I am of the opinion that properly shot Rec 709 that is intended to be delivered in Rec 709 is technically superior to shooting LogC. While this may be technically true it is not common practice these days as everyone has opted to shoot LogC under the assumption it's going to give me more to work with in post. When you say it trades big depth in some areas of exposure I would think it trades bit resolution more so than bit depth. In my basic understanding the top and bottom of exposure are rolled off so they have fewer steps or millivolts of data range at the top and bottom. To me that would mean that a gradient would have more banding in the high and low exposure areas. This is how I view it but please correct me if this is wrong.
From the most basic stand point when I get Arri LogC the un lutted range on my scope is typically 100 to 550/600 millivolts. Right away the exposure modification of the sensor data has left a 100 or more millivolts of potential image contrast/detail at the top and bottom lost. I realize the idea behind the LogC is to avoid clipping and try and take the data from the more optimal range of the sensor. So once you've compressed the image contrast using the LogC math when you stretch it back out you are adding noise to some degree and I would assume the quantizing steps are stretched out so some subtlety of detail is being lost. I have just assumed the lack of clipping etc... outways these inherent issue. For me LUTs are pain than gain but I realize I seem to be in the minority in this area. Every time I have to color correct just to get to a square one of the basic look it takes more time and time is not something I get much of. In my experience the whole Log workflows get confused in many ways and as you say when things are not properly exposed in Log things are more work to correct. Arri LogC, Sony S3 Gamut etc..., and Panasonic Vlog seem to play pretty nice but I've battled footage from Cannon c300 log that had no consistency so I could not apply a generic LUT to all the footage so it just became easier to drop Luts and color correct each shot. That is where I have the most issue with Luts in my world.
---In Avid-L2@yahoogroups.com, <pat@...> wrote :
Log is about trading bit depth in some areas of expisure to gain latitude. Don't need or use the latitude and you are just losing.
Pat from his mobile.
Posted by: bigfish@pacbell.net
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