Cheap bins...

Acquired a pair of cheap 10x 50 Prinz binoculars secondhand for general use,
but would like to try them out to look at the stars. Tonight's been a bit
crap, what with the rain and all, but yesterday, had a bit of a go, and was
quite impressed with the extra stars I could see. However, got a couple of
problems, wondering if could have a couple of suggestions.

When I took them outside into the cold, they fogged up quite quickly, the
binoculars are not sealed as all the parts unscrew. Is there any way of
avoiding the condensation? Keeping them in the fridge before use perhaps?

This one might be just me. When I look through them, I see two different
images, by which I mean the same image slightly offset, because of the two
eyepieces. Happens more with objects in foreground. I asked someone else to
take a look, and they can't seem to replicate problem, even though they seem
to understand what I'm saying. They say I'm using each eye to focus
seperately, but I dunno what else to try. For now, I'm just closing one eye
and using one eyepice as a monocular. Don't know if it's the binoculars that
are knackered, or what?

Marcus

Marcus Fox wrote:
[...]
When I took them outside into the cold, they fogged up quite quickly, the
binoculars are not sealed as all the parts unscrew. Is there any way of
avoiding the condensation? Keeping them in the fridge before use perhaps?

If the fogging is internal, then no. Refrigerating them beforehand will
cause the condensation to occur, but will not get rid of it. What would
be better is to put them in a warm, dry atmosphere, or in a container
with some desiccant. Normally, internal fogging is eliminated by
nitrogen filling, but there is no point with centre-focus Porro-prism
binocs because they cannot be gas-tight.

If the fogging is external, try to keep them warm -- e.g. hang them
inside your jacket when not actually observing with them.


This one might be just me. When I look through them, I see two different
images, by which I mean the same image slightly offset, because of the two
eyepieces.

The two sides are out of collimation (the term has a slightly different
meaning when applied to binocs than to telescopes), aka alignment. These
particular binocs are not worth having redone commercially -- it will
cost far more than the binoculars are worth. However, you *may* be able
to improve things for yourself.

Firstly, check the prisms. To remove the eyepieces, remove the cover
plate at the objective end of the centre hinge, and shove a screwdriver
up the hinge to undo the screw that you will find up there. then "focus"
the eyepieces right out. (If you dismantle from the eyepiece end, you
will probably have hell trying to get the hinge tension correct again.)
Then unscrew the remaining eyepiece guide tubes and remove the prism
cover plates. Check that neither of the two prisms you can see has
slipped. They are usually held in place by glue and a metal clip and, in
these binoculars, are not usually adjustable. If one has slipped, then
reseat it and put a few small dabs of epoxy adhesive to hold it in
place. Then remove the objective tubes and check the two prisms you can
see there. Be *very* careful not to cross-thread anything when
reassembling it -- it is remarkably easy to do.

This will probably *not* solve the problem, but you may be lucky and,
anyway, you will learn how to dismantle and reassemble binocs, and it's
best to learn on ones that are already knackered. Your only recourse may
be to adjust the objectives, and this could take you hours of fiddling
and you may still not get it right. WARNING: YOU MAY END UP MAKING THEM
WORSE.

Firstly, remove the objective covers. Then remove the retaining rings;
ideally you should use a peg spanner but, if you don't mind risking
getting scratches on the lenses, you can usually use a small screwdriver
in one of the slots in the rings -- try not to let it slip! By doing
this you will expose the eccentrics around the objective -- there is
usually a small hole to enable you to rotate the eccentric. A
combination of rotating the lens assembly itself and rotating the
eccentric will shift the image. Normally, this adjustment is done on an
optical bench, but you *may* be able to improve things without. Mount
the binocs and set the hinge to your inter-pupillary distance (IPD).
Then, by adjusting the objectives and eccentrics, see if you can
persuade the images to merge. Tiny amounts of horizontal misalignment
are tolerable (but, if too great, can cause strain and headaches); our
eyes cannot tolerate vertical misalignment. Note: even if you manage to
get them acceptable for you, they will almost certainly only be
"conditionally aligned", i.e. still be misaligned for someone with a
different IPD.

