John

I think this scope, mount and some of the eyepieces are of Vixen origin Mark. The mount looks like a Polaris EQ which was an early Vixen model. The scope has that "Vixen" look to it as well. The H.M. 12.5 eyepiece is a huygenian-mittenzwey 2 element design which were supplied as stock with Vixen refractors such as the SP102M in Europe.

The V in the circle is an early Vixen trademark I think. Probably 1970's / very early 1980's in vintage.

The Tupperware type box on the tripod central tray is a Vixen thing as well I think.

1 hour ago, UKDiver said:

Hi John,

When times are right, what society would that be? I think my nearest would be the Norman Lockyer Observatory, but I'd be interested to hear of others that might be worth a visit.

Adrian

Mine is Bristol AS.

The N.L.O is definitely worth keeping an eye on.

There is also the Tiverton and Mid-Devon AS:

http://www.tivas.org.uk/

Great report Paul

It is the right call but it is also a shame. One of the things I've missed the most over the past 18 months are the public outreach sessions that I used to do with my astro society

We will just have to make up for lost time when we can all safely get together again and observe

In many eyepiece designs the 1.25" barrel assembly also holds one or more of the lens elements in place. In long eye relief and wide angle eyepieces the 1.25" barrel often houses a lower optical set and the field stop, depending where the optical design needs it to be.  Swapping the barrels in many eyepieces is not a simple business because of such things.

I agree with Jeremy - people going "scope to scope" is going to be too risky. Not practical to disinfect the eyepiece / focuser in between each observer using it.

Either each take and use their own kit or setup a system where the views are shared on a screen.

20 minutes ago, globular said:

I read somewhere that Patrick Moore's formula for limiting magnitude puts a 130mm at about 13.1 - so you must have close to perfect optical train, viewing conditions and good eyes - better eyes than Patrick at least. 🤣
The same formula gives mag 14.0 for an 8" - but I'd imagine, as and SCT with a central obstruction, it will be slightly dimmer in reality?
Definitely worth a go though.

The figure that I get for the 130mm refractor is mag 13.4 under dark transparent skies observing close to the zenith. It was a few years back when I got Triton with the 130mm. I'll give it another try at the next opportunity. I agree that it's on the very limit for the aperture and for me. The scope has a LZOS triplet objective so most of the light goes where it's supposed to go

Neptune is lower in the sky now which scubs a little of the brightness off.

7 hours ago, globular said:

...  I did view the lovely blue Neptune - only the colour giving away that it was not just another star.  I didn't try for it's moon.... but now I know it's possible I'll give it a go next time.  I suspect my 8" might not be enough though??

I have seen Triton with my 130mm refractor on a clear, steady night of good transparency so it should be possible wtih a 200mm. It helps to use high magnifications, eg: 250x - 350x to tease out the faint point source of light. Some type of averted / de-focussed vision technique is also worth trying. I find that helps as well

Triton is usually found around 10-15 arc seconds from Neptune's disk.

2 hours ago, Deadlake said:

APM EP’s have a 1.25 to 2” adapter that screws in. For EP’s less then 20 mm this solution works fine and for APM and UO works from a cost perspective. 


Maybe a similar adapter could be 3D printed?

The Ethos SX 4.7 and 3.7 use just that approach as well. I was using my 4.7 last night and it's a great high power eyepiece with my 12 inch dob

I could see that a smooth 2 inch barrel option could be provided at a reasonable cost.

For 1.25 inch eyepieces (eg: the Panoptics that @JeremyS pictures it's more difficult unless folks simply add a smooth sided 1.25 - 2 inch adapter and leave it on the eyepiece. Something like this:

https://www.firstlightoptics.com/adapters/moonlite-2-to-125-low-profile-eyepiece-adapter.html

Part 2 of this session comprised the 3 gas giant planets, Saturn, Jupiter and Neptune.

