Panasonic GX1 + Olympus 14-42 video exposure changing rapidly when zooming

Started May 5, 2013 | Questions
bethonos
New MemberPosts: 7
Like?
Panasonic GX1 + Olympus 14-42 video exposure changing rapidly when zooming
May 5, 2013

I've got Panasonic GX1 with Olympus Zuiko 14-42mm II. The lens is great for my needs (more compact than panasonic non-powerzoom model and better quality than powerzoom model + with the WCON wide converter really nails my photo needs).

However, i found one issue with this lens. Please check the video below and observe how the exposure rapidly changes (observe "flashes" of brightness in the image as I zoom out):

http://youtu.be/ZhoPXcHYfVo

I don't have any other zoom lens for this camera to compare. I see this effect also on display when i zoom in/zoom out the lens.

1) I'm not sure if this is the issue of the lens itself or is simply my lens broken?

2) Will it be any better with Panasonic 14-42 lens?

bethonos
New MemberPosts: 7
Like?
Re: Panasonic GX1 + Olympus 14-42 video exposure changing rapidly when zooming
In reply to bethonos, May 5, 2013

Just to add on the original question. Here are examples of Panasonic 14-42 zoom video I've found by other users NOT showing any flickering:

http://www.youtube.com/watch?v=toQPX9D_rb4 - standard lens

http://www.youtube.com/watch?v=13ltoBx9qy8 - power lens (X series)

And here is example of olympus 14-42 showing same effects as mine, used with olympus body:

http://www.youtube.com/watch?v=dqfxoFwC7qY

So, does it mean Olympus lens are far inferior for video...?

Reply   Reply with quote   Complain
bluelemmy
Contributing MemberPosts: 797
Like?
Re: Panasonic GX1 + Olympus 14-42 video exposure changing rapidly when zooming
In reply to bethonos, May 5, 2013

On the example you give from longboardrider there is the same flickering that you are getting. I didn't look at the others.

Your camera is metering a scene and the scene is changing. It changes its exposure with the different framing, as it should.

Experienced video makers tend not to zoom during shots and use manual exposure partly for the reasons you are finding.

A slight under or over exposure for short periods  in the video is less annoying than the flickering effect.

As you are finding, modern cameras are great but they do not remove the need for all intervention.

As a general rule, zooming during sequences looks pretty amateur and awful unless done for a specific effect or obvious reason.

I tend to use manual focus too since there is massive depth of field with CSCs and and the hunting focus effect just stamps everything 'bad video'.

-- hide signature --

David
www.dthorpe.net

Reply   Reply with quote   Complain
xi5
xi5
Regular MemberPosts: 338
Like?
Re: Panasonic GX1 + Olympus 14-42 video exposure changing rapidly when zooming
In reply to bluelemmy, May 5, 2013

bluelemmy wrote:

Your camera is metering a scene and the scene is changing. It changes its exposure with the different framing, as it should.

The GX1 can't "lock exposure" for video, but reportedly the upcoming GF6 will be able to do that so the exposure will remain constant throughout.

Reply   Reply with quote   Complain
Fredrik Glckner
Senior MemberPosts: 2,485
Like?
Re: Panasonic GX1 + Olympus 14-42 video exposure changing rapidly when zooming
In reply to bethonos, May 5, 2013

Some people have reported seeing the same kind of problem when using the GH3 and Lumix X 12-35mm premium lens. I have not seen it, though, but then again, I don't zoom during video too often.

http://m43photo.blogspot.com/

Reply   Reply with quote   Complain
bethonos
New MemberPosts: 7
Like?
Re: Panasonic GX1 + Olympus 14-42 video exposure changing rapidly when zooming
In reply to bluelemmy, May 6, 2013

I've ordered Panasonic 14-42 lens for comparison. I've tested today the camera with Panasonic 45-150 (f4-f5.6 AFAIK), and the effect was much less visible or almost absent. I think Panasonic handles their own lenses with some different algorithms and *probably* does some exposure compensation behind the scenes.

As soon as my lens arrives, I'll let you know how does that work.

Reply   Reply with quote   Complain
bethonos
New MemberPosts: 7
Like?
Re: Panasonic GX1 + Olympus 14-42 video exposure changing rapidly when zooming
In reply to bluelemmy, May 6, 2013

As a general rule, zooming during sequences looks pretty amateur and awful unless done for a specific effect or obvious reason.

You are right and I tend to avoid it as much as possible, I also don't do long cuts that people usually do (2 minutes between cuts ;). The example I've posted was done solely to demonstrate the problem. But then, sometimes, I just need to zoom. And for those rare ocasions I'd like the effect to be as minimized as possible

I tend to use manual focus too since there is massive depth of field with CSCs and and the hunting focus effect just stamps everything 'bad video'.

I'm either using constant focus through shooting or manually do focusing (which tends to be tricky on some lens like Panasonic Leica 25mm f/1.4

Reply   Reply with quote   Complain
bethonos
New MemberPosts: 7
Like?
Re: Panasonic GX1 + Olympus 14-42 video exposure changing rapidly when zooming
In reply to bethonos, May 23, 2013

OK Guys, I've tested both Olympus and Panasonic 14-42 lens. Here are the results:

http://youtu.be/gUloVvJh_7M - Olympus lens

http://youtu.be/9iyAbP1bewU - Panasonic lens

Now just to remind you, the body in both cases is Lumix GX-1. For the results:

  1. During zoom-in both lenses show similar levels of exposure change, a bit noticeable, but nothing dramatic. The brighter areas seem to flash a bit.
  2. During zoom-out the difference kicks in:
  • Panasonic shows a slightly more noticeable exposure change. The darker areas seem to flash a bit.
  • Olypmus shows much more noticeable exposure change. The darker areas seem to flash a lot. For me, this is a deal breaker and this might look even more dramatic (see my original video in the first post)

So, altough you've been right about the cause of the effect and it is always in there (you can limit it sometimes by turning on "flicker reduce", but it doesn't always work well). But for the Oplympus lens, it's much more dramatic and for me this is unacceptable.

Not sure why, maybe the Panasonic firmware works better with Panasonic lens (I've updated all equipment to latest firmware, the lenses too). However, if you have choice between theese two and you are into doing video shots, go for the Panasonic. And the effect is noticeable also on LCD when doing shooting, which is a bit annoying.

selected answer This post was selected as the answer by the original poster.
Reply   Reply with quote   Complain
Keyboard shortcuts:
FForum MMy threads