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Focus Problem PLEASE HELP


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#1 Marty Stano

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Posted 31 July 2005 - 01:55 AM

Hi OK,
I have a DVX100a and I've been shooting with it for about 4 months and I haven't had a problem with it until now. Last weekend I shot a wedding in 30p and it was generally low light conditions and i was unable to pull a good focus. I would zoom all the way or nearly all the way in (Z90-99) on my subject pull the focus and then when I went to zoom out, the focus blurred dramatically. This happened even outside in daylight. Then, I shot a student video a few days ago in 24A and I ran into the same problem with sufficient light. I'd zoom in and focus and when i pulled out it went dramatically out of focus. At one point, I couldn't even pull a focus at all. My image was blurred when I was zoomed all the way out (Z0). The funny thing is: typically (i think) when your zoomed out wide (Z0) the focus is fine at (MF90-99), but at this focus my image with the subjects at least 6ft away, was closest to being in focus at MACRO MF0. I have no idea what's happening. My focus for subjects more than 6ft away comes in best with MACRO focus of MF0-35. Oh and just in case this info is necessary for assement at the wedding reception, the f-stop was OPEN but i still had this problem on the set of my student film with the aperature at f-6 or more.

PLEASE HELP- THIS IS SO STRANGE.

THANKS.
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#2 Lisa Wiegand

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Posted 09 August 2005 - 10:46 AM

Well, it sounds like you need to take the camera in for service - those problems seem severe. And since there is no way for you to adjust the backfocus on the lens, I think you need to have a technician take a look at it. I've had some similar problems in the past, but not to the degree you are talking about & a trip to the service center was all that could help. Good luck.

Lisa
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#3 Bob Hayes

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Posted 08 October 2006 - 09:02 PM

I?m starting to see that as a reoccurring problem with the VX 100 A. The manual focus which is supposed to set a depth of field 1/3 in front 2/3 behind the subject actually is almost 100% behind the subject. I shot yesterday and I think that happened several times. I check out a camera at a rental house last week and saw this effect with a different camera. I think when you are wide you need to pull the focus closer until the back ground starts to go. I think this is a flaw in the camera system.

I'd love to hear if other folks are seeing this [problem in manual zoom on the wide end.
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#4 Stephen Williams

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Posted 09 October 2006 - 02:04 AM

Hi OK,
I have a DVX100a and I've been shooting with it for about 4 months and I haven't had a problem with it until now. Last weekend I shot a wedding in 30p and it was generally low light conditions and i was unable to pull a good focus. I would zoom all the way or nearly all the way in (Z90-99) on my subject pull the focus and then when I went to zoom out, the focus blurred dramatically. This happened even outside in daylight. Then, I shot a student video a few days ago in 24A and I ran into the same problem with sufficient light. I'd zoom in and focus and when i pulled out it went dramatically out of focus. At one point, I couldn't even pull a focus at all. My image was blurred when I was zoomed all the way out (Z0). The funny thing is: typically (i think) when your zoomed out wide (Z0) the focus is fine at (MF90-99), but at this focus my image with the subjects at least 6ft away, was closest to being in focus at MACRO MF0. I have no idea what's happening. My focus for subjects more than 6ft away comes in best with MACRO focus of MF0-35. Oh and just in case this info is necessary for assement at the wedding reception, the f-stop was OPEN but i still had this problem on the set of my student film with the aperature at f-6 or more.

PLEASE HELP- THIS IS SO STRANGE.

THANKS.


Hi,

Remember the camera does not have a zoom lens (with back focus adjustment) but a vari-focal lens. The lens has to be refocused (by software) as you 'Zoom' it's an engineering set up that needs to be re-set.

Stephen
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#5 Brian Drysdale

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Posted 09 October 2006 - 04:41 AM

People have noticed similar focus effects when using a W/A converter on the Sony PD150.
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#6 Bernhard Zitz

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Posted 13 October 2006 - 08:43 AM

I have a DVX-100A (Pal), sometimes it looks like focus ist breathing a tiny little bit without touching anything (autofocus off). When I do fast zooms it takes maybe two or three frames to get in focus again, I always thought it's a matter of lensdesign with this cheap prosumer lenses that have servofocus, but I'm not an expert, no idea if thats the point...

cheers, Bernhard

Edited by Bernhard Zitz, 13 October 2006 - 08:45 AM.

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#7 kpv rajkumar

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Posted 27 November 2006 - 08:53 AM

I?m starting to see that as a reoccurring problem with the VX 100 A. The manual focus which is supposed to set a depth of field 1/3 in front 2/3 behind the subject actually is almost 100% behind the subject. I shot yesterday and I think that happened several times. I check out a camera at a rental house last week and saw this effect with a different camera. I think when you are wide you need to pull the focus closer until the back ground starts to go. I think this is a flaw in the camera system.

I'd love to hear if other folks are seeing this [problem in manual zoom on the wide end.

it sure is a flaw, bob. and looks like it runs in the ag dvx 102 family too ! some six months back i was shooting trucks and i had out-rigged the camera on an elaborate truss system ( a la, bob richardsons' tigerland !) which gave me a menacing 3/4 angle on the left front wheel+cab. i screwed on a w/a conversion lens, engaged the 1/64 nd, set the exposure, put it on auto focus and told the driver to floor it on the circular test track. but what i got was all out of focus, especially the wheel in the fg. later i reshot the whole thing on manual focus mode and it worked fine this time.
from what i understood, it looks like the lens on af mode needs a few frames( or, a few seconds) every time to get its act together. but with the truck travelling in circles at high speeds, the optics experiences what i call a condition of 'continuous bewilderment', what with the constant new deals in terms of staging/blocking happening all around it and so loses focus literally!
rajkumar
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