Yesterday, while shooting at the New York International Auto Show I experienced a strange focus problem. Before leaving I was wondering around shooting some random b-roll. I had my Olympus 12-40mm 2.8 Pro lens on the camera. I was shooting in HD at 50Mb 422. While at the Toyota display I shot the FV2 concept vehicle and experienced a strange loss of focus while zooming out. It only happened with this particular vehicle. The other b-rolls I shot were okay. The lens was set for manual focus.

JVC LS300 Focus Anomaly on Vimeo

Very strange if the camera is set to manual focus. Auto-focus could get confused by the dark reflections but if those sudden jumps are not from stopping the camera I couldn't say what is happening.

As you undoubtedly know, that particular lens has a focus ring that slides forward and back (one of the features that attracted me to it). Forward engages with the camera for auto (sometimes iffy on the LS300).. Sliding it back disengages auto for smoother manual focus.

If the ring was back, then accidentally slid forward while attempting to manual focus, the focus can change awkwardly - I've had that happen several times (clumsy fingers)... That could have been the problem here since it's only the one incident...

Checked the focus ring after seeing the focus problem in the LCD. Focus ring was set to manual.

As you undoubtedly know, that particular lens has a focus ring that slides forward and back (one of the features that attracted me to it). Forward engages with the camera for auto (sometimes iffy on the LS300).. Sliding it back disengages auto for smoother manual focus.

If the ring was back, then accidentally slid forward while attempting to manual focus, the focus can change awkwardly - I've had that happen several times (clumsy fingers)... That could have been the problem here since it's only the one incident...

Steve, I'm sure the lens focus ring was set to manual. I shot over two hours of footage that day in manual focus and the only focus problem I experienced was with the FV2 concept vehicle. After shooting the FV2, I shot the Ford GT, the Dodge Demon, and general scene shots in the Crystal Palace area. No subsequent focus problems. I'm wondering if the highly reflective semi-translucent body of the FV2 caused the camera problems. I'll email JVC support Monday and see what they have to say.

I've learned that with that lens even a slight forward push while focusing can shift it out of manual... I'm not saying that's what happened, but I honestly don't think it's a JVC issue - I've been using the camera for over a year and have never experienced anything similar - except those few times I blew it with the Olympus 12-40..

Yesterday, while shooting at the New York International Auto Show I experienced a strange focus problem. Before leaving I was wandering around shooting some random b-roll. I had my Olympus 12-40mm 2.8 Pro lens on the camera. I was shooting in HD at 50Mb 422. While at the Toyota display I shot the FV2 concept vehicle and experienced a strange loss of focus while zooming out. It only happened with this particular vehicle. The other b-rolls I shot were okay. The lens was set for manual focus.

JVC LS300 Focus Anomaly on Vimeo (https://vimeo.com/213120244)

I was at a pro video trade show in the Boston area today and spoke with Ken Freed, a JVC District Sales Manager, regarding this focus anomaly. Ken looked at the video I posted on Vimeo and said it was a lens issue. Ken said that the camera does not have any control of lens focus. Ken thought because the Toyota concept vehicle was translucent, the lens did not have the edge contrast required to maintain constant focus. You'll notice when I zoomed out and the edges of the vehicle appeared, focus snapped in. Apparently, there is software (firmware) in the lens that works to maintain focus while zooming.