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-   -   Focus Issue's- Your Thoughts (https://www.dvinfo.net/forum/sony-trv950-pdx10-companion/36745-focus-issues-your-thoughts.html)

Steve Tapping December 22nd, 2004 06:57 AM

Focus Issue's- Your Thoughts
 
Here is a link to a short piece of footage that I shot with the PDX10P.
http://users.tpg.com.au/tappings/MattyA-FocusIssue.mov

As you can see the shot remains in focus up until about the 5 second mark when the rider is Airborne. The image gets soft here. Is this the limitations of the lens or can I some how avoid this? DOF issue maybe.
I set my focus to infinity, I some how think I will have even more problems if I set it to auto with that much movement happening.
The cause and solution of this problem is what I need. Thanks.

Rob Lohman December 22nd, 2004 07:07 AM

I find it hard to see with the compression and all.

However a few things come to mind:

1. you are on manual focus (don't know your camera) I understand from your "infinity" remark? If not then auto focus might have been lost

2. you where zooming in? your f stop may have changed because of this resulting in a depth of field shift

Boyd Ostroff December 22nd, 2004 07:42 PM

I can't really tell what you're talking about there either - I actually thought the video looked very cool! But the combination of small size and compression really make it impossible to judge focus in that clip. Looking at still frames from the section you describe, your "focus issue" looks more like motion blur to me.

You may have better luck with autofocus, I wouldn't assume that infinity is really what you want when zoomed way in. I was just shooting something today and focused at infinity. I then zoomed all the way in and noticed it went way out of focus. As a compromise, try setting manual focus and get in the habit of periodically punching the "push auto" button as you shoot.

Steve Tapping December 22nd, 2004 08:24 PM

I should have cleared a few things up. I'm using a waterhousing and getting the shot by sitting on my board in the water. Although zooming is possible, in that shot no zoom(in or out) has occured, The shot is zoomed in to about halfway through the zoom range. about 6x. I have to set focus before I go out because I have no controls to alter it when the camera is in the housing. It could be just water on the port. Shouldn't be though. maybe from the spray. I will have to do some more experimentation. It's just that I had rarely noticed it before this.

Boyd Ostroff December 22nd, 2004 08:37 PM

Aha, that sort of changes everything then, huh? :-) Try autofocus, but you're probably right that it will try to focus on water droplets on the housing, etc. But really, from that low res clip I didn't see much of a problem. I'd expect to see some motion blur in that sort of shot. No doubt the problem is more obvious when the raw footage is viewed on a good monitor.

Chris Beacham December 24th, 2004 02:29 PM

Hi Steve,
As someone who has just purchased a PDX10 for surfing shots (and some Scientific work as well..) I was pleased to see a 16:9 clip from your PDX10.
It seems to me that the camera performed in focus until you had another subject (the surfer in the foreground...) enter the frame. When the camera reacted to focusing on this, you lost focus on your original subject.

What underwater housing do you use?

This is my first post here. While I have shot 16mm back in the '60s this is my first week with the PDX10 and I very much appreciate the informed discussions in this forum. I felt like I knew the camera before I started shooting!

Boyd Ostroff December 24th, 2004 04:50 PM

Hi Chris and welcome to DVinfo! Will look forward to hearing your impressions of the PDX-10.

In Steve's first post he said the camera was manually focused at infinity, so unless he was mistaken that would rule out any autofocus reaction to a foreground subject.

David A. Smith December 26th, 2004 03:55 PM

While I dislike auto focus as a rule, your situation might call for it since the lens is inside your waterproof housing. I've only recently started using the PDX10 so am not too familiar with how it would react, but the Program AE feature set to Landscape mode is supposed to prevent the auto focus from tracking close objects. That might prevent water on the housing causing a focus error. Take a look at page 66 in the manual.

I think Boyd may have a point about motion blur creating the problem you're seeing. Playing with a higher shutter speed might be helpful. It also may be that he's just gotten so much closer at the point you loose focus that the infinity setting was no longer appropriate.

This is certainly an interesting issue to solve so doing some playing on non essential footage, and taking good notes about the settings for each take, would be a good way to go.

David

Steve Tapping December 26th, 2004 08:35 PM

Chris I use a custom made housing specifically for surf work made by an Australian guy named Dave Kelly. He does the majority of surf housings for professionals and amateurs in oz. At $2000AUD a housing the target is at the professional market with high quality custom craftsmanship. He lives in Newcastle so just a little north of you and surfs himself. He is such a nice guy and a pleasure to deal with. If you would like his contact details I can give them to you. He is extremely busy however and you will be put in about a 6-month waiting period.

I spoke to a friend who does a lot of water work and he notified me that he uses auto focus and just makes sure the port is always clear. I'll be sure to test all options and get back to everyone.

The shutter speed I was using in that shot was 1/600. Using shutter speeds of 1/50 or 1/100 the motion blur is incredible and can only be used if I want that effect. I am in fear of going over 1/600 because of the smearing with light reflecting water. Some how I think it was a focus issue however because it occurred in another shot in a completely different situation.

Anyway thanks for your help Rob, Boyd, Chris and David much appreciated.

Chris Beacham December 27th, 2004 11:02 AM

Hi Steve,

I look foreward to seeing more surf clips...!

Yes, I am interested in Dave Kelly's email address, and I would be grateful if you could contact me: cbeacham@tig.com.au


Hi Boyd,

Well, it looks like I have my work cut out for me with the PDX10....shooting into the Sun in the morning and shooting the Sky at night! I will start a new thread when I have a bit more experience with the camera.....

Ronald Lee January 3rd, 2005 04:58 PM

HI Steve,

I didn't really want to post this, as this will be an unpopular answer, but....after seeing your video, are you sure that the camera is on manual, not auto focus?


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