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Old November 25th, 2010, 01:58 PM   #1
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NX5 loses focus as you pan

The NX5 has great difficulty holding focus as you pan in the auto focus mode, anyone else notice this? My Z1 didn't have the slightest difficulty holding onto a focused distance as I panned round, but the NX5 just gives up and blurs out. I know, I know - I should be using manual focus. But there are times in life when there's no time in life.
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Old November 25th, 2010, 03:38 PM   #2
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Hi, Tom. I have had the odd blurry pan, yes. Not often enough for me to worry much about it, and if I recall correctly, the lighting was less than ideal when it happened. I ran into the same thing a few times with my Z5 (when I had it). Maybe an issue with the newer G lens system if the Z1 never hit this.

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Old November 25th, 2010, 10:13 PM   #3
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Nxcam

Just a note, my FX1000 does the same thing, especially in lower light settings on Auto. I agree with previous comment about related to the new G lenses system being a contributing factor.
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Old March 16th, 2011, 09:24 PM   #4
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Re: NX5 loses focus as you pan

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Originally Posted by Tom Hardwick View Post
The NX5 has great difficulty holding focus as you pan in the auto focus mode, anyone else notice this? My Z1 didn't have the slightest difficulty holding onto a focused distance as I panned round, but the NX5 just gives up and blurs out. I know, I know - I should be using manual focus. But there are times in life when there's no time in life.
Tom let me tell you I am glad that someone else is experiencing the same problem I am. I have been going crazy trying to eliminate the problem playing around with shutter speed aperture and so on but I was not able to even minimize the problem. I do agree it must be the lenses. Unfortunately I noticed this problem 3 weeks after I got the camera and so I could not return it to BHPhoto. I think that the problem shows up in both autofocus and manual mode A couple days ago I took the camera to the Sony authorized service center in Teaneck NJ and they told me that it is normal. They recalibrated the focusing but it did not improve anything. I believe we should demand some satisfaction from therm. We paid good money for our camera and they should acknolewdge the fact that there is a problem and solve it for us. I think everyone who is having the same problem should call Sony. The more people reporting the problem the better. One final thing Tom. Could you do an experiment for me. Mount your NX5U on your tripod. Connect it to your High definition TV or computer monitor with an HDMI cable. Position an object with writing on it about 7-8 ft away from the camera. Zoom in onto the writing, manual focus on it and pan slowly back and forth. You should clearly see the out of focus happening on your monitor. I did the same experiment with 2 other high end cameras of friends of mine and it did not do it. Please report back to me and let me kinow the result. Thank you, Umberto.
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Old March 16th, 2011, 09:41 PM   #5
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Re: NX5 loses focus as you pan

Umberto, if your camera is having a hard time holding *manual* focus, there is "something else" wrong. This thread is about autofocus, not manual focus. I've done plenty of things similar to the test you suggest and have never had a problem. The *autofocus* on the NX5 does tend to be a little touchy, and when panning with autofocus and a bit of zoom, it does tend to lose focus and have to "search" a bit more than some other cameras I've used. That said, I owned a Z5 before this camera, and it had the same tendency, so it's not just an NX5 issue.

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Old March 17th, 2011, 03:23 AM   #6
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Re: NX5 loses focus as you pan

Are you sure that the effect is actually 'losing focus', especially if it is the same on manual and auto focus. If it's on manual focus, it won't be trying to focus, and if the scene's features are positioned such that they should stay in focus, then it must be something else.
AVCHD, just like HDV, is an interframe compression codec that relies on tracking the changes in the frames between the keyframes, (every 12 or 15 frames for HDV). Most of the codec's bit budget is committed to the full keyframes, the interframes then do what they can with what's left.
Even at 24Mb/s, AVCHD is still relying on a great deal of similarity between successive frames, as would be encountered in most normal shooting. If you exceed this, the codec takes short cuts. This does happen on the FX1 and my HC3 so I have to bear that in mind. It depends on how much detail there is in the scene through the pan of course.
As an experiment, why not try (in manual focus) shutting the aperture down to, say f5.6 or f6.8, i.e. just before diffraction is a problem, and using fixed focus, pan the camera accross a scene with equidistant features, i.e. something at least 30 metres away which should be well within the len's depth of field. In this setup, the lens would not be expected to lose focus on the scene's features. Try panning at both low and higher speeds. It might be worth repeating the test at a lower bitrate, where the effect would be more pronounced.
I suspect the the faster the pan is, the more blurring occurs. If it does, you are just looking at a limitation of interframe compression. If the compressor didn't soften the image, the bitrate shortfall would just create blocks that would be more obtrusive.

