Barry Goyette
Second Officer
Flight distance : 14928 ft
United States
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Hi Salvador -- I'll skip the sideshow (terminology, retractions/corrections, and forum fame) and dive right into the subject at hand.
Your video is compelling. But I'm having a difficult time understanding what's going on in that last clip. You've chosen not to use the supplied raw to log conversion and LUT on that clip for some reason, so it's difficult to ever see the complete range of the file in one shot. It's obvious in the first two clips that the sky is clipped in the red channel and green channels. And that clipping doesn't go away when you do the log conversions, meaning those two shots are clipped
On the last shot, we see no evidence of clipping. We see a lot of tonality up in the highlights, and we see elevated shadows, but this only indicates, in EI mode, that you've exposed at a higher EI. If I had to guess, based on the waveform, is that you exposed it at 1600, which pushes all the highlights up into the stratosphere making it looked clipped (whereas the first two clips ARE clipped). So when you drag it down, it looks dramatic as you are simply removing the gain.
What we don’t know is how the last clip was exposed relative to the others. It appears to be shot at a different location, and I’m guessing a different day, certainly a different time, probably a different sunset, with a different EI and a different mode. If you were shooting that shot at 1600 and your go4 waveform looked like the one in FCPX, I don't know how you'd set exposure accurately. If it were me looking at that waveform, I would have probably decreased exposure by a little bit….actually more than a little bit. I’m suggesting to you that this is, in fact, what you did...which is why the last shot "isn't clipped" like the first two — it simply was exposed differently.
So If I had to guess…what we’re seeing has nothing to do with EI mode, and everything to do with exposure.
A nice test for you would be to shoot the same shot, at the same time, using the same exposure settings In EI mode -- shoot one rated at 1600 and one at 100, (The 1600 wf will look clipped like this, the 100 wf will look underexposed). While you're at it, switch to normal mode and shoot the same shot...and don't touch any exposure controls. Now place them all in the same timeline and then adjust them to match. What I bet you'll find is that they do match, and that the shots clip at exactly the same point, and the shadows die at the same point. (my testing would indicate these results.)
Honestly, shooting sunsets isn't the best way to get quantifiable data regarding camera exposure, dynamic range, latitude, ISO, EI et al. Light levels and color vary spontaneously, continuously and dramatically when the sun is near the horizon due to atmospheric conditions. It would be near impossible to get consistent light levels between two shots (let alone the 4 or 8 it would take to test all modes and codecs) due to the time it takes to change modes in go4. I rejected two previous tests of my own that were taken under late day sunlight, because I could see that variation in the light levels were affecting my conclusion. That's where the charts, and some good studio lighting come in handy.
Finally if all you're wanting to show is that by shooting EI mode at higher speed ratings, that you can decrease your exposure and therefore record more highlight range, fine. Please realize that this works in any mode with this or any camera, and is related to exposure, not the gamma or gain or EI fairy dust applied to the image. If on the other hand, you do mean to show that EI mode and increasing speed rating results in expanded highlight latitude, exclusive of exposure change, then this video doesn't conclusively show that.
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