Comments below...
If it isn't lens-related, I'd be very interested to hear how come
stopping down the lens has a significant effect on it.
when you stop down the lens you let less light in,there fore you do
not overload the sensor and it gives less purple
Sorry, that doesn't wash. In order to get the same exposure, you
need to get the same amount of light to the sensor: if you stop
down, that means you need to leave the shutter open longer. The
sensor doesn't care whether the light comes in all at once or over
a longer time.
Your description applies to film cameras, and to DSLRs (which,
for purposes of this discussion, are converted film cameras).
It may, or may not, apply to a digicam like the 828.
I'd be willing to bet that the 828 has NO mechanical shutter,
for two simple reasons:
1. It makes no mechanical noise, and
2. Mechanical shutters are expensive and trouble prone.
There MAY be an electronic equivalent of a focal-plane shutter.
However, I don't recall seeing any such device in front of the
sensors in the digicam drawings I've seen. So the shutter effect
may simply be the period that the sensor is allowed to integrate
the incident light (if that's what it does).
I note that Phil's specification table describes the A1 shutter
as a combination of electronic and mechanical (?); but his
828 spec table does not characterize the 828's shutter
implementation.
Are there anyone out there that can provide links showing
exactly how the 828 implements its shutter function...
or even a "typical" CCD digicam's shutter function?
In order to really know what is going on in the 828, it would
require an understanding not only of the shutter implementation,
but also of the new sensor's reciprocity characteristics.
BTW, even film has reciprocity issues. The departure from
ideal intensity/time equivalence is called "reciprocity failure,"
and is sometimes part of published film tests.
A simple experiment that might shed some light on this would
be the following:
1. Find a fringe-producing target, and shoot it with manual
settings.
2. Add an ND filter, and shoot it at the same aperture,
compensating with a shutter speed change.
3. With the same ND filter, shoot it again using aperture
compensation, and the original shutter speed.
All of this would probably work best with a rather subtle case
of fringing. A total sensor blowout would probably just look
like a total sensor blowout with any of these variations.
Any 828 users want to try it, and report back?
