New Olympus 17mm 1.8

Started Mar 7, 2014 | Discussions thread
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Anders W Forum Pro • Posts: 21,465
Re: "strictly controlled conditions"

Steve Rushing wrote:

Unfortunately this is hard to achieve with my grand kids.

Perhaps with your grand kids but not with moving targets in general. There are highly controlled tests of that kind carried out by the French laboratory called FNAC for example.

I've had the 20 since launch. I think very highly of its objective measurements and how they manifest themselves in the photographs under approximately 90% of the my shooting situations.

But. The problem with slow focus, especially hunting, is problematic in situations where I need exceptionally fast focus, i.e., when indoors and I can't demand that everything be perfectly controlled on behalf of the lens.

In many earlier threads on the subject, I have pointed out that there are indeed conditions where the AF of the 20 will be slower than that of other lenses. One of them is when it hunts (although it is not more prone to hunting than other lenses, just slower when it does it). Another is when you focus between extremes, like from minimum focus distance (0.2 m) to infinity (but 0.75 to infinity as in my test is not a problem). A third situation for which the lens is not suited is AF-C (on Pany bodies it won't even be allowed to enter that mode) and a fourth is video (if you want to AF during a clip).

However, I am hard pressed to think of a situation where it is practically important to quickly AF from 0.2 m to infinity and as to hunting, the practical solution is simply not to allow the lens to hunt or hunt to completition. This is largely a matter of knowing your equipment, its limitations, and how to overcome them.

I will keep the 20. There are times when the combination of its objective measurements are superb and make it to the photograph. I was going to buy the 17 for the situations where the combination of the 20's objective measurements are less far less than superb - sharpness doesn't count if I miss the fleeting moment of a child's experience. I abandoned this idea when the 12-40 was announced and purchased it instead. Even though some of its objective measures (and some subjective such as size & bulk) are less than superb or ideal, it is now constantly on my camera because it gives me a higher keeper rate in less than "strictly controlled conditions".

BTW, I admire your analytical thinking, but hope you also understand that it is often extremely difficult to parse and control individual variables, permutations and their interfaces in the messy real world of application, especially when you throw people into the System such as photographer+camera+lens+lighting+subject .... Analytical thinking is entirely correct for mechanical testing and reviews. However, its necessary, but not sufficient. Move to the application of people taking photographs and Systems thinking, for me, is certainly messy, but very informative in the sense that posts from users here give me an understanding of the Systems behavior in situations important to me. That is, I rely on both objective analysis of tests and subjective posts of users to whom I relate because my performance criteria aligns with theirs. We often shoot similar subjects under similar conditions.

I understand all of the above. The main reason, however, that tests are insufficient is that there are too many potentially different situations for tests to cover them all well enough. Consequently, I too listen to the experiences of others. Sometimes, however, I find reason to question that reports about such experiences are valid descriptions of the objective facts. As I hope you realize, the step from subjective experiences to objective facts is sometimes a very long and complicated one.

The 20/1.7 and its AF behavior is a case in point here. I have seen quite a few forum members recognize, after discussing the matter in detail, that perceptual complications play a part in the impression that the AF of the 20 is slow. One of these is that you hear the lens AF (in sufficiently quite surroundings), which is likely to strengthen the impression of duration. Another is that the slow hunting behavior is what is most likely to make a lasting impression.

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