Workshop – Exposure Triangle – Shutter speed and freezing action

By | 31st October 2024

Tuesday 29 October 2024

This evening was a practical session run by Kevin, to review the Exposure triangle and specifically Shutter Speed.

To get the correct exposure requires the photographer to get the right balance of ISO, Aperture and Shutter Speed, but as Kevin pointed out, with today’s modern cameras ISO isn’t the issue it once was. This leaves the photographer with the creative decisions regarding Shutter Speed and Aperture.

Following Darren Pullman’s talk the previous week, Kevin reminded everyone that in Auto all cameras assume the correct exposure has an average tone of 18% Grey. However, that isn’t always what the photographer wants.

Kevin also pointed out that a Camera sensor sees less light than a human eye, but that can be overcome by creating a High Dynamic Range (HDR) image. This is more than one photo and the process is often referred to as “bracketing”.

A few single images were reviewed to highlight that 18% Grey isn’t always appropriate: Hi-key, low-key, high-contrast (dark shadows and overblown highlights).

Then we held the practical exercise, which demonstrated how at higher shutter speeds the sensor will freeze all motion, but as the shutter speed slowed first the limbs blurred and then the person, until at 1 to 2 seconds the person disappeared completely. However, a bright light source (e.g. torches), would be captured throughout the exposure, creating lines.

Following the exercises Kevin raised a few related points.

Be careful when using the electronic shutter mode (“silent shutter”), as the way the sensor registers light will cause it to catch a LED light source flashing. Creating banding across the image. Also, on faster moving objects it will cause them to appear mishapen.

Finally, Kevin covered other ways of freezing motion. These are using a Speedlight and using a Strobe, the latter is used for extremely high speed action (e.g. a bullet passing through an Apple).

Finally, Kevin showed an image by Trent Parke (“Moving Bus”), which demonstrated extreme creativity in exposure and shutter speed.  See The Art Gallery of South Australia