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Cheapest scope to split the Double Double


Stu

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Ok, just a bit of fun, and the rules will be suitably twisted so I stand a chance of winning 🤣🤣

Some years back I bought three 60mm scopes for £15 off eBay, just to play around with. I never really did anything with them as I didn’t want to spend more money on rings to mount them etc

Anyway, over time various bits of kit have assembled themselves, generally as surplus bits from other kits, effectively free of charge.

The bit I can’t claim is cheap/free is the mount, my lovely Unitron 114 AltAz which takes the little Prinz 550 very nicely, but that’s where I shall bend the rules. We are just considering the scope here 😉

Anyway, I have a Vixen 6mm Ortho giving x151, a prism diagonal of dubious background and a couple of 1.25” to 0.965” adaptors (one each way) and so I have a hopefully workable setup.

If this deluge ever stops, I shall give my challenge a go with my £5 scope! It will likely be floater city, but that shouldn’t matter on doubles. I’ll report back when I have either succeeded or failed miserably 😂😂

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I'll be interested to here how you get on Stu :icon_biggrin:

Incidentally, I used to have some of those Vixen Orthos which I took apart to clean once. I found that they had an optical configuration of two doublets like a plossl or symmetrical eyepiece rather than the singlet + triplet configuration of the classic abbe ortho.

They were very good performers though.

It's going to be difficult to beat a £5 scope that will split Epsilon Lyrae I would think. My old Tasco 60mm F/13.3 cost me £45 about 40 years ago but that did include mount, tripod, eyepieces etc.

Hope the skies clear soon so you can have a go !

 

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6 minutes ago, John said:

My old Tasco 60mm F/13.3 cost me £45 about 40 years ago but that did include mount, tripod, eyepieces etc.

Thanks John. Let’s see! I assume your old Tasco would do it?

I should have kept the Carton 60mm I used to have, that was likely better optically.

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2 minutes ago, Stu said:

Thanks John. Let’s see! I assume your old Tasco would do it?

 

It's been so long since I observed it with the Tasco, I can't recall to be honest with you :rolleyes2:

I'll have to get the scope setup again sometime and give it a go. Theoretically a 60mm should make a 2 arc second split so it's possible.

When I was messing with the ED120 stopped down to 52mm I was surprised how close that got to splitting both pairs and also how high powers were still working OK - 225x and even 257x, while dim, were useful.

 

 

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My Vixen 80M Custom cost me £40, and that included the mount. Split Epsilon Lyrae at around x80 the other day.

I was using 1.25" eyepieces though and haven't tried with the original 0.96"  fittings and eyepieces. 

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I have an old Celestron branded chinese 90mm F/11.1 OTA knocking around which I think cost me £30 a while back. The star test on that is not that great but it does split the "double double" quite easily despite that, as practically any 90mm should.

Many years back I acquired one of those 76mm "bird jones" type catadioptric newtonians. Despite being made in Japan that was an awful scope I'm afraid and could barely split Mizar as I recall. The star test with that one was "can you see that it is a star ?"

One of these, if anyone else has tried one:

Tresor Telescopio Tanzutsu Tasco 132T 76MM-F.600MM | Telescopio Astronomico  Principianti | Telescopio Dobson | Telescopio Bambini | Telescopio Inventore

 

 

Edited by John
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4 hours ago, John said:

I have an old Celestron branded chinese 90mm F/11.1 OTA knocking around which I think cost me £30 a while back. The star test on that is not that great but it does split the "double double" quite easily despite that, as practically any 90mm should.

Many years back I acquired one of those 76mm "bird jones" type catadioptric newtonians. Despite being made in Japan that was an awful scope I'm afraid and could barely split Mizar as I recall. The star test with that one was "can you see that it is a star ?"

One of these, if anyone else has tried one:

Tresor Telescopio Tanzutsu Tasco 132T 76MM-F.600MM | Telescopio Astronomico  Principianti | Telescopio Dobson | Telescopio Bambini | Telescopio Inventore

 

 

I always fancied trying one of those for fun. I won’t bother now! 👍

I set the scope up and gave it a go. I have some inwards focus issues due to the adaptors, so I may have to source a 0.965” prism with a shorter light path. Don’t want to spend a fortune obvious so will likely place a wanted ad for one. In the meantime I can go Japanese style, straight through observing. The quality of the view in daytime seems ok even at x151 so I’m cautiously optimistic. A star test could easily destroy that optimism though! 🤪

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I wonder what William Herschel will make of it. He discovered the double double with his 7 foot reflector which I believe was 6 inches in aperture and in the preface of his catalogue of doubles stars he warns that the closer doubles in it are beyond the abilities of a 3ft achromat. Equipment has improved quite a bit since then :)

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1 hour ago, Astroscot2 said:

Stu, Im  sure I read in one of  Steve O'meara's books he split the double double naked eye 😉

Sometimes I wonder if he isn’t a different Steve….

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Well, I’m pleased to be able to report success last night! I was using the scope Japanese style, straight through until the diagonal arrives, so it was fairly uncomfortable!

I had a quick look at the moon which was a bit wobbly but fun to see. Floaters were an issue with the 15mm (x15, 0.39mm exit pupil) but still surprisingly sharp. Schröter’s Valley was on display and well illuminated. It’s a long way from my Telementor (not surprisingly) but not bad.

A star test on Vega was OKish. Possibly a slight flaring to one side but not disastrous. Will check this more when I have the diagonal, a darker night would also help.

So, the Double Double. I can claim a definite split on the easy pair, and a probable on the harder. I think this was mainly to do with it being so bright, the dimmer star was quite hard with such a small exit pupil.

More to come, but good fun and seems like it is actually capable of it 👍

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So, thanks to a very kind gentleman@Saganite, I have received a 0.965 to 1.25” diagonal which looks like it will do the job perfectly. It looks like it has a very short optical path length so hopefully I will be able to reach focus even using the 1.25” to 0.965” adaptor so I can use my little (free) Vixen Orthos.

The addition of a rubber band under the silver fitting at the end means I can now clamp the diagonal in place firmly. Got to keep these costs down! 😀

Awaiting clear skies to test it out.

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13 minutes ago, bingevader said:

Aw, I was hoping this was going to be your second entry!

Splitting the double with Steve's bionic eye! :D

This raises an interesting question - what is the closest pair that can be separated with the naked eye (non-bionic) ?

I believe that Epsilon Lyrae is possible but pretty challenging - the two pairs of stars are separated by 3.5 arc minutes.

 

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22 minutes ago, John said:

This raises an interesting question - what is the closest pair that can be separated with the naked eye (non-bionic) ?

I believe that Epsilon Lyrae is possible but pretty challenging - the two pairs of stars are separated by 3.5 arc minutes.

 

The ultimate cheap kit! 👍

I think I’ve heard of people that can do this but I can’t. Age, isn’t it a pain!

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  • 4 weeks later...
5 minutes ago, Roy Challen said:

My Tal 1, which cost £0, unless you count the fuel cost, split the double double last night. Wasn't as easy as I expected though, needed the 15mm and the x3 barlow to guarantee it.

Nice one Roy! Can’t get cheaper than that!! 👍👍

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