Problem with Autofocus in the EX1 - Page 2 at DVinfo.net

Go Back   DV Info Net > Sony XAVC / XDCAM / NXCAM / AVCHD / HDV / DV Camera Systems > Sony XDCAM EX Pro Handhelds

Sony XDCAM EX Pro Handhelds
Sony PMW-300, PXW-X200, PXW-X180 (back to EX3 & EX1) recording to SxS flash memory.


Reply
 
Thread Tools Search this Thread
Old July 29th, 2008, 10:47 AM   #16
Major Player
 
Join Date: May 2002
Location: West Central Florida
Posts: 762
On a related note, does anybody know where the autofocus detects these changes? I'm assuming that it is detecting changes inside the small center square but I'm not sure.
Dave Morrison is offline   Reply With Quote
Old July 29th, 2008, 10:51 AM   #17
Trustee
 
Join Date: Jun 2004
Location: Denver, Colorado
Posts: 1,866
You can observe the behavior of the auto focus by leaving peaking on. Set the color to red, level mid or high.

It's pretty understandable what it keys on, tilt the camera up or down a few degrees on your subject and observe the change. If it's locked down and the subject doesn't move, neither does the focus.

It also helps immensely to have detail ON. You can adjust the parameters of the detail setting to eliminate most of the concerns with it, namely the ugly EE halos. For example, for 60i turn the detail level to +10, the frequency to +50, the black limit to +50, and the white limit to -50. You'll struggle to see any halo-ing at all. For 24/25p, that's way too much sharpening however, turn the level down to -13 or whatever suits your preference. The salient point, is that contrast within the details is what the auto focus keys on. If you want to use auto focus, your opportunities are reduced when you turn detail off.
Tom Roper is offline   Reply With Quote
Old July 29th, 2008, 11:13 AM   #18
Regular Crew
 
Join Date: Oct 2006
Location: Surrey
Posts: 77
Quote:
Originally Posted by Tom Roper View Post
...If it's locked down and the subject doesn't move, neither does the focus.
Thats not what I get with mine. I get constant hunting once focus is achieved. Its as if the AF is constantly moving to focus slightly either side of the current focus point to assess the sharpest focus. I know I am not alone because there was a lot of discussion on the subject in the early days. Are you sure yours stays rock solid in focus if you leave the AF switched on Tom?

Quote:
Originally Posted by Tom Roper View Post
...The salient point, is that contrast within the details is what the auto focus keys on. If you want to use auto focus, your opportunities are reduced when you turn detail off.
Again. Are you sure Tom, I haven't got my camera here to check but it would seem crazy to make AF effectiveness dependent upon the detail setting. Detail does affect the display of peaking however so if detail is off peaking is reduced and you don't see so much peaking when things are in focus, doesn't mean they aren't just as in focus though.

M
Martin Drew is offline   Reply With Quote
Old July 29th, 2008, 11:24 AM   #19
Trustee
 
Join Date: Jun 2004
Location: Denver, Colorado
Posts: 1,866
Quote:
Originally Posted by Martin Drew View Post

Again. Are you sure Tom, I haven't got my camera here to check but it would seem crazy to make AF effectiveness dependent upon the detail setting. Detail does affect the display of peaking however so if detail is off peaking is reduced and you don't see so much peaking when things are in focus, doesn't mean they aren't just as in focus though.

M
That's a good point Martin. It would seem crazy to make AF effectiveness dependent on the detail setting. But then why make peaking dependent on it?

What I am sure of, is that I see the focus hunting stops after 2-3 seconds, on clear targets in front, with non-confusing uncluttered backgrounds. I know this because the distance/depth of field display stops moving, and the distribution of the peaking dots.

When you get back to your camera, will you try turning the detail on for a test? Interested in your finding. Again, I'm getting decent auto-focus performance, with detail at the above settings, std3 gamma.
Tom Roper is offline   Reply With Quote
Old July 29th, 2008, 11:43 AM   #20
Regular Crew
 
Join Date: Oct 2006
Location: Surrey
Posts: 77
Quote:
Originally Posted by Tom Roper View Post
That's a good point Martin. It would seem crazy to make AF effectiveness dependent on the detail setting. But then why make peaking dependent on it?
The video signal displayed on the LCD is post processing, which is a plus because it means you can see the effect when you change the level of detail or gamma etc, etc. Peaking, Zebra, and other operational information is applied to that processed video signal for the LCD so they are affected by the processing previously applied. So it isn't ideal if you are using peaking as a focus assist for manual focusing, but it is understandable why it is done in this way. In contrast, I can't see any advantage to using a post processed signal for AF feedback, it would seem to make more sense to take that pre-processing and add any function specifically appropriate to improving AF effectiveness. That doesn't mean I am right of course, just seems odd to me. I will have to check on my camera when I get a second.

Quote:
Originally Posted by Tom Roper View Post
What I am sure of, is that I see the focus hunting stops after 2-3 seconds, on clear targets in front, with non-confusing uncluttered backgrounds. I know this because the distance/depth of field display stops moving.
Not for me. locked off camera, siemens star filling the entire frame and it still hunts. Not dramatically but very noticable if you are looking for it. It could be that some cameras are better than others. I hope that is that case, if it is I will get mine fixed.

M
Martin Drew is offline   Reply With Quote
Old July 29th, 2008, 11:48 AM   #21
Regular Crew
 
Join Date: Oct 2006
Location: Surrey
Posts: 77
Quote:
Originally Posted by Tom Roper View Post
...When you get back to your camera, will you try turning the detail on for a test? Interested in your finding. Again, I'm getting decent auto-focus performance, with detail at the above settings, std3 gamma.
Will do

M
Martin Drew is offline   Reply With Quote
Old July 29th, 2008, 03:06 PM   #22
Trustee
 
Join Date: Jun 2004
Location: Denver, Colorado
Posts: 1,866
I do agree with your logic Martin, except I don't understand why peaking should be displayed post processing. I do understand why Detail ON would be displayed post processing, but not peaking.

Peaking is a very functional focus aid, doesn't have any other purpose, and could be made even more functional if you didn't have to enable the Detail ON circuit to obtain the full benefit of the peaking. Why wouldn't the same level of peaking be displayed preprocessing?

It's that specific peculiarity that makes me question whether Detail ON is contributing to improved Autofocus behavior, or as you would say...not.
Tom Roper is offline   Reply
Reply

DV Info Net refers all where-to-buy and where-to-rent questions exclusively to these trusted full line dealers and rental houses...

Professional Video
(800) 833-4801
Portland, OR

B&H Photo Video
(866) 521-7381
New York, NY

Z.G.C.
(973) 335-4460
Mountain Lakes, NJ

Abel Cine Tech
(888) 700-4416
N.Y. NY & L.A. CA

Precision Camera
(800) 677-1023
Austin, TX

DV Info Net also encourages you to support local businesses and buy from an authorized dealer in your neighborhood.
  You are here: DV Info Net > Sony XAVC / XDCAM / NXCAM / AVCHD / HDV / DV Camera Systems > Sony XDCAM EX Pro Handhelds

Thread Tools Search this Thread
Search this Thread:

Advanced Search

 



Google
 

All times are GMT -6. The time now is 07:21 PM.


DV Info Net -- Real Names, Real People, Real Info!
1998-2017 The Digital Video Information Network