Even early Leica R4 (which had a very unreliable electronic shutter)
aren't repaired today, while much older mechanical Leica II or III can
still be serviced by a decent repairman.

It depends... a circuitry with analog shutter speed control can be
built very simply. I once tried to repair a Paratronic shutter on an
Agfa rangefinder camera and found an IC inside that obviously once was
available for the public, too - at least I found some data on it in a
public library. They did not need more than four or five resistors, a
variable resistor and a capacitor (plus a solenoid, of course) for the
control circuitry.

However, most shutter control circuits are built with custom-made ICs.
You can see this evolution on the Yashica Electro rangefinder cameras.
The very early models had a circuit composed from three or four
transistors and some resistors. In later years they first switched to
a moulded module which could be swapped as a whole only, and the last
models had their custom-made IC - and therefore will be unrepairable
if this guy fails.

Another issue are electro-mechanical problems, like wear and/or
corrosion on switch contacts, resistor tracks etc. The more of these
you put into a camera, probably the less reliable it will be (even
many of the early Yashica Electros suffer from slide switch problems).

There are quite a few mechanical cameras out there which have worked
for decades. I once checked the shutter speeds of a 1931 Zeiss Ikonta,
and they were dead on after a little cleaning of the innards. I have
severe doubts that any of todays electronic cameras will still work in
70+ years from now.

Winfried

Too bad you didn't tell that to Neelon Crawford who did Antartica with
the Rollei 6008 or to the RAF who was flying the 6006 in an unheated pod
under the wing of a Jaguar fighter for air to air work at -20C.

Depends on the shutter and how you protect the power supply to keep it
warm.

Since the Rollei shutter is magnetic and has no lubrication it was no
problem to keep it running.

But if you don't put the proper lubrication in a mechanical system you
can have all kinds of problems in extreme cold or heat.

When you talk about electronic shutters you can mean several different
things. For instance some cameras have a mechanical shutter that is
electronically timed. Others, like the Rollei Linear Motor Shutter for
medium and large format cameras have only 7 or 8 moving parts, no
springs, + the blades and are electronically driven and controlled and
timed.

Jeremy,

I will give you one practical comparison example.

There was a company that made cameras to photographic traffic
intersections for cars that went too fast or disregarded red lights or
RR signals.

They made their own camera and back and originally used Hasselblad 150mm
Sonnar lenses. However they needed a true shutter speed of 1/500 so they
had to add more tension to the springs in the shutter so they could
actually achieve 1/500. When they did this the average number of
exposures they could get out of a lens with the Prontor Hasselblad
shutter was 150 shots.
Of course the camera might have to take that many shots per day so this
was not acceptable. The lens had to have a leaf shutter as each shot was
exposed with a high output flash unit since no one new what ambient
lighting would be like at the time of each exposure.

They then started using Rollei 150mm Sonnar lenses (same 150mm Sonnar
lens) but with the Rollei PQS high speed shutter. The average number of
exposures was well in excess of 150,000 between downtimes shooting at
speeds of 1/500 and higher. They even got this number of exposures out
of cameras that ran in the desert areas of Australia as well as those in
the US.

The repeatability, reliability and control of this type of shutter is
simply not achievable with a mechanical shutter. The shutters they used
has shutter speeds in 1/3rd steps from 30 seconds to 1/1000 with full
flash synch at all speeds (it is a leaf shutter) and apertures in 1/3rd
stops as well. The view camera version of this shutter has aperture
control in 1/10th stop intervals. So do some other electronic view
camera shutters.

As for repairs, Zeiss has already discontinued shutter manufacture at
Prontor Werke so the Compur and Prontor shutters have not been made for
several years now. As parts run out the possibility for repairs with new
parts will become impossible. So only scavanged parts will be available
at some future time. Old Copal shutters don't use all the same parts as
current Copal shutters, Seiko shutters have not been made in years.

All of these shutters, mechanical and electronic will become
unrepairable to some extent - depending on parts and the availability of
people with the know how and experience to repair them in the future.