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slow AF on N50

 
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ManWearPants



Joined: 18 Feb 2010
Posts: 74

PostPosted: Sat Sep 04, 2010 12:00 pm    Post subject: slow AF on N50 Reply with quote

The AF on my N50 is slow, steady and silent. You can actually count 1,2,3 while it moves to be in focus. This is different from my N24-85 and N17-35 which jolts to be in focus.

Is the focusing speed of the N50 deliberate? if yes, why so? Is it possible to tune the focusing speed of the N50 to be faster, like the other 2 lenses?
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ManWearPants



Joined: 18 Feb 2010
Posts: 74

PostPosted: Sat Sep 04, 2010 12:02 pm    Post subject: Reply with quote

A separate question from the one above. What else does the aperture ring do other than changing from AF to MF?
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conurus
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Joined: 15 Aug 2006
Posts: 795
Location: Vancouver, Canada

PostPosted: Mon Sep 06, 2010 6:23 am    Post subject: Reply with quote

The 24-85 and 17-35 are internal focus lens designs. The moving masses and the distances that the focusing lens groups travel are not that great. They have great AF speed (by Zeiss standards).

The classic Planar design moves the whole chunk of glass back and forth in one group. In the particular case of the N Planar 50/1.4, the ultrasonic motor, the lens' CPU, and the electromagnetic aperture diaphragm move as well. The moving mass is almost the entire weight of the lens (although the lens is light) and the distance of travel is long, too. The lens is geared slowly because of the moving mass. It autofocuses significantly more slowly than the ultrasonic zooms.

The N-Planar 85/1.4 (not ultrasonic), again an internal focus design, has much higher AF speed.

In movie capture, the aperture ring of the lens can be used to control the lens' aperture in P, Av and Tv modes. In M mode you continue to use the camera body to control the aperture.
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ManWearPants



Joined: 18 Feb 2010
Posts: 74

PostPosted: Mon Sep 20, 2010 9:40 am    Post subject: micro-adjustments Reply with quote

Firstly, thanks for explaining all that. For all those reading and concerned that the AF for N50 is slow. It is not that slow on its own and is defintely usable. It is a tad slower than the AF on N24-85, 17-35 which is why I asked.

Secondly, I remembered someone mentioned you can do micro-adjustment for near, mid and far distances. However, I cannot find any such info in your micro-adjustment thread on N50. Did I mis-interpreted that the near, mid and far are for the focal length and not for focusing. Which means that for N50, there is only one micro-adjustment setting required.
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Tom Berkowski



Joined: 16 Sep 2008
Posts: 13

PostPosted: Mon Sep 20, 2010 8:59 pm    Post subject: Reply with quote

In my experience, focus on 50N is not terrible. It's not the fastest in the world, but I don't blame it for missing any shots. Also, it's pretty accurate in my experience.

Indeed, I got 50N because I wasn't completely happy with Canon 50 offerings. I never had all lenses at the same time, but here's comparison from my memory:
- I prefer Contax N autofocus to Canon 50 1.4. By this, I'm referring to hunting/accuracy. Contax may not be faster, but Canon 50 1.4 isn't all that fast either. Also, Canon 50 1.4 has reputation for fragile focus.
- Contax N autofocuses slower than Canon 50 1.2. Canon 50 1.2 was not perfect with focus, though, even though it was fast. I missed some shots w/50 1.2 because of huntlng. It wasn't a huge problem but not what I expected given Canon 50 1.2's high price.
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conurus
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Joined: 15 Aug 2006
Posts: 795
Location: Vancouver, Canada

PostPosted: Sun Oct 03, 2010 12:11 pm    Post subject: Reply with quote

To clarify, mid, near and infinity are really distances, So a converted 50/1.4 is equipped with 3 configurable settings.

A converted zoom lens would let you individually configure 3, 4 or 5 different focal lengths. A 17-35 for example would have a total of 9 settings because there are 3 individually configurable focal lengths times mid, near infinity for each. A 24-85 would have 4 focal lengths times 3 distances for a total of 12 settings.
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