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Old January 13th, 2012, 10:39 AM   #1
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Focus Issue with NX5U

When I record video with NX5U and go back to editing I notice that there are soft focus spots in the clips, especially in the face of the subject. This problem is not noticeable in the viewfinder when recording the clips. Here the image looks sharp and in focus. It is only when I view the clips in editing the face of the subjects look out of focus and only the face, the rest of the image looks in focus. If anybody knows of a correction to this problem please let me know how I can fix it. Thank you
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Old January 13th, 2012, 10:43 AM   #2
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Re: Focus Issue with NX5U

Are you manually focusing or using Auto Focus?
If using AF you need to remember it can be fooled and it hunts. AF works off of contrast and it the face is out of the range it will go soft. Especially if working at the longer end of the lens (zoomed in) AND the lens is working at a fairly wide F/stop. In that case, it's best to manually focus and use focus assist if the NX5 has it.
What do I know? I'm just a video-O-grafer.
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Old January 13th, 2012, 07:45 PM   #3
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Re: Focus Issue with NX5U

What Don said plus I am wondering if you are seeing motion blur rather than focus issues?

The reason I suspect motion blur is that the loss of focus seems confined to a few faces rather than whole areas or zones in the picture. With my NX5, when I get autofocus problems, my NX5 is either focus "hunting" (i.e., moving in and out of focus) or else the picture has a whole zone that is out of focus.

To be sure, the auto-focus on the NX5 is not great. I and others (particularly Ron Evans) have pointed out that auto-focus on Sony's little CX cams (and presumably the NX70 derived from them) works much better than the one on the NX5. Some of this is because autofocus with tiny cams is physically easier because there is a lot less stuff that has to be moved around. But a lot of it is that the CX cams simply have better programming for their auto modes. Other DVinfo members have pointed to some focus artifacts that can occur in some situations when using the NX5's enhanced "active steadyshot" rather than the other optical image stabilization options on the NX5. (Sorry, I can't find the thread on this, but I think it was last summer or spring and I think that Dave Hardwicke was one of the participants).

I am assuming that you are not having those kinds of problems. Also, I am assuming that you are seeing the loss of focus while playing the video in motion and not just while looking at individual frames of video. I mention this only because some people reading this thread later might be new to high def video editing and might expect every frame to be "perfect." (I see postings about this every few months). So for any newbies who read this later, we are talking about focus problems seen while the video is playing.

Another question to ask: if you hook your camera directly to TV --- use an HDMI cable because the the yellow composite cable with the RCA plug does not carry a high def signal --- do you see the same loss of focus in the faces?

If the footage is in proper focus on the TV but not during playback on your computer while editing, you may have your editing program's playback resolution set too low. Setting playback resolution to, say, 50%, may speed editing and playback but it can make footage look out-of-focus.

With those things out of the way, what comes immediately to mind is three things on the NX5 that can yield motion blur.

1. What shutter speed you were using when you shot the footage with the faces seeming to lose focus?

2. If you were shooting progressive modes, were you shooting 720/60p or something slower like 1080/30p or 1080/24p?

3. And, finally, were you recording in the FX format (25 Mbps AVCHD) or one of the lower bit rate modes such as the FH (17 mpbps AVCHD)?

First, I have noticed something like the effect you describe when shooting, say, dances at wedding receptions or recording concerts with somewhat dim lighting and when when I have set my NX5 shutter speed down to 1/30th second. Going down to 1/30th avoids grain that would result if I boosted the gain. (By the way, that would be 1/25th if you are in PAL land.) But, the trade off with a 1/30th shutter speed is that the slow shutter speed increases the risk of motion blur. It is particularly noticeable when there are faces in motion and I am panning or moving the camera. Even when people are standing still, they often move their heads and faces, sometimes quite rapidly. At slow shutter speeds, that can produce blurring.

This is not limited to 1/30th second nor is it peculiar to the NX5 . Motion blur happens anytime something is moving faster than can be cleanly captured at a camera's shutter speed. We tend to notice it more with faces because our brain tends to zero-in on the faces when we look at images.

So, I would check the data codes for your footage to see what your shutter speed settings were. If you had the NX5 on full auto, you might try manual shutter speed settings the next time you shoot in similar conditions and see if that avoids the problem with face focus.

Another second thing that can produce a similar blurring effect is when you have chosen to use a recording mode other than the highest bit-rate of 25 mpbps AVCHD under FX mode. The NX5 gives the option of shooting at lower bit rates such as the 17 mbps of FH mode, While these settings allow you to record a lot more video, the increased compression translates to motion artifacts and a loss of detail that may appear as lack of focus on playback.

The third thing that comes to mind is the use of progressive recording format. If you are shooting in 720/60p we can rule out the format. But, if you are shooting in 30p or 24p, then you may very well be seeing motion blur for the same reasons seen when using slower shutter speeds. It is a part of the "flim look" that some folks are passionate about. This blurring can be good or bad, depending on your intent. But, if you have been using 24p or 30p modes, try shooting in 720/60p or 1080i.

Hope this helps you figure it out.
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Old January 14th, 2012, 08:40 PM   #4
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Re: Focus Issue with NX5U


It sounds like you're just not focusing correctly. Assuming this to be the case, here are some tips.

-Use manual focus when possible
-Use the expanded focus.
-Zoom in to focus, and then zoom out to frame your shot when possible.
-Use the viewfinder rather than the LCD.

In the focus game, close is often not good enough. Keep practicing.

Alec Moreno
Wedding Art Films - Southern California - Los Angeles - Orange County - Video
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Old January 15th, 2012, 09:45 AM   #5
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Re: Focus Issue with NX5U

Also make sure ant-flicker is OFF. It`s on by default. Focus is VERY critical with the NX5U and most HD cameras. Follow Alex approach( I still use the LCD ) and also have peaking on to make sure that things stay in focus as you move around. Check the distance scale too to make some judgement as to what makes sense. Also keep your iris F4 or more ie F2.8 to F4 as I believe this is around the sweet spot for the lens and sensor size. At first I thought the NX5U was no better than my FX1 and certainly not as good as the XR500 or SR11 consumer cams. It has taken me a little time to get the focusing and exposure to definitely now see the difference. Default black level is too high, colour a little low, detail a little less than the consumer cameras. So play with the picture profiles to get what you want.

Ron Evans
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Old January 15th, 2012, 10:38 AM   #6
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Re: Focus Issue with NX5U

Sounds like the Skin Tone setting is turned on. This function will detect and soften the face with the idea of eliminating or softening wrinkles and blemishes. It's on by default when you first get the camera.
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Old January 15th, 2012, 11:52 PM   #7
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Re: Focus Issue with NX5U

A very good point which I had forgotten about. My camera came with Skin Tone set to "off." But, I briefly experimented with settings after getting my NX5 and noticed this kind of effect in crowd shots, and have left Skin Tone off. Ron's advice about "Anti_flicker" is also a thing to check. (Basically, you want anti-flicker set to on when you are shooting computer screens or Power Point projections.) If you have either set to on, turn it off.
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Old January 19th, 2012, 07:03 AM   #8
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Re: Focus Issue with NX5U

Thanks everyone for your tips. I will play around and record different times with all your suggestions. I'll keep in touch if this problems continuous to occur.
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