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

Started 10 months ago | Discussions thread
Ulfric M Douglas
Senior MemberPosts: 4,039
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Re: At those apertures 0.1ev is significant
In reply to tt321, 10 months ago

tt321 wrote:

Pixnat2 wrote:

tt...

This also depends on how the manufacturers and DXO do their rounding. If you put the PL25 on a camera and monitor the F stops the camera can set, you will see 1.4, 1.6, 1.8 and 2. So in their terminology 1.4 is 1/3 EV faster than 1.6 which is again 1/3 EV faster than 1.8 which is 1/3 EV faster than 2.0. There is no 1.7 in spite of Panasonic liking that number - and disliking 1.8, on their primes. On the other hand, presumably DXO has no such obligations and puts their T numbers where the nearest approximate is. So T1.7 is better than T1.8, but this 'better' could be between almost 0 and almost 0.2 because of the precision of the reported T numbers.

According to this patent, the PL25 is actually F1.44319, any narrower it should be called F1.5! It's also slightly longer than 25, at 25.6692. So if the Olympus turns out to be 23.5571 and F1.75812 just to throw some arbitrary numbers around there could be only F0.3 in the difference. And this gets translated to T0.3 difference with one at 1.7 and the other at 2, very roughly speaking and massively into the realms of speculation now...

Good post TT,

(On m4/3rds forum a lot of posters got the wrong end of the stick and assumed Robin was saying the PLF1.4 was dimmer than the new Olympus.)

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Cheksa wrote:
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