mikeDnight

Pilkington Glass used to produce optical crown and flint and would cut it into disks of any specified size. They also made ED glass, but I haven't heard from them for over 20 years, so maybe they are nolonger in business.

From what I remember, the dew shield on the ST just pulls off, although it may be a bit tight to begin with. It would be easy to replace. Having said that, because the ST is a short tube refractor the dew shield can help balance the tube on the mount so it isn't too back-end heavy.

This may be helpful in pinpointing Olympus Mons visually. The top cylindrical grid and the bottom right sketch shows (near the limb) the position of O Mons relative to other features, as do the two globes. The curved dusky features leading to O Mons are relatively obvious once detected. Olympus Mons itself can be seen as a dark patch more often as it approached the central meridian, possibly because we're looking through the mist at its thinnest rather than from the side when close to the limb.  

Below - Cylindrical grid from the 2016 apparition showing the northern hemisphere tilted toward us. (Prism diagonal view - 4" refractor). Olympus Mons shown as a dark spot near 5 o'clock position on right hand disk drawing.

Below is a cylindrical grid from the 2003 apparition with the southern hemisphere tilted toward us. (5" refractor) Direct view without diagonal!

And home made globes from observations made (left 2016) & (right 2020) apparitions,  both made using a 4" refractor and both showing Olympus Mons and environs. (Both prism diagonal views).

I enjoyed following your reasoning and am batting for you, (I like Meade blue too!). I hope the 10" is everything you hope it to be. The massive central obstruction did make me "EEK!" out loud though. 

If you  scribble some graphite pencil on a spare piece of paper, you can use a cotton bud to lift the graphite and transfer it onto the sketch. This is a great way to gradually intensify the limb darkening without leaving hard edges. If drawing the limb of the Sun, the graphite can be gently lifted using a putty rubber to produce a granulation effect and faculae.

With the planet's, the same softening can be applied to planetary limbs, polar hoods on the gas giant's, and the terminator of Venus, Mars and Mercury.

2 hours ago, Alan White said:

Mike see the first post and you will see why it’s been written this way, might make you feel a bit of an ass…. I did say ass 😉
 

Well that's nothing fresh! 🐎

19 minutes ago, JeremyS said:

Super visit and report 

I am a late adopter of Tele Vue eyepieces, but have developed a particular liking of the Ethos series as well as the Nayglers 

"Nayglers"? 😂

2 hours ago, Andy ES said:

Correction I’m not a nerd I’m actually a GEEK 😂

 

I'm not sure Andy - statistics don't lie! And what was it that good old Patrick used to say - "Every nut thinks Every other nut's a nut'! That's quoted from the book Bureaucrats and How to Annoy Them, by R. T. Fishal. (Patrick Moore). Which incidentally I've loaned to some lower than life individual who I've just remembered hasn't returned it. If only I could remember which lower than life individual I loaned it to??😕

24 minutes ago, vlaiv said:

I was aiming more on funny side rather than informative, but hey ....

(I edited the post and inserted the actual image instead of hot linking it ...)

That's great!  Using Venn diagram and bringing the discussion into the mathematical world really clinches it for me. We all now know without doubt where we stand in the greater scheme of things. 

18 minutes ago, vlaiv said:

Just to be sure on terminology there ...

Unfortunately Vlaiv, my tablet won't allow me to open your link, which I'm sure would be highly informative as usual. 😆

On 21/02/2024 at 20:43, ScouseSpaceCadet said:

I thought hanging around with middle class nerds might rub off...

 

Seriously I was looking for advice, found some and decided on the whole SGL is one of the better internet hang outs I've used. Four years down the line I'm a fully fledged & somewhat integrated geek, spending too much money, joining an Astro society, doing star camps, jumping up and down in the garden thrashing branches because another neighbour has erected a LED light, comfort eating & considering smoking because I'm depressed about two week's cloud cover. All the usual stuff. 😀

 I've never been so insulted - middle class nerd indeed!  I'll have you know I'm a working class nerd and proud of it. 😉 

10 hours ago, quasar117 said:

I can see it in all my EPs: 24mm ES 68°, 12.5mm Ortho, each focal length of the 3-8mm SVbony zoom. I mainly use the SVbony at 4mm to do the star test.

