6" f5.9 Newtonian (Astro Systems) , ongoing project …… Hinds Mirrors

[Alan White]

I recently aquired a fine looking Astro Systems built by @Peter Drew I believe.

Have changed the cast rail and made up with some engineering aka shed tinkering a normal vixen rail.
THis now sits on my mounts easily.

Anyway, checked collimation with my cap, looks ok, did a star test and its a bit off, not a full circular ring, 
and here the challenge begins.

No obvious means of adjusting either mirror?

The Primary is flat on the back plate, not obvious screws or access.

The Secondary can be moved up and down, but how do you alter its inclination?

The scope and new rail.

The secondary.

Can anyone shed some light on this please?
I am hoping to use this as my take to my Astro Club and use with starters in the hobby as and when I can.

 

Edited November 5, 2022 by Alan White

[Peter Drew]

This version was an attempt to provide a factory set collimation with no need for the entry level beginners to alter the settings.  The David Hinds primary mirrors had their backs ground flat parallel to the optical surface so no wedge to correct for.  The secondary, as mentioned, could be adjusted up and down and for rotation.   The tilt of the secondary could be adjusted by loosening the screws holding the secondary support and using the clearance holes to move it as necessary.  Once done it should remain set almost indefinitely.  I have one which must be pushing 40 years old now and still in good collimation.  The David Hinds aluminising is still good as well.  HTH.   🙂 

[Alan White]

Thank you Peter, that all makes sense and explains it’s how it is.

The collimating is just out enough to bother me, but not a new astronomer, so I may just leave alone.

The aluminising on my one still at first look is spot on as well on the Primary.
Until I acess the Secondary better, I am unsure.

You made a fine scope, that has stood the test of time.

Edited October 13, 2022 by Alan White

[Alan White]

Having now had some use with the scope, I managed to get a longer Vixen Rail fitted and use the scope.
Amazingly good, nearly collimated and a very pleasant focal length indeed.

Made me look more and dig out some details on it / them.

Lets start with an old Astro Systems brochure, same scope differing mounting set up I think.

The above is from a Cloudynights Posting, 
a scope known to many here on SGL if the CN thread is all spot on.

I can report that my above note that the coatings were all good was a bit off,
the Secondary is terrible, the Primary just starting to go on one edge.
But based on this and the views shown on an average night, well I want to turn this into a keeper.
This little revelation stunned me, I had turned from Reflectors to Refractors only, now rethinking this.

I am so pleasantly surprised that it has David Hinds decent mirrors, at least 1/8 grade or better,
Are these the Hinds A Grade I wonder?

So the dismantle and rebuild starts, it will be slow, I have too much going on for it not to be the case,
But once completed then I think it will be a mighty fine instrument.

I have a hankering now to build a new scope with these mirrors, make it collimatable in a present day way 
and enjoy it.

Sometimes its hard to improve on a classic design and build, but I will try and do it justice, watch this space....

Edited October 13, 2022 by Alan White

[Alan White]

The mirrors are bonded with Thixofix or similar contact adhesive via a Baize material.
Clearly fine glue as its still well bonded.

But to recoat the mirrors have to come off.

I soaked the Secondary in White Spirit and that slowly did the job, now shows how poor the coating is.

 

Now to find a big enough tub to do the same for the Primary, thankfully for doemstic harmony, the Tupperware etc. is all too small or far too big.
Off to the A to purchase something.

 

 

Edited October 13, 2022 by Alan White

[Alan White]

OK after pondering, no purchase needed just some big enough and very carefully cleaned Plant Pot Saucers reqd.
The long soak now begins.

 

Edited October 13, 2022 by Alan White

[Alan White]

Soak in White Spirit did the job, Primary now off clean and better than I thought it was.

Anyone able to comment on the David Hinds mirror markings on the side or serial number please??

Start with the highly polished back, 

note the lines on the side seen through the glass (bottom rhs)

 

Then the front coatings, just going on edge.

The lightly engraved (serial) number

Edited October 14, 2022 by Alan White

[NGC 1502]

I don’t know if David Hinds is still around to ask, he would be the best source to find out what those numbers mean.

What I do know for certain is those Astrosystems Newtonians were and are top quality scopes, definitely worth restoring.

As a previous owner of the 8.5” f5 version I deeply regret selling.  It gave exceptional planetary and double star views and great deep sky too.

I’ll be following this thread with interest.

Ed.

[RobertI]

Lovely looking scope Alan, you’ve got something special there. Looks especially good on that pedestal mount.  I shall watch progress with interest. It’s inspiring me to get my Newt out again. 🙂

[Alan White]

An update, not a lot done as distracted with many things going on.

I have fully inspected the main mirror against a bright light and it has lots of small holes in the coating.
So mirror recoat is needed, but let’s face it for its age that’s rather good.
 

I also wish to make the rebuild collimatable, so a rear cell needed and this will move into the tube, so focuser etc moved up, 
but not enough tube left….

So how about a new home for the mirrors?

Do I try and build a Dobson and make it portable?

Talk to someone like OOUK and get a special vx6 made?

I really do not know what way to go, so any suggestions will be much appreciated, please fire away…..

 

[NGC 1502]

Hi Alan, please see incoming email.

Cheers, Ed.

[Alan White]

I see we have a near identical unit in the classified section at the moment.
 

 

[Alan White]

Having looked at the pictures a few differences between it and my one.
The main thing being the Baader upgrade on the focuser and the single sided secondary support.

