Originally posted by Marc Sabatella It's not really necessary, though. All ISO 3200 does on the K100D is shoot underexposed at ISO 1600 and then push the result in the on-camera processing. You could achieve exactly the same results yourself.
Thanks Marc.
I was skeptical about pushing ISO1600 -
since film pushed normally is not as good as film with the higher ISO rating.
So I did some ad-hoc experiments late last night and thought I got results that showed straight ISO3200 was clearly better than ISO1600 pushed 1 stop....
However I thought about it this morning and re-did my experiment with slightly better control and got the opposite result - so much so I repeated it two more times to be sure.
Under incandescent light - 60 watt (closer) and 40 watt softwhite household light bulbs. K100D tripod mounted - Shake Reduction Off - Tv - shutter speed set at 1/15sec to be similar to my actual shooting conditions, Incandescent White balance.
Target -
I deliberately set my lens to get a crop of about 450x300 from the central area that would give enough coverage at 100% to be meaningful.
Processed the ISO3200 crop to get the best image I could - then processed the ISO1600 (1 stop Underexposed) try to match the ISO3200.
100% (actual pixels) Crops JPG (top set) -
one can see in JPG (the top set) the ISO1600 Pushed shot is noisier/grainer -
BUT it is also noticably sharper!!
How about RAW?
There seems to be lot less difference between ISO3200 RAW and ISO1600 RAW pushed -
(beacuse of I cannot see the shots side-by-side it was hard to match the ISO1600 RAW shots to the ISO3200 - so I did it twice (being relatively a novice in RAW and Pentax Lab) as it was I still had to do a bit of brightness/contrast adjustments to get the ISO1600 RAW pushed shots to match the ISO3200 RAW.
I think the straight ISO3200 RAW may just be a bit better.
I'm impressed for the Pushed JPG results -
in fact of all the crops the ISO1600 Pushed JPG seem to me to be the best.
so perhaps under similar circumstances I'll be pushing ISO1600
even though it does take quite a bit more post-processing to get the image just right
and experiment with some noise reduction.....
However in RAW shooting straight ISO3200 seems to be as good (or a just a fraction better) as ISO1600 RAW pushed without the slightly extra post-processing effort.