Best Practices for Shooting Anamorphic on the GH5
3. Why Bitdepth Matters for images?
You may have heard that the GH5 can capture color detail at 10-bit. What this means is that the camera’s sensor has more color and shadows and highlight information than an 8-bit 4:2:0 camera would in general. Essentially the more detail you capture the more information you have to work with later when making changes or color grading the footage. A common thing to look for is that 10-bit footage will tend to show more color graduation in stuff like water or sky shots where light is creating very specific color banding and shows horribly on some 8-bit footage.
4. Why does Chroma Sub-sampling matter for images ?
The GH5 as example can do 4:2:2 color sub-sampling but the Luma (blacks greys and whites of the footage) values all stay sub-sampled. Color sub-sampling is essentially a way in which the Camera’s sensor stores the color information and reproduces it by approximation. 4:4:4 would mean that the camera is storing a full red, green and blue color information for each pixel which provides the most accurate reproduction available. Most consumer level cameras can’t do this level of detail on their sensors and currently only high-end cameras can. This means a more accurate sensor but also more color information is stored to reproduce this. 4:2:2 means that every green and blue information it is doubled within the pixel (less accurate and interpolated but still a best approximation of the color). 4:2:0 would mean that the blue color is essentially not being sub-sampled and filling up the second half of the pixel. This means a lot less accurate of a color to the eye but still approximates the original color information. 4:2:2 then is fairly accurate and in some cases 4:2:0 can work however the differences are in when you try to color grade or change the color in dramatic ways that the problems show up.
**Note: RAW footage does not have these issues generally due tot the fact that only the Luma values are applied to the footage. Color Grading can occur afterwards with more precision and control because the color is not baked into the footage like with other codecs such as H.264 or H.265. RAW formats are generally proprietary in their scope of what they retain and are generally very large file sizes.
5. Anamorphic mode choices on GH5!
H.265 LongGOP
Open Gate shooting on the GH5 uses H.265 codec. The main reason is that the cameras system cannot go above 400Mbps datarate and since the higher resolution of the camera (4992 x 3744 pixels) requires more data rate to maintain quality.. the only thing left is compression codec to handle more compressed data. This requires a substantial on-board processor to handle the new Codec to compress and decompress at these high rates. The GH5 compresses to 200Mb/sec versus 400 Mb/sec but retains the same amount of detail.
Space is also a concern when choosing a codec.. if you don’t have a lot of room on your hard drive, RAID array or the camera’s memory cards but you want to capture as much detail as you can use H.265 (HEVC) codec with Open Gate Anamorphic shooting. Keep in mind however when you try shooting Open gate and put the footage on your timeline and experience the dreaded computer stall… Your computer isn’t up to the task of H.265 Timeline editing and will grind to a halt because of the LongGOP recording alongside the extra H.265 processing your machine has to do. Most likely your machine is not optimized for it. Welcome to the next generation codec H.265.
If you are lucky you will have one of the newest Graphics cards such as NVidia that supports encoding and decoding H.265. If you don’t, be prepared to use H.264 in ALL-I mode and make sure you have lots of space!
H.264 ALL-I frame
Okay so if your like me, I don’t have a latest graphics card to handle H.265 but I have some Hard drive space, Option 2 is my only real choice to work with 4K in a reasonable manner!
3328 x 2396 – H.264 400 Mbps 24p ALL-I frame
When that is used with an anamorphic lens you are getting = 6,656 x 2396 or 2.77:1
cropping that down in post you can get the proper aspect ratio.
So 6K with Anamorphic running ALL-I frame! That isn’t bad!
This will result in buttery smooth footage that is quite editable on a computer that still has a graphics card that can decode H.264 footage.
File sizes are a problem however at nearly double the size. so that 98 Gigabytes that the H.265 gave us is around 196 Gigabytes /hour. Ouch!!
Big TIP here!
Use the telescoping feature of the GH5 to crop back in if you need that little bit of reach!
The on-board Telescoping mode crops in by 1.4 times again without losing native resolution!
Let me explain:
