John

Superb image !

Catena Davy (crater chain) caught beautifully as well - challenging one to observe as well as that 🙂

4 hours ago, paulastro said:

I still prefer to see the same image orientation through a telescope as I see with my eye alone - others can make their own choice 😂.

 

How do you achieve that with a newtonian ?

5 minutes ago, Mr Spock said:

From Stelle Doppie

name       cst      SAO         coord                        wds_name       last       obs    pa    sep    m1    m2      d_mag

Grafias    Sco    159665    16 04 22  -11 22 23    STF 1998 AB    2019    626    12    1.1    4.84    4.86    0.02
 

Thanks - a 1.1 arc sec separation in Scorpio - that should be fun 🙂

6 hours ago, paulastro said:

.... The main reason I  bought it is I have never liked the mirror image of standard prisms/diagonals as it is a 'false' view which does not exist in reality.  This applies to every object of course, not just the Moon.....  

 

I think our brains flip the image that our eye projects onto the retina. Who is to say what is "reality" ?  🙂

Hope you enjoy your new diagonal 🙂

2 minutes ago, Zermelo said:

Where did you find this, please, John?

I "borrowed" it from this CN thread:

Anatomy of a 20mm Erecting-Eyepiece - Eyepieces - Cloudy Nights

According to the Stella Doppie database, there is nearly 1 magnitude difference between the stars of the close pair of Tegmine. 

I wonder, at what point is a brightness difference going to start adding to the challenge of splitting these stars ?

Does anyone know of a more equal pair of around the same separation ? - it would be interesting to compare those with Tegmine.

If the eyepiece is one of the 20mm erecting eyepieces, the optical layout looks like this:

So the top lens in this case would be concave side towards the eye and convex side downwards. 

These top lenses do fall out easily apparently so you are not the first one that this has happened to 🙂

If yours is a different sort of 20mm eyepiece, let us know and I'm sure someone will be able to advise further.

1 hour ago, SuburbanMak said:

This tallies absolutely with my recent side by side observation using a 5" SW Mak and my 4" Tak FC100 DC. 

The Mak (which actually operates around 120mm,  so slightly less than 5") showed a clean black line between the two elements, the 4" Tak showed a "snowman" - overlapping discs, so resolved but not split.   

I'll be interested to see if there are conditions under which a good 4 inch can get a definitive split of the close pair of Tegmine. As someone else said in this thread, seeing any stars at all has been a challenge over the past months, let alone actually splitting these close ones 🙄

It might be difficult to split them without damage - the 2 elements are cemented together and the cement is quite tough.

Best leave that pair to see if the moisture will evaporate naturally I think.

16 hours ago, Flame Nebula said:

Nice account! 👍

One part that I omitted was that even after collimation of the SCT my ED120 was putting up sharper views of Epsilon Lyrae with 4 perfect airy disks while with the (collimated) SCT the stars were still a bit fuzzy around the edges. At least they were clearly split now though.

Here is one example. At an astro society observing event, I looked through an 8 inch SCT that could barely resolve the pairs of Epsilon Lyrae. The owner seemed to think the performance was OK but we did a star test and found the collimation a little off, not massively but definitely off. We adjusted the collimation and got a decent star test after a few tries. Both pairs of Epsilon Lyrae were duly properly, and rather nicely, split which seemed to rather surprise the scope owner. He later subsequently (a few weeks later) told me that the scope was now clearly showing Jupiter's Great Red Spot and Saturn's Cassini Division whereas he had not previously aware of these features being shown. 

Sometimes, it takes a look through someone else's scope to realise that yours perhaps has a little more that it could give 🙂

A lot of observing (probably the majority ?) goes on solo though so it is very helpful to read reports from other observers on places like SGL to get a feel for how you and your scope are doing and how hard you are pushing it. It is also reassuring at times to know that poor seeing is more likely to be the cause of lacking performance, if reported by others in your part of the world. 

27 minutes ago, paulastro said:

Thanks Louis.  Is the zoom you mention supposed to be better than the Baader?  If its half as good as the 3-8 it will be a cracker.

 

I've ordered the Svbony 7-21 to give it a try. It will be good to see how it compares with the 3-8mm. I have a nice Parks Gold Series (Japan) 2.2x barlow to use with the zoom to compare the shorter focal lengths including the Nagler 2-4mm zoom. Should be interesting 🙂

Are you seeking evidence, or otherwise, regarding the need for accurate collimation ?

