Abel Cine Measures Sensitivity & DR

cheezweezl said:
Am I missing something? In the video he says 11.5 stops range. However, the wfm shows 4 stops above middle grey and 5.5 stops below. Isn't that 10.5 stops?
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I'm going to have to agree with you here. I went back and looked at their old review (http://blog.abelcine.com/2011/05/27/sony-fs100-ratings-and-dynamic-range/#more-12208) which goes from +4 to -5 which they called 10 stops. This one goes from +4 to -5.5 which is 10.5 stops (and matches the AF100 as well).

Does the chart start counting in half increments at the bottom range? Just wondering why it goes in 1 stops then goes to a .5 stop increment.
 
speedracerlo said:
I think you count from 0 so the range from 0 to +4 = 5 stops and 0 to -5.5 is 6.5 stops = 11.5
notice how the middle gray is split in two
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Middle grey is split in two so you can easily identify middle grey. It's split like that on the chart if I'm not mistaken.

Beyond that, I don't understand your math. Can you clarify?

My math goes like this, stops are as follows. -5, -4, -3, -2, -1, 0, 1, 2, 3, 4. That's ten stops. Add the "-5.5?" and that's another half stop.

Right?
 
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Rick Burnett said:
I'm going to have to agree with you here. I went back and looked at their old review (http://blog.abelcine.com/2011/05/27/sony-fs100-ratings-and-dynamic-range/#more-12208) which goes from +4 to -5 which they called 10 stops. This one goes from +4 to -5.5 which is 10.5 stops (and matches the AF100 as well).

Does the chart start counting in half increments at the bottom range? Just wondering why it goes in 1 stops then goes to a .5 stop increment.
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I don't know what the deal with that is? The -5.5 stops has a question mark by it. Does that mean that they aren't really sure what that means?

The old test had the same question mark by the -5 stop mark
 
Not sure you can show more than 10.5 stops on a waveform monitor. Frame images of the DSC chart viewed on a wide gamut monitor would be more useful.

Edit: Linear DR of an NTSC waveform monitor from 0-110 IRE is about 6.5 stops.
 
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I can see an argument for reading 10.5 off that original chart, I was trying to be conservative at the time I guess. With my new test I pushed it to the extremes.

Razz16mm, you can show many more stops than 10.5 on a waveform, it will show anything that you feed it.
 
Mitch Gross said:
If you compare the old waveform v. the new, you can clearly see there is at least one more bar than there was before.
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Gotcha. I did see one more bar on this test, which was labeled as -5.5. So to me, it looked like half a stop more than the first test. So if i understand what you and Andy are saying, you label the stops that you see as definite, then estimate the latitude from the other stuff that is not clearly defined? I think that's where my confusion is coming from.
 
From what I'm reading and hearing, if you'll notice, Andy say "almost 11.5 stops" several times. Also, if you count the steps visible in on the waveform, you'll see 12. I don't know what the WF looked like with the prototype, nor the other cameras, but I can see how one would interpret this as over 11 stops.

I also think it's interesting that the WF shows Cine 1 with the highlights stretched out, and the blacks crushed. I don't have my camera yet - does this translate to a softer rolloff in the highlights in a real image?
 
stevedocmaker said:
I also think it's interesting that the WF shows Cine 1 with the highlights stretched out, and the blacks crushed. I don't have my camera yet - does this translate to a softer rolloff in the highlights in a real image?
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That's the idea. Then you can use the black gamma settings to help pull some of those shadow details up.


BTW, here is the link to the original test, if anybody doesn't have it...

http://blog.abelcine.com/2011/05/27/sony-fs100-ratings-and-dynamic-range/
 
Rick Burnett said:
Does the chart start counting in half increments at the bottom range? Just wondering why it goes in 1 stops then goes to a .5 stop increment.
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No, it's always 1 stop increments.

The reason we would call that a half stop is because it's not cleanly and clearly resolved away from the noise at the bottom. It's obvious that the camera is resolving something, because it's jutting up out of the noise floor, but it's not clearly resolving that stop because it's still "connected" to the noise, on the waveform. I might have been more generous and called that a resolved stop.

And yeah, that's 10.5 stops. Don't know why Andy is calling it 11.5. Just count the bars that are displayed -- it's 10 and a half, if you want to call that last one a half stop.
 
Thanks Barry, not having a lot of test chart experience myself I was trying to figure out what was going on there. I could see saying 10.5 being pretty close.
 
Andy, you mentioned black gamma settings at the end of the video. I am stretching those out, myself. If you have a chance, could you test these settings out and see what, if any, effect black gamma has on knee settings. I don't have all the fancy test gear or your brain :-) it would be awesome to see those results.
 
I just counted the bars again and the old test did have 10.5 bars and the new one has 11 bars, maybe 11.5?
I think it was wrong to read those numbers, counting the bars makes more sense to me now

like Cheeze said above
I think maybe with the ITU 709 or Standard Gamma with 80% knee point -1 slope with some black gamma levels turned up might resolve the shadow bars a little better? I don't know..
 
Shipsides said:
I can see an argument for reading 10.5 off that original chart, I was trying to be conservative at the time I guess. With my new test I pushed it to the extremes.

Razz16mm, you can show many more stops than 10.5 on a waveform, it will show anything that you feed it.
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Technical signal levels for broadcast HD video are the same as for NTSC. 100 IRE legal max white is 700mv. 1 IRE is 7mv. This range expressed in dB is 20log(700mv/7mv) = 40dB. Divide that by 6dB/stop and you get roughly 6.7 stops of linear DR that a legal broadcast signal can display, that is with equal height steps per stop value on the scope. The standard reflective 11 step chip chart displays 5.5 stops from black to 90 IRE with equal separation between steps with linear gamma = 1. Cameras are capable of capturing much more range than that these days, which is why gamma curves are used to compress the extra range into legal values and retain some detail in both shadows and highlights that would otherwise be lost. But you do not get the full DR displayed on screen or on the scope. MTF values for detail contrast at the extreme ends of the range are compromised. Screen shots of the DSC back lit DR chart would give a more useful impression of how the various cameras and gamma curves display relative values at the extreme ends of the scale in both highlight and shadow IMO. The S-log curve applies some of the same kind of knee and compression at the highlight end of the range that you see in the shadow compression with the gamma curves you have shown for instance.

As far as HD video is concerned, all of these new gen cameras are effectively "HDR" capture devices. It comes down to how well various camera settings map the available DR into the final HD image and what creative control you have over that in camera and in post.
 
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