Re: Old lenses and *ist D

[Peter Alling]

No extra code is required for stopdown metering with M42 lenses.  If the code
for the camera is properly written, (I'll make no bets on that, I've seen 
some awful code,
but assuming they did a good job) then the amount of code used  a.) to make 
the camera not
fire when a lens isn't set to A, or doesn't have an A setting, (if properly 
written that should
be the same code, it's looking at the same sensor), or b.) Overrides that 
function to turn off
the meter and allow the shutter to fire, could be re-written to call the 
module to stop down the
lens and the module to turn the meter on, thus giving K/M lenses stop down 
metering at least.

At 07:54 AM 10/9/03 -0500, you wrote:


John Francis wrote:


Peter Alling wrote:

I have three things to say, if simpler is better 1.) Don't use
Actually they *did* have to write one piece of code - the piece that checks
to see if a pre-"A" lens is mounted, and won't trip the shutter unless the
appropriate Pentax function is set.  But that's one small, simple piece of
code.  Code to support K/M lenses would reqire significantly more code to be
written.  As there is no mechanical aperture sensor the only functionality
that could be provided would be stop-down metering.  That's not code that
is needed for anything else, so it would have to be specifically written.
That is true, they had to write a *small* bit of code to support the flag that
the user can turn on if he wants to use manual with non-A lenses.
The very presence of that flag is pretty much proof that they took the 
attitude "user beware", and probably didn't test this area very much.


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