Giving a used GH2 a go

Started Oct 14, 2011 | Discussions thread
Anders W
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Re: Giving a used GH2 a go
In reply to Najinsky, Oct 23, 2011

Najinsky wrote:

That isn't highlight recovery, it's exposure. Recovery is data beyond the normal range that can be shifted in (only) when needed. Underexposing makes it always part of the normal range at the expense of moving everything a stop into the shadows, and beyond.

I wasn't saying that recovery and exposure are the same thing. I was saying that if you want more highlight headroom, you need to expose accordingly. And what exactly do you have in mind when you use the concept "normal range"? Aren't you simply talking about the way the camera or the RAW converter would scale the RAW data into jpeg values by default (which may of course vary with the camera or RAW converter/default profile used)?

The clipping warnings are also based on the converted JPEG. You can recover clipped areas from raw.

While the clipping warnings are indeed based on jpegs, I have found them to give quite accurate clipping indications as far as RAW is concerned on my G1 (provided that the WB is reasonably close to what it should be). And although you can certainly make areas where one or more channels have actually clipped (i.e. exceeded full well capacity) look better than they did when you first opened them in the RAW converter, you can rarely make them look quite as good as they would have if you had exposed so as to avoid clipping (i.e. avoid exceeding full well capacity).

That said, you obviously have to weigh the benefits of perfect highlight rendering against the cost of increased shadow noise. On the G1, I am usually ready to take that cost up to about two stops worth of shadow underexposure at base ISO. With a GH2, I would presumably be ready to go a bit further than that.

As I say, the clipping warning is also based on JPEG. If you are over cautious (underexpose) you are unnecessarily throwing away nearly a stop on a camera that is already in the lower bracket for DR. We all find shooting styles that suit us, but it's not one I would adopt as a general shooting style (perhaps when severe clipping is a danger and preservation of highlights is the priority).

Here's an example I just shot to highlight (sigh!) this.

This is how it looked in camera review, with all bright white area blinking to show saturation:

And here it is with the highlights recovered:

It works pretty well in this case since the sofa is very close to neutral white. But I am pretty sure that some color information as well as some luminance information is nevertheless lost here too.

With the 5D2 and the Ricoh GXR, and now the X100, I found centre weighted metering combined with raw headroom was enough to capture the majority of unexpected shots, and for those that missed, sometimes there was a second chance, sometimes there wasn't, thats life. This approach wasn't as successful with the GH2, although the fact that it already deliberately underexposes sometimes helped (and sometimes hindered).

Yes, different exposure strategies and different use of the various indications the camera can give you are needed for different camera models due to the way different manufactures calibrate things like ISOs, metering, and jpeg conversion. But it is a good idea to try to separate these calibration problems from the DR capacity of the sensor itself.

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