[Klaus]

[quote name='Yakim' timestamp='1331626363' post='16638']

Someone please correct Klaus as well as he consistently makes claims like: [url="http://www.opticallimits.com/nikon--nikkor-aps-c-lens-tests/705-sigma1770284os"]f/4.0-5.6 (full format equivalent, in terms of depth-of-field - not speed)[/url]. Or is speed different than light gathering?

[/quote]



Where is the problem ?



Example:

Full Format lens: 50mm

Equivalent MFT lens: 25mm



You can take the same scene (field-of-view) from the same focus distance. So far d'accord ?



Now take a depth-of-field calculator -say-

[url="http://www.dofmaster.com/dofjs.html"]http://www.dofmaster.com/dofjs.html[/url]





and enter e.g.

focus distance: 3m

focal length: 50mm

aperture: 2.8

Format: Canon EOS 5D II



Result:

Depth of field Near limit 2.73 m

Far limit 3.33 m

Total 0.61 m





Then enter



focus distance: 3m

focal length: 25mm

aperture: 1.4

Format: Panasonic GH-2



Result:

Depth of field Near limit 2.72 m

Far limit 3.34 m

Total 0.61 m



Then compare the results.



Depth-of-field:

50mm f/2.8 (full format) = 25mm f/1.4 (MFT)



I'm very baffled that we are having this discussion over and over again.