Been and gone and done it now - Bought a Fullerscope

[RLWP]

Charles Frank mount on Ebay: http://www.ebay.co.uk/itm/VINTAGE-EQUATORIAL-MOUNT-/271923668123?pt=LH_DefaultDomain_3&hash=item3f4fe9e49b

Someone buy it - I don't need another mount

There was a Charles Frank reflector this week too

Richard

[RLWP]

This is the finderscope - it doesn't seem to feature in the catalogue. Anyone recognise it? 

Playing about with it, it separates into three parts. It looks like you can assemble it without the centre part:

I would like to have a go at trying some old school polar alignment as shown on page 11 (page 13 of the PDF): http://geogdata.csun.edu/~voltaire/classics/fullerscopes/BCFcatalogue_1985.pdf

So, I need to fit a reticle with a circle on it, diameter = 0.015 times the focal length of the objective. But...

How do I work out the focal length of the objective?

Where do I fit the reticle? I think it goes just in front of the middle section

Richard

[RLWP]

How do I work out the focal length of the objective?

With a light bench, of course:

A length of angle to keep things in alignment, a metal block with a piece of card stuck on as a screen and a rule to measure the FL

Using a high-tech light shield, I moved the lens until I got a clear image:

Notice the garden table projected onto the screen

130mm. So my circle needs to be 130 * 0.015 = 1.95mm.

Richard

[Paul M]

With a light bench, of course:

A length of angle to keep things in alignment, a metal block with a piece of card stuck on as a screen and a rule to measure the FL

Using a high-tech light shield, I moved the lens until I got a clear image:

Notice the garden table projected onto the screen

130mm. So my circle needs to be 130 * 0.015 = 1.95mm.

Richard

Just one question.. how did you get your garden table infinitely far away?

[RLWP]

It isn't infinitely far away, it's infinitely small

I learned all my physik on Craggy Island

Richard

[RLWP]

So, armed with some numbers, a sheet of transparency film and Microsoft Visio, I drew up this:

cut it out:

and put it into the finderscope in front of the eyepiece (not the erector lens - that didn't work):

From this I learned: Transparency film isn't made to optical standard; inkjet printers don't make continuous lines; a thinner line would be better; taking pictures of garden tables through a finderscope isn't easy!

Hmmm

Richard

[RLWP]

With a thinner line, and viewing an object further away:

That image is both better and worse than the view through the finderscope. The defects in the plastic don't show up as much, but the line looks more dotty than in real life. The off centre circle seems real though - very odd

I think this is worth trying out

Richard

[Laurie61]

This is the finderscope - it doesn't seem to feature in the catalogue. Anyone recognise it? 

Playing about with it, it separates into three parts. It looks like you can assemble it without the centre part:

I would like to have a go at trying some old school polar alignment as shown on page 11 (page 13 of the PDF): http://geogdata.csun.edu/~voltaire/classics/fullerscopes/BCFcatalogue_1985.pdf

So, I need to fit a reticle with a circle on it, diameter = 0.015 times the focal length of the objective. But...

How do I work out the focal length of the objective?

Where do I fit the reticle? I think it goes just in front of the middle section

Richard

I don't recognise it but it looks a bit 'military' to me. Maybe an old gun site? I used a riffle site on a scope and it was not too bad, better at least than the plastic lens jobbie that came with it. 

[HD-AP]

This is the finderscope - it doesn't seem to feature in the catalogue. Anyone recognise it? 

Playing about with it, it separates into three parts. It looks like you can assemble it without the centre part:

I would like to have a go at trying some old school polar alignment as shown on page 11 (page 13 of the PDF): http://geogdata.csun.edu/~voltaire/classics/fullerscopes/BCFcatalogue_1985.pdf

So, I need to fit a reticle with a circle on it, diameter = 0.015 times the focal length of the objective. But...

How do I work out the focal length of the objective?

Where do I fit the reticle? I think it goes just in front of the middle section

Richard

It's not a finderscope from fullerscopes .

