Re: [Leica] ELCAN lenses

[Paul Chefurka <pchefurk@ca.newbridge.com>]

Pascal wrote:
> 
> On 13-07-1998 15:29 jeremy.kime@bbc.co.uk wrote:
> 
> >
> >If you can recall the specs. of the 'whole battery of lenses' I'd
> >certainly be interested.
> 
> Sorry Jeremy, the only thing I can remember is that there were a number
> of them (I believe 8) mounted together in different directions, and that
> on the lens barrel it was said "ELCAN - made in Canada", and that the
> lens opening was f/2.8. But I don't recall the exact focal length. I
> should have written it down! I suspect these lenses must be quite
> excellent, how could they otherwise serve for reconnaissance purposes
> from at or around a supersonic speed.
> 

Actually, the speed of the aircraft wouldn't determine the required
lens quality, it would determine the minimum shutter speed required
to stop blurring.  The shutter speed would actually depend on an
equation involving speed and altitude (apparent motion is less at
high altitudes) as well as relative image size and the desired
resolution.

You'd need a much faster shutter speed travelling at Mach 1 at 300m
than you would at Mach 1 at 10,000m.

The quality of the lens would determine the ultimate resolution
limit at any given shutter speed.

'Course with Leitz optics they should be able to count the hair
follicles in your bald spot from 10,000m at Mach 1.  Especially
for the prices the military probably paid for them!  (Apply the
$500 hammer rule to figure out the military cost of a Summicron :-)

Paul