Three old dames, two doubles and one full Moon

[Stu]

I wasn’t expecting much in the way of observing last night, but having managed to successfully make a simple wooden adaptor to allow me to fit my Vixen Super Polaris Mount to a Berlebach tripod, I wanted to at least give it a quick try out. I also fancied giving the old Vixen Fluorite a run out as it sits so beautifully on the mount. Surprisingly the mount and tripod are still quite light to carry out as one piece which makes it very useable. If clear today I will try it with my PST mod on it.

Aside from this I have also been adding a few touches to my Peashooter and Light Thimble rig which I am also really enjoying using. I recently painted the rings on the TAL Alkor black and felted them which looks great, and have now fitted a handle and 6x30 RACI finder to the Telementor. Both scopes are mounted side by side on my Ercole on the Gitzo tripod, are aligned well even at high power and there is a Rigel on the TAL too so they are very easy to use and compare on the same target. I used the Nag Zoom at 6mm in the Telementor giving x140 and at 5mm in the Vixen giving x180 and the eyepiece, spacer and Barlow in the TAL giving x133.

Before dinner I had them all out and pointed at Venus and was getting excellent views through each of them. It is interesting to compare the very different views. The Telementor gives a slightly yellowish rendition, nice sharp crescent but surrounded by a purple haze of CA. Venus is about the worst target for this scope, the CA is much less obtrusive on other objects.

The little Alkor delivered a very sharp crescent, very clean and white and only a tiny bit of atmospheric CA. It is amazing that I can get  up to around x150 or more by pulling the eyepiece and Barlow out as far as they will go whilst still being held properly, giving an exit pupil of around 0.4mm and the image is still very good.

Finally the Vixen. In many ways this was like a brighter version of the TAL, perhaps not quite as stark white and with a little more atmospheric CA but a very nice image none the less. I don’t see any detail on the surface of Venus apart from perhaps a little vague something along the terminator. I do love the current crescent shape and am looking forward to continued observations as it gets finer.

My two regular doubles seem to be Izar and Castor currently, and just wanting some known targets to compare the scopes on I revisited them again. I must say, both of these doubles in the TAL make my little heart sing; I could look at them for hours. Castor appeared as two perfect round bullet holes on black, with equally perfect single diffraction rings around each. The view in the Telementor was lovely in isolation, but not quite as magical as the TAL. The Vixen at high power was again more similar to the TAL.

Moving the TAL to Izar did, I confess, take my breath away. The primary a perfect airy disk, again that single diffraction ring and the blue grey secondary sitting like jewel on a ring; tiny and perfect! Just about as beautiful a view of a double as you can imagine, to my eyes at least. The Telementor again split them perfectly clearly but the secondary was not as tight and the separation not quite as wide as a result. Still a lovely view, just not as stunning. Yet again, the Vixen at higher power was just like a brighter, higher power version of the TAL although a little more affected by the seeing. In good conditions it would be equally stunning.

Finally on to the Moon. This is where the resolution of the Vixen came into play. The other two presented perfectly good views, but the detail on the small terminator was much clearer in the Vixen. The crater Neper really stood out for me, looking very prominent right on the terminator. The last picture here highlights Neper.

The Vixen Fluorite is a very lovely scope, whether or not it is quite up there with the Tak remains to be seen, but I love the character, looks and history around it, and it is much more useable with the rotatable Moonlite fitted. I need to remove the original Vixen finder shoe so I can shift it further forward in the rings for best balance, but other than that this setup is something I will continue to use regularly. I have an old controller which gives me tracking in RA which I will use next time.

My apologies for continuing to wax lyrical about the TAL Alkor, but it really is a little jewel. I bought it off Dave for about the price of a used ortho and imagined it as a toy for the children to experiment with. The reality is that it is optically superb and just a bit too fiddly to look into for children; there are better options around. For something so small, the views are beautiful and I will continue to treasure and use it regularly. For me the aesthetics of the views on certain objects are hard to beat.

A fun little evening, something and nothing really as my observing often is, but interesting to see what these old dames can deliver. Quite a lot is the answer!

 

[JeremyS]

Great report @Stu - thanks!

