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Old July 4th, 2011, 09:52 PM   #1
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Keeping focus of fast moving objects

Is it me, or does the NX5U seem like it has a lot more difficulty in auto-focusing quickly (and maintaining it), especially when it comes to shooting sports?

This is in comparison to the Sony V1.

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Old July 4th, 2011, 10:30 PM   #2
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Re: Keeping focus of fast moving objects

To me my NX5U is a little worse than my FX1 which I rate as poor !!!! My SR11, XR500 and CX700 focus fast and accurate and most of the time maintain focus. The FX1 was never very good in auto focus and the NX5U carries on this tradition !! I always use manual focus for the NX5U and try to manage depth of field to cover the content. I wish it had spot focus like the smaller single chip Sony`s. For my projects I use the NX5U for medium shots with my wife with one of the smaller cameras doing the closeups. With spot focus these are always pin sharp something I find difficult to compete with on the NX5U.

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Old July 4th, 2011, 10:55 PM   #3
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Re: Keeping focus of fast moving objects

So my thinking is ... how can Sony release a camera that is "this good" when it comes to auto-focus?

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Old July 5th, 2011, 08:24 AM   #4
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Re: Keeping focus of fast moving objects

Well it is sold as a Pro camera and most Pro cameras don't have autofocus at all. It works, just not as well as the consumer cameras that have image tracking and face tracking etc that work to get a much better image on average when in auto focus. I don't know why Sony don't include these functions either . They are likely in the DSP in the camera !!!! Since the NX5U uses the touch screen LCD I don't know why they wouldn't include the consumer features. I for one would like that especially the spot focus feature.

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Old July 5th, 2011, 02:27 PM   #5
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Re: Keeping focus of fast moving objects

I believe the reason for this is because the sensor of the pro cameras are larger than the tiny sensor of the smaller ones as well as the lens elements of the pro cameras are much more and makes it "slower" to focus. Maybe i am wrong though.

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Old July 5th, 2011, 02:45 PM   #6
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Re: Keeping focus of fast moving objects

All the Sony's are 1/3". Small ones have a single chip with more sensor sites the NX5U and FX1 have 3 chips. Lens is different though. 37mm and 72mm.

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Old July 5th, 2011, 07:58 PM   #7
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Re: Keeping focus of fast moving objects

Actually, I could handle it if it was a little slower to achieve that focus. It's losing the focus on fast moving objects (such as football players) that is disheartening.

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Old July 5th, 2011, 10:17 PM   #8
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Re: Keeping focus of fast moving objects

If you think football players are moving fast try basketball...smaller area, closer to action...or even better, try NASCAR at 180mph. Been there done that. For sports I found AF just simply doesn't cut it no matter what camera it is. Better off zone focusing and using DoF for safety.
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Old July 5th, 2011, 11:10 PM   #9
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Re: Keeping focus of fast moving objects

Interesting. I'd never heard of the concept of "zone focusing" before but it makes sense to me.

Would it be sufficient to say that within the depth of field there are a range of 'object distances' that will be in focus whilst at the one manual focus setting on the lens?

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Old July 6th, 2011, 05:25 AM   #10
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Re: Keeping focus of fast moving objects

Yes there will be a certain amount of area that will be in focus both forward and behind your point of focus because of the DoF.

Now having said that, let's look at the downside. There are a lot of mitigating factors when using zone focus at sporting events. First where is the camera placed in relationship to the field of play? Second, how far away is it? Third, how much zoom is needed to frame out the shot you need? Fourth, what's the lighting (consider F/stop and Shutter Speed) Fifth, how much area of coverage do you need? IOW are you going to be on top of the pressbox (say 50 feet off the ground) covering the whole field of play (say 100 yards) from sideline to sideline (say 55 yards) during bright daylight hours and your shooting position on the pressbox is about 100 feet from the field of play? If so give a "yahoo for you" cause you have it made in the shade (relatively speaking). BUT!!!!! Consider the other side. Say the lighting isn't as good or you have to zoom in more to frame the shot or covrer the field or the position of the camera is lower, farther away or closer. remember when up higher the panning isn't as fast, with brighter lighting you can work at a higher value F/stop for added DoF, you zoom in the iris closes (not always what you want but it will help in the DoF department...just hope for good lighting) oh yeah, a major factor, lense length. A 12X (whatever that means) on a 1/3 inch camera is going to be different than a 40X on a 2/3 inch camera. EVERYTHING about it will be different BUT the principle is the same. Find a spot on the field, focus on the spot, check your focus 10 yards in front of and 10 to 15 yards behind that spot, pan left and right to check the focus and if all the conditions are right, you win. If not then keep you hand on the manual focus ring and try to keep up.
This is why sporting events have up to 40 cameras covering the event.
When I did the NASCAR stuff we would have up to 10 robotics on the walls, at least 1 boom, 10 to 15 hard cams and heaven knows how many handhelds and none of them were 1/3 inch cams with 12X lenses. Not saying it can't be done because it can, you just have to work harder.
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Old July 6th, 2011, 06:46 AM   #11
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Re: Keeping focus of fast moving objects

I shoot my theatre stuff with the NX5U focused on a point about 1/3 from the front of the stage at about the centre of the stage. The NX5U is then used without focusing for the whole show for medium zoom shots to get most of the actors on stage BUT closeups are done by another camera that is focused for every shot a full stage fixed unattended camera is always there to fall back on in the edit. When the action is close to my focus point I can also zoom in for a close up. I alter gain to keep iris above f3.4 if I can so I do not get any ramping from the lens on zooming and to get consistent depth of field. Since I am usually 50 to 100 feet away from stage most things on the stage are within the depth of field for most of the time depending on stage lighting.

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Old July 6th, 2011, 07:47 AM   #12
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Re: Keeping focus of fast moving objects

Quote:
Originally Posted by Andrew Smith View Post
Is it me, or does the NX5U seem like it has a lot more difficulty in auto-focusing quickly (and maintaining it), especially when it comes to shooting sports?
It's not just you, it's me too Andrew. The actual finding focus is OKish, but any pans or tilts (with macro focus on or off) means it simply gives up completely, dissolving into a blur and taking time to come back sharp again.

My FX1 and Z1 were never like this. I could work off a tripod and pan from best man at the end of the long table to the bridesmaids at the other knowing the lens would maintain lens to BM distance and refocus when I stopped on the BMs. Not so with the NX5. You've gotta pan stupidly slowly to stop it wandering off into its bleary-eyed zone.

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Old July 6th, 2011, 07:59 AM   #13
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Re: Keeping focus of fast moving objects

It's almost as if the autofocus had a very late night involving lots of alcohol.

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Old July 6th, 2011, 03:47 PM   #14
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Re: Keeping focus of fast moving objects

Me three on this. It seems to have inherited its disability from its cousin the EX-1. For years I shot with a VX-2000 and don't remember ever having to focus unless I had specific reason to do so. So this is something that Sony has known how to do for more than ten years.
Yes, yes focus is more sensitive in hi-def but really, distance is distance....
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Old July 7th, 2011, 12:01 AM   #15
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Re: Keeping focus of fast moving objects

I would have thought that in a megabucks camera (not as much as others, of course) they would put in an autofocus system at least equivalent to one in their other cameras such as the V1. I mean, why would you go second-rate when putting out a new camera model???

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