GH4 i.Dynamic

Not a derailment at all, seeing as this thread has the word Dynamic in the title :)

Really any proper test of i.Dynamic vs Highlights / Shadows vs Contrast settings needs to have a Stouffer test in it anyway!

RE: lighting: yes, as diffuse and even a backlight as possible is ideal. Eg a lightbox style setup.

Also if you put the wedge so that the brightest part is not centered but nearer a diagonal corner, that'll help test accuracy as then lens flares will likely go to the other diagonal rather contaminate the wedge. Reference here (Art Adams' excellent Arri dynamic range article):
http://provideocoalition.com/aadams/story/alexa_dynamic_range_its_all_in_how_you_use_it/P2

However all of that is academic: eg if you want to compare with other Stouffer tests and want to keep all variables constant.

If you're just testing different settings on the same camera (eg "this setting has 1 more stop than that setting" vs "this camera has 9.38 stops of DR"), you can do whatever you like!

Also, cameras can have different DR at different white balance settings and with different lighting conditions (because the R, G, B filters may mean different channels are noisier than others and also clip at different points). So you may get a different result if you use a tungsten bulb vs a fluorescent bulb or a Kinoflo or an HMI or whatever.

If you don't have a waveform monitor, I think the simplest way would be to set 100% zebras and then expose so it looked like all detail was being completely clipped out of the top couple steps (eg you want at least 3 steps to be totally clipped). Then you just count from when it is clipped to where you can't see anything.

Bruce Allen
www.boacinema.com
 
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VMT said:
All very interesting, everyone. Thanks for the early adopter testing. I am waiting for the hack to clean up the native 1080p on this beast. What's that hacker's name, vital or vitality? When does he come into this?
Click to expand...

You might be waiting a long time. He never got around to hacking the GH3.
 
bruceallen said:
Not a derailment at all, seeing as this thread has the word Dynamic in the title :)

Really any proper test of i.Dynamic vs Highlights / Shadows vs Contrast settings needs to have a Stouffer test in it anyway!

RE: lighting: yes, as diffuse and even a backlight as possible is ideal. Eg a lightbox style setup.

Also if you put the wedge so that the brightest part is not centered but nearer a diagonal corner, that'll help test accuracy as then lens flares will likely go to the other diagonal rather contaminate the wedge. Reference here (Art Adams' excellent Arri dynamic range article):
http://provideocoalition.com/aadams/story/alexa_dynamic_range_its_all_in_how_you_use_it/P2

However all of that is academic: eg if you want to compare with other Stouffer tests and want to keep all variables constant.

If you're just testing different settings on the same camera (eg "this setting has 1 more stop than that setting" vs "this camera has 9.38 stops of DR"), you can do whatever you like!

Also, cameras can have different DR at different white balance settings and with different lighting conditions (because the R, G, B filters may mean different channels are noisier than others and also clip at different points). So you may get a different result if you use a tungsten bulb vs a fluorescent bulb or a Kinoflo or an HMI or whatever.

If you don't have a waveform monitor, I think the simplest way would be to set 100% zebras and then expose so it looked like all detail was being completely clipped out of the top couple steps (eg you want at least 3 steps to be totally clipped). Then you just count from when it is clipped to where you can't see anything.

Bruce Allen
www.boacinema.com
Click to expand...
Thanks again for the detailed response, Bruce! It will be interesting to play around with my own tests when I get my hands on this camera. Cheers!
 
bruceallen said:
If you do something that brings up the shadows a lot, you might not find a ton of usable data. Just a bunch of noise... and then you're wasting bits on noise
Click to expand...

Hi Bruce, is wasting bits a big concern? The videos i'm putting through mediainfo show around 80mb/s. Haven't seen any above that yet.
 
ralfmouth said:
Hi Bruce, is wasting bits a big concern? The videos i'm putting through mediainfo show around 80mb/s. Haven't seen any above that yet.
Click to expand...

Good question. Only testing will tell - and it will have to be a very smart test. Like, having a Stouffer chart as well as a monitor in the shot playing a loop of video with high-frequency detail in the background to stress the compressor.

Personally I am having exactly the same results as you - even though I've boosted the shadows and turned NR off, my bitrates rarely go above 80. I'm just being over-cautious because I don't want to give advice that may harm things. But yeah, I think that you are on the right track!

Bruce Allen
www.boacinema.com
 
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