Friday 19 August 2011

Shutter speeds

I was looking at a photography book in a shop the other day. In the section on sports and action photography, it gave some tips for minimum (i.e. slowest) shutter speeds recommended to freeze the action. For football, they suggested 1/500s for a player running across the frame, and 1/250s for a player running towards the camera. I would not disagree, and in an afternoon game at this time of year, I would expect to get them without difficulty, like this one, from Cables' game at Woodley Sports, everything frozen at 1/1250s.
However, at our level of the football pyramid, for about two thirds of the season, lighting conditions are likely to be sub-optimal, and in some cases, that will be putting it mildly.
Once it starts to get gloomy, we have to start trading off - freezing the action, against lighting, against the size of image. I will look at kit in a later post, but for the following discussion, I am using a Nikon D5000, which has an ISO range up to 3200, extendible to 6400 equivalent. Going above ISO 3200 means full noise reduction is not available, but I have found the results to be quite acceptable. The main lens I use for football is a 70-300mm f4.5-5.6 zoom. In bright light, I just select the sports preset mode, and let the camera take care of the shutter speeds, apertures and ISO. As the light fades, I switch over to shutter priority mode and work down through the shutter speeds, starting at 1/320s just before the lights come on, and working down as it gets darker.

So, just how slow can you get away with? It depends to a certain extent how sharp an image you want. If the player's head and torso are clear, I will accept a certain amount of blur on the faster moving feet, hands, and of course the ball. By the time it is fully dark, so the only light is coming from the floodlights, I have moved down to 1/200s, which is about as low as I think I can go and get a reasonable number of acceptable shots from which to choose for the slide show.

That is not to say you do not sometimes get one that seems to be defying the laws of optics. Take this, from Prescot Cables' game at home to Cammell Laird, of Cables' Joe Gibiliru.
That was at 1/125s - I had not noticed how low the speeds the sports setting was offering had gone. You can see blurring on the hands and feet, but otherwise movement is still reasonably well frozen.

Then came the next one, at 1/100s - you can really see the blurring on the Lairds player's right leg, but the rest of the shot is still quite crisp.
I have never tried deliberately using this speed for a sustained period: I think the number of usable shots would be low enough to make it of limited use, but in low light I am happy to use all the tricks to catch the most of the light that comes my way.

The slide show from the match is available here.

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