DOF with Pro90

[wenyao]

I noticed that most of my photos with the Pro90 tends to have a lot of DOF, even when taking "normal" portraiture shots at f/2.8. On the other hand, when I was using my Canon EOS 100 with a 50mm f/1.8, I could get perfectly blurred portraiture shots with little DOF at the same f/2.8.

It seems rather weird that with film or digital SLRs, we can get the DOF required by adjusting the f-stop, but why is it so with the P&S like the G1 or Pro90, we are unable to do the same thing/achieve the same effect.

Both type of cameras (P&S and SLR) do stop down the lens, don't they? So by right, I *should* be able to achieve the same effect of less DOF when using a D30 with a 50mm lens at f/2.8 and the Pro90 at 50mm zoom at f2.8 as well. But it doesn't seem to be the case however..

could anyone give an explanation for this? Thanks!

[danielchtong]

That is a big topic
Look at http://www.students.tut.fi/~vahonen/.../digiphoto/DOF which talks about G1. Actually it applies to the case in question as well.
50 mm zoom at Pro90 is at least equivalent to 200MM in 35 MM as it has a 10X optical zoom.
Hope that can be of some help to you.
Daniel at danielchtong@yahoo.com