Originally posted by Scorpio71GR I see no real advantage to the lower ISO. To me it seems the higher shutter speed trumps any advantages gained from the lower ISO setting.
I've sort of experienced the opposite. If I raise my ISO too high, to gain a faster shutter speed, there seems to be a harsh sweet spot. For me, with the K3, DA* 300, and the 1.4 TC, above ISO 800 is noticeably, not incrementally,
less sharp. and ISO 400 seems noticeably, not incrementally, sharper than 800. I know earlier I moaned that I've been seeing a more drastic fall off in IQ with the 300&1.4 than others seem to be able to achieve. However I did shoot this sparrow image, with that combo, and it is remarkably clear IMO. However, this sparrow was really close to me - approximately 20ft. My complaint is I want a 400+mm set up to produce images that are clear with subjects that are usually much further away than 20ft, which is why I'm so close to purchasing the 150-450 thinking/hoping/expecting it will have a vast increase in IQ over the 300+1.4. Again, I'm willing to bet a large piece of my problem is me, and my technique. I'm sure I have room to improve. Having said that, I don't think my technique or support equipment is terrible either. At least testing and trying to get better means taking more and more pictures! And that's a good thing.