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GH4 ISO capabilities and quirks


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#1. Compared to my 5DMK3 the GH4 seems brighter at similar ISO's.

 
It may seem brighter even if you have the same amount of light per pixel. For instance, a picture profile can make it look brighter - there's no raw, so the picture is always altered in some way.
 
According to DXO, if you choose ISO800 setting, you get ISO452 and ISO641 for GH4 and 5DMk3 accordingly. (I've added Pentax for the reference).
 
So, GH4 compared to Mk3 should be darker at same ISO settings (if we shoot RAW stills). GH4's actual ISOs are much lower (almost twice) than indicated.
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I'm in the same camp as Inazuma – I can't believe the GH4 can't match the GX7 at ISO 3200? My GH2 and GH3 produce dirty noise at 3200 (it's coloured), but the GX7 doesn't (in a custom standard profile, NR normally at 0). Is the GH4 worse in a particular profile or something?

 

I sometimes wonder whether people are a little too adverse to noise – like every shot needs to be perfectly glossy clean or it's unusable? I never think the cinematographer is bad when I see noise in a film =)

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Guest Ebrahim Saadawi

The GH4 noise is very fine and small, much more like C300 noise not 5D. Canon noise is NOT nice. So it's fine and film-like but there's a lot of it. And shooting 4K has more detail and a bigger amount noise, as internal downscaling is a very effective noise reduction tool. So viewing the 4K image natively the camrera is about two stops worse than a 5D, that's in terms of when the image becomes too noisy, but the thing is that the 5D has that better noise levels mainly due to the intense downscaling to less than 1080p and applying heavy noise reduction, this gives noise the blotchy horrible quality. The Gh4 gives you the "raw" image at full resolution and no noise reduction. This gives the immediate impression of bad ISO performance.

If you apply heavy noise reduction that loses detail until the image reaches the 5D level of detail, and then super sample it to 1080p, the noise performance is not that far behind the 5D, a little worse but not even a stop difference.

I shot great night images with the GH4, the recipe is

-Using fast primes, f0.95/1.2/1.4
-Applying Neat Video to the 4K image
-then downscale to 1080p.

With a far prime you can get a proper exposure at 800 ISO at night anyway, it's perfectly capable of shooting in low light.

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Guest Ebrahim Saadawi

Dug this out from when I had the GH4.

This is Canon noise (5D mk II here but all Canon DSLRs while vary in the amount of noise, they have that exact same noise pattern/look/structure)

kLdvkdn.jpg

This is the GH4 noise 

h2dC2vq.jpg

Much nicer!

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Guest Ebrahim Saadawi

Yes that's a very important advice too, add it to my three above. -Expose to the right.

It's my exposure method will all cameras right now. Under exposure is a noise-inducing factor more than high ISOs. If you under expose at 200 ISO you're going to get a noisy image, if you have a uniformly highly-exposed scene at 1600 it will virtually show no noise. That's why it's the shadow areas of the image that show noise not the correctly exposed ones (shadows are under exposed).

So expose as far to the right as possible (brighten up the image until the point before clipping important highlights), even by using a higher ISO (and wider iris, lower shutter, more lights), then adjust your desired exposure in the editing stage ( my workflow starts with darkening the image using an inverse C curve). This makes all the difference in getting higher image quality with less noise and even better colours. The sensor gets more information. But be careful regarding clipping. Use an RGB histogram ideally to make sure you don't clip any colour channels not just luma ones that shows with the normal histogram and waveform. Sometimes the normal histogram/waveform show no clipping but when you take the image and bring it down in post you find weird colour shifts, this is due to colour clipping.

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