Re: Aperture and shutter speed in Digital cameras + general discussion

On a Canon DSLR (20D) you can see the aperture opening/closing through the
lens. Not a CCD power scenario, it is mechanical.

I personally think that the lack of large CCD's (or the CMOS sensors with
Canon) are due to idiotic marketing staff. I.E. The marketing/sales
department not knowing their arse from their elbow. They could have easily
provided full frame sensors with not that much of a cost increase to the
consumers, but they choose not to because they can make more money by having
APS-* sensors and also full/semi-full frame sensors.

However, it has bitten Canon in the arse, because they have lost a huge
amount of sales of wider 'L' lenses as a result of producing the lack of non
full frame bodies. For example, the 24-70 2.8 is a great lens, but on a
APS-* body, it is a crap focal range, as are the 16-35 and the 17-40 lenses.
Also remember, crop factor makes no difference when it comes to depth of
field. A 55mm 2.8 lens, is a 55mm 2.8 whatever.

All DSLR's should have had a minimum of 35mm sensor size! Of course, if the
20D had a full frame sensor, then the majority of pros would have bought one
instead of a pro body, but the short sighted marketing staff didn't
anticipate the huge amount of sales they would have got from 'L' lens sales
as a result. But hell, what do I know?!? Honestly, I am tempted to go back
to film until things settle down a bit.



"SS" <xsx2000x@xxxxxxxxx> wrote in message
news:XFWWf.26354$Nh7.23145@xxxxxxxxxxxxxxxxxxxxxxx
In a conventional camera an iris controls the aperture and a mechanical
shutter is altered to control the shutter speed - is this the same in a
digital camera? I have not 'seen' anything that looks like an iris and
presumably shutter speed is controlled by how long the CCD is powered up
or
sampled, not a mechanical device. Of course ISO is a function of
amplification of the signal (hence noise problems at high ISO) and focus
has
got to be by movement of the lens - or could this be done better by
movement
of the CCD? Since the lens retracts anyway i assume this function is used
also for focus. Speaking of which how does auto focus work? i assumed that
the camera 'sees' a small area of high contrast and then focusses until
the
change between the 'gradient' of change between the 2 areas of contrast is
steepest (or more sudden = sharpest focus). What is the best method - do
some cameras do a better job and why? presumably as aperture gets smaller
focus becomes less critical as the characteristics of the lens reduce and
the 'pinhole' effect takes over.

Final question/tipic for discussion - as a larger CCD is supposedly much
better re. noise why don't we see larger CCDs on (all) cameras? Surely if
mass produced the cost increase would be negligible? Or is in camera
software/processing going to take the lead in picture enhancement? Would
this have to be done in camera or could the same effects be produced
(better?) post capture?




.

Relevant Pages

  • Re: Canon 10d
    ... My budget is of about $800-900, and I would prefer to go for a Canon ... as I've a lens to go with it. ... I want a camera that would do everything ... It does not take EF-S lenses. ...
    (rec.photo.digital)
  • Re: Newbie to digital SLR
    ... let me tell you a little more about my needs and camera ... which included a lens. ... As for the Canon lens that came with my EOS-300; ... I've been looking towards Nikon. ...
    (rec.photo.digital.slr-systems)
  • Light fall off on dSLRs - an experiment
    ... Following from the discussion here over the past few days about light fall off on the Canon 5D and whether this is worse that it was with film I decided to try a little experiment. ... The first step was to eliminate any effect of light fall-off caused by the lens, which was quite simple - eliminate the lens! ... The Canon 5D camera without lens was mounted on a tripod about 80cm from this LED source in a darkroom, so the only light reaching the camera was from the LED. ... The second with the camera rotated on the tripod head so that the light source cast a shadow across the centre of the frame - the most extreme angle of incidence that it is possible to create from any lens through the Canon mount. ...
    (rec.photo.digital.slr-systems)
  • Re: Testing for back focus
    ... In this case the lens can most ... your camera or not. ... Scott never bothered to look and see if it was possible for a Canon lens to "look" focused whilst not actually being in focus before he started on me. ... Couple the two possibilities for soft images from a Canon DSLR and you get a situation where you might "think" it's back focus error causing your soft images when in fact it could well be the lens causing it. ...
    (rec.photo.equipment.35mm)
  • Re: Canon 10d
    ... My budget is of about $800-900, and I would prefer to go for a Canon ... as I've a lens to go with it. ... I want a camera that would do everything ... any K1000 lenses you may have. ...
    (rec.photo.digital)