[markse68]

I should dig my Alcor out of storage! Nice report Stu. I spent a very enjoyable evening getting to grips with the setting circles on the telementor mount- have just about got them cracked now 🤞 Izar and Castor were lovely and I was pleasantly surprised at easily splitting the double double despite it still being quite small in the fov and the stars pinpricks! I didn’t expect to see Polaris’s partner but there it was- a tiny sharp spec with the 16mm and even fainter with the 6- but definitely there! I might have seen Y4 Atlas but hard to be sure and probably not- nothing that looked like a comet anyway and I might have seen Herschel’s Garnet star but if I did it wasn’t very red! Really fun night though 😉

[Stu]

2 hours ago, markse68 said:

I should dig my Alcor out of storage! Nice report Stu. I spent a very enjoyable evening getting to grips with the setting circles on the telementor mount- have just about got them cracked now 🤞 Izar and Castor were lovely and I was pleasantly surprised at easily splitting the double double despite it still being quite small in the fov and the stars pinpricks! I didn’t expect to see Polaris’s partner but there it was- a tiny sharp spec with the 16mm and even fainter with the 6- but definitely there! I might have seen Y4 Atlas but hard to be sure and probably not- nothing that looked like a comet anyway and I might have seen Herschel’s Garnet star but if I did it wasn’t very red! Really fun night though 😉

Yes do, it will be worth it and fun to compare. It’s amazing how easily these like scopes will split the Double Double, and such lovely tiny star shapes. Polaris is a challenge from here just because of LP, it shows sometimes but needs a darker sky to reliably see it in such little scopes.

[markse68]

That’s why I was so surprised- the sky was awash with thin high altitude cloud cover! I had no hope finding M13 with those conditions though and didn’t even try for the ring neb

[John]

Great report Stu !

It was not a DSO night at all here so, after Venus, I had a fine time with my favourite double stars and the Tak FC-100DL. Zeta Herculis included !

By the end of the session I could only see the brightest constellation stars so had little to navigate around by.

Delta Cygni was my final stop - the dimmer secondary was only just visible because of cloud obscuration.

 

[Stu]

1 hour ago, John said:

Great report Stu !

It was not a DSO night at all here so, after Venus, I had a fine time with my favourite double stars and the Tak FC-100DL. Zeta Herculis included !

By the end of the session I could only see the brightest constellation stars so had little to navigate around by.

Delta Cygni was my final stop - the dimmer secondary was only just visible because of cloud obscuration.

 

Sounds great John. Next time out I will try a few more doubles although to be honest the seeing did not look like it was going to be amazing so I kept it simple. You do seem to crack Zeta Herc quite easily!

[Mark at Beaufort]

Really enjoyable read Stu. I really wish I had a nice refractor so I can enjoy double stars. Okay the Skywatcher 150P is pretty good but I do miss my old Astro Tech.

Looking forward to Venus becoming a slender crescent.

[Stu]

Interestingly I tried these out again last night and for some reason the Telementor was performing much better, very similar to the Alkor. Still a slightly yellow cast in comparison but stars were pretty much as tight. I used a TAL 6.3mm eyepiece which gives a virtually identical x133.3 mag as the TAL high power, very handy for comparisons.

One interesting finding was on Polaris. Here the Telementor reliably showed the secondary as a tiny pinpoint star with no need for averted vision, whereas the TAL didn’t really show it well at all; it was there occasionally with averted vision. @markse68 would be interesting to know if you find the same thing when you get your TAL out. Perhaps the secondary obstruction comes into play as a difference due to the small aperture?

I had the TAL 100r out last night too. I had been struggling with a slight miscollimation on it which was affecting high power views, so the other day I stood it upright, loosened the retaining ring on the objective, and tapped the tube all round before tightening up again. I’m pleased to say that it appears to have fixed the problem! Everything appears concentric and the performance is much better; a clear and sharp split of Izar. That means I can start doing some more meaningful comparisons using this scope too 👍👍

[chiltonstar]

Great report Stu - I love the enthusiasm! The last two nights here have been excellent for seeing so I've been wandering round old favourites (DD, Vega, Zeta Her, Delta Cyg included) with my 180 Mak on one side and my little Mak on the other side of the mount, just to compare the two. For 127 (119) mm the small Mak really does perform well sometimes.

Chris

[markse68]

2 hours ago, Stu said:

Iso the other day I stood it upright, loosened the retaining ring on the objective, and tapped the tube all round before tightening up again. I’m pleased to say that it appears to have fixed the problem! 

Yes I find whacking things usually does the job too Stu! 😂

I didn’t get to bed till 4 this morning- such perfect conditions and what an incredible huge moon! Out with the telementor- a mixture of joy and more frustration with the mount and inaccuracy of setting circle goto- I will master it eventually! First view this season of old favourite Albireo, failed to split Pi Aquila, failed to split Zeta Herc, couldn’t find ring or dumbbell- probably jiust the moon drowning them out but did split a few other beautiful doubles, saw a very bright bolide (could I have actually heard it?!), and had packed up when I noticed a new bright star on the SE horizon- first and rather perfect view of mini Jupiter and Saturn- wonderful 😊

I will dig out the Alcor Stu- hope it still works as haven’t used it for decades 😳 I don’t remember Jupiter looking anything like as sharp as it did last night in the mentor though, but it had perfect pin point stars.

