John

For anyone interested in Ernest (Ernie) Elliott and Gerry Morris at BC&F / Telescope House, there is some more information here: Ernest J Elliot - Broadhurst Clarkson and Fuller Ltd (bcftelescopes.co.uk)

I believe it is lacquered. I'm going to take a "light touch" with regards to polishing. I'm happy for the finish to age gracefully, within reason 😁

Thanks Jeremy. The scope has been stored in it's original wrapping by Richard Day since he acquired it apparently. It certainly does not show any signs of having been used. It may well have been displayed at some point though. I have added the 1.25 inch eyepiece holder to the bare focuser tube and the objective cell was tightened down onto the counter cell for transit so I have needed to sort the collimation out, which is achieved through 3 sets of tiny "push-pull" screws. The tripod is one that I've had for sometime but not used much lately. I may change the spreader arrangement to a brass chain which would be more in keeping with the scope I think. There are a few further small works such as that to do but that's part of the fun of such a project 🙂

Thats great Michael 🙂 I've not had such good seeing here, even when I had larger aperture scopes.

First solar white light for this 75mm F/16 traditional brass refractor. This instrument was one of a batch of 20 units made by Ernie Elliott at Telescope House just prior to his retirement in 1992. Almost certainly Gerry Morris, who worked with Ernie for a few years, was also involved in creating these telescopes. The objective is by Carton, Japan. I have been gently fettling the instrument since I acquired it a few weeks ago from Richard Day of Skylight Telescopes. Although "only" 30 or so years old this telescope uses a design and manufacture approach that has been used since the 18th century. Nighttime use has been limited to some star testing but the results have been very encouraging as you might expect from a Carton objective lens. The view of Izar a few nights ago was simply lovely at 150x and held up well even at 200x. Today, despite plenty of scudding clouds, the solar disk and various sunspot activity regions were contrasty and sharply defined up to 171x. Solar filtration was provided by a 1.25 inch Lunt Herschel Wedge. Although I intend to use a dovetail bar and the Giro Ercole mount for more serious observing, the traditional pillar arrangement I used today proved surpisingly stable and it certainly looks the part ! I feel privileged to be the first observer to look through this telescope since it's manufacture 🙂

Sub-arc second splits are rarely easy under UK skies, regardless of the scope used, at least that's what I've found 🙄

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

How do you achieve that with a newtonian ?

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

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 🙂

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.

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.

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.

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

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 😉