Back focus often out. at DVinfo.net

Dennis Robinson · January 31st, 2009, 07:04 AM

Hi,
I have the 13x lens on my JVC111 and lately the back focus needs to be adjusted. Is there any reason for this?

Shaun Roemich · January 31st, 2009, 09:40 AM

Temperature changes, accidental bumping, accidental movement of the Flange Focal lever instead of the macro, leaving macro engaged accidentally, lock knob not tightened enough, gremlins messing with it when you're not around...

Dennis Robinson · January 31st, 2009, 10:28 AM

Quote:

Originally Posted by Shaun Roemich

Temperature changes, accidental bumping, accidental movement of the Flange Focal lever instead of the macro, leaving macro engaged accidentally, lock knob not tightened enough, gremlins messing with it when you're not around...

Thanks Shaun,
I must admit it has only been happening lately and could be due to the temperature. It has been very hot in Perth these days and there is no doubt I will have to check it each time I shoot from now on. The camera has never acted like this before. i feel confident that all the knobs were tight. If temperature will do this, it is because of taking it in and out of the airconditioned car into a warmer environment.

Shaun Roemich · January 31st, 2009, 11:13 AM

Very likely that's it, then. AC to heat (must be nice! It's been -20 celsius here for 2 weeks!) is often enough to throw out the delicate adjustment.

Adam Letch · February 1st, 2009, 06:24 PM

mate I test my backfocus at start of the day for every shoot, as you know that if you not on your game, you might be the slightest bit out and your shoot looks soft. Especially when like in perth it can 20C in the morning 40C by 4pm, that's a lot of expansion and contraction of metal, not that we leave our camera's in the direct sun of course.

January 31st, 2009, 07:04 AM	#1
Dennis Robinson Major Player Join Date: Mar 2004 Location: Perth, Australia Posts: 250	Back focus often out. Hi, I have the 13x lens on my JVC111 and lately the back focus needs to be adjusted. Is there any reason for this? __________________ Dennis Robinson G5, , 30 inch display, FCP6 Studio 2, JVC-GYHD111

January 31st, 2009, 09:40 AM	#2
Shaun Roemich Inner Circle Join Date: Sep 2002 Location: Vancouver, British Columbia (formerly Winnipeg, Manitoba) Canada Posts: 4,088	Temperature changes, accidental bumping, accidental movement of the Flange Focal lever instead of the macro, leaving macro engaged accidentally, lock knob not tightened enough, gremlins messing with it when you're not around... __________________ Shaun C. Roemich Road Dog Media - Vancouver, BC - Videographer - Webcaster www.roaddogmedia.ca Blog: http://roaddogmedia.wordpress.com/

January 31st, 2009, 11:13 AM	#4
Shaun Roemich Inner Circle Join Date: Sep 2002 Location: Vancouver, British Columbia (formerly Winnipeg, Manitoba) Canada Posts: 4,088	Very likely that's it, then. AC to heat (must be nice! It's been -20 celsius here for 2 weeks!) is often enough to throw out the delicate adjustment. __________________ Shaun C. Roemich Road Dog Media - Vancouver, BC - Videographer - Webcaster www.roaddogmedia.ca Blog: http://roaddogmedia.wordpress.com/

February 1st, 2009, 06:24 PM	#5
Adam Letch Major Player Join Date: Feb 2006 Location: Perth, Western Australia Posts: 414	Hey Dennis mate I test my backfocus at start of the day for every shoot, as you know that if you not on your game, you might be the slightest bit out and your shoot looks soft. Especially when like in perth it can 20C in the morning 40C by 4pm, that's a lot of expansion and contraction of metal, not that we leave our camera's in the direct sun of course.