To ETTR or not to ETTR...?

Started 3 months ago | Discussions thread
The Ghost of Caravaggio Contributing Member • Posts: 701
Re: Have I got it right?

timo wrote:


If, using the camera's metering system and with your EV dial set to 0, your shot is already just about triggering blinkies,


What have I missed?

Blinkies are better than nothing, but –

Blinkies come and go based on in-camera JPEG settings. One could choose in-camera rendering settings that would unnecessarily underexposure the sensor compared to other settings – underexpose and then over brighten in-camera. In-camera JPEG options that offer pull-push automation (Active D-Lighting for Nikon, DRO for SONY, DR for FUJIFILM, etc.) intentionally underexposure the sensor. These automation tools are useful because they protect inexperienced in-camera JPEG users from unintentional over exposure. However with raw files these data are always less informative compared to just than maximizing exposure. Using blinkies and automated pull-push invoked would be self defeating.

Blinkies can indicate both sensor over exposure and signal clipping caused by an unnecessarily high camera ISO setting. To maximize exposure only the former counts as ISO signal gain occurs after the shutter closes. This is typically most important when using base ISO.

Blinkies will appear for specular reflections from sunlight and other very bright point-source light sources. The light from these is uninformative. Even if you use a 6 stop ND filter and sunlight reflections are not overexposed, they will render as white. If the on-camera LCD resolution is insufficient to distinguish between blinkies caused by uninformative bright light sources and blinkies in regions of interest, you may unnecessarily underexposue the sensor.

ISO Is An Important Parameter

Use the lowest practical ISO consistent with practical shutter times and or aperture settings. This maximizes sensor exposure. If your camera happens to use dual conversion-gain sensor technology there will be two minimum ISO settings. One for low gain (bright light) to optimize sensor analog dynamic range in bright light and another for high gain to maximize sensor sensitivity in low light.

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