GH2 Is my GH2 faulty?

Matthew P

Matthew P

Well-known member
Right, just got my GH2 today and did a few tests to make sure everything was okay with it. One of the first things I noticed was a horizontal purple streak wherever there's a bright light. It mostly happens at higher ISOs (like 1600), and it's not down to lens flare or anything (tested with different lenses).

I just want to make sure that this is typical for the GH2, otherwise I'll send it back for a replacement.

Here's a clip demonstrating the 'issue'...


http://vimeo.com/26926384
 
Matthew -- that should not be there, no matter what your settings were. Sadly, I think you're going to have to send it back :-(

Bill
 
Hold on to it - this happens with cmos sensors.
It even happens with the Red MX to an extent.
A super bright exposure point and high iso will cause electrical horizontal interference along the pixel readout lines affected by the bright spot.
 
Sage, isn't that CCD sensors that do that? CMOS are supposed to be immune to it, I thought?

How come no one else's GH2s seem to have this artifact? If someone could try shining a flashlight into their lens at an iso over 1600 and report back, that would be great. I've noticed that it's most obvious in stills mode (previewing) at ISO 12k, with a tiny aperture and a flashlight.
 
There was a similar problem someone noted with bright warehouse lights in view of the camera, where there was 'ghost' images of the lights.

This can be cause by a couple of things, such as reflections on intra-lens surfaces, but also the sensor array which is 'highly polished, perhaps with a 'glass' filter, and so can also reflect on to the back surface of the lens, which is then 'folded' into the image.

The main 'correction', is to not have such a bright light in the shot...

This would be true for any camera, for any film, for any sensor, but for some cameras, film or sensor, it may be more noticeable.

Some people actually go for this sort of thing, waxing eloquent on the the 'flair' from anamorphic lenses...
 
I had it with mine - notably when I used iso 1600, a very dark space, and an extremely bright bulb
(fwiw in practice, even with only available lights, and lenses set to f2, I never go above 800)

*its different from lens/sensor reflection ghosts; this is a sensor amplification issue
 
Matthew P said:
Sage, isn't that CCD sensors that do that? CMOS are supposed to be immune to it, I thought?

How come no one else's GH2s seem to have this artifact? If someone could try shining a flashlight into their lens at an iso over 1600 and report back, that would be great. I've noticed that it's most obvious in stills mode (previewing) at ISO 12k, with a tiny aperture and a flashlight.
Click to expand...

Since I have a GH-1 not GH-2, I've not gone above 1600 ISO... but from years of shooting film... I just don't tend to put lightbulbs or 'bright window + interiors' in the same shot... There maybe a rare shot or two... but not a typical setup.

If a practical where in the shot, I'd think about putting some ND material if there were a lampshade, or the like. But in any case, with the higher ISO values... expect the worst... Film was no different in the sense that with higher ISO, one had more obvious grain, and with such, often would lend to the human perception of 'softer' image... so many things that affect the perception of quality would fall apart with high ISO... just only would use it if there was an absolute need...
 
Well, it's true that I'd rarely see it in normal use. It's not THAT bad anyway, and is as you say, very similar to a anamorphic flare in the majority of cases.

BUT, I need to know whether this is typical for a GH2. I might as well send it back for a replacement if it's not. There's no point sticking to sub par when you can return it for a better one. ;)
 
I can't locate the thread(s) Mathew but this was a hot topic some months back when the GH-2 first appeared. It's a a known issue (but not only on this camera as Sage suggested).
 
I looked at your clip, Matthew. Nothing wrong. Totally normal. That's the way it is. Same thing on my camera. Think of it just as another lens flare.
 
That shot has everything working against it!

Over exposed interior...vastly overexposed exterior (window).

You are blowing the sensor off the range that it can cope with dynamically.
 
I have two GH2s, the silver and black bodies, and both emit this flare artifact at high ISOs. In my experienced, it's normal for this camera so watch your exposures and how the camera is angled towards surrounding light sources. You might have to rethink your angle.
 
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