[Sylvain]

Fellow Zoners,



I don't think it has been posted here before and I did use the search function so forgive me if it has. It's rather fresh so...



Reading a french website, I found this article :

http://www.luminous-landscape.com/essays/an_open_letter_to_the_major_camera_manufacturers.shtml

&

http://www.dxomark.com/index.php/en/Our-publications/DxOMark-Insights/F-stop-blues



It's stating very interesting findings.

Among which:

-widest aperture setting provokes a light loss that can render its light collection as "bad" as closing the aperture down

-high pixel pitch sensor are negatively impacted by too wide an aperture (e.g. 7D @1.4 -0.65 EV vs 7D @1.2 -0.95 EV. This would make the use of a lens set at 1.2 rather pointless beyond the DOF aspect.)

-That DOF aspect might itself be questioned by the light ray lost due to above mentioned issue (DxO labs studying it).

-some camera makers are compensating through ISO boosting

...



Some questions :

-I'm not knowledgeable enough to assume but can we consider the light loss from a canon ef 50mm f/1.2L @ 1.4 comparable with a ef 50mm f/1.4 @1.4? My guess would be no, considering that the lens design is different.

-Is focal length of any relevance (for zooms, beyond the scope of this article)?

-Shouldn't they provide "absolute" light transmission data (not sensor based) for a thorough analysis of what's really going on? or is this not measurable?

-How can we interpret the difference between Canon 550D & 7D that are supposed to have a similar sensor?



I'm eager to read more about this and know how it could possibly prove that certain higher specced lenses at certain settings will not give you any advantage over a lesser model in light gathering abilities (sharpness, CA control, etc put aside).



Hope you find it interesting,

S.