Given this, the biggest impact you can have on the image with the menus (as opposed to lens settings like iris and focus) is your choice of ISO or ASA setting. After our tests and some advice from John Bowring at Lemac, for 'The Combination' i set the ISO at 500, up from the nominal setting of 320 ISO. If you are using the waveform and monitor output to set exposure, then this essentially underexposes the sensor by two thirds of a stop, helping to protect the highlights in the scene from clipping and in effect increasing the useful dynamic range. Of course in a controlled studio environment the contrast of a scene can usually be manipulated with lighting so there is less need to underexpose. But shooting a low budget feature on location presents many situations where the contrast in a scene cannot be easily controlled so i know that if my highlights are starting to clip on the waveform, at 500 ISO there is a little more headroom on the RAW image. In fact the more contrast in a scene, such as full sun onto white shirts with a shaded wall in the BG, the higher the ISO can be set to hold details in the highlights on the shirts.
Even though low light and nighttime shooting typically has less contrast - except for any light sources in frame - i find 500 ISO a more intuitive speed to use thanks to years using 500 ISO film for night shoots, knowing what lamps are needed to cover given areas to a particular T-stop and so on. So i left the ISO setting constant throughout the shoot. However, this does present a problem when shooting in bright sunny exterior day conditions with a camera rated at 500 ISO . The amount of ND filtration required to get down to a T stop of around 2.8 or 4 is about 5 stops - which unfortunately creates an magenta tint to the image caused by excess infra red hitting the sensor compared to the visible light. While it can be graded out in post there are IR cut ND filters becoming available to deal with this issue.
Jim Jannard (RED's founder) touches on this relationship between ISO setting and dynamic range in a recent post on the RedUser forum. It sounds like the forthcoming Build 16 will have much improved ways to judge exposure at the sensor rather than just the HD monitor output which will be very helpful if it works. The most difficult part i find of working with HD video and the RED as compared to film is setting exposure and containing highlights.
Other settings we had were frame size and frame rate - we shot at 4K 2:1, using the full width of the super 35mm sized sensor, then setting the monitor frame line markers to 1: 2.40 aspect ratio. Base frame rate was true 24fps (not 23.98). For slow motion footage up to 50 and 60 fps, we changed resolution to 3K 2:1 then set variable speed mode allowing recording on the same media, in our case usually the Red drive. We shot at Redcode 28 compression rather than the higher quality Redcode 36 to save on disk space with the 2.2 terabytes of original footage duplicated twice for safety backups. Redcode 28 gave us a higher top frame rate also, up to 60 fps at 3K.
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