f/1.8 on m4/3, ASP-C, FF; are they the same?
DOF is a subjective phenomenon and depends solely on:
--allowed size of circle of confusion
Lens DOF markings (and strangely enough on-line calculators) date back to Barnack's 1912 assumptions based on 19th century CoC standards.
On a 10x8 inch contact print looked upon from one foot a circle of 1/100 inch was considered the "sharpness" limit. This roughly translates to today's 36x24mm frame CoC of 0.03mm magnified 8x to ca A4 print (0.03 mm x 8= 0.24 mm or ca 1/100 inch).
The 19th century assumptions of eyesight strength are rather inadequate, many 20/20 vision individuals (and correction glasses wearers) will see double or triple the detail. Computer pixelpeepers demand a "pixel-level sharpness", etc etc. Therefore many believers in zone DOF and relying on lens markings and DOF calculators are deeply disenchanted with results. In fact to get at the 20/20 vision level sharpness expectations those suggestions must be tightened 2-3 times and aperture closed 2-3 stops to make CoC that much smaller (eg. 0.01mm on full frame).
All that assuming that the lens resolution is good (40lp/mm), camera perfectly steady, focus ideal and diffraction not a factor.
btw, it also seems like the GH2 "fixed" the underrated ISO values... that might also contribute to the "cleaner" higher ISO's that people are seeing. We'll have to take that into account.
I agree. I am sure they did it for marketing reasons. Some thought the GH1 was not very good at higher ISOs because they were comparing apples to oranges. I just happen to own a T2i and a GH1 and know the truth.
The other thing that hurts Panasonic is the difference in quality in these sensors. I have seen some GH1s with terrible banding at ISO 1600, and other that were perfectly clean. If anyone wants to find "bad" GH1 pictures, they are out there.