Is the Panasonic 25mm a real f/1.4 lens?

Started Feb 17, 2014 | Discussions thread
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Pixnat2
Pixnat2 OP Veteran Member • Posts: 3,795
Re: Take all tests with a grain of salt...

Paul De Bra wrote:

Robin Wong works for Olympus. His tests are completely honest but the choice of what to test has a hint of focusing on the points where the Olympus lens is (objectively) better than the Panasonic.

The test that shows that DOF is not as shallow as a 50mm f/2.8 on FF uses misfocused shots resulting in more or less background blur depending on the focus.

The DXO T-stop measure is very likely to be accurate but f/1.4 is about the diameter of the pupil and corresponding DOF results and does not state anything about light transmission. You cannot assume that the T-stop difference between an f/1.4 and f/1.8 lens is the same as the F-stop difference.

So the Panaleica is really f/1.4 and the Olympus is really f/1.8. That's not a matter of "thoughts about it" but of physical properties.

Your're probably all true Paul. But a bit of discussion is interesting, especially about F-stop vs T-stop. It was a kind of eye opener for me and I will definitely check DXO if I plan to buy an ultra-fast (and ultra expensive) lens!

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