HTH

Steve
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Old March 17th, 2011, 07:20 AM   #7
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Re: NX5 loses focus as you pan

Ok, I realize that I did make a mistake describing my problem as a focusing problem. My focusing works perfectly. It's just a blurring problem when I pan. And yes it does get worse as I pan faster. Also while I am focusing, if I use peaking, is it normal that the sparkling action ( from peaking) goes away as I pan? Thank you, Umberto.
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Old March 17th, 2011, 07:59 AM   #8
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Re: NX5 loses focus as you pan

I thought I should explain why I thought it was a focusing issue. If the sparkling action that you get from focusing with peaking turned on is an indication that you are focused onto the subject then if it goes away when panning should not that also be an indication that you are loosing focusing? Please let me know if this makes sense ! This is my first experience with both High def video and professional video camera. Thank you.
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Old March 17th, 2011, 10:09 AM   #9
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Re: NX5 loses focus as you pan

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Originally Posted by Umberto Palmeri View Post
...This is my first experience with both High def video and professional video camera. Thank you.
I have both the Z5 & NX5 - I would not call them "professional" video cameras. Sony might want to call them as such but it's just another marketing description thrown around. They do the job for certain projects but can fall short for others. But I guess the word "professional" does get over used - yes it's got this, that, and the other, therefore it must be... but it simply isn't. Now if you were to tag the word "professional" to the user, then you might have a more accurate description. It really is a case of knowing the pros and cons of any camera and getting the best from it - hopefully everytime.

Getting to Tom's OP, it's something I've seen in the past. Following one experience, I did some lens tests and found the lens assembly not to come up to what I have seen from the results of say the EX3 or P2 format used for other stuff. So Steve may have a point in relation to bit-rate too.

One thing I did see as regards a focus issue under certain conditions is that the ND filters are not the best and have caused me some problems in the past with focus tracking - and once a poor result on a long pan too. I sent both cameras back to Sony and they came back as NFF (no fault found). One reason why I now switch the ND out and stop the lens to no more than f5.6 in my exteriors - changing shutter speed to compensate. I add ND only if I'm forced. I now know better.

I am about to move to an EX3 (assuming there are no surprises at NAB this year) - smooth as glass in comparison. No help to Tom, but I don't see Sony doing anything about it (nor admitting there is any issue to address).
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Old March 17th, 2011, 10:53 AM   #10
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Re: NX5 loses focus as you pan

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Originally Posted by Umberto Palmeri View Post
Ok, I realize that I did make a mistake describing my problem as a focusing problem. My focusing works perfectly. It's just a blurring problem when I pan. And yes it does get worse as I pan faster. Also while I am focusing, if I use peaking, is it normal that the sparkling action ( from peaking) goes away as I pan? Thank you, Umberto.
Yes it is normal for the peaking indication to disappear when you move the camera.

What is being described in this thread is what happens when the video codec runs out of bandwidth. It is pretty easy to get HDV and AVCHD to do this.

First and foremost to understand is this is not a defect but a limitation.

On the plus side AVCHD has a more pleasing effect when the bandwidth is exceeded where the macroblocking in HDV is chunky and looks worse in my opinion.

If you need good looking and sharp pans you need to consider using an off camera recorder or moving to a camera with a higher bitrate codec such as XDCam. My EX1r is much less susceptible to macroblocking.
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Old March 17th, 2011, 12:53 PM   #11
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Re: NX5 loses focus as you pan

Are there any recommended settings to minimize the blurring which occurs when we pan? Higher shutter speed? I have to make a video of the inside of a jewelry store. I have some panning to do and I would appreciate if anyone could tell me what settings should I use to minimize the blurring effect. Thank you.
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Old March 17th, 2011, 01:20 PM   #12
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Re: NX5 loses focus as you pan

Selecting the highest bitrate setting is the most you can do to reduce the motion blur inside the camera.

Some things to improve the situation and reduce the needed bandwidth is to minimize the detail in the scene around the subject. More detail + movement equals more bandwidth required for blur free image capture.

Make sure the scene is well exposed. Make sure there are no highly saturated and noisy areas in the shot.

If the above doesn't not solve the issue sufficiently you must consider an external recorder such as the NanoFlash. You will not have bandwidth problems with that recorder.
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Old March 17th, 2011, 02:50 PM   #13
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Re: NX5 loses focus as you pan

Umberto,

If panning is an issue for you, you could try shooting at 720p 60fps to see if you get a more pleasing picture.

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Old March 17th, 2011, 03:26 PM   #14
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Re: NX5 loses focus as you pan

Actually, 720p/60 may give a better result for 2 reasons:

1) the reduced amount of data per frame will give more compression bandwidth

and

2) for a given angular pan rate, there will be less change per frame as the frames are more frequent. This will also help the codec on some image types

Steve
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Old March 18th, 2011, 10:11 AM   #15
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Re: NX5 loses focus as you pan

I sincerely want to thank you all of you for trying to help me. I got more information and satisfaction from you guys than I got from Sony Tech Support. I will definetely try the 720/60p and see if the results will be better.
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