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Old January 2nd, 2014, 01:21 PM   #1
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PMW-320 focus problems

I have my PMW-320 two + years and never had any problem like this before with this camera.
Just noticed it hard to focus at a wedding a few days ago.
When I zoomed in tight and then pulled out the picture was out of focus, I thought it had something to do with back focus. It wasn't like this in the earlier part of the day, it was focusing OK, as far as I am aware.

When I got home from the wedding I record a good few test clips and sure enough there was something wrong with the focus. The lens on the camera is a Fujinon XS17x5.5BRM-M38 BTW
I adjusted the back focus as best I could but nothing seemed to make any difference so I switch off the camera and removed the lens to see if this would help. I fitted the lens back onto the camera, did a black balance and I did think removing the lens made a big improvement. Everything looked good and sharp in the viewfinder, the way its suppose to.

I don't know why or what would have caused this but what I did notice a week or so back but didn't pay enough attention to was, that while viewing the clips on HDTV, playing from a HD timeline the pictures looked sharp in the center of the TV screen but looked that wee bit softer towards the edges of the screen.

I had a wedding the following day and I was hoping that this focus issue was sorted.
Everything did stay in focus for me until we got to the reception and once again I have out of focus clips.
I don't know what is going on, is it the lens or the camera?
The camera didn't get hit against anything to cause this, no knocks or bumps, its well looked after.

Any ideas and thanks in advance.
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Old January 2nd, 2014, 01:28 PM   #2
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Re: PMW-320 focus problems

almost certainly a back focus problem as it goes out as you go wide. I have one idea. Not the same lens, but a similar one I have on an older HD camera - check the back focus ring very carefully where the lock screws in. On mine, I can only assume over zealous tightening had crack the aluminium - as I gave the last bit of turn on it, it was opening up the crack and forcing the ring to move slightly. I tried all sorts to cure it, but in the end decided that it was simplest to simply do the back focus, and then secure the ring from turning with a thin strip of gaffer tape, onto the camera. Ugly, but it works - and has been like that for three years now. Taking the lens off is a real problem, because it goes nasty and sticky, but on this camera, lens removal is rare. If I screw in the locking knob when focus is perfect, the final turn wrecks the focus point.

Hopefully yours won't be like this - but just in case, worth checking as my symptoms were very, very similar.
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Old January 2nd, 2014, 01:44 PM   #3
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Re: PMW-320 focus problems

Thanks Paul for that speedy reply, I'll try and get the back focus adjusted but I wonder why was the earlier part of the recording 100% then at the reception it wasn't?

Thank you Paul.
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Old January 2nd, 2014, 02:14 PM   #4
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Re: PMW-320 focus problems

Does the lens have a Macro ring on it?

Sometimes when adjusting Macro, restoring the ring back to LOCK, you don't QUITE get it locked, which throws out the flange back, ergo the back focus.

Happened to me a couple of times with my JVC HD200's...
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Old January 2nd, 2014, 02:50 PM   #5
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Re: PMW-320 focus problems

[QUOTE=Shaun Roemich;1826359]Does the lens have a Macro ring on it?
QUOTE]

Hello Shaun, yes it has. I'll check that out too.

Thanks.
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Old January 2nd, 2014, 07:08 PM   #6
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Re: PMW-320 focus problems

Quote:
Originally Posted by Shaun Roemich View Post
Does the lens have a Macro ring on it?

Sometimes when adjusting Macro, restoring the ring back to LOCK, you don't QUITE get it locked, which throws out the flange back, ergo the back focus.

Happened to me a couple of times with my JVC HD200's...
Yep. Just happened to me on my HM700 with the Fuji 17. I was killing time playing with the macro during a break at a seminar and just before the break was over I snapped it back out of macro and I looked thru the VF and I'll be damned. Everything was fuzzy. I thought I had my glasses on (never use them using the VF). Then I remembered the macro ring and sure enough, wasn't "snapped in" like I thought.
I have since decided not to play anymore when I'm on a break and I'm bored.
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Old January 3rd, 2014, 03:42 AM   #7
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Re: PMW-320 focus problems

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Originally Posted by Don Bloom View Post
Yep. Just happened to me on my HM700 with the Fuji 17. I was killing time playing with the macro during a break at a seminar and just before the break was over I snapped it back out of macro and I looked thru the VF and I'll be damned. Everything was fuzzy. I thought I had my glasses on (never use them using the VF). Then I remembered the macro ring and sure enough, wasn't "snapped in" like I thought.
I have since decided not to play anymore when I'm on a break and I'm bored.
Thanks Don,
In the earlier part of the morning I did use the Marco setting to get a close up of the rings but am almost sure it went back into its off position, because the clips recorded after that we're fine.

