Fastest focusing mFT prime?

Started Apr 25, 2012 | Discussions thread
NZ Scott
Senior MemberPosts: 3,230Gear list
Re: 14mm AND 17mm ...
In reply to Anders W, Apr 27, 2012

Anders W wrote:

NZ Scott wrote:

Anders W wrote:

NZ Scott wrote:

Anders W wrote:

bowportes wrote:

digifan wrote:

I'd skip the 20mm anyway because of it's not so ideal focal length.

There's no such thing as a "not so ideal focal length." It depends upon what angle of view you "see" photographically with. The 20mm is often better for groups at gatherings than either the 14mm or the 25mm. I would choose it for formal group shots at a family reunion, for instance, over any other MFT prime focal length.

Correct! For me 20 mm is a very good focal length (clearly better suited to my preferences than 25). In addition, the claims that the 20 has slow AF are vastly exaggerated. As shown in this test by Pekka Potka, it's about as fast as other MFT lenses, including the new, and reportedly very fast, 12/2 (see "update" at the bottom of the page):

That said, I am not sure if it's ideal for the OP's purposes (shooting kids at pretty high magnification). The 45 should be ideal for that (if enough distance can be kept) but the 25 might work too and would give less perspective distortion at the same magnification than the 20 (but more than the 45).

I think you're relying a bit too much on a single website test. This guy tested focusing speeds under controlled conditions, shooting a standardised target at a set distance. Most users who shoot under real-life conditions say that the 12/2.0 and 45/1.8 are significantly faster than the 20/1.7.

Feel free to point us to other systematic tests if you like. Such tests, performed under comparable real-life conditions, are more reliable than second-hand impressions like yours of the impressions of other users under incomparable real-life conditions. And I do not need to rely on a single test inasmuch as I have the 20/1.7 myself and can check the extent to which Potka's results are reasonable.

As already suggested in prior threads, a likely psychological reason why the 20 is perceived as slower is that its AF mechanism is more audible than that of other MFT lenses.

Go down and read g2van's post. He owns the 20 and the 45 and says that the 45 is faster "without a doubt".

I already read it. It's just another subjective user impression, no systematic evidence. But when did I say anything contrary to what he claims? All I have said is that the 20 is not much slower than other MFT lenses.

I have the 12 and the 45, and the 12 is even faster still. I've shot with the 20 and I thought it sluggish. The reason was not psychological.

How do you and we know that?

The reason was that the 20 has a front-focusing element whereas the 45 and the 12 have internal-focus mechanisms. The latter is nearly always faster than the former.

Yes, as you might have seen if you had bothered to read the thread, I have already pointed out that this is the likely reason why the 20 is slightly slower as well as noisier than most other MFT lenses.

The test that you are relying on involved a person shooting a picture of a newspaper at a set distance under controlled lighting conditions, and his test did in fact find that the 12mm nad 45mm were faster than the 20/1.7.

The 45 wasn't tested. And sure, the 12 mm is faster, but only marginally so: 0.74 versus 0.87 s. Compare this to the across-the-board difference of about 0.60 seconds for MFT lenses recorded when switching form the E-P2 to the E-P3. The differences between lenses are trivial. The difference between bodies substantial.

When I start shooting indoor photographs of newspapers then I might find that website to be useful.

Can't say I am surprised that you reason that way. Don't know why I or anyone else should care though.

I'm not the only person who thinks this way. Read the rest of the posts in this thread. A lot of people who own the 20 consider it to be slow. Your voice is a lone one. You've based your view of this subject on data from a single website, and I would suggest that you try to broaden your mind a little.

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