One thing has me puzzled though and this may be a question of refractors in general but I’ve noticed stars appear as tiny disks in the mentor- perfect round as you say “bullet holes” which seem to vary in diameter according to brightness. I never noticed this with my big dob which shows pinpricks just with varying fiery noise depending on brightness. It’s quite attractive these disks but it’s not real is it- is it a phenomenon of refractors? Any idea what causes it? Stars are so far away they should appear as infinitesimally small point sources shouldn’t they? 🤔 I think these refractors cheat! Pretty though 😉

 

Edited May 9, 2020 by markse68

[markse68]

Oh I just realised I seem to be exactly copying you Stu 😳 I too have an 8”f8 (well ok an 8.75 f7.4 but if I stop it down it’s the same), now a telementor, an Alcor (well I had that before you I think) and am about to build up a 100rs! Not consciously doing it I promise 😂 (what were your other scopes Stu? 😉)

[Stu]

14 minutes ago, markse68 said:

Yes I find whacking things usually does the job too Stu! 😂

I didn’t get to bed till 4 this morning- such perfect conditions and what an incredible huge moon! Out with the telementor- a mixture of joy and more frustration with the mount and inaccuracy of setting circle goto- I will master it eventually! First view this season of old favourite Albireo, failed to split Pi Aquila, failed to split Zeta Herc, couldn’t find ring or dumbbell- probably jiust the moon drowning them out but did split a few other beautiful doubles, saw a very bright bolide (could I have actually heard it?!), and had packed up when I noticed a new bright star on the SE horizon- first and rather perfect view of mini Jupiter and Saturn- wonderful 😊

I will dig out the Alcor Stu- hope it still works as haven’t used it for decades 😳 I don’t remember Jupiter looking anything like as sharp as it did last night in the mentor though, but it had perfect pin point stars.

One thing has me puzzled though and this may be a question of refractors in general but I’ve noticed stars appear as tiny disks in the mentor- perfect round as you say “bullet holes” which seem to vary in diameter according to brightness. I never noticed this with my big dob which shows pinpricks just with varying fiery noise depending on brightness. It’s quite attractive these disks but it’s not real is it- is it a phenomenon of refractors? Any idea what causes it? Stars are so far away they should appear as infinitesimally small point sources shouldn’t they? 🤔 I think these refractors cheat! Pretty though 😉

 

Tee hee. They were gentle whacks 🤣🤣

There are a few effects going on with stars I think. I’ll get some of this wrong but perhaps others can carry it on.

You are seeing the airy disk in the refractors and the size reduces with scope diameter according to the formula sin (theta) = 1.22 x gamma / diameter where gamma is the wavelength of light, diameter is your scope aperture and theta is the angle at which the first minimum occurs at the edge of the airy disk. More here:

https://www.fxsolver.com/browse/formulas/Airy+disk
 

This means that a smaller scope shows a larger airy disk and this is closely link to its lower resolution. What you are seeing is real is it is a true representation of the physics at work.

A larger dob has to contend with the fuzzy nonsense you get with these shaving mirror scopes (🤣🤣), but the larger aperture gives higher resolution so the airy disk is much smaller and needs higher power to resolve in the same way. The larger scope will resolve tighter doubles given excellent seeing conditions.
 

Refractors just give lovely clean star shapes, that’s the thing I love about them.

Does that all make sense?

[Stu]

13 minutes ago, markse68 said:

Oh I just realised I seem to be exactly copying you Stu 😳 I too have an 8”f8 (well ok an 8.75 f7.4 but if I stop it down it’s the same), now a telementor, an Alcor (well I had that before you I think) and am about to build up a 100rs! Not consciously doing it I promise 😂 (what were your other scopes Stu? 😉)

Nothing wrong with that Mark, I’ve copied others too, knowingly copying @John’s Vixen/31mm Nagler/OIII filter combo to view the whole Veil, I now use a Genesis to do this but started with an Astrotech 106mm f6.5 triplet, lovely scope.

Hmmm, you need to get yourself all these....

Telementor

Alkor

TS 72mm Doublet

Televue Genesis

FC100DC

Vixen FL102S

TAL 100r

Vixen 102mm f10 PST

Heritage 130p

Orion Optics 8” f8

Mewlon 210

There is also a 12” Truss dob project and a 150mm f10 refractor for a further PST project when I can afford the ERF!

