- Posts: 210
- Joined: Wed Aug 29, 2012 11:43 pm
- Location: Los Angeles, & Santa Fe, New Mexico
Hi everyone,
I received my BMCC MFT last week and have been shooting numerous tests in al kinds of lighting and exposure situations. I am wondering if anyone else has been experiencing a similar problem. I found a discussion about this on another forum:
http://96.30.50.45/showthread.php?4992-I-really-need-help-with-exposing-footage-correctly-with-black-magic-cinema-camera
but thought I would bring it up here in hopes of getting some feed back potentially from Black Magic staff.
When trying to expose for 100% zebras my screen (exposing ETTR) goes so white and bleached out long before I see any zebras appear, so much so it is extremely difficult to judge the framing on the scene.
I decided to shoot a series of test shots as in the other forum users were complaining that they were getting their zebras, or exposure aids appearing on their external monitors like a TV Logic long before the cameras screen. In the test I shot two sample clips at 100%, 95%, 90%, 85% and 80% zebras, one just as the faintest hints of zebras appears and one with no zebras at all. I then took the samples into Resolve and looked at the scopes and here are my results:
at 100%, 95%, all of my shots showed some amount of clipping both with Zebras appearing and just without.
At 90% with no zebras showing, I was clearly safe from clipping but so close I could see that I was at risk of specular clipping over time.
at 90% (with some slight amount of zebras just showing) I had a safe margin in post to lift the highlights a bit if I needed and plenty of room to pull down the mid tones and shadows without introducing extra noise.
at 85% I was losing headroom I could otherwise recover in camera which would introduce unwanted noise in post if I lifted it them
In the other forum some users suggested that the Black Magic zebra was giving different values than the external monitors because the BM zebras were a direct indication of the sensor values while the SDI stream feeding an external monitor was being translated into a Rec 709 space and thus not as reliable.
At this point I am using the 90% just showing zebras to judge exposure but I am unclear whether there is something in my camera which is out of calibration or not.
Thoughts?
I received my BMCC MFT last week and have been shooting numerous tests in al kinds of lighting and exposure situations. I am wondering if anyone else has been experiencing a similar problem. I found a discussion about this on another forum:
http://96.30.50.45/showthread.php?4992-I-really-need-help-with-exposing-footage-correctly-with-black-magic-cinema-camera
but thought I would bring it up here in hopes of getting some feed back potentially from Black Magic staff.
When trying to expose for 100% zebras my screen (exposing ETTR) goes so white and bleached out long before I see any zebras appear, so much so it is extremely difficult to judge the framing on the scene.
I decided to shoot a series of test shots as in the other forum users were complaining that they were getting their zebras, or exposure aids appearing on their external monitors like a TV Logic long before the cameras screen. In the test I shot two sample clips at 100%, 95%, 90%, 85% and 80% zebras, one just as the faintest hints of zebras appears and one with no zebras at all. I then took the samples into Resolve and looked at the scopes and here are my results:
at 100%, 95%, all of my shots showed some amount of clipping both with Zebras appearing and just without.
At 90% with no zebras showing, I was clearly safe from clipping but so close I could see that I was at risk of specular clipping over time.
at 90% (with some slight amount of zebras just showing) I had a safe margin in post to lift the highlights a bit if I needed and plenty of room to pull down the mid tones and shadows without introducing extra noise.
at 85% I was losing headroom I could otherwise recover in camera which would introduce unwanted noise in post if I lifted it them
In the other forum some users suggested that the Black Magic zebra was giving different values than the external monitors because the BM zebras were a direct indication of the sensor values while the SDI stream feeding an external monitor was being translated into a Rec 709 space and thus not as reliable.
At this point I am using the 90% just showing zebras to judge exposure but I am unclear whether there is something in my camera which is out of calibration or not.
Thoughts?
Last edited by Patrick Finnegan on Sun Sep 08, 2013 9:02 pm, edited 1 time in total.
Finnegan's Wake Films
Director/ Cameraman
Director/ Cameraman