In my previous post, I complained about image quality and other shortcomings of the Blazar Mantis 35mm f/2.0 1.33x anamorphic lens. I was unsuccesful at selling it. And I used it on an occasion on which I had the chance to experiment.

Here are some things that worked well, and some other observations.

The Occasion

This weekend there was an event at a local youth club called “VIZIT”, organized by the Jazz-Pop-Rock department of the local music school, “Academie Wilrijk”.

Both my kids and I are enrolled at the “Academie”, and I am grateful about their approach to musical performance and general work.

The event was that all ensembles were supposed to perform two or three songs or compositions from their repertoire. Four blocks, 22 bands in total, three and a half hours net live performance. Three hours, twentyfive minutes and thirtythree seconds, to be exact - which I know because I filmed them all. I just got carried away by the great music, people I knew in that or the other group, and my great view from the camera spot. Several of the coordinators and teachers signalled that they would love to have videos. So I kept filming. And much enjoyed the concerts from the best view possible.

This is my first recommendation of the day. If your local music department organizes a showcase: be there and enjoy. All the students did their best, prepared well, were more or less closely supported by professionals, and delivered a show. Every band was worth it, and I am thankful to all the participants for the good entertainment.

The Unexpected Use Case

I had brought two lenses: the Zeiss Distagon 35mm f/2.0 (regular) and the Blazar Mantis 35mm f/2.0 (1.33x anamorphic). I started using the Zeiss, of course, in “pixel by pixel” mode, 4k DCI (what Panasonic calls “Cinema 4k”). The aspect ratio did cover the podium well, “pixel by pixel” allowed me to move back a good distance to an inconspicuous spot behind the sound engineer.

Two downsides:

• I ran out of SD card memory too quickly (>10GB for 5min).
• Audio was of limited quality, because I was standing behind the audience (“pixel by pixel” crop).

I got support by the academy organization who brought extra SD cards, for which I am thankful. But still, it was clear that I had to use a lower resolution. “HD/1080p” would be the minimum (this defines a resolution with 1080 pixels in height; width can vary).

But HD is not ideal for the stage. It is 3:2 aspect, covers a lot of empty space above and below the stage (memory and resolution burden). Also, if I record HD “pixel by pixel” (for the low rolling shutter), then the crop and therefore zoom factor would require me to move even further back, and ruin audio.

And this is where the anamorphic lens came in.

• If you only require limited resolution (less resolution -> less sharpness required),
• … and would like to film something in an aspect ratio wider than 3:2, e.g. 4.8:2
• … and if you want to record “full sensor”, in a 3:2 standard video mode,
• … and if the subject is sufficiently well lit for f/4.0 or higher

… then the Blazar Mantis might actually work.

I finally did see those orange flares when filming against the stage spotlights! (They are not worth the money for a “cine”-lens.)

So the limitation of the standard sensor resolutions (HD, full sensor) with 4:3 aspect ratios, combined with a wider desired aspect ratio, and/or a situation in which memory is limited enough to force HD, actually turned my balance in favor of the Mantis.

However, far more important were the following gadgets.

The Software: FFmpeg

Readers of this blog (Grüß Dich, Mama!) will know that I have been using FFmpeg during my PhD project.

ffmpeg -i <input_file> \
    -c:a libopus -ac 2 -ar 48000 -b:a 96K \
    -c:v libsvtav1 -crf 20 \
    -svtav1-params preset=6:tune=0 \
    -vf "lut3d=VLog_to_V709_forV35_ver100.cube,scale=1.4*iw:1.0*ih:flags=lanczos,setsar=1" \
    -pix_fmt yuv420p10le \
    <output_file>

This is quite a butter bum (it is not, they say “boterham” here in Flanders).

• The ffmpeg command is initiated to work on an input file.
• Audio is set in the second line (48 kHz, 2 channels, 96k bitrate).
• The video is recoded with the SVTAV1 codec, at constant rate quality (-crf 20). Some parameters are set for that codec on the next line.
• Video filters are applied with -vf:
  • lut3d directs to a LUT file (here: the Panasonic official VLog to Rec.709 conversion)
  • a width rescaling to the anamorphic squeeze factor (here: 1.4) with Lanczos interpolation
  • setsar=1 will enable the anamorphic desqueezing with scale (which otherwise fixes aspect ratio).
• -pix_fmt fixes the 10 bit color depth.
• Finally, the desired output file is the last element of the command.

I have been using a simple Python script since about 2021; I dumped it here for the moment and might clean it up in the future. It can convert all videos in a folder, applying the extra command blocks above on videos with a dedicated filename modification.

I have been following the AV1 timeline quite a while and I am glad that I can finally use it for my home videos. It is an extremely impressive codec, also used in web streaming. Quality is great, multiprocessing works; with ffmpeg, I can batch-apply it to all the videos I made and save hugely on the backup drive space.

Besides ffmpeg, I manually intervened for the audio. I reluctantly used audacity for noise reduction and amplitude normalization. Then, another round in kdenlive will finalize the video: loading the clip and the better audio, aligning them, cutting to a good start and end, adding start and end fades as desired. Then another “render” to SVTAV1 at 1080p.

Voila!

The Camera

I am also glad about some aspects of the camera, the S5II X. For example, that they have a log color mode, which is useful in some video situations. And that Panasonic offers a lut to remove the log.

Log is a bit hard to comprehend. As I understood it, it morphs (math.: “mapping”) the lightness values (from “dark”, to “bright”) onto a logarithmic curve. Darker values are stretched to a bit wider space, whereas brighter color/lightness pixels are “squeezed” into less room at the top of the bit range. The advantage is that you get better color distinction in darker areas. You also loose some color finesse on the light parts, which I have regretted on a video of someone on a stage with white walls and graduated lighting.

Most stages are “low key”, so a log color space is justified. The lut (“lookup table”) will revert the video to normal colors. Took me a while to wrap my head around this: I once sent a hazy washed unrecovered f-log birthday video. My bad!

There is more to the camera: audio is quite good, “pixel by pixel” is a useful mode, anamorphic and log preview convenience functions are in place, I use a custom function button for a “punch-in-zoom preview”. Rolling shutter is an issue, but I have a tool to literally fix that a priori.

The Accessories

Some gadgets made it to my personal hall of honors.

• The battery! I got a V-Mount battery (that just describes the attachment) rigged to the back of my camera. It continuously powered camera and screen for four hours and still had 32% left. I did not expect that extraordinary battery endurance.
• A Monopod! One of these things I bought once long ago because I thought I would need it, but now I finally needed it. The monopod was extremely useful as a camera foot for long time steady recording.
• External Monitor. Helped me to manually zoom. I attached the sun shades and tilted it down so that the screen light would not distract the audience behind me.

There was another item, worth its own paragraph.

The Sound

I have long owned a Zoom H5 recorder. It was mounted on top of my camera with a little arm. If you record music, get a good audio recorder.

The zoom ones are simply outstanding.

And, by the way, it also works as a high quality mic for online meetings, or as an audio interface for your computer to record line-level instruments.

The Light

Not everything was perfect. I was not in charge of the podium lights, and apparently no one was. They were “blue-yellow” spots just randomly directed for most of the time…

… until someone found the swithc for proper light about halfway through the last set.

What a difference a day(light) makes…

If you are “the video person”, do not hesitate to ask “the light person” to get good light.

Summary

This is just a brief sketch-up of the things I learned during an unexpectedly long video recording session. I much enjoyed it, and hope that you recover some ideas for your own practice.

I felt a bit creepy to keep filming all those young musicians. But since I uploaded the videos, I have received a huge lot of web traffic and very positive feedback; both teachers and students seem to be glad about the output. And I am glad that I got this great chance to learn something.

This post is work in progress. I might add a photo of my camera rig, or a good video of all the recordings (if I get explicit permission by one of the bands). I promise to proveread at some point in time; please excuse that that time has not come yet.

Thank you for reading!