Best,
Stephen

Remove footfrommouth to reply

--
+ + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +
+ Stephen Tonkin | ATM Resources; Astro-Tutorials; Astro Books +
+ (N51.162 E0.995) | http://astunit.com +
+ + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +

"Marcus Fox" wrote in message news:mT4Cc.206$785.117@newsfe3-gui...
Acquired a pair of cheap 10x 50 Prinz binoculars secondhand for general use,
Don't know if it's the binoculars that
are knackered, or what?

Marcus

If your Prinz binos are anything like my own pair (1970's?) they
should only be considered as fodder for making finders. Unscrew the
objective and fit the thread end into a length of PVC pumbing pipe.
Make a plywood ring to go in the other end of the tube and fit one of
the eyepeices into this. You an turn a plywood ring on a long bolt in
in an elctric drill chcuck with sandaper.
Open out the bolt hjole when the outside is a good fit. A matching PVC
reducer will also do the job nicely.
You don't need to re-focus once you have the right length of pipe to
reach infinity focus. Paint the inside of your PVC tube matt bblack
and you have a much better astro instrument for low power sky viewing.
Albeit it upside down and a brighter image. (Swings and roundabouts)
On of my recent projects was an all brass finder (contrasting yellow
and red brass like the great classic refractors) Still using the same
30 year old crappy Prinz objective and eyepiece.

I seem to be lucky. I've bought 5 pairs of 7x50 or 10x50 binos in the
last year (or so) from charity shops for less than a tenner each. They
were all vastly better than the Prinz after a bit of "tweaking".
Except the yellow tinted ones which are fairly crappy. Don't waste
time re-aligning Prinz binos. It's a lifetime's work! The prisms just
won't stay still. You only have to shake them slightly for the
alignment to go off again.
Do as I did and start a lifetime of telecope making. All thanks to a
pair of crappy Prinz binoculars! ;-)

Chris.B

Acquired a pair of cheap 10x 50 Prinz binoculars secondhand for general
use,
Don't know if it's the binoculars that
are knackered, or what?

Marcus


I bought some 10 x 50 Prinz bins in the '60s, and even then they were
diabolical. I just didn't know enough before buying them. The easy approach
before you dismantle them (which is indeed very probably not worth bothering
with) is to hit them over your knee in a couple of directions to see whether
that moves the offending prism favourably! I have tried it on a number of
bins subsequently and sometimes it does work. But they are not worth taking
apart.

Try Lidl, who sell 10 x 50 bins for £14.99 which are just excellent.


Brian

In article mT4Cc.206$785.117@newsfe3-gui,
Marcus Fox wrote:

[10x 50 Prinz binoculars]

they fogged up quite quickly, the
binoculars are not sealed as all the parts unscrew.

If they are anything like mine, somebody gooped greasy stuff around the
threads and other parts in a vain attempt to seal them. I say "vain", as
they are clearly not sealed.

The image through them looks bleary and low in contrast in daylight use,
and has got worse over time. Cleaning the lenses inside and out did nothing.

Probably smoke damage (nicotine) if not just creepage of the sealing grease.

It turns out the prisms are coated in a thin film of junk ...

This one might be just me. When I look through them, I see two different
images, by which I mean the same image slightly offset, because of the two
eyepieces.

This is possibly because someone has opened and cleaned them.

I realised that they prisms had to be removed to be cleaned, and did so. Got
them nice and sparkly, and even reseated them exactly back in place, nestling
against the cement that fixed them.

Wrong

I now have two, clear, monoculars on a common mount. The images don't quite
align enough to call them binoculars, and I'm fed up of tweaking the ****ing
prisms back and forth. But they're not bleary any more. Wahey ...

and using one eyepice as a monocular. Don't know if it's the binoculars that
are knackered, or what?

It's either the bins that are knackered, or your eyes

HTH.

Mike.
--
--------------------------------------+------------------------------------
Mike Brown: mjb[at]pootle.demon.co.uk | http://www.pootle.demon.co.uk/