Hmm it does look truly classic, perhaps I should stick with the classic build and look with my one after all??

[JTEC]

It’s me selling it 🙂. The scope ‘natively’ took .925”  eyepieces; the Baader adapter enables 1.25” and adds a helical component to the focusing.  Years ago I ran an astronomy course in London and Rob Miller lent me one of these, saying ‘Wait till you see the views through that … ‘  I remember having good views of Mars. That scope had the same finish as this one, so, yes, I think that’s the ‘classic’ look.  I have another one, which I’ll keep, that someone has painted white.  The views are identical through both scopes - excellent.  From memory, I don’t think the original had the right angle finder, but Peter Drew would know.  I’m happy with a Telrad on the other one.  I have other scopes as well but this is the ultimate ‘quick and easy’ with very good optical quality and the resolution of a 6” scope. It’s a one handed lift, takes little time to settle thermally and is smooth in operation. And, unlike my other scopes, not a wire in sight!

[JTEC]

Just remembered, Rob built me a 10” Newtonian, again with Hinds optics - that had a single arm support for the secondary. My other 6” has a straight through finder (which I don’t tend to use, the RA finder is much more comfortable and convenient), slightly different clamps/knobs on the altaz head and a ‘straight across’ double arm secondary support, though the concept and implementation are otherwise identical.  

[JTEC]

In case it’s any use, here are a couple of pics of the one I’m keeping.  As you can see the altaz clamps are a bit different and there’s a two arm, one piece secondary support.  Someone has also fitted a helical focuser - I don’t know whether this was original or not.  It feels a little wobbly compared with the rack and pinion/helical focuser on the other one but works well when you’re used to it. You can also see the polythene lid that I believe the scopes were supplied with. This scope is not so ‘tidy’ as the one for sale but the images are every bit as good.

[Alan White]

Thank you, that is helpful @JTEC

My one is across of both scopes

I take it the primary is glued to the rear of the tube?

 

[JTEC]

I asked Peter Drew a while ago as I wondered about having the optics realuminised - not that they appear to need it. I’ll dig out his reply. From memory, the primary is glued to a layer of felt which, in turn is glued to the tube end disc.  But I’ll check.  

[JTEC]

Alan, here’s Peter’s reply. It was a PM and I don’t know how to share it, so attached here as a screenshot image.

[Alan White]

Thanks @JTEC, that’s really helpful.

The glue is spot on; my one was bonded this way and released with a White Spirit soak.

I think I am convinced to recoat mirrors and rebond them, I may change the secondary holder to thinner material.

I was so impressed with my mirrors even with old coatings, amazingly good.  
Your one should be snapped up pronto by someone for this very reason.

Again thank you for the images and information, very helpful indeed.

 

 

[NGC 1502]

On 05/11/2022 at 09:26, Alan White said:

I also wish to make the rebuild collimatable, so a rear cell needed and this will move into the tube, so focuser etc moved up, 
but not enough tube left….

 

Hi Alan, just a thought…..      You wish to make the primary cell collimatable.  Presumably, as the original construction excellent it would only need a very minor tweak.

I recall that the cell is fixed to the tube with 3 small screws into the edge of the cell.  I know those screws are near the end of the tube, but is it possible to enlarge them a tiny bit?   Then the cell could be moved a bit, hopefully to tweak the collimation into precise alignment by trial and error.  Any movement could not be inwards because of the lip on the cell, but the enlarged holes could allow tiny movement of the cell away from the tube.

I don’t know exactly how close those 3 holes are to the end of the tube, but you only need a smidge….

The above would allow you to fix mirror to cell as originally, then the focuser could stay as it is, plus the classic look would be retained.

Ed.

 

[Stu]

@Alan White that’s a lovely looking scope. I must say I think I would stick with the original as much as possible, such an elegant design.

I’m sure that it is designed so that the primary is orthogonal to the light path so collimating adjustment not needed. Perhaps just look into the secondary? You could replace the secondary holder with a modern four vane jobbie with collimation adjustment? TS do them I think or you could make one. That way the looks would be preserved but you would be able to do that final tweak easily.

[JeremyS]

What an interesting thread 👍🏻

[SthBohemia]

9 minutes ago, JeremyS said:

What an interesting thread

Agree totally, have never considered gluing down a primary mirror, might give it a go with the latest endeavour.

[NGC 1502]

15 minutes ago, SthBohemia said:

Agree totally, have never considered gluing down a primary mirror, might give it a go with the latest endeavour.

In 1994 I purchased a 6” f6 Hinds primary and flat, and built it into a Dob.  A recent rebuild included recoated mirrors at Galvoptics Basildon.  To fix the primary to cell I used double sided foam tape. Please note I did not use double sided tape, but thicker foam tape.  This secures the mirror without introducing stress to the glass. To further secure the mirror I used 3 brackets around the edge made from aluminium angle, with foam tape between bracket and mirror and between bracket and cell.

Two things to note. I used top quality branded foam tape intended for outdoor use.  The 3 brackets do not intrude onto the optical surface of the mirror.

The views are excellent. The scope splits double stars beautifully.  Saturn easily shows cloud bands, Cassini division, shadow of the globe on the rings…..quite stunning in good conditions.  Similarly Jupiter is a fine sight, much belt detail, GRS, shadow transits like inky black bullet holes on the cloud tops……

Recently I took this scope to Alan’s house while he was contemplating his fine AstroSystems 6”.

Mr Kipling made fine cakes, Mr Hinds made fine mirrors😊

Ed.