A Proper Amateur Refractor!!

[F15Rules]

[F15Rules]

I've recently acquired some old (1969) copies of Sky & Telescope magazine, and this scope was on the front cover of the March 1969 issue.

As it's such an old issue, I hope I'm not infringing any copyright rules by copying the accompanying article here, for our members interest, with full acknowledgement to Sky and Telescope as the original source over 50 years ago. If I have that wrong, my apologies and Mods please delete this post.

The scope  just made my jaw drop, being a home built (apart from the objective) 12" F16 achromat. 

You have to admire the owner's vision and determination to build such a huge scope and then use it!.

I hope you enjoy the article🙂.

Dave

 

 

 

Edited November 6, 2020 by F15Rules
Photos reoriented for easier reading

[John]

Amazing !

Reminds me of John Pon's creations.

When I see scopes like that I wonder how they put it all together. My Istar 150mm F/12 was a pretty awkward thing to get onto a mount - goodness knows what something much bigger and longer is like

Thanks for posting this

[F15Rules]

Thanks, John. Exactly my thoughts too! It just looks amazing, and I'd love to have looked through it. I wonder where it is now?

Dave

[JeremyS]

30 minutes ago, F15Rules said:

Is that a pair of skis under the pier?
I suppose it would help getting  the instrument from storage in the dining room out to the field.

[F15Rules]

2 minutes ago, JeremyS said:

Is that a pair of skis under the pier?
I suppose it would help getting  the instrument from storage in the dining room out to the field.

No Jeremy, the wooden posts were meant to be for a handle, but he couldn't lift them high enough..🤔

Dave

[Mr Spock]

Amazing scope. A proper scope at that. But you have to admit a Newt is far more practical.

[andrew s]

2 minutes ago, Mr Spock said:

Amazing scope. A proper scope at that. But you have to admit a Newt is far more practical.

Always! Regards Andrew 

[RobertI]

Fascinating article thanks for posting. That scope is both awe inspiring and hilarious at the same time! Interesting that it's a cardboard tube, and it looks relatively lightweight when you look at the smallish counterweights. It must have been a challenge to collimate. Would have been nice to hear more about the kinds of observations that were possible - I expected a bit more than "..the whole instrument performs satisfactorily". 

Edited November 6, 2020 by RobertI

[Peter Drew]

I well remember drooling (Drewling?) over this article at the time.  I did have a 12" F15 objective for a while, I intended to build a folded refractor but I ultimately sold it at a price I couldn't turn down and it ended up as the objective for a Camera Obscura.  I still have the folding flats should another 12" crop up.     🙂 

[F15Rules]

1 hour ago, Mr Spock said:

Amazing scope. A proper scope at that. But you have to admit a Newt is far more practical.

..and there was I thinking that you Newt guys would like a Refractor that looked like a ships' funnel!!😊

Dave

[Rusted]

With the direct experience of owning a 7" f/12 I suggest that the cardboard tube was no lightweight.
I have grave doubts that the cardboard tube of the 12" was remotely stiff enough.
I laminated a 12"Ø cardboard tube from commercial concrete piling tubes in 1/4" thickness.
It was only 2m long but sagged overnight between end supports and constantly went out of round. 

My own variations on a theme of tubing materials all weigh much the same as each other.
Thin steel/thicker aluminium/thicker cardboard/PVC/plywood rings and tubes or dowels. Even CF and modern Tufnol!
I finally settled on straight seamed, steel extractor ducting for my 7" f/12, 6" f/10 and 5" f/15.

Rolling a multilayer, aircraft ply tube, laminated around thin, structural baffle rings is good.
This was lightest tube I ever managed to make for my home made 5" f/15 but very hard work to get right.

The mounting of the 12" looks so utterly inadequate that I doubt the image stayed still for a fraction of second at a time in still air.
My far more modest 7" f/12 exceeded the limits of my Fullerscopes MkIV for serious use.
I made a folded version but it weighed much the same as the straight tube version and was very bulky!
Collimation is a bore and avoiding stray light even worse. Be warned unless the folded OTA is permanently and adequately mounted.
A compact folded refractor is impossible to baffle properly. You must be overly generous with reflecting angles and flat mirror sizes.

A Berry-style offset and counterbalanced fork on a proper pier would be the most affordable and useful support for a big [amateur] refractor.
An adequate, home made equatorial for a 12" should probably have 4" shafts and welded, plate steel bearing housings.
Cheap enough, made from scrap materials but incredibly heavy!

A steel pier pipe should be the same diameter as the telescope's main tube and supported on a big concrete block foundation.
Chimney blocks make useful, tall piers. Or you can take up half the garden with a pyramidal pier constructed from heavy timbers, like mine.

Lifting a long OTA [arranged horizontally] is straightforward if you tie two, stabilized ladders together at the top to support a hoist.
The height of the ladders must allow more than enough room for the hoist when the OTA has safely reached the mounting.
Ask me how I know all of this?

[F15Rules]

Hi Rusted,

Thanks for your fascinating insight into the challenges that building such a Behemoth presents: you clearly have extensive experience of these challenges!

All joking aside, and as a lifelong refractor fan, (including long focus achromats, on which I cut my teeth, so to speak, hence my F15RULES handle😁), I totally see that for anything much over 6"/150mm aperture, reflectors of whatever type are much more practical for amateurs to own and use regularly.

Given the practical issues, especially of mounting, associated with such large tubes, you can perhaps see why the owner of the 12" in this article sounded "muted" in his actual observing experience of using the scope!

