Z7 Major problem??

bruceo wrote on 4/11/2008, 8:35 PM
I always shoot full manual and one of the main compositional/setting places I live when shooting is at full tele, fully open iris. What I have found on both Z7s that I have is when you zoom in full tele to pull focus and then zoom out to compose the image gets slightly soft at the right and center and the left side gets very blurry. See screen shot here http://www.firstsightpictures.com/z7blur.jpg

So if you zoom into a bridal party or couple from a distance or anything at all to get a shallow DOF the focus plane on the left will be out of focus as you see the tree on the left out of focus. Yes i did do the auto and manual flange/backfocus adjustment but there was still no change in the result. This is EXTREMELY bad for any manual shooters who shoot creatively.

So Z7 users. Put the cam in full manual use ND and or shutter to bring your exposure into range and then zoom in fully to a lineup of subjects that are the same distance away if your iris is wide open it should be at 2.0, ten back out until you see the iris limit go to 1.8. In this range you should see the inconsistency at it's worst. I have already confirmed with another user that his Z7 does the exact same thing but the blur is on the right side.

Here is a short video clip http://www.firstsightpictures.com/z7blur.wmv of my closeup cam on a dance performance. You can see where I go in tight to pull focus twice during the clip and zoom out for a head to toe and it gets a little soft and then anytime the performers are in the left side of the frame it gets even blurrier. You can't see it at all on the Z7 LCD, even with peaking it looks to be in focus.

Comments

Spot|DSE wrote on 4/11/2008, 10:38 PM
Bruce, you're the second person to bring this up....it's unfortunate, but not surprising. I don't have one in my room to check, but I do have a focus chart in my training area; I'll see if mine is doing this. I did have a problem with the blur on another cam (not the Z7), but haven't caught it on the Z7. If it's really a factory issue, hopefully it's a firmware upgrade like the EX was.
farss wrote on 4/12/2008, 1:58 AM
Well as far as I can tell from all the posts at DVInfo the EX1's backfocus problems are not fixed by any firmware upgrade.

One problem area is that going from no ND to putting the ND filters into the optical path is the back focus changes. Not exactly a new problem and I think even between each ND filter you can get a shift unless they're all optically matched.

I had hoped on the EX1 the firmware was smart enough to keep a backfocus lookup table for each ND filter setting but from tests others have done we're not so lucky. Short of replacing the ND filters this would be the only way to fix the problem that I can think of.

Well the other way is to get the BF right for no ND and use external ND filters in front of the lens. If Sony can't solve the problem on the EX1 that's what we'll be doing.

Aside from that though if you're getting delta focus across the frame that's a worry. At least one EX1 user seems to be having this problem too. However on a camera with an interchangeable lens that's even more of a worry as it could indicate the mount is off.

Bob.
bruceo wrote on 4/12/2008, 9:32 AM
So far the 4 we've tested 3 exhibit it exactly the same on the left side and the 4th is exactly the same but on the right side. This is extremely bad for event shooters because even in auto for most situations that is where the camera settings are going to live. Bob, this is exactly the same no matter what ND filter is chosen Here is a new video version of the pic after about 5 automatic and manual flange adjustments.

http://www.firstsightpictures.com/Z7blur2.wmv
bruceo wrote on 4/13/2008, 7:50 AM
If you have a Z7 you better test it, so far everyone we've tested has it and it is not good.
Here is a focus chart screen grab.

20 meters away centered exactly on the middle square. Pulled focus on the left target and zoomed out about 20% F1.8

http://www.firstsightpictures.com/z7focuschart.jpg