Can I use eyeglasses cleaner on the lens with a tissue/ cotton bud?

Yes, eyeglass cleaner is fine  and safe to use. Only spray it onto the tissue and nor directly onto the lens just in case it seeps between the elements. 

Which eyepiece are you using? Is it one particular eyepiece or do different eyepieces show the same effect?Sometimes oily residue from eyelashes, oran accidental touch of the eye lens on the eyepiece can create a bluring effect on the image. Perhaps try cleaning the eyelens with a lens tissue or cloth.

Amazing and a great way to make the sketch more than just a pretty picture. It's a nice deep dive into M44. 

Not sure if its still available, but there's a Meade 127 triplet on AB&S. It's a terrific scope and colour free. Though it is heavier than a Equinox 120, it is better corrected, yet can be carried on a Vixen GP providing the tripod is very strong. It's very well designed with retractable dew shield and a finder that rotated around the focuser so it would always be accessible. 

Here's the one I used many times from some 13 years ago with my friend Phil standing alongside. It was his scope.

Photography/imaging is far too stressful for me, but I struggle with a TV remote. Just reading the OP stressed me out and I needed to lie down. It's little wonder that all the imagers I'm familiar with tend to be stress heads and complain continually as they seek a long enough clear spell, or destructively criticise their own efforts. Better to buy a good book with lots of astro pictures, and spend time contemplating the real thing at length through the eyepiece.

I've an even better idea Jeremy. Give your old counterweight to me, then order yourself some nice polished stainless steel weights. Problem solved! 🙂

1 hour ago, JeremyS said:

I’ve got an old Vixen cwt that I want to spruce up as it’s seen better days.

I don’t want the original Vixen green. I’m thinking black or silver. Perhaps white.

Which type of paint should I use? I want something that won’t rub or flake off. I seek a nice finish.

 

I'd give it a clean up with some steel wool then wash off any dust. You can use warm water and fairy liquid, then dry with paper towel and allow to dry on a radiator for a few minutes. Duraglit wool is also good to help clean up any bare metal but also needs cleaning off afterwards. Rust-Oleum sage green spray paying gives a nice finish. It's not an exact match but its close enough not to be obvious. It's also pretty hard wearing once completely dry. It's also cheap, so weights etc can be resprayed whenever necessary.

P.S.

Had a great time on the moon tonight!

37 minutes ago, bosun21 said:

No longer the case it would appear John.

Having used a number of old ED's, even from long established top end manufacturers, knowing the glass type isn't a big thing to be honest. The old Vixen 102ED didn't disclose the glass type as far as I'm aware, yet when my friend Derek bought a 102ED F9 we were both blown away by its stunning definition on Saturn (c2004). The colour correction on that scope was equally impressive and almost indistinguishable from the legendary FL102. When Derek told me he was about to exchange his 102 ED F9 for a 102SS ED F6.5 I was convinced he was making the biggest mistake of his life. He made the change anyway and I was proved wrong yet again. The 102EDSS was stunning both as a rich field scope and for lunar and planetary. I'm not sure if the Vixen ED's used FPL51 or an equivalent but the point is it didn't make a jot of difference. The scope was a jewel. So I think we should trust the choices made by the optical designers and the skill of the optical engineers and just enjoy the great scopes they provide us with.

1 hour ago, Alan White said:

You would be building a larger observatory first Mike.

Yes, it would need to be a redesigned obsey for a Parks Newtonian. I'd probably build a rotating building. It wouldn't take me long if a Parks came my way.

 At present my Newtonian collection is quite minimal. I have a 4.5" Newt' which is a nice little scope, made by a long gone local telescope company, yet the telescope itself is still going strong more than 30 years down the line. And I have a 6" given to me by paulastro.  I have also had a couple of lovely larger apertures, a 10" on loan from Peter Drew which was very nice optically, though I didn't enjoy the OO dob mount one bit, and a 8" F6 which I used on my observatory equatorial. It was very nice but my 4" apo was more pleasurable to use so the 8" was moved on.