Oops!

 

[markse68]

🤔 its good to know there’s an explanation but that maths- no not really 😂 So the Alcor produces similar disks? I don’t remember but it might

[markse68]

1 minute ago, Stu said:

Hmmm, you need to get yourself all these....

Telementor

Alkor

TS 72mm Doublet

Televue Genesis

FC100DC

Vixen FL102S

TAL 100r

Vixen 102mm f10 PST

Heritage 130p

Orion Optics 8” f8

Mewlon 210

I’m bailing 😂

[Stu]

2 minutes ago, markse68 said:

🤔 its good to know there’s an explanation but that maths- no not really 😂 So the Alcor produces similar disks? I don’t remember but it might

😉

Simply put, smaller scope, larger air disk. Stars are never points, but the disk is much smaller in larger scopes and is often hidden in the secondary obstruction ‘noise’ until you get to higher powers.

Last night the Alkor and Telementor were giving very similar views, same disk size.

[John]

That "loosen the retaining ring and slap the cell all around it's edge" trick is really useful. The scope should be pointing upwards of course but it does help "settle" the objective elements and their spacing.

Good thread this - lots of tips for having fun with smaller aperture low cost scopes.

Given some TLC and knowing what to point the at, I reckon most scopes can produce some really pleasing results

I really must get my old Tasco 60mm refractor out again and feed it some photons.

[Mark at Beaufort]

44 minutes ago, Stu said:

Nothing wrong with that Mark, I’ve copied others too, knowingly copying @John’s Vixen/31mm Nagler/OIII filter combo to view the whole Veil, I now use a Genesis to do this but started with an Astrotech 106mm f6.5 triplet, lovely scope.

Hmmm, you need to get yourself all these....

Telementor

Alkor

TS 72mm Doublet

Televue Genesis

FC100DC

Vixen FL102S

TAL 100r

Vixen 102mm f10 PST

Heritage 130p

Orion Optics 8” f8

Mewlon 210

There is also a 12” Truss dob project and a 150mm f10 refractor for a further PST project when I can afford the ERF!

Oops!

 

Stu that is a fair amount of OTA's. Does Suzie know this 😄

[Stu]

34 minutes ago, Mark at Beaufort said:

Stu that is a fair amount of OTA's. Does Suzie know this 😄

Probably not the full list Mark, but they do appear around the house and garden quite a lot so she must have some idea! She has got a lot more relaxed about it over the years though fortunately 🤣. I try to limit their appearance together to three or four at a time...

[Stu]

41 minutes ago, John said:

That "loosen the retaining ring and slap the cell all around it's edge" trick is really useful. The scope should be pointing upwards of course but it does help "settle" the objective elements and their spacing.

Good thread this - lots of tips for having fun with smaller aperture low cost scopes.

Given some TLC and knowing what to point the at, I reckon most scopes can produce some really pleasing results

I really must get my old Tasco 60mm refractor out again and feed it some photons.

Yes, I think I got that trick from you John, very effective and has sorted the scope nicely 👍👍

I think that’s what I’m trying to achieve myself and to share thoughts on. Given the right targets, small, inexpensive scopes can provide a lot of fun. I’m not saying I don’t enjoy my Taks, but the variety helps keep my interest going. I bought my Heritage 130P OTA from Astroboot for about £50. It split Pi Aquilae for me which I was majorly impressed by, so it shows you can have plenty of serious observing even with little outlay if you know what you are buying and how to get the best out of it.

[John]

I think reports of what small, low cost scopes both old and new can do are very valuable, especially to encourage those with tight budgets or with similar scopes stuck in lofts that they can see some good stuff with them and enjoy astronomy

I'm going to see if I can find my old 60mm Tasco now. I may be gone a while though ......

 

[Stu]

10 minutes ago, John said:

I'm going to see if I can find my old 60mm Tasco now. I may be gone a while though ......

 

There's almost a Captain Oates quote in there somewhere John 😉

Good luck, hope you find it.

Somewhere I have three 60mm f15 ish scopes which I bought as a lot for £15 off eBay. They are a bit ropey but I was trying to see what was the cheapest way of splitting the Double Double. I could dig them out and try them at some point.

[F15Rules]

2 hours ago, Stu said:

Does that all make sense?

Yes it does Stu...especially the bit about "these shaving mirror scopes"!!

🤣😂🤣

Dave

[Stu]

10 minutes ago, F15Rules said:

Yes it does Stu...especially the bit about "these shaving mirror scopes"!!

🤣😂🤣

Dave

Tee hee. I hope some big burly dob boys don’t come an duff me up on a dark night now 😉😉