I'm curious about the purpose of your question that's all ! 🙂

Anyway, this thread covers some points, with examples, and is only a few months old so worth a look:

Laser Collimation Guide for Newtonians - Discussions - Scopes / Whole setups - Stargazers Lounge

I've found that some refractors need collimating as well, although it's usually a one-off process.

One idea would be to go along to a show such as the International Astronomy Show where lots of vendors and some manufacturers gather under one roof. You could broach your ideas with a number of people at the same time, to test the water 🙂

Vendors – UK Astro Show

4 minutes ago, Flame Nebula said:

Hi John, 

I wonder if OO would be prepared to make a bespoke 12" that could get below 10kg (for the right price... 😂) and be capable of equatorial mounting. 

They are already down to 14 kg with their VX12, so I'm sure they could 

 

In the past OO have been prepared to undertake bespoke requests. No sure what their position is now though.

It's not just the cost though, you might have to be rather patient to get the instrument as well 😉

I'm in the same camp as @Stu on this one. High quality standard prism or mirror diagonal for me and I accept the L&R reversed views. 

Stellarium and Cartes du Ciel have fairly easy to use facilities to flip the image E&W / N&S / both and I'm sure other such tools have a similar function somewhere.

Orion Optics primary mirrors tend to be thinner than most, and therefore lighter.

One of those honeycomb or strut back type designs is needed to lighten further I guess. Skywatcher use  something like that on their 14 inch and upwards dobs I seem to recall.

Congratulations and thanks for the interesting and helpful input to SGL 👍 

Poor Zaphod - he and Ford Prefect grew up together on a planet in the vicinity of Betelgeuse 😬

Still, he would have wanted to go out with a bang 😉

Nice capture 😀

I managed to snap it once back in 2020 with my old mobile phone at the eyepiece when it was close to Venus in the sky. Nowhere near as nice as your shot but at least you can just about see a phase:

10 hours ago, lunator said:

I've had a look through my imaged and had dug out 2 pics, one from 2007 and one from 2022. It amazing to see the orbital motion over 15 years. The image scale is very different but hopefully it is clear.

Cheers

Ian

Very interesting images Ian 🙂

I must dig out the sketches I made of Zeta Herculis when I first split it and more recently. I recall that those showed a noticeable change in position angle over a period of a few years as well. Unless it was just my lousy sketching 🤔

The Universe in motion - great stuff 🙂

1 minute ago, Littleguy80 said:

Pons-Brooks was nothing short of spectacular this evening. Looked amazing through the 4” frac and 10” dob. The tail prominent in both. My best look at it to date. Grab a few snaps with my DSLR too which I’ll need to process. I really love comets!

Sounds lovely Neil !

It's a pity that this comet is really badly placed for me. I've managed to catch it with binoculars and my 4 inch refractor a couple of weeks back but the part of the sky that it is currently in is just about the hardest for me to get a clear view of from home.

No opportunity to take a scope somewhere else currently so I'm having to enjoy it vicariously through reports such as yours 🙂

You should get good views of your targets of interest with both those scopes. Patience is needed with the planets though, because they are not always in favourable observing positions. Photos can be misleading because the camera can often capture more than the eye can see. Have a look for sketches done with similar scopes for a more accurate guide to what might be achievable visually.

For the Sun you must use a suitable solar filter of course. Apologies if you know this already.

I've been doing a few measurements of where eyepieces reach focus. Of mine, the Svbony 3-8 zoom is the one that needs the most inwards focuser travel and the TV Panoptic's (and other TV par-focal group "b" eyepieces) need the most outwards travel. With the scope that I have been testing with (a long focal length refractor) the range of focuser travel I needed to accommodate the needs of both extremes was ~16mm when the scope was focused on Polaris.

1 hour ago, tomato said:

There is a 16” Explore Scientific ultra light Dobsonian in the classifieds, it is a truss tube design but there aren’t many 16” dobs out there which are lighter and more compact. I have a 16” SW flextube but it is not the easiest scope to to move around.

I'm not sure that the ES Ultra Light's are any lighter than the Skywatcher equivalents 🤔

It's worth checking.