I accidentally placed this thread on the Canon XA and Vixia Series AVCHD
camcorders site.

“My GH4 came with the Panasonic 12-35 mm f2.8 lens. When I zoom with this lens I see a flickering on the finder screen that is recorded. Without zooming the image is flicker free.

If I use an 18-35 Sigma there is no flicker on either the screen or the recording.

My guess is that the Panasonic lens has a problem.

Is there anything I can try before returning it to my supplier?”

I would like to thank Noa Put for his reply on the Canon site: -
“It looks like this is a typical behavior of this lens, see also here: ”

This probably depends on how Panasonic made the lens able to hold f2.8 throughout the zoom range. My experience with their other zoom lenses the exposure changes in sudden increments. At least that's my experience. These are not video style zoom lenses where the exposure change is smooth.

I get flicker with the Panasonic 14-140mm and 100-300 lenses if zoomed during filming.. Like William, I think that is the way these lenses are designed to work.

Thanks Willard and thanks William,

I have just tried the 12-35 on a BMPCC with the same flickering result. The flickering seems to be worse at what I would call a slow rate of zoom and may almost disappear at other rates.

Unfortunately a cine-style zoom lens for a large sensor camera is way beyond most people's budgets. A few weeks ago I was researching renting a cine-style zoom for the Canon C100 and here were the costs: one day Canon C100 camera - $150, one day Canon cine zoom lens - $350. The replacement costs for the cine zoom lens: over $45,000. Probably the best lens I would have ever touched if the job had happened but this is the realm of buying one lens for life and replacing the camera when technology changes.

I do think with this kit we should think more of using camera movement rather than zoom in as your recording, these lenses are not designed for it at all, i'm sure ones will come out in the future so in the meantime just use the zoom to make the frame size you want and track the camera in and out on a dolly or jib etc the way film makers do. Smooth zooms are almost impossible on these little lens with no servo control.

Agreed, I think people expect a gh4 to function as a videocamera as it has video oriented functionality but it will never have the same smooth zoom as a real videocamera. If you want flicker free, smooth and variable speed zoom you have to buy a videocamera with a fixed lens.

That's why I have a $5000 video camera as well. Some jobs are highly ill suited for the GH cameras or any DSLR.