John

What a great report 🙂

Raining (again !) here 😒

Gives me time to fettle my new project though 😉 

I've had an ED120 for ages now (over a decade I think ?) and I think it's a really excellent telescope. I never tried the stock focuser because mine arrived (pre-owned) with a William Optics dual speed focuser on it which I later changed for a Moonlite dual speed. 

When I purchased my Tak FC100-DL and TMB/LZOS 130 F/9.2 a few years back I thought the ED120 might be overwhelmed by it's premium room mates but it holds it's place in my scope fleet very well and I still have it and use it a lot. I'm told that I must have a particularly good example but obviously I can only talk about the one that I have 🙂

5 hours ago, jjohnson3803 said:

I'll have to try it with my 72ED just for grins, although I rather doubt that's going to work.  Then I can try my ST102.

 

I could see the close pair was a double with my 70mm ED - two closely overlapped airy disks, kind of peanut shaped. No split though.

2 hours ago, Don Pensack said:

Don't waste your money, Louis.  I could see serious lateral astigmatism in the Baader 36mm at f/10 !.

So could I at F/12 !

I don't know what Baader were thinking with that one 🙄

26 minutes ago, Swoop1 said:

So the slot is just to allow full insertion of the adapter whilst maintaining the correct length of cell for focus?

Yes. A number of 2 inch diagonals, 2 inch barlows and Moonlite focusers use a similar approach. It enables a low profile design 1.25 inch adapter to be used.

26 minutes ago, mikeDnight said:

Telrad's are excellent, but they are just about the ugliest finder design ever devised, and all plastic. They look ok on Dob's but not on an elegant refractor. Just saying!  The Baader on the other hand is an all metal construction and more aesthetically pleasing. Personally I love the look of an optical finder on a refractor. They look more aerodynamic!  Nuts I know!!

The Skysurfer III is plastic, the IV is the metal one.

I use optical finders on my refractors (mostly) as well 🙂

2 minutes ago, Space Hopper said:

I'm guessing its like trying to spot Phobos around Mars, but harder still.

I think so. I've not managed to observe a martian moon either, as yet

My society (Bristol AS) has two "telescope surgeries" each year with a similar purpose.

We meet in central Bristol so actually observing during those sessions is usually not practical but we do invite attendees to bring their scopes to our out of town observatory to get some "under the stars" experience.

I enjoy those sessions a lot 🙂

Just finished off my short session with a small scope with nice splits of Iota Cass, Izar and Epsilon Lyrae at 120x. Nice work for the 70mm aperture.

A late decision to stick a little 70mm refractor out has rewarded me with some lovely lunar views and some nice binaries 😀

This is the 2nd time in a few days that my ultra-portable 70mm has delivered astro enjoyment when the motivation to set up something larger was lacking 👍

Much as I'd love to see Amalthea, I have never been able to see more than the 4 Galilean moons around Jupiter, even when using my 12 inch dob. Amalthea might have been possible with that scope when at it's furthest elongation from Jupiter and under excellent conditions but I've yet to see it. 

I believe it's magnitude is around 14.7 ?

While it might be the 5th largest moon of Jupiter it is much smaller than the Galilean moons - around 150km in diameter I think ?

Bob's comments are very interesting.

Seeing something for the 1st time is always the big challenge. Once you have done it and know what to look for, you often find you can achieve something similar under slightly less favourable conditions and / or with a smaller aperture.

Perhaps it's a good argument for having larger apertures earlier in your "career" in the hobby rather than later ?

10 minutes ago, jjohnson3803 said:

And I thought I was the only one praying for power outages.  🙃

Plus a smoky volcano in Iceland to keep the planes out of the skies.

We don't ask for much, after all ! 🙄 

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 😃

6 hours ago, Acrab67 said:

A while ago I was carefully comparing my SLV 5mm with the Svbony zoom 8-3mm with my TS 125 f7'8 refractor in double stars and planetary and, apart from the better eye relief of the SLV, I found the optical performance very similar, including the contrast and dispersion. The SLV didn't show anything I couldn't see with the zoom. Regardless of this, I prefer binocular viewing with relatively cheap eyepieces to monocular viewing with the more expensive eyepiece.

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

3 hours ago, Flame Nebula said:

Thanks John. Was that with your 12 inch dobsonian? 

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.

3 hours ago, John said:

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

 

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 👍

6 hours ago, Mr Spock said:

There might be a few clear patches on Saturday according to CO. It may not be a record 100% cloudy March after all...

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

3 hours ago, johnturley said:

You could ask whether Rother Valley Optics could carry out a Zygo test on a C9.25 purchased from them, or whether they would allow you to reject the scope if it did not come up to the expected standard.....

 

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 ?

41 minutes ago, Cosmic Geoff said:

I think you should have a good look at what a 12" scope looks like when mounted on your preferred mount.  I had a 8" f5 Newtonian on an EQ-5 and was not pleased to find that with the tripod legs fully extended the eyepiece was about 7 feet off the ground with the scope aimed near the zenith.

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.