Fullerscopes finder's were japanese normaly  NS or nihon seiko ,who also supplied unitron so their finderscopes are usually one and the same ,yours looks like a rifle sight painted white ,and the finders don't separate into 3 parts like yours .

Unsurprising really as at the time the unit purchase plan allowed so many options ,many buyer's would use what they had availiable at the time ,so if they had a finderscope they would only order the tube rings etc to save money.

As an interesting aside (famous old quote ) astronomers today have never had it so good . The range quality ,and choice these day's is mind bogling  ,in the past the choice was 2 or 3 manufacturer's  ,and they were expensive ,compared with today's telescope availiability.

As an example i have a fullerscopes 10 inch export newtonian on a mk4 mount dual axis drives 4 inch export guidescope 6 inch pillar with feet 3 eyepieces and a barlow , The cost of this when adjusted to today's prices would be the eqivalent to £ 5000

in 1975 this was a serious financial commitment ,you get so much more bang for your buck ,and choice these day's   that today's amatuer astronomers really haven't had it so good .

Mind you today's optics' and mechanics arn't so robust or massive or accurate or well made ,i'd put my my 10 inch up against a modern 10 inch anyday.

[RLWP]

The finderscope is in three parts:

Objective lens and tube (this could be a pair of lenses)

An erector lens (definitely a pair of lenses)

Eyepiece. (Another pair of lenses)

It's a pretty sophisticated bit of kit!

It could be a rifle sight. If so, as far as I can tell it has always been white

Richard

[RLWP]

The focuser. This is the Fullerscope one:

A simple rack and pinion with a chromium plated draw tube and plastic knobs, one of which is a bit loose. Oh, and an RAS thread and no eyepieces

I was going to fit this:

A Revelation Crayford that will take my 1 1/4" eyepieces. I've been going to fit this for some time, it doesn't seem right for this scope though. 

So, I got this from Ebay:

It's a helical focuser:

  

Also with an RAS thread. And:

which as far as I can tell is an eyepiece and a Barlow lens. Both of which fit:

the Fullerscope rack and pinion.

So, I have an eyepiece and a Barlow lens for the Fullerscope, and a choice of two focusers

Which is likely to be the best of the two focusers, the rack and pinion or the helical?

And, what's a sensible source of ancient eyepieces?

Richard

[RLWP]

Hah! I just discovered something:

The Fullerscope rack and pinion has a sliding draw tube inside it! (it's over extended in this image)

Richard

[RLWP]

Even better. The draw tube is, of course, 1.25" diameter. So my 1 1/4" eyepieces fit straight in to the focuser if I take the draw tube out

Hurrah!

Richard

[DaveS]

That helical focuser brings back memories.

I had one like that on my first semi-home-built 6" f/8. When I replaced it with a R&P it was re-used on a home-built spectroscope which I used at school for demos. A stupid physics teacher chucked it out while my back was turned and without asking me. She didn't know what it was          .

[RLWP]

When I replaced it with a R&P

I suspect you have just answered one of my questions!

Richard

[RLWP]

I have been busy:

Now I can use my 0.965" eyepieces with the Fullerscope.

Richard

[RLWP]

I have been finding the mount a little limited compared to my cheapo EQ mount I use for the Prinz. It's very rigid and so on - it lacks a fine control on the Dec axis. So I made one:

It's pretty well a copy of the Fullerscope mechanism:

And I have adapted an old Prinz mount flexible drive to be like a Fullerscope one:

The flexible part is longer, and the white bit is an aluminium tube rather than a fibreglass rod. Otherwise, it works and looks the part

I have only had a short observing session since I fitted it, it seems to work well. I find I have one of the controls in each hand, which makes browsing the sky a real pleasure

Richard

[RLWP]

This made me smile. The mount has three cast legs with no adjusters, and a big rusty bolt for setting the polar axis. Not an easy combination to adjust. 

The most obvious thing to do was to drill the legs and put bolts through them, but how would that work on grass?

So:

These are the new feet:

I drilled and tapped the leg, very easy as they are cast aluminium:

That meant I needed some nice big feet with a cupped surface. That was going to be a real faff to make until I remembered these:

I made three, and I have a spare I haven't machined yet:

Well, what else do you do with scrap BMC 1500 pistons?*

I need longer bolts with the head above the leg, and I'm going to turn the cap around on the mount to put one leg in line with the RA axis. Then I can use one bolt to adjust the polar alignment

Richard

*that's going to create some weird google search results 

[Paul M]

Ah! A south facing leg!

A man after my own heart

But seriously, that's a nice job. 

My MkIII mount came with slo-mo on the Dec. axis but had an AC synchronous motor on RA. I fitted a motor to the DEC myself and built a dual axis inverter/driver with a joystick controller. That all got trashed years ago by vandals. So more recently I binned the motors and resurrected slo-mo on the RA using the flexi doo dah I still had in safe keeping.

It surely needs a paint job now. It's just the preparation I can't face...

[RLWP]

Ooh, a tricky one that. Do you strip it all back, prime it and then use wrinkle finish paint? Or powder coat for durability? Or do what I did - slap some black paint on for now and say that will do?

Retro astronomy - is it about restoration or preservation?

Or just having fun

Richard

[Paul M]

Best bet is to not get too hung up about it.

My old MkIII still holds the scope very well. Aesthetics aside, I don't even miss the motor drive.

It's just me, a scope and a starry sky.

I simply keep that primary in tip top condition with Ye Olde Brillo pad and a sprinkle of Vim.

Sent from my HTC One using Tapatalk

[RLWP]

It's been a real revelation having both axes controlled by the long handles and flex drives. I can stand at the eyepiece with an axis knob in each hand and scroll backwards and forwards over an area very easily.

Vim, you say...

Richard

[Paul M]

Vim, you say...

Richard

I take it that you don't have a problm with the Brillo Pad then?

[RLWP]

You never know where an opportunity might arise.

This is the now redundant focuser from the Konus telescope:

The holder for the 1 1/2" eyepieces unscrews:

So, with a suitable adapter, it could fit the Fullerscope:

The first challenge with the adapter was cutting the external RAS thread. Next, and scarier, was cutting the internal thread.

I did the outside one by screwcutting under power (can't remember the pitch, could be 25tpi). The inside one I did by pulling the lathe chuck by hand. It should be 36mm x 0,75mm pitch, but I cheated. It's near enough 32 tpi, and I had a chaser for that so that's what I used. The thread length is only short, three or four mm so the pitch difference doesn't matter

Richard

[25585]

Found this thread on Google looking up Fullerscopes.

I had the 8.75 inch F8 with A mirror, door in tube, budget tube but slip ring and the end splayed rims which were good for standing the OTA on end.

I chose a Vixen focuser that took the 36.4mm 32mm Erfle eye piece, Vixen circle V.

My Mk 3 GEM was on a pier, and had RA drive through a transformer, speed of tracking controlled by a single dial paddle. Metal dumbell weight and locking collars.

So much for nostalgia. Polar alignment was terrible. To turn the mount in azimuth, the 3 gripping bolts had to be loose then the scope and weighted mount hauled round, while the bolt for fixing the mount to pier top needed loosening for altitude. All this peering through the finder to get Polaris in approx FOV, then quickly tightening the azi bolt, followed by pier grab bolts. Sometimes having to repeat the drill above if the mount had moved due to being knocked too much.

I used it half a dozen times in all. Went dob after that. Thinking back, I wish I had kept the OTA, and made a Dobsonian mount for it, the A mirrors and long focal length were great for double stars. Never needed collimation because the sturdy cell kept that primary in a vice like grip. 

Maybe an OO VX8L 1/10 or CX8L is closest to the old FS. But they are only F6. And have no door in the tube.