Back Focus Again

[Lee Berger]

I spoke to another V1U user over the phone today. He reported the same back focus issues with his unit. He suggested it may be a design flaw.

[Piotr Wozniacki]

Lee, now you're getting me interested! I've never spotted anything like that on my V1E, but am willing to check again... Could you sum up the best procedure (conditions when the problem is most evident; lighting, distances, iris values etc)?

[Ian Campbell]

Hi Piotr . . .

Do your testing with your V1 camera with the aperture as open as possible (my testing was in the f1.7 - f2) range. As someone rightly pointed out, doing a test at a higher f value will likely mask the focus issue due to the greater depth of field. As you know getting a shallow depth of field is a challenge with these small sensor camcorders.

I spotted the back focus problem in footage we just shot in Ethiopia (documentary shoot). The softness is subtle. When you pull out of a tightly focused shot (in my case interview footage) where the subject's face is in tight focus the reframed medium and wide shots are somewhat soft looking. Hair and facial detail seems to disappear -- totally taking the wind out of Hi-Def impact. I believe this is a design flaw (maybe only with the "U" (NTSC) cameras. Since both my cams do the same thing, I feel it's like the lens isn't properly matched to the sensor.

Piotr, I would be very intersted to know what your testing indicates.

As mentioned, one of our little HC1 cameras totally blew the V1U's out-of-the-water when it came to putting it through the same testing as the V1U's.
Your profile suggests that you used to have an HC1. If you still have access to one, try the comparison by doing the same tests with both model camcorders.

I used Lee's testing scenario by setting the camera 8.5 feet from the subject. Lee used a skull and cross bones hat . . . I used an embroidered pillow with a design. The pillow had lots of detail, texture and contrast which worked nicely. As I mentioned in a post from last night the focus is very puzzling.

Try this: Focus tightly on your subject. Pull out about 1/2 way from telephoto toward wide. Play back to compare this result with what you find by focusing at 5', 6' . . . 10', 11', etc. I found that the image looked sharp at 18' -- again this is when the subject was reframed to about half way through the zoom range. This is not aceptable. If you look at the footage on a good monitor you will see the difference IF you have the problem.

Since I have two of these defective units and didn't notice until several months after my purchase, I suspect that others will find the flaw too after close examination. The soft focas can be subtle. But with my Sony 0862k wide angle adapter some of the bad footage really jumped out as unusable.

Note: Today I took my two Sony V1U's to Sony Canada (their Canadian headquarters) and had the privilage to see a tech. I showed him some of the footage that is soft, BUT he only had CRT diagnostic equipment to view the footage on . . . which didn't show off the flaw easily. He said he could see the issue even on the small screen we watch on. He said that he might need to contact the Japan offices regarding the issue. He hasn't heard of this back focus issue with the V1U before, but did say that it might be something that needs investigation.

I hope I have the units back within a week since the project I'm shooting is for broadcast and the shoot isn't completed. The worst part . . . all the African material can't be reshot. With over 80 hrs. of footage shot, I'm not looking forward to looking at footage that can't be used due to a Sony flaw. Not good.

Note: Someone posted that Sony told them that the back focus problem was because the user left the camera in the default "macro" mode. Both Lee and I find that it dosn't matter.whether the macro is set to on or off. The footage is poor regardless.

Lee . . . if you require my support (or wish to talk about this issue) please feel free to write to me at ian.campbell@digitalplayhouse.ca. I would be happy to provide my phone number. I suspect that if this IS a more common problem than first realised we might need to help one another get the message to Sony.

Piotr . . . I do hope that your unit is perfect. I hope your testing gives you good results. Keep us posted.

Ian

[Lee Berger]

Originally Posted by Piotr Wozniacki

Could you sum up the best procedure (conditions when the problem is most evident; lighting, distances, iris values etc)?

Sure Piotr,
I did the test in my office, daylight coming through the window. I connected the analog component out to my Sony Professional NTSC monitor. I placed a hat on my desktop, approximately 8.5 feet away from my V1U set on a tripod. I set the focus to manual, and zoomed all the way in on the hat, adjusted the focus. Then I zoomed out to frame the hat. I noticed on the monitor the image appeared soft so I adjusted the focus to compensate (had to go to infinity). I then zoomed in again and the hat was out of focus. I repeated the test several times, from close up, to full shot, to wide shot. All were out of focus until I made a focus adjustment. I double checked to see if the macro mode was engaged and it was not (it didn't seem to make any difference anyway). The apateur was fully open (gain at 0db), but gaining up and choosing a smaller apateur made no difference. Here is my original link with pictures
http://www.dvinfo.net/conf/showpost....11&postcount=1

[Greg Laves]

Here is a link to a site with a good back focus chart. I think you will find this is superior to other objects that you are currently using to test for back focus. I printed mine out on 11 X 17 photo paper and it worked great. If you don't have a large printer 8 1/2 X 11 will work also.

http://www.rondexter.com/focus_pattern.pdf

[Lee Berger]

Thanks Greg! It would be even more useful if you could actually adjust the back focus.