough to visit the place last September Our Chair has proved very good at coordinating these things. I'll let you know how the Friday session goes.

I guess you will have seen the Taurus website Steve ?: https://www.taurustelescopes.com/en/home/ There is a review of the 16 inch T400 in English linked to from there. I don't know anything about them personally but I have to say that they look rather nice and 23kg for a 14 inch is very light.

If you find something of interest feel free to ask about it on here - there is sure to be someone who has one or has used one at some time

Tak fans have been wanting an FC-125 since the FC-100's came out. A modern incarnation of the superb FS-128. I think that would deserve two little devils if it ever came out

Of course next year the DZ+ will come out ........

That's my main "tests" as well. Counting the stars in the square of Pegasus is another, when it's visible.

So if your eyes are like John's buy a Nirvana but if they are like Baz's (Steves) you may prefer the BST

Not everybody finds them to their taste: