John

How heavy are the 130 F/6's ? My F/9.2 weighs 9.4kg including tube rings / finder / diagonal and Losmandy DT bar. I think the optical reports with the LZOS refractors are to demonstrate that the objective meets or exceeds APM's lens spec. Or at least that's what Markus at APM told me. In practice they tend to independantly test a little better I think. It's not just the raw strehl, RMS and PV figures. The lens surfaces are hand finished and matched to each other on an objective by objective basis and then fitted into a precision cell where the contact points and spacing are precisely aligned, again by hand. So each objective is an individual work, as it were. It's what you would expect for their cost of course. The LZOS objectives on their own in LZOS cells are fearsomely expensive: https://www.teleskop-express.de/shop/product_info.php/language/en/info/p11283_APM---LZOS-130-mm-f-6-Triplet-Apo-Objektiv-in-Zelle.html Here is the APM minimum spec for the objectives: APMApo-Linsen-Spezifikationen.pdf That is a superb pair of scopes @Stu. Unless aperture fever strikes, they should set you up for a lifetime's observing And I'm sure you have a couple of other quality "lightweights" for travel / grab and go observing as well

Keeping away from the NV debate .......

I think it helps but we were not that high up - maybe 350 metres ? I think what made the skies dark were very few man-made light sources in the a sparsely inhabited valley and the surrounding hills shielding any light domes from nearby towns (the nearest was 8 miles away). I've taken a 6 inch scope to a dark sky and had similar deep sky performance to a 10 inch at home. My back yard is not too bad as long as you avoid the horizons to the SW and NE where large cities lurk. I've seen the Horsehead Nebula with my 12 inch dob a couple of times which I feel is a reasonable achievement from a garden in the edge of a large town. It was lovely to get under a really dark sky for a while though

I'd miss my 12 inch dob more than any of my other scopes if I no longer had it

I can tell you Stu that my jaw nearly hit the ground when I stepped outside on the first of the clear nights I've experienced a couple of dark nights at the SGL star parties but nothing like this. I think the location of the cottage quite high up (for Devon) but in a valley and rather remote from other houses was a contributory factor.

Got to have something worthwhile to use that Ethos 21mm in

I've just returned from a week under very dark skies indeed, the darkest that I've experienced as far as I can recall. We stayed in a remote cottage deep in a valley on Dartmoor. No WiFi or mobile signal which is why I've not been on the forum for a week ! We had 3 nights of totally clear skies and they were fabulously dark. There are no street lights in the valley and only a handful of scattered cottages. When the lights of our cottage were turned off there was literally no man-made light around at all. No moon intruding either so I had these wonderful late summer skies to myself and my 11x70 binoculars Using the naked eye, the milky way was really obvious and bright from Cassiopeia through to Altair. It could easily be traced much further than that reaching down through Perseus on one side of the sky and down into Scutum on the other. The great dark rift in Cygnus was stark with the bright, dense star fields of our galaxy flowing like rivers either side of it. Deep sky objects such as the double cluster in Perseus and Messier 31, the Andromeda galaxy were really prominent and easy to see even for my wife who usually struggles with anything faint. As my eyes adjusted to the darkness I found that I could see objects such as the North American nebula and, the bright globular clusters Messier 13 and 92 in Hercules without any optical aid at all. The last mentioned was not at the zenith and is magnitude 6.3 so I reckon the naked eye limit towards the zenith was around magnitude 7, possibly even better. As Triangulum rose higher in the sky the misty patch of Messier 33 could be identified with averted vision and on and off, directly. That's not something that I've experienced before. Using the 11x70 binoculars (hand held) was a further revelation. The sheer volume of stars, even in parts of the sky which I though were relatively barren from home, was overwhelming. Messier 31 showed not only it's bright core but the extended nebulosity of it's spiral arms extending well beyond the edges of the 4 degree true field of view of the binoculars. Added to that, Messier 32 and Messier 110 were very clear accompanying the Great Andromeda Galaxy. Messier 33 was very prominent and took on an "S" on it's side form from the spiral arms. In Ursa Major, Messiers 81 and 82 were very notable and both showing their distinctive shapes normally only seen with scope. U. Major's other notable galaxes such as M51 (two dim eyes) and the often elusive M101 were also straightforward binocular targets under these conditions. Looking towards the zenith, Cygnus dominated the sky but the famous Lyra and Vulpecula planetary nebulae of Messier 57 (the Ring) and Messier 27 (the Dumbbell) were clear even at a paltry and hand held 11x. The highlights within the mighty Swan were the North America and Pelican Nebulae (NGC 7000 and IC 5070 / 5067) with their full forms and relative locations very distinct and to cap it all the whole of the Veil Nebula, the delicate feathery curl of the Eastern segment, the twisted spike of the Western and the very delicate tapering haze of Pickering's Wisp. Marvelous sights and truly memorable The only astronomical equipment that I had on the trip were my eyes and my 70mm binoculars but under those skies they provided more than enough memorable sights. No filters needed, even for the nebulae. Needless to say I will be pressing for a return to Dartmoor and it's skies soon !