Saturn was subject to variable seeing conditions. During the steady periods the detail was nice but not outstanding I feel. The advantage that the 12 inch dobsonian had over my smaller aperture refractors tonight was that the "C" ring was showing clearly in the gap between the ansae of the "B" ring and the planetary limb. The "C" ring could be seen as a sharp edged change in contrast about halfway across that gap, on both sides of the planet. Like this (but smaller even at 338x of course):

The extra light grasp of the 12 inch also showed a 6th moon, Enceladus, along with Dione, Tethys, Rhea, Iapetus and Titan. Enceladus was quite close to the outer edge of the "A" ring which made it tricky to tease out of the glare from the ring system and the planetary disk. What I was hoping for 

Moving on to Jupiter, the giant planet showed best at 199x. The Great Red Spot was not on show but the 6/7 belts that crossed the disk showed lovely tones of brown, tan, rust, grey and cream. Rather lumpy edges to the north and south equatorial belts but no obvious white ovals and I could not see any barges on this occasion. The 4 Galilean moons were strung out in a 3 + 1 formation either side of the planet with Europa on it's own tonight.

Finally I managed to find Neptune which was a little tricky with the moons glow starting to invade that part of the sky. Once in the eyepiece I upped the magnification to 338x again and the pale blue planetary disk showed nicely. I do feel that the colour of Neptune and Uranus seems more saturated if the planets are observed with the moon relatively nearby

I did some careful observation of the planet using what I call my "1000 yard stare" method where I'm trying to de-focus my eye and look beyond / past Neptune if that's possible. It is rather like the technique used to view those "Magic Eye" 3D pictures. This does work, for me at least, in picking out faint point sources of light and sure enough one such pinpoint did pop in and out of view a little to the S and W of Neptunes tiny disk. A check on Stellarium confirmed that this was Neptune's largest and brightest moon Triton and I always get a thrill from seeing it 

So observing these 3 planets with the 12 inch scope delivered a few "extras" as I'd hoped it would.

Together with the planetary nebulae hunting session earlier, a very enjoyable night of observational astronomy

Here is the Stellarium view of Neptune and Triton tonight. Triton is a LOT fainter than shown in this (newtonian view) simulation though:

Dobbing Jupiter with the 12 inch:

43 minutes ago, Louis D said:

That "discontinued" 17mm AF70 shown above in my pic has a removable 2" barrel without an undercut.  I seriously doubt it added $50 to the cost of that eyepiece.  Was TeleVue considering having Starlight Instruments CNC machine them at that price?

That works fine where a 2 inch barrel is added to a fixed 1.25" barrel.

For 1.25 inch eyepieces the replacement barrel would also have to contain the lower optical set which many of the Tele Vue ranges use. Either that or a complete re-design of the lower half of the eyepiece would be needed to provide a lower optical element housing and a 1.25 inch sleeve to fit (and lock) over that, either undercut or not according to the owners preference.

My main aim this evening is to observe Saturn, Jupiter and possibly Neptune with my 12 inch dob. So far this gas giant "season" I've been using my refractors.

While I wait for the above to rise from behind the nearby rooftops, I've been having some other planetary fun - planetary nebulae in and around Sagitta.

To kick off I went straight to Messier 57 in Lyra which, towards the zenith, was looking pretty good as usual. Then to Messier 27 in Vulpecula which again was bright and well defined. The central star of this nebula was gleaming dimly at the central axis of the "dumbbell" lobes.

Having "got my eye in" so to speak I moved on to some more challenging planetary nebs. My "browsing" magnification for this task was 122x (Ethos 13mm) but more was needed at times. No filters used, unless mentioned:

- NGC 6886 in Sagitta which is just 7.6 arc seconds in diameter and glowing at magnitude 11.4.

- NGC 6879 in Sagitta which is even smaller at around 5 arc seconds - I needed 250x or more to show that this was clearly a PN rather than a star.

- IC 4497 in Sagitta, another really tiny one at about 3 arc seconds but elongated. Needed 338x to definitely ID this one !

- NGC 6905, the "Blue Flash nebula" in Delphinus. Somewhat larger in diameter at 23 arc seconds and a clearly defined glowing patch between 2 stars. Very faint central star visible intermittently.

- NGC 6891 in Delphinius. Smallish patch 18 arc seconds in diameter and again showing a very faint central star.

- NGC 6765 back in Lyra. Very faint, small, irregular patch set in a triangle of dim stars. This one needed a UHC filter to see anything of it. An O-III filter was not quite as effective, oddly.

While moving around the sky between the above, I also had a look at the globular clusters M71 (Sagitta) and M56 (Lyra) to throw into the deep sky mix.

