Pana 20/1.7 (version II) vs Oly 17/1.8?? Need help deciding.

Started 5 months ago | Discussions thread
Anders W
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Re: Pana 20/1.7 (version II) vs Oly 17/1.8?? Need help deciding.
In reply to kenw, 5 months ago

kenw wrote:

I have the version I 20/1.7 and the 17/1.8. By all accounts nothing changed optically or AF wise on the version II.

IQ is nearly the same, I tested mine carefully. Small differences in whether edges or center slightly sharper.

Size wise bulk about the same, 20 wider but flatter 17 narrower but taller.

AF is no contest, the 17 is way, way better than the 20. Fast and quiet. The 20 is noisy and slow.

Hi Ken,

I think that statement needs to be qualified.

First, the AF of the 20 is certainly more audible than that of the 17 (and other lenses with internal focus). And if you want to shoot video with the lens and want to be able to AF during a clip, that might be a problem. For stills, it's a non-issue. The photographer can hear the lens AF in quiet surroundings. Anyone else would be hard pressed to hear it even in a quiet room.

Second, is the AF of the 17 (or other lenses with internal AF) significantly faster than the 20? This is an issue that I (as well as some others) have investigated/tested rather carefully and the results can be summarized as follows:

In ordinary AF-S, it is usually about as fast as any other lens. While I am sure the max speed of the lens AF mechanism is lower than for other lenses, this doesn't matter much because the main bottleneck is body processing rather than the AF mechanism.

The exception to that rule is if you refocus between really extreme distances (like from the minimum focus distance of 0.2 m to infinity; 0.75 m to infinity is no longer in the range I'd call extreme here) or if the lens starts hunting. In this case, there is a noticeable difference. On the other hand, I have yet to encounter any situation where I needed to AF fast from infinity to "macro" distance or the reverse and there is no reason to allow the lens to hunt (and do so to completion). So I am not really bothered by either of these shortcomings.

AF-C is a special case as well: On my G1 (and I would guess other Pany bodies), the lens won't even be allowed to enter that mode. On my E-M5 (and I would guess other Oly bodies), the body permits the lens to use AF-C, but performance is so-so and there might be other potential problems too (overheating with intensive uninterrupted AF operation?), which may be why Pany bodies don't allow AF-C. Then again, this is a lens where I personally don't see much use for AF-C so I have never missed its limited capability in that mode.

Finally a few words about sharpness: I know that you know how to test lenses and am ready to take your word for it that your own copies of the two lenses are roughly on a par in that respect. On the other hand, nothing I have seen so far suggests that this is true more generally. On the contrary, both the samples and the MTF figures that I have seen indicate that the 20 has a pretty clear edge in this regard. This doesn't mean that the 17 does poorly. But I'd say that in this regard, it is merely decent whereas the 20 is excellent.

Personally, I would have swapped my 20 for the 17 if the 17 had been on a par with the 20 optically (since I have a marginal preference for 35 over 40 mm EFL). But since that didn't turn out to be the case, I abstained from the 17 and kept the 20.

Personally I don't use the 20 anymore, never did much actually, but the 17 gets pretty frequent use.

To me the 20 is a great optical lens and good pancake form factor ruined by an awful AF implementation. Why they didn't fix the AF with version II is beyond me.

Both will take great photos, the 20 will just do it with noise and slower AF. Not a good choice for video. But if you don't mind the noise and a bit slower focusing the 20 is a very nice lens.

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Ken W
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