is this true? a cropped sensor changes the distance to subject? i set hyperfocal as i would with a film camera on my m8 all the time and i have never had an issue. please correct me if i'm wrong.
It's true. There is roughly a one-stop difference with an M8 size sensor, and a two-stop difference with an R-D1 compared to full-frame. It may not make a difference for many styles of shooting, but for mine it can and I need to be aware of it.
It's most apparent when I'm compressing space closer to the camera.
I like to think of a picture challenge, and then work the situation and equipment to meet that challenge in a way that produces successful images to me.
Using 40mm and 28mm lenses to illustrate (as these become close in equivalent focal lengths, and are lenses I have and can confirm the markings on the lens barrels):
I'm in a crowd, I need to shoot at f8 to get the shutter speed I want. I want as much DOF as possible starting from about 5ft in front of me (wanting anyone closer then 5ft to be out of focus).
Full-frame: 40mm at f8
What I do is set the f8 zone focus mark that is on the shallow side of the lens barrel to match up with 5ft on the focus ring = zone of acceptable focus from 5ft-10ft per the bookends of f8 marks on the lens barrel.
- Per DOF Calculator (an Apple widget) Focus distance is 6.5ft = zone of acceptable focus from 5ft-9ft
- Barrel markings roughly confirm this zone
M8: 28mm at f8 (37.4mm eqv)
- Per DOF Calculator (an Apple widget) Focus distance of 8ft = zone of acceptable focus from 5ft-18ft
Barrel markings for f8 DO NOT confirm this zone. f5.6 markings are more accurate. One stop difference.
R-D1 (and x100): 28mm at f8 (42.7mm eqv)
- Per DOF Calculator (an Apple widget) Focus distance of 7ft = zone of acceptable focus from 5ft-12ft
Barrel markings for f8 DO NOT confirm this zone. f4 markings are more accurate. Two stop difference.