The best Newtonian I've ever owned was a 6" F10 made by my friend Phil. I told him I didn't want a spider, so he made it with an optically flat window to hold the secondary. Double stars in that scope were droolworthy! The problem with it was I'd mounted it on a steel pier with three welded feet. The pier itself was an sizeable old oxygen bottle that the chunky equatorial was bolted to. The whole thing was dragged out of my garage onto my drive, which was a bit of a task. Phil also painted the tube with black hammerite using a brush. It looked crubish and couldn't love it despite trying hard.

My current 6".

3 hours ago, Alan White said:

Let's be honest on this, to an extent we all have bias on scope type, aperture etc.
It may be a unconscious bias, but we will all have it and that will navigate our response to the OP question.

I did laugh at @Earl and his Bank Balance answer, which is patently correct.

I have always flip flopped about Newtonian and Refractor scopes, I have a deep love for both.
My last direction was all refractor and I quickly added back a reflector to the mix, as horses for courses applies.

This year due to a back issue, that is long term, I find I cannot sit and use a refractor of the aperture and focal length that I like without making my back far worse for days on end. 
I am presently only using Newtonians from 6 to 10 inch aperture and thoroughly enjoy my lot.

One thing to bear in mind is the question posed needs to take into account funds available and mounts available,
A badly mounted 5" or 8" or even 10" is a scope that will be a drain on the pleasure it could bring to its user.

 

If someone were to give me a Vintage Parks 10 or 12 inch Equatorial Newtonian I would be in astro heaven. No modern manufacturer I know of comes close to reproducing their beauty.

13 minutes ago, Flame Nebula said:

Mike, 

This is fantastic stuff! Exactly what I was after! And certainly justification for both. 😉

Thanks 

Mark

 That was only one night of course, and afterwards the 8" went back to its owner, and I continued using the 120ED for many more years. Had I have continued observing with the 120ED and 8" Dob, there may very well have been times when the opposite occurred. Either scope could have been the scope of a lifetime, but I suppose my love of refractors has given me more hours using them and seeing great sights along the way. 

15 hours ago, Deadlake said:

Ok here is one I cannot explain, and maybe a little of topics.

I had a 105 mm and C11 mounted side by side.

Observing Orion's Nebulae I can make out more nebulosity using the 105 mm then the C11. 

A 20 mm XWA in the 105 mm and a 30 mm UFF in the C11.

The C11 is wrapped.

I was surprised.... 

Doesn't this go to show there's nothing written in stone when it comes to one aperture or scope design vs another!  A number of years ago I'd been loaned a very nice SW 8" Dob which I'd set up in my garden at around 3pm on a clear afternoon. Alongside the Dob was my Equinox 120ED and both spent a good six hours standing in the cool air before being aimed at the Moon. My friend Derek witnessed this event as we looked at the Moon using the 8" and both genuinely felt the view was quite literally as good as it could ever possibly be. I knew in my heart that the 120ED would be hard pushed to get anywhere close to the 8", but when we looked at the Moon through the 120ED standing alongside, we were both in awe at the improved sharpness. The night had excellent seeing and both scopes were giving their best.  It would have been very easy to assume the 8" would be unbeatable by a smaller scope had the smaller scope not been standing right alongside, and anyone with that 8" would have had a seriously great scope.  

 It didn't stop there however, as we next aimed the 8" at Saturn which was high in the south east, and again the 8" gave what appeared to be another unbeatable view of the planet and its rings. Again I felt that the 120ED would struggle to get close to the view given by the 8" as it was perfection. Anyone seeing that 8" perform as it did on Saturn would be convinced it wouldn't be possible to get a better view through a smaller scope, as the A ring, Enke minima, Cassini's division, variations in the brilliance of the B ring, and the Crepe ring were all visible with ease, as well as globe detail. Nervously I aimed the 120ED at Saturn and Derek took the first look. His response to what he saw was littered with expletives which made me want to push him out of the way and look for myself. Instead I patiently waited for my turn to look, and when it came I was gobsmacked at the improved definition. The rings in the 120ED were as in the 8", but unlike the 8" were littered with the finest grooves similar in appearance to the grooves on a vynil record.  Derek likened the view to a Voyager image! 

Better planetary definition. Never seen an 8"  Newtonian give sharper views than a good 5" refractor.