I get it that when you slow down the SS and expose the image for longer the NOISE risk/factor increases because of the longertime. I get it that a faster Apeture (2.8 cf 5.6 for example) reduces the risk of NOISE for the same reason: less time consequential to a wider apeture and therefore more getting into the shot.
But what I dont get is when people say higher means less overall in said image- Why dont I get it ? Because an increase in means you end up with a faster SS (less time) and the based increase of the amount of hitting the sensor compensates for the lack of coming from the Apeture (smaller hole = less ) - no ?
Questions Im asking myself include
A. If that is factual, why ?
B. Does it apply to all focal lengths from say 10mm-400mm
C. Does it apply to all (including L series Canons and other higher quality )
D. Does it apply to all conditions and
E. Is it the NOISE factor alone that messes with with higher settings
I dont shoot above 200 even with my 50D which copes with alot better than my 400D did but I leave the AUTOISO alone (sometimes why I dont use it) so /NOISE issues wont be a problem for me unless/until I am doing something like star trails with long long times which I can overcome to a degree with the in camera NR function etc etc.
Thoughts, comments and rueful shaking of the head at my probably misinformed ignorance most welcome