Whenever in trouble, shoot F/4. All will end well!
E-500 with Zuiko Digital 11-22mm f2.8-3.5,
22mm, f/4, 1/45s, ISO400
Ever heard the quote, "F8 and be there."? Well, this phrase emphasizes the importance of being on location to capture the shot than meddling with the technical details.
It was coined during the height of 35mm film cameras, to remind gearheads that the picture matters not the gear!! This is where the aperture stopped at F8 at most general focal lengths will result in the images having adequate in-focus sharpness for most of the frame. Somehow, this is a type of a hyperfocal distance hack, of sorts. If you have a 135 format camera, it's safe to say that you are at the optimum sweetspot of the lens coupled with the ample depth-of-field for general photography.
A quick scan at the depth-of-field table for a typical 35mm and 50mm focal lengths yield adequate depths-of-field for scenes shot from a 10-foot distance. With a 35mm lens, the backfocus will have acceptable focusing depth of up to 24 feet, and with a 50mm lens up to 14 feet.
Now, will this apply with the Fourthirds system?
Definitely, not!! Simply because it's a different format from 135; and being smaller by 2x, the effect changes.
I have long abandoned F8 ever sinced I moved to digital. And the digitals I have been using eversince have never been larger than 135, there is never a need for me to shoot at F8 for general photography.
With 4/3, I have to readjust a lot of things I learned with the 135 format. One of it is to shoot F4 instead of F8!!! It's no easy task, but at least the 2x crop factor is much easier to calculate than the 1.5x or 1.6x.
When shooting with E-system cameras, to get similar F8 just use F4! In this case, I will use a lower ISO compared to 135 format for a similar lighting situation. I won't say that this is an advantage of achieving lower ISO, but it's just different.
With a 25mm lens, all I need is an F4 to mimic the situation of a 50mm lens in 135 format stopped to F8.
* Note: when I mean F8 or F4, it also includes the +/- o.3ev of the range.