So that was a very nice way to give Saturn and Jupiter time to show themselves - I'd better get outside again !

Nice approach Jeremy

I have used a parfocalising ring with my Nagler 2-4 zoom and Panoptic 24 but that was to make them closer to par focal with my Pentax XW's rather than to mitigate the effects of the undercut.

I can't recall when Tele Vue changed the design of their undercuts. My collection contains both styles.

I'm using my Ethos set this evening with my 12 inch dob so I promise that I will be VERY careful with the drawtube insertion / removal process

If I snag one on an undercut and drop it onto the patio, I'm in for some very large portions of humble pie !

1 hour ago, Alan White said:

I knew mentioning undercuts would keep folks busy for a while.
Yes you have to adapt some items, but when spending good money, why should you?

I still have undercuts on most of my eyepieces by the way, just not a fan, but I olny use alt az mounts,
if I were a equatorial user, then my liking might be proportionaly higher.
 

Fair enough Alan.

I'm an "alt-az only" person as well so the security aspect is not as high a priority for me.

Maybe an acceptable compromise would be undercuts on eyepieces over a certain weight but smooth barrels on the smaller ones ?

18 minutes ago, fozzybear said:

any more questions ask away 

Yep - and welcome to the forum by the way

3 minutes ago, IB20 said:

Well if the conditions are kind I bet the views through the 12” will be stunning. I used my 8” dob for a planetary session a week or so ago and Jupiter looked incredible.

I'm also hoping to see Enceladus with the larger aperture and  traces of Saturn's "C" ring. These have eluded me so far with the smaller aperture refractors.

Neptune's moon Triton might be favourably placed as well.

I think the problem is that the adapters you have are not holding the eyepiece in the correct position to allow them to reach focus within the range of travel that the focuser has.

You need to use adapters like the ones in the photos that @fozzybear has posted. You current 1.25 inch adapter is too short and your 2 inch eyepiece needs to go in a 2 inch adapter. The adapter on the end of your focuser tube is not actually a 2 inch one - it is a little wider to accept the flared ends of the correct adapters that you see in the photos.

5 minutes ago, jetstream said:

?? Yu dont suffer any center lens droop storing them vertically?

 

Actually the figure of the objectives have all improved over time with the gravity assistance. They are all .99 strehl now

Ideally I would keep mine horizontal but I have quite a few and there just isn't room so they are stored vertically.

Fortunately, I've not noticed any issues with stuff dropping down the tube onto the back of the objectives.

4 minutes ago, Stu said:

.... I was just making what I had work together…

Yep - it's great to share these little tips and wrinkles

11 minutes ago, Stu said:

Well…. They unfortunately do if you want to use them with a Tak prism without problems. It worked fine after doing that, but I’ve now sold the prism and like you have Baader Clicklock on my diagonals/prisms now, apart from the Televue Everbrite. Perhaps I can remove the tape now 🤪🤪🤣

Given that the majority of eyepieces have undercuts or tapers machined into their barrels and have done for years now, maybe it's Tak that need to re-think their clamp ?

I guess the Tak system would also struggle with their own UW eyepiece barrels as they mirror the Tele Vue design

Hello and welcome from me as well - another south west UK based amateur astronomer

Shorter focal length eyepieces are indeed readily available to fit your scope and will deliver higher magnifications, as would using a 2x barlow lens with your existing 10mm eyepiece.

One of my friends at the Bristol Astronomical Society has the Astromaster 130 and it delivers some nice views of the moon, planets and deep sky objects when the conditions are favourable.

1 hour ago, Mr Spock said:

Eyepieces costing hundreds of pounds should not need tape to make them useable!

They don't. The Tak compression system is not good - I really don't like mine even with  barrels with no undercut. Fortunately my actual eyepieces go into an excellent Baader adapter which uses lateral pressure rods and handles all profiles of eyepiece barrel without any drama.

Otherwise I use Moonlite, Tele Vue and Astro Physics compression ring eyepiece holders all of which also seem to cope with undercuts.

Clear night forecast here tonight so I'm hoping to get my 12 inch dob onto Saturn and Jupiter

I've not done much planetary observing with that scope lately so it will be good to see how it does.