Hi all, my Z7 has major back focus issues, and I was wondering if someone could check something for me?

its impossible to get it sharp when wide, and it doesnt just look soft, it looks slightly refracted, which lead me to inspect the lens itself.

Could someone take their lens off, and look at the back of the lens. When you tilt the lens back and forward, can you see the back lens element moving back and forward as you tilt it? Im 99% sure this should not be happening! I can literally see the back most lens element moving a full centimeter back and forward as i tilt the lens.

My first thoughts were that you were seeing something related to the optical image stabilization. But I looked into the back of mine and I am not able to see any obvious movement.

Well Peter,

Either bad news for me, or good news for you. My lens moves a bit. (Took a bit to finally see it.) See if you can watch the attachment & let me know if that is what you're getting.

Also, have you tried to do the "back flange," or something like that, which is talked about in the manual. The lens my just be out of adjustment & if you run one of the menus that might fix it.

Next, try to make sure the lens is sitting correctly, all the way it is suppose to. Something silly, but often that can be the problem.

Let us know.

Hi Zach, thanks for the video. Thats exactly what my lens does, and im convinced it shouldnt do that! I havent used any other broadcast lenses that have any lens element that can freely move like that.

anyway- re: flange back- im familiar with larger cameras and lenses, so im aware of back focus or 'flange back' as sony refer to it. The Auto flange back still leaves the wide shots looking soft. With manual flange back adjustment, I can get it close, but its still not sharp- i rotate the ring, it gets close, and then it just runs out of adjust. i just need it to go a bit 'more'

Ive had a friend whos a focus puller take a look, and we're both agreed that something isnt right- either in the lens or the camera.

Tried a fujinon lens on this morning (from a jvc camera), and that lens has a proper back focus ring, and that looks fine when set up, so have a suspicion something isnt right with the lens itself, rather than the camera.

Ive rung sony prime support, and the engineer I spoke to seemed to know what i was on about- he said he'd had a few back like this, and 'if its what i think it is, we'll replace the flange back element and have it back in no time'

Heres a couple of screen shots of some focus charts. Camera was 2 metres away from chart, chart was lit with a 3200K colour temp tungsten lamp, and the cam was white balanced. Cam is fully on manual, and I used ND to achieve correct exposure. Shot in 1080i.

These are cropped to 100%:

Tele end of the lens, F2, focused manually:

http://i7.photobucket.com/albums/y271/Fordimus/focus1-teleendF2manualsharpsmall.jpg

You can see looks reasonably sharp. A little electronic flare perhaps, but nothing out of the ordinary for a small sensor HDV camera.


Wide end of the lens, F1.6, back focus set manually. Couldnt get it sharper than this:

http://i7.photobucket.com/albums/y271/Fordimus/focus2-wideendF1small.jpg

which just doesn't look right. To me, it looks also slightly refracted a bit. thats as far round as it would adjust too.

Strangely if I half engage an ND filter, when wide, the image sharpens up a little. Also founf the only way to make the image sharp, is to go to infinity focus, which isnt right for a focus chart which is 2 metres away

You can download full size, non cropped screenshots of the above here:

http://www.realpropertytours.com/tours/misc/focus1.jpg

http://www.realpropertytours.com/tours/misc/focus2.jpg


once sony have had a look at the camera and got back to me, i'll let you know if that lens element movement is normal or not!

After watching Zach's video, I was able to reproduce the same internal element movement. When I got the camera, my lens wouldn't adjust the flange back automatically but I was able to get it to adjust properly using the manual method. I have not had any issues with sharpness that I have noticed. I do use a Fujinon broadcast lens much of the time. But I will do more testing with the stock lens.

Well I'm guessing that the lens is supposed to move the way it is. Although, if I was getting soft images & saw the lens move like it is, I would probably think something was busted too.

Let us know what Sony finds. Sorry to hear it is happening to you. The stills you posted are horrible, something needs to be fixed. Hopefully they can just swap you a new lens & get it back to you.

My camera went back to Sony, and theyve reported its a problem with the lens, so they're ordering a new lens.

I think that lens element movement must be normal, since everyone elses does it!

But keep an eye on your cameras, the chap on the phone mentioned he'd had a few back like this