--- Julian Loke <[EMAIL PROTECTED]> wrote:
> > "Mortimer Snerd" <[EMAIL PROTECTED]> wrote:
> > The standard check for decentered elements is to
> use
> > an optical device called a collimator. These tend
> to
> > be exensive, but Tomas Tomosy's "Camera
> Maintenance
> > and Repair" (Volume 2, I think)
<snip>
> Was it Thomas Tomosy? Volume 1? or Volume 2?
> http://amherstmedia.com/Books/1158.htm
> http://amherstmedia.com/Books/1558.htm
I'm pretty sure it's volume 2, because Volume 1 was
*very* basic stuff. Both books are pretty enjoyable,
though, as are his books on restoring antique cameras
and "Repairing the Classic Cameras, 1945-1970". It's
mainly for the mechanical stuff.
There is also a shutter speed tester in there I'm
interested in building, too... it's similar to the one
described on Robert Monaghan's site. It uses an
integrator to charge a capacitor, the charge will be
proportional to the length of time the shutter was
open, which you can measure with a meter.
I've heard a lot of people whine about how bad
Tomosy's Leica and Nikon books are, I don't think they
are that bad... most of the repair info I've been able
to find isn't as clear or as well illustrated as
Tomosy's books. Their main fault is in their
incompleteness... you cannot totally tear down cameras
just by reading his books. But it ususally isn't
necessary. The alternative is somebody like Ed
Romney... not much of a choice, huh? :-)
> Does your auto-collimator look like this:
>
http://idccdata.members.easyspace.com/Mark/collimator.htm
Quite a bit like that. Tomosy used a wooden frame, but
did not paint his. I put mine together in a black
wooden box, I think if I were going to do it again I'd
go with metal, like an LMB chassis box from an
electronics store. I used a pair of junked binoculars
I found at a gun show for the optics, and Edmund
Scientific had the semi-silvered mirror. I used a bulb
and reflector from an auto fog light, and power the
mess with a Nikon F36 motor drive battery pack.
Notice the builder references Tomosy and his books at
the end of the page?
> What method do you use to
There is a procedure in Tomosy's book, along with a
crosshatched test pattern you can photocopy onto an
overhead transparency sheet (any copy shop can do this
for you.) I'm sure there are better patterns out there
(Air Force resolution charts would be great) or you
could draw some on AutoCad.
> Or do you maybe this method (using an EOS Elan IIe,
> I believe):
> http://www.kyphoto.com/classics/collimator.html
That's the infinity focus check. You're looking for
asymmetry/edge blurriness in the test pattern to spot
de-centered elements. Most lenses will be slightly
blurrier at the edges anyway, bad blurring is a bad
sign. It's a good way to get a warm fuzzy that a
camera/lens combo hasn't been horribly abused/dropped
over its lifetime; if there are no other obvious signs
of external damage.
> Or do you use a laser pointer?
Hadn't thought of that, but the beam would be awfully
narrow to look for for decentering, unless you swept
it mechanically (focusing rail?) across the field of
view somehow.
MadMat
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