John

You can find yourself in an interesting quandary if and when you do get under very dark skies with a scope and that is balancing going for targets that you simply cannot see from your normal observing locations with observing more familiar targets to see how much more you can see of them or in them. Often you do a bit of both, of course. In such circumstances it is good to have an observing buddy (or a number of them at a star party !) who can contribute suggestions as you go along. While being under really dark skies is nice on ones own, it does get a whole lot more fun with a few more folks and scopes around 😃

The Svbony 8-3mm zoom is turning out to be a bit of a revelation 🙂

Yes, my 12 inch dob. Hardest thing I've ever observed I think. Easy for the EEVA users though 😉

Quite a few years back now I went to an SGL star party which was held near Hereford. I had a 6 inch mak-newtonian with me on that trip and we had a couple of really dark nights. My friend Mark and I had a memorable night chasing galaxies with our 6 inch scopes (he had a Skywatcher 150 F/5 with him I recall). On that trip I reckon my 6 inch scope was showing DSO views as well as my 10 inch could on a dark night at home. That said, I have seen the Horsehead Nebula a couple of times from my back garden so I do occasionally get really, really good nights here as well.

The cloud gods were vigilant tonight. They spotted my little scope and the clear holes have been small to say the least. The moon through clouds has been my staple diet so far tonight. Maybe it will get better later ? - probably not, looking at the forecast 🙄

ED120 and C925 for me. I've seen and used the ED150 and a C11 but they are too much bulk and hassle for me to enjoy regularly I reckon. Fine if they are someone elses and they can set them up / tear them down 😀 I'm not sure that the C925 would see much starlight to be honest but it's got more chance than a C11 with me ! I'd be out with the ED120 all the time ....... I'm just a lazy good for nothing space tourist though 😉 I'm sure you will get the best out of whichever you decide to go for 👍

There are clear patches here this evening, some quite big. I hoped the cloud gods would not notice if I put this pipsqueak out 😀

That begs the question of what the expected / reasonable standard is for a mass produced scope ? Practically all of them would claim to be "diffraction limited" but as I understand it, that's not too high a bar. How much above that would it be reasonable to expect from an "average" and acceptable example of an instrument ? Then there is the issue of system strehl vs primary strehl ......... maybe best not to go there ! 🙄

As @mikeDnight posts above, the whole cell (the white bit) should unscrew and come off of the tube. The example photo that I posted came off a 2 piece Skywatcher cell. Yours is a 1 piece cell. Your lens does look to be in fine condition though.

Remove the lens cell containing the objective first. It unscrews from the scope tube. Careful when putting it back on that you don't cross the threading on the tube. Once you have the objective cell with the objective in it off the scope, you can reach the inside surface of the objective which might be enough for your needs. If you need to remove the objective from the cell, this photo illustrates the method. The lens retaining ring does need to be unscrewed to allow the objective cell to be lowered leaving the objective elements clear of it. The back surface of the lens rests on an optical cloth supported something that is a little smaller than the diameter of the objective - I think I used a sellotape roll in this instance: It's a delicate job because you need to ensure that the elements are put back in the same alignment (hence the black marker) and the same orientation with any spacers used in exactly the same position.

With regard to Berlebach Uni tripods, I used to use the wooden tray but added the spreader stopper a while ago and just use that now. It's a bit quicker to deploy than the tray was. I do wonder if the tray made the tripod a little more stable, by adding stiffness though. I'll need to dig the tray out and try it again. Has anyone else any experiences of spreader stopper vs wooden tray with the Uni tripods ?

Thats just what I meant about turning the scope into a bit of a "monster" 😲 A well designed dobsonian mount can be compact, lightweight, observer friendly and vibration free even with a big OTA mounted on it.

My 12 inch F/5.3 dobsonian used an Orion Optics SPX optical tube - these went on to become the VX12's. Mine was bought 2nd hand though so I have not had the pleasure of going through OO's customer service experience. Mine was on a custom made dob mount and I would not personally have used it on an EQ mount because it would have moved from being a relatively easy to set up and handle 12 inch scope to a bit of a monster ! I prefer to stand while observing and my scope was tailored with that in mind. I reckon the F/4 version would be much better suited to the seated observer. Plus I don't image (apart from the odd moon snapshot with an old mobile phone), I'm just a visual observer. Quality wise I would say 9/10 optics in a 6/10 tube. But it only cost me £250 so I'm not complaining 😁 The VX series have probably raised the fit and finish standards, to be fair. The focuser in the pic below is the Moonlite which I replaced the stock single speed GSO one with. All in all, not a lot of use to you but the scope was really good and I had loads of enjoyment from it during the decade or so that I owned it 😀 Gratuitous pic for old times sake:

I've owned lots of TV plossls and I've tried lots of the Vixen SLV's as well. Optically they are pretty much in the same league I feel. For the glasses wearer (which I'm not) the SLV will be somewhat more comfortable. I did find the 6mm SLV pretty indistinguishable from the 6mm Baader Genuine Ortho when I compared them - except that the SLV has a much larger eye lens, about 5 degrees more AFoV and much more eye relief.

It's still in development but it will have a traditional look to it 🙂

Hi Nigel, Thanks very much for that and for the Calotherm cloths. It was good to see you again on Friday 🙂 Since Friday my other half has OK'd the project so I've been able to think it through in more detail. I will keep in touch with you as things develop 🙂 John

Thanks for these replies and suggestions folks 🙂 I have a measurement for the inside diameter of the drawtube (taken with a digital caliper) of 35.4mm. I'm wondering if the thread is one used by Tak and Vixen of 36.4mm but that might be a touch wide 🤔 Are thread diameters usually measured from the top edge of the thread or the valley between the threads ? Thanks again 🙂

The message you don't want is "We've got it and we rather like it so we are going to keep it" 😁

Still "kicking the tyres" David 😉

I may have the need to have a custom adapter made in the not too distant future. It is going to be 1.25 inch fit on one side and an as yet unknown male thread on the other. Brass would be my preference but alloy would also be OK. Can folks suggest any places that I might approach when my specs are more certain to undertake such work ? Many thanks 🙂

My 12 inch dob was as quick as my 100mm refractor to setup. A little more time to cool though - useful after 20-30 minutes.

A pictorial history of some of mine. Yellow stars = I still own it, except for the 12 inch dob which I parted with last year. There have also been some duplicates over the years which are not pictured:

I rather optimistically had a bash as this one with my Tak 100mm tonight 🙄 The transparency is not too good so that did not help. I managed to get down to magnitude 12.6 stars near the location of 3C-273 but I really needed to be able to go half a magnitude fainter to be in with a chance of spotting the quasar. It was good to remind myself of the star patterns in that part of Virgo though, for the next time I try. On a slightly better night with the 120mm refractor I think I'm in with a chance 🙂

We did a similar thing when we visited Alice Springs in 2018. Unfortunately it clouded over before we got to using scopes 🙄 It was odd seeing Orion rise "feet first" ! Seeing the Magellanic Clouds and the magnificent globular cluster 47 Tucanae with my 8x56 binoculars on another night was pretty special though 🙂 I've seen Saturn looking like that with a C8 many years back when it was high in the sky here in the UK. Almost like the Voyager 1 images !

I suspect my scopes of being quite rude to one another, when I'm not around 🙄