I know from my own experience of owning a quite wonderful D&G USA 5" F15 achromat (see photo below of "Andromeda", of which I was the first owner, but which is now in the care of Steve (Saganite), and my thanks to him for the Pier photograph),  that secure, solid mounting is everything if you want to truly exploit the scope's optics to the maximum..and this scope was "only" c2 metres long..the second photograph shows Andromeda I believe on an EQ6..the Pier was much more suitable according to Steve, and I believe it!

Is there any chance of us seeing some pictures of your own collection? I'm sure I'm not the only one who would love to see and admire them?😊👍

Thanks again for your insight.

Dave

[Peter Drew]

It's a little known fact that Rusted and myself are clones, although he is a later version.  So much of our experiences and current activities are mirrored, we are both DIY'ers, build our own telescopes, mounts and observatories.  My 8.5" F12 refractor and mount are built from whatever was to hand at the time, my OTA was made by joining two undrilled 8" Newtonian tubes supplied by OOUK.  The mount is on top of a concrete block pier.  Before retiring, making folded refractors was part of my business resulting in over a dozen including several 8" F20 to F25.  As Rusted says, they can be tricky to build and collimate, but as with most things, once you know what you're doing it's reasonably straightforward.    🙂

[Rusted]

Hi Dave,

Wot Peter said. He's the professional. I am the bumbling amateur. 
Most of my stuff is built from scrap metal.

Here is a random selection showing my home made equatorial mounting with 50mm shafts.
The other mounting is my old Fullerscopes MkIV with 1.25" stainless steel shafts.
My blog has images scattered throughout of my various telescope projects.
The massive, mobile pier under the MkIV was to cope with our high hedges and trees.
It is very unsafe to push around due to its high CofG.
The dome is 3m diameter, self made from plywood and mounted on a hexagonal building.
All DIY working entirely alone. The Newtonian project is an ongoing 10" f/8 with a premium mirror.

[Space Hopper]

Amazing stuff....

[F15Rules]

Hi Rusted,

Wow, wow wow!!

I am truly in awe of your creations, they look amazing and I can only imagine the views and satisfaction of having built them yourself.

I especially love the look of the first photo, on the wheeled dolly? 

I knew Peter was a wizard scope maker, both from his reputation and having been to Todmorden just once, he kindly helped me to collimate a Russian Mak I had at the time: he kindly showed me some of the amazing stuff he keeps in his domes, this was some 12 years or so ago, maybe more.

I take my hat off to you both, and thanks so much for sharing your insight and images, you've made my day✌️🤘👍😊😎

Dave

 

[Rusted]

Thanks. I try to keep the builds "tidy" but functionality the most important aspect.
I made a 12" Dob from scratch decades ago for somebody I never met.
A friend of a friend. He could have been profiting off my hard work for all I know.
Huge effort went into achieving a decent mirror [plate glass] and the finish on the varnished birch ply.
Made to a tight timetable [with nagging] and I hardly broke even on the materials alone!
That put me off making telescopes for other people for life!

[Peter Drew]

I made loads of telescopes for loads of people but never loads of money!.  A "labour of love".     🙂

[John]

Some superb scopes featured in this thread

As I mentioned John Pons in my earlier post I thought that I'd add some pics of his creations:

Edited November 7, 2020 by John

[Rusted]

6 hours ago, Peter Drew said:

It's a little known fact that Rusted and myself are clones, although he is a later version.  So much of our experiences and current activities are mirrored, we are both DIY'ers, build our own telescopes, mounts and observatories.  My 8.5" F12 refractor and mount are built from whatever was to hand at the time, my OTA was made by joining two undrilled 8" Newtonian tubes supplied by OOUK.  The mount is on top of a concrete block pier.  Before retiring, making folded refractors was part of my business resulting in over a dozen including several 8" F20 to F25.  As Rusted says, they can be tricky to build and collimate, but as with most things, once you know what you're doing it's reasonably straightforward.    🙂

Thank you Daddy!   
In reality, your skills and achievements totally eclipse my own, very humble DIY ATM.

The folded design is crying out for extended collimation rods back to the eyepiece.
Then you can watch the changes you make "live" instead of endlessly running back and forth.
Then forgetting why and what you just did and making things much worse.
Another roundtoit.

[F15Rules]

6 hours ago, Peter Drew said:

I made loads of telescopes for loads of people but never loads of money!.  A "labour of love".     🙂

Fancy building me a nice 6" F15 as a labour of love, Peter?? Pretty please???😊😋

Dave

[Peter Drew]

1 hour ago, F15Rules said:

Fancy building me a nice 6" F15 as a labour of love, Peter?? Pretty please???😊😋

Dave

Join the queue.     🙂

[John]

I nearly bought a 6" F/15. I went for the F/12 instead. When I met with John from Peak2Valley to collect the scope he also had the F/15 in his van. It was packed in one of the  the longest boxes I'd ever seen 

I was glad that I went for the F/12 - even that posed a lot of challenges to get mounted well. I think I concluded that the best place for these long, large aperture refractors is permanently mounted on a massive mount in an observatory.

It was fun "having a go" with one though

It did go to a good home with someone who did have the hardware and experience to handle it.

 

Edited November 7, 2020 by John

[RodAstro]

Yep F15 rules

Here is a picture of what I own and use day and night over the past 15 years. Mine is one of three that is in private hands, only two are working.

The 6" lens is in the class of apochromatics visually and is of steinheil design, flint first.

One of the great things of F15 refractors is they have wonderful flat fields and are very tolerant of eye position at the eyepiece, unlike modern short apos, even F8s.

This is the public observatory at Brisbane as it shows the size of the scope. The scope was designed to fit a six foot observatory, mine is in a seven foot observatory and hard to get a photo that shows its size.

Cheers Rod