Kate's Photo Journal

The Canon EOS 400D has the option to use a 'Continuous Shooting' drive mode in the following Modes: Sports Mode, Portrait Mode, Program AE (P Mode), Shutter Priority AE (TV Mode), Aperture Priority (AV Mode), Manual Exposure (M Mode) and Automatic Depth of Field (A-DEP Mode). So I thought it would be handy to write a brief article exploring how continuous shooting works and when and why it can be helpful to use it.

How Many Photos Per Second?

According to the Canon Manual, continuous shooting allows "up to 3 shots per sec" to be taken. I have just carried out a crude test of 'continuous shooting' speed in two modes (Program AE - P Mode and A-DEP Mode) and using two different AF (auto focussing) Modes - One Shot Mode (camera will focus only once during continuous shooting) and AI Servo (focusing will be continuous during continuous shooting). The results were were as follows:

Program AE - P Mode

• One Shot Mode
  • Max duration of continuous shooting - approx 9 secs
  • Number of photos taken - 24 photos
  • Photos per sec - 2.6 photos per sec
• AI Servo
  • Max duration of continuous shooting - approx 8 secs
  •  Number of photos taken - 16 photos
  • Photos per sec - 2 photos per sec

A-DEP Program

• One Shot Mode
  • Max duration of continuous shooting - approx 14 secs
  • Number of photos taken - 34 photos
  • Photos per sec - 2.42 photos per sec
• AI Servo
  • Max duration of continuous shooting - approx 28 secs
  •  Number of photos taken - 43 photos
  • Photos per sec - 1.5 photos per sec

So, it does seem that in some modes it would be possible to take up to 3 photos a second. However, the number of photos that can be take per second will be affected by various factors, such as:

1. The AF (auto focus) mode used - if you use AI Servo AF whilst doing continuous shooting the number of photos per second will be lower. This makes sense since in this AF mode the camera is continuously adjusting its focus for each shot, which will inevitably reduce the shot speed. You can see this in the above figures - within both P-Mode and A-DEP mode less photos per second were taken when AI Servo was used as compared to One Shot AF Mode.
2. The use of flash - according to the Canon Manual you can use the flash whilst shooting in continuous mode, but this will reduce the number of photos taken per second because the flash needs time to recharge.

Duration of Continuous Shooting

The camera will not go on 'continuously shooting' photographs indefinitely, instead there will be a 'burst' of continuous shooting of a limited duration. This is because you are shooting pictures too quickly for the camera to be able to directly save them to the memory card. Instead the Canon uses its 'buffer memory' to store the images in the short term (while you are still shooting) and then transfers them across to the memory card once you stop shooting. However, obviously the 'buffer memory' will have a limit as to how much data it can store, so the Canon will eventually stop taking photos and display the word 'busy' in the viewfinder when the buffer memory is full. You then have to wait a few seconds before recommencing photographing.

Examples of these 'bursts' of continuous shooting can be seen in the results of my tests recorded above, since when carrying them out I simply let the Canon continuously shoot until it stopped due to the buffer memory being full. So in P-Mode using One-Shot AF the Canon EOS 400D's buffer memory filled up after 9 seconds (24 large photos) - that doesn't seem too bad to me.

Obviously the number of images that can be taken in one 'burst' of continuous shooting will vary according to the size, quality, shooting style, ISO etc of the photographs.

When is continuous shooting useful?

The speed at which photos are taken means that continuous shooting is particularly useful when shooting moving subjects, e.g. children playing, sports events, animals etc.

Clearly, for moving subjects such as at sports events, continuous shooting is advantageous because it allows you to shoot lots of photos very quickly - therefore creating a set of consecutive images that almost recreate the movement of the athlete. Earlier this summer I took some great shots of the Tour De France using Sports Mode (with continuous shooting). Using a 'Single Shooting' Mode would make it much harder to capture the sense of movement and waiting for the camera to take a shot could result in opportunities being missed.

Even when photographing more 'still photos', e.g. of people sitting down and talking (perhaps for candid photography) continuous shooting can be a valuable asset since it allows you to capture different facial expressions that could be missed with a slower shooting speed.

I tried out continuous shooting when out walking in Kent recently - my mother threw a stone into the river and I managed to take the following shots on the first attempt:

These aren't the greatest shots in the world, but I'm pleased with the fact that I managed to capture so much of the splash (which was pretty small and short-lived). I was using the AI Servo AF Mode since I wanted the camera to refocus on the water droplets as they reacted to the impact - as already discussed this would have reduced the continuous shooting speed. One tip I do have for these types of shots is to start the continuous shooting a little before you expect anything to happen, since this should prevent you from missing any of the initial movements.

As a comparison, my mother also tried to photograph the impact of a stone on the river using her FujiFilm FinePix 6900 Zoom without continuous shooting - this was the result:

She tried twice and both times the camera did not respond quickly enough for her to capture more than the ripples left after the stone had sunk under the water.

Disadvantages to Continuous Shooting

There are many situations in which continuous shooting is really the only (or at least the easiest) way to get good photos, however it does have downsides that should be borne in mind. One of these is that continuous shooting can drain the camera's battery quicker than single shots, so if you were planning to take photos at an event whilst relying largely on continuous shooting you would need to go prepared with spare batteries and a charger. Additionally, since continuous shooting results in large numbers of photos being taken very quickly your memory card can fill up much faster than usual - I've certainly been caught out by this in the past!