Old telescopes
3.5-inch f/5.65
This was my first telescope. First light was Christmas Day 1992. It was built by my dad (with a bit of
help from me) following plans from the Junior Astronomical Society
(JAS, as was, now Society for
Popular Astronomy). I can't find the plans I used anymore.
They used to be online. If anyone has a copy please email them to
me. The mirrors were made by British
optician David Hinds who
unfortunately no longer makes mirrors. Actually I've not been able
to find anyone who sells 3.5-inch mirrors anymore. The photo on
the left is the only one I have showing the scope on its original
Dobsonian mount. This was taken during S&DAS's 1993 exhibition
where we had, among other things, a sample of moon rock!
This configuration was probably my favourite
version of the scope. It doesn't get any simpler than this. It's
just a short Dobsonian rocker box made from melamine shelving
material from a local hardware store, at the perfect height for
comfortable viewing on a small stool. The finderscope is a
sighting tube made from a length of PVC tubing.
The photos to the right show the tube assembly just before I removed
the mirrors to make my travel scope. The
side bearings are gone, as the scope was long ago changed from
Dobsonian to a homemade equatorial based on "A truly economical
telescope" from the Dec 1993 S&T (I never really liked equatorials,
but I'll try to dig out a photo). The focuser can be seen in more
detail. 
It's a Herschelian design in which the eyepiece simply
fits into a hole and focusing is accomplished by sliding a platform,
with the secondary mirror mounted on a stalk, along the length of the
tube.
This is a nice simple design. The only problem was that the
focus would slip if the scope was pointing upwards and the tube became
moist with dew. Also, I'm not too keen on the relatively thick single vane
"spider", which causes a prominent diffraction spike (i.e., stars look like:
---o--- ).
8-inch f/6
This was
the original version of my main scope, the 8-inch. It was built mostly
by my dad, but I handled the mounting of the optics, and various
upgrades after the original build. It saw first light on December 10
1993. This photo was taken shortly before
I disassembled it in 2002 to rehouse the optics. Points to note are the large
melamine Dobsonian rocker box which houses a cupboard for storing all
my books and other accessories; the homemade finderscope made from
salvaged 8x40 binocular lenses housed in PVC drainpipe -- I loved this
finder but don't know where it is now; and the very crude focuser made
from just a steel tube held by friction in a wooden block. I put this
scope together for little more than the cost of the mirrors plus a bit
of wood (which was all I could afford with my savings plus a birthday
present). I'm still amazed that one can buy a modern Asian 8-inch
dobsonian for less than the money I spent on this! I've done more
observing with this scope than any other (I'm adding up the time as I
type up my log, out of interest, but I suspect
it's hundreds of hours!). I used exclusively 9mm and 18mm 0.965" barrel
Orthoscopic eyepieces which I bought for the 3.5-inch. These were
actually excellent eyepieces (particularly for planetary work) and I'm
intending to get a 0.965-inch -to- 1.25-inch adaptor so I can use them
with my current scopes. Also note the wooden platform behind the
finder (the white cable ties holding it to the truss are visible) which
allowed me to bolt the 3.5-inch scope piggyback on the
8-inch. The shroud (folded away) just above the altitude bearings is
now used as my observing hood.
8-inch f/6 version 2
The
first rebuild of my scope looked like this. After the large and bulky
original version (which took up a lot of space while it sat in storage
at my parents' house) I wanted to make something which would fold up
small. This is what I came up with. It's loosely modelled on Ron
Ravneburg's Alice. The
animation shows the set up procedure, unpacking it from a compact box
with a carry-handle. This was my first attempt at building a scope by
myself, and also my first real attempt at woodworking. I was never
happy with this version and so it didn't stay like this for long. It was
quickly rebuilt into the next version. It was a valuable learning experience, though.
8-inch f/6 version 3 (string scope)
I was never quite happy with this version. The carbon fibre tubes I'd been given were simply too thin to be rigid enough in a string scope design and I found that the strings kept getting tangled during set-up/tear-down. Also, my woodworking skills improved considerably while I was making this, so I wanted to rebuild it since I knew I would do it better next time. The version I'd wanted to build ever since I saw the design when I was halfway through building version 2 was something more closely based on Albert Highe's design which is very close to what I have now. These photos were taken during construction (July 2004).
