Best Practices for Shooting Anamorphic on the GH5

Hello Readers!

The Last few weeks I finally was able to start playing around with Anamorphic shooting on the GH5.

I’ve learned a lot in a short amount of time and I’m sharing my experiences here for you.

I would advise you all to watch my first video on Anamorphic on a budget to get a sense of my first attempts at anamorphics as well as my custom single focus solution.

This will give you a better starting point for the system i am working with.

Topics

1. Open Gate versus non-open gate shooting on the GH5
2. The H.265 Issue & Codec choice for shooting on GH5 in Anamorphic
   + Your Editing Machine may not support all of the different options
3. Bitdepth and color information on GH5
4. Why does Color Sub-sampling matter
5. Anamorphic Mode Choices on the GH5
6. Custom Anamorphic solutions can sometimes lead to issues.
7. Lighting matters
8. A little bit about Depth of field
9. Determine Distances to subject that you are shooting
10. Know your Anamorphic capabilities

1. Which Anamorphic Mode for shooting 4K? Open gate versus non-open gate

On the GH5 there are a couple of options for Anamorphic shooting in 4K.

1. C4K Anamorphic @ 200Mbps LongGOP 24p – Open Gate shooting which uses the full sensor to record from – 4992 x 3744 pixels which is essentially 5K.
2. 4K UHD @ 400 Mbps ALL-I Frame 24p – Uses a portion of the full sensor in 4:3 aspect @ 3328 x 2396

You may ask what the differences are here, let me break this down and explain which Option i choose and why (although i tested both of them).

Let look at the first option.

This is shooting with the full sensor which means that when a 2X Anamorphic lens is put on it is stretched by a factor of 2 to get your proper image.

This equates to 9,984 x 3744 pixels of image (nearly 10K horizontal image).

Sounds great right? yes lots of options here, but consider another factor.

How much space is that taking up and whether the codec used here is the best in terms of Editing this footage ?

The Cinema 4K setting on the GH5 in anamorphic mode is using H.265 or HEVC codec.

2. The H.265 issue

Each Codec is meant for different purposes and have different aspects to consider. H.265 is nearly twice as efficient as H.264. That is a good thing! But file sizes for that size of footage still take up quite a bit of space. Just to give you an idea, I shot a scene on the GH5 that was near 1 hour and 7 minutes. using this codec. It took up aprox 98 GB of space. Yes 98 Gigabytes. This is still better than H.264 which would be nearly double, however since we don’t have an option for shooting open gate with H.264 we are forced to use H.265.

Here is the fatal flaw of shooting H.265 today for me.

If your computer does not have hardware support for H.265 playback and encoding, good luck, your CPU will struggle with this footage and at that high of a resolution you will not be able to edit that footage at all.

What is LongGOP, ALL-I frame, Interframe, Intraframe and RAW ?

H.265 is not a problem by itself as the codec is meant to be able to be played back even without hardware support (although slower), the bigger issue with the mode on the GH5 that gives us Opengate is that it is 200 Mbps in LongGOP or interframe mode.

For those not aware Interframe means that for every I-frame or regular picture frame, the computer tries to calculate the changes for each additional B and P frames. IBP frames are all part of the MPEG (Motion Pictures Experts Group) standards that these codecs are meant to compress. MP4 is a container name but also stands for the MPEG standard version 4. the Codec used inside this container and used to compress or decompress can be variable however most video for the web these days use H.264 encoding.

Interframe encoding is more efficient and saves space but at the cost of CPU or GPU time to decompress or decode during playback and editing. It is an end customer format (versus a mastering format) and it is lossy due to compression and decompression. Artifacts can show up in footage more easily and the codec can not be re-encoded without loss of data or more artifacting.  It is meant for an end product codec (like Youtube or other web video) or consumer based codec. YouTube uses this codec for all of its Videos. It is a good end product standard when mastering a final product to.

Intraframe or ALL-I frame codecs are larger as each frame is a picture of its own. similar to taking every frame like a JPG (there can be compression within each frame not across frames like Interframe). These pictures are then put together into a video format creating larger files than interframe but hold on to a lot more detail in the images due to less compression and artifacting from image to image. Each image is compressed separately or none at all. This format is much better mastering format to use (a format that you can edit and then export to a consumer format) but not as good as RAW.

RAW formats are essentially the digital negatives of your image. Full lossless data with no color information applied or any details baked into the images yet. You need to adjust the exposure (within the dynamic range of your camera) you can without any ill effects however when shooting RAW however. Because RAW files haven’t been processed with a codec or color profile they tend to be more flexible in getting the image correct afterwards without worry much about pushing things too far and creating artifact or other issues in the footage. If you need a different color profile its easy enough to change. These files tend to be extremely large however due to being uncompressed but allow your editing application to manipulate to a much higher degree the video files without problems. In photography RAW files are what professionals use to generate stunning images of detail and color that are not always captured in frame. RAW files also keep track of other data such as timecode, whitebalance or luminance values among others. RAW files are the true mastering format because of their flexibility for post processing. RAW video files tend to also be proprietary in nature as most higher end Cinema cameras will have RAW but most lower end DSLRs for example do not. The GH5 does not shoot RAW.