I use both - the knobs with shorter telescopes and the cables with longer ones.

Sorry for the delayed response but I've been away under very dark skies but with no WiFi or mobile signal Many congratulations on acquiring the 130mm F/6 APM/LZOS @Stu I hope you enjoy it as much as I do my TMB/LZOS F/9.2 version

My old Konus branded 150mm F/8 was not far off !

Yep - he was "converted" from traditional achromat refractors, initially by a mak-cassegrain 180mm and then by a Skywatcher 200P dob.

Wrong glass as well - it's a "Poodle" as Neil English would have said !

Yep, that's what I would get if buying from scratch again. Important to get the Bandmate Type 2 though. The Type 1's are still out there but are not as effective. Tele Vue switched manufacturer and spec for the Type 2 and that has really paid off.

If it's not a white tube with black and / or brass fittings, it's plain WRONG !!!!!

The most expensive glass will be the ED element - in the case of the ED 102R this is FPL-53 from Ohara. What matters about the 2nd element (the mating element) is that it is a good match for the ED element in terms of it's optical characteristics. To me this is more important than whether or not it is a lanthanum glass or not. With the cost of using FPL-53 for the ED element it seems unlikely to me that a manufacturer would use anything other than a well matched glass for the mating element. In 2017 FPL-53 glass cost 18 times as much as the BK7 crown glass which would be used in an achromat objective. So, personally, I think the lanthanum thing might be a bit of a "red herring".

The O-III is worth having for the Veil Nebula complex alone. There really is so much to see there A UHC will show it but an O-III is has much more impact.

Trouble is, it's really nice to have a 100/102mm AND a 120/130mm Nice summary of the joys of a fine 4 inch refractor Rob

The run of focal lengths that I use with my 900mm focal length refractors (100mm and 120mm aperture) is: 24mm - 17.3mm - 14mm - 10mm - 7mm - 5mm - 4mm-2mm zoom To be honest I tend to skip the 17.3mm very often and move straight from the 24mm to the 14mm. Don't know if that helps

I'm so pleased that you have spotted Triton Stephan That's a great report as well !

My Intes maksutov-newtonian model was the MN61 as I recall. The MN6 part makes sense but I'm not sure what the 1 signifies

I use a sort of "1000 yard stare" approach when trying to spot faint point sources. Similar to the technique for viewing those "Magic Eye" 3D pictures. Deliberately de-focussing the target seems to help faint point source type targets to "pop through". This technique has worked for me on faint supernovae and faint planetary moons. I don't know what the science behind this is, but it does work

I certainly think there is a gap in the market that needs to be filled somewhere between the Skytee II and the ~£1K mounts such as the Losmandy AZ8, AZ100 etc. I also agree that slow motion controls are very nice to have as well though.

I think the Bresser 152S / 760mm has a 4 element optical system. An F/10 achromatic doublet at the front end and a two element corrector further down the tube. There has been some argument over the years as to whether the design is a true Petzval type or not but it's along those lines. So pretty much as @Stu says. I believe the colour correction is similar to one of the F/8 doublet achromats so still plenty of false colour but less than a doublet F/5 would show. The field is flatter with the quad design. They are quite heavy scopes and will require a stouter mount than your current AR 102 / 1000. If the prime interest is in lunar and planetary observation there might be better options ?

That sounds a plausible explanation

I knew that I would regret posting that pic !