What I can't understand is, why did this out of focus kick in when the macro or the back focus wasn't touched after that? that's the odd thing.
If all clips were out of focus I could understand.

Thanks Don.
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Old January 3rd, 2014, 08:10 AM   #8
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Re: PMW-320 focus problems

The macro ring adjusts the internal relationship between the lenses, and maybe it takes a focus in to out, to let the spring loaded pin drop back in?
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Old January 3rd, 2014, 08:48 AM   #9
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Re: PMW-320 focus problems

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Originally Posted by Paul R Johnson View Post
The macro ring adjusts the internal relationship between the lenses, and maybe it takes a focus in to out, to let the spring loaded pin drop back in?
Hi Paul, looking through the viewfinder and connected to a 42" HDTV all looks 100%. and nothing adjusted since the out of focus recorded clips, so what gives, strange.
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Old January 3rd, 2014, 12:05 PM   #10
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Re: PMW-320 focus problems

I suppose you need to now try combinations - so that if there's an internal fault in the lens, you can prove it to yourself. So maybe zoom in, rotate focus back and forth, up to the stops, then focus on an object and then pull right out and see if the image remains in focus? The do the same at different focal lengths, and see if you can force the fault to re-appear. If it does, you can then see what you need to do to make it go away. I guess you have to eliminate the back focus and macro features. I do think they are still the area to look at, but remotely, it's very difficult. Best of luck.

If it has only just started doing this - practically, something must have happened?

Just a thought, but check the f stop setting - is there any chance that there's a dirty contact somewhere that is forcing the iris to be wide open all the time which would make the back focus adjustment more critical - but perhaps hide it when the iris closes down. Are you having any exposure issues too?
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Old January 3rd, 2014, 07:04 PM   #11
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Re: PMW-320 focus problems

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Originally Posted by Paul R Johnson View Post
If it has only just started doing this - practically, something must have happened?

Just a thought, but check the f stop setting - is there any chance that there's a dirty contact somewhere that is forcing the iris to be wide open all the time which would make the back focus adjustment more critical - but perhaps hide it when the iris closes down. Are you having any exposure issues too?
Hi Paul, yes, its only just started doing this.... exposure issues,in what way Paul?
I was busy today trying to get a computer up and going for a friend but will try all you suggested tomorrow Paul.

Thank you.

Last edited by Anthony McErlean; January 3rd, 2014 at 07:39 PM.
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Old January 4th, 2014, 05:55 AM   #12
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Re: PMW-320 focus problems

Looking at a few out of focus clips on the PC timeline, I notice that the foreground is in better focus than the background.
Does this give any of you a better idea what might have happened? :)

Thanks.
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Old January 4th, 2014, 06:32 AM   #13
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Re: PMW-320 focus problems

All I was thinking was that maybe when the lens appeared ok the f stop was fairly high, f16 maybe? So that the possible lens internal problem was hidden by the small iris, then when the shots with the problem were evident was that also an exposure setting where the lens opened right up? If you have bits more in focus than others kind of suggests the lens is misbehaving - but the degree could be hidden by depth of field increases as the lens stops down? It's just a stab in the dark?
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Old January 4th, 2014, 07:52 AM   #14
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Re: PMW-320 focus problems

The only time I encountered something like this was shooting on a doco in Fiji. Why I mention Fiji is the fact that when I worked out what was wrong I knew had a problem. No service centre.

I only discovered what was happening when I did a slow tilt on the camera. One of the lens internal rear elements had become marginally loose. I could do a back focus and fix the problem but depending on movement of the camera the lens element would move a fraction and of course focus was lost again. I could move the camera a couple of more times and it would come back into focus again. Move it again and it loose it again. Luckily I had a wide angle lens with me and managed to finish a couple of weeks shooting with that. My problem was there was no Canon repair shop in Fiji. It was either Sydney or Hong Kong

It's worth checking out just in case this turns out to be your problem.

Chris Young
CYV Prooductions
Sydney
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Old January 4th, 2014, 02:32 PM   #15
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Re: PMW-320 focus problems

You should always check the back focus on a lens with the iris wide open to see if it is tracking. It could easily look okay at f4 and above but look soft when the lens is wide open.
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