Anyone else shooting with a a900 let's compare tips, tricks and techniques.
Here is something every a900 owner should spend some time on (if one is using raw of course).
Take a series of images in different lightning conditions keeping the aperture and shutter speed unchanged while changing the ISO.
For example, take a camera and meter the scene using ISO 3200. Check the exposure; you may add something like +0.5 or +1eV correction with a900.
Now, make a series of images keeping the aperture and shutter speed unchanged but change the ISO.
For example, if you got something like 1/200 @f8 with ISO 3200, take additional frames with 1/200@f8 and ISO 1600, ISO 800, ISO 400, ISO 200, ISO 100. Yep, with this one will underexpose for 1-5 stops.
Repeat the same procedure while metering for ISO 1600 or ISO 800. And then again, repeat the whole thing in different lightning conditions.
Use you favorite raw converter and try converting the files compensating the exposure (EV sliders) as much as needed. You may be surprised with the results you may get even with significantly underexposed captures. Do you believe a ISO 3200 file will beat ISO 400 (underexposed by 3 tops) or ISO 200 file (underexposed by whole 4 stops!) ? Well, try it. Each of us should learn about this personally and not keep our faith in what common sense may tell us.
Of course, this is where RAW converter comes to play; some are excellent (RPP on mac or raw therapy on windows for example but you are free to try other as well) while some are quite bad for this kind of processing (ACR and lightroom for example).
You may think this is contrary to what ETTR technique suggest, but the whole point here is to learn up to which ISO setting ETTR (on the camera) is useful paying attention to.
But the whole hassle may be worth the effort since you will learn more about the camera and raw converter (raw converter should be really considered as an camera extension; it may be equally important as camera sensors are) and without knowing our tools we will never take advantage of their capabilities.
Happy shooting !