03 Mar 2019

Opinion: Challenging "traditional" assumptions about cameras, lenses, recorders, dynamic range, etc

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Opinion: Challenging "traditional" assumptions about cameras, lenses, recorders, dynamic range, etc Craig Marshall

Index

Roland asked: "Even the quantifiable aspects (of cameras) have subjective elements to them — one camera may claim higher sensitivity but may be no better than a lower spec camera with the gain turned up. When does picture noise become unacceptable? And whatever the quoted dynamic range, what do the pictures actually look like in high contrast situations? Does the viewfinder give you any idea of what the pictures really look like?”

To answer this, I'll give a recent example: a Korean crew I met on the Sanjo Bridge had one of the more modern rigs I saw in Kyoto. It consisted of a Sony A7s mirrorless full frame camera set in a heavily machined 'cage' housing mounted on top of one of the heaviest fluid tripods I've seen and to cap it off, they had an Atomos 'Shogun' 4K recorder perched alarmingly on top of the whole structure. They were shooting a timelapse sequence of still images at the time so there was plenty of opportunity to talk about cameras, which we did.

The Koreans raved about the quality of the 4K images they had captured with the A7s/Shogun combo and the ones they showed me certainly looked fantastic on the ProRes recorder's big monitor but after examining my diminutive setup, they seemed stunned at the excellent low light sensitivity my camera exhibited there and commented words to the effect: "you know, that's a really great setup and after lugging all this gear around Japan for two weeks, we really envy your mobility!"

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Midnight Special! Diminutive and super sharp Zeiss 50mm f/1.7 gives f/1.2 at the sensor with the Speed Booster attached

Of course, what they may not have realised was that with my diminutive Zeiss 50mm F1.7 lens fitted, I can shoot sharp HD video or RAW stills with the iris set wide open. The 'slower' Zeiss 50mm is as sharp as a tack wide open at f1.7 unlike its more expensive brother, the 50mm/F1.4. With the Speed Booster performing its optical light boosting thing and restoring the full frame lens' original field of view on to the Super 35 sensor, I can achieve a remarkably good 'low light' sensitivity of F1.2. Add into the mix some additional Gain coupled with the 4:2:2 colour space achieved by the ProRes HDMI recorder and the resultant HD pictures are more than acceptable for a three year old video camera.

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This ProRes 4:2:2 frame grab is with 20dB of Gain applied but even so, the Zeiss 25mm F2.8 competently handles highlight flare

One problem faced when shooting on the streets at night is Dynamic Range. Street lights are very bright and the shadows are very dark. The human eye can easily differentiate between the two extremes but cameras find it very difficult. Modern imaging devices are now quoting truly remarkable DR figures but I have no idea what the DR of my camera is, nor do I really care. What I do know, is that I need to be careful not to burn out too many highlights and I need a viewfinder which must:

  • exclude all extraneous light
  • offer accurate picture framing
  • offer accurate focus confirmation
  • offer accurate light metering and indicate when the highlights are about to clip.

There's not much more I need from a viewfinder, except perhaps the usual conformation of shutter, gain and audio levels from the camera's external microphone. I certainly don’t need colour information. Back in the 80s and 90s, I cut my teeth shooting hundreds of TV commercials and corporate videos with Betacam/SP recorders mated to Sony and Ikegami cameras equipped with high resolution monochrome CRT viewfinders. Once you set up your viewfinder's brightness and contrast using the camera's internal colour bar generator as a reference, you next selected the 'tungsten' or 'daylight' filters (or set up a 'white balance') and off you went.

The camera's ability to shoot accurate 'colour' in the field was a given but of course, you had to be sure that your camera tech had set it up correctly in the first place so somehow, I never feel the need to see 'colour' in the viewfinder. I never used a field monitor either and I still don't for nearly all fast moving situations. If you (and your client) are confident in your camera's ability to record a perfect picture (in my case, broadcast legal REC.709) so what more do you need? (until BT.2020, becomes mainstream, anyway) I should mention too that in Kyoto, the use of daylight balanced LED shop and street lighting is much more common than here in Australia, even with Japan's relatively cheap electricity prices. Consequently, I just leave the camera's white balance set to the 'Daylight' preset so that nicely covers the transition from afternoon to evening and night.

Read part two of this article here: Challenging "traditional" assumptions about cameras, lenses, recorders & more - Part Two




Craig Marshall

Retired freelance TV commercial and documentory producer/director/camera/editor

Website: www.HDvideo4K.com

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