----- Original Message ----- From: "Kevin Waterson" Subject: *istD and prime lens aperature
> With istD making all our old primes x 1.5, > is there any change to the aperature eg: > > a 135mm f1.8 becomes effectively a ~=200mm > but is there any change in the effective aperature? Your 135mm f/1.8 is still a 135mm f/1.8. That hasn't changed. What has changed is how much of the image circle the digital sensor is seeing. The 135 is a mid length telephoto on the ist D. You should start trying to think in terms of the new format on it's own. I find it is less confusing, anyway. William Robb
