[Leica] Best flash for M8?

[red735i at earthlink.net (Frank Filippone)]

Don, I was in the data acquisition business for 25 years and another 5 years 
in imaging.  I understand the system as a whole, and a
lot of the parts really well.   I am not a PJ, never was.  Thanks for the 
comment about the good humor, I do try.

It would make no sense to use a mechanical shutter to time the exposures of 
a fully electronic system.  A gated system would be
infinitely more capable and reliable, to say nothing about the lower cost 
because the components of the mechanical shutter could be
lousy, tolerances great, and the system would still work to a really tight 
spec.  

As I see it, the baffle opens, the light hits the CCD.  The timing nulls the 
CCD ( and follow on circuitry)  offsets to effect zero
black.  Then the gate opens, light charge builds,  gate is shut off, charge 
gets multiplexed, conditioned,  measured, and sent to
the uP for further processing or just plain recording on the memory card.  

The specific difference in our thinking is when the cells start recording 
light for the image capture relative to light hitting the
sensor.  Your thinking is that as soon as the light hits the sensor ( the 
opening of he mechanical shutter) , the process starts.
My thinking has the sensor starting to measure the light after and under 
different and electronic gating control from the thing that
lets the light hit the sensor.

Cells in sensors leak ( stray light, temperature, mismatch, battery voltage, 
IC production tolerance, and a myriad of different
issues).  In addition, the system of the M8 ups the gain in times of low 
light....But the leakage is then multiplied by the higher
gain.... bottom line.... you get an image that is over exposed if you have 
not set up the system to behave differently in "B"
shutter situations.  What happens to the image capture when you use the B 
setting for 1 second as opposed to using the 1 second
setting on the camera?  Is it different?  Try it and tell me.

I have written a more detailed description of the working of the M8 
electronically gated shutter speeds.  Read it for more technical
reasons why the mechanical shutter of the M8 has nothing to do with image 
capture......it is a baffle.



Frank Filippone
red735i@earthlink.net