Idle thoughts 2 ? Shutter speed


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Idle thoughts 2 – Shutter speed

9 Jan 2015 12:30PM   Views : 505 Unique : 334

Continuing my trawl through the things that I've spent a lot of time repeating in the Critique Gallery...

A couple of years ago we were at the Sage Gateshead with a photographer friend. She's the leading light of a local camera club, expected to be crowned their 2014 champion next week. Her studio work – flower studies, Still Life - is stunning.

Anyway we were on the first floor balcony, immediately above the café area, and we were looking for candids, which was way outside her comfort zone.

After a bit she said 'There's something going wrong. I'm on F8 and 100 ISO but everything's coming up fuzzy.'

I looked and she was shooting at 1/8 second. At 200mm (full-frame equivalent 300mm).

We tried to explain what was going wrong. Her lens has image stabilisation, which helps to counteract the effects of camera shake, and we were looking down which is much easier than holding a longer lens horizontally; plus we were leaning on a rail, which is always good. But you don't hold 300mm at 1/8 second, full stop.

Plus our subjects were engaged in lively conversation and she was going in close. I suggested that given the particularly helpful circumstances she might get away with 1/125 second. She was horrified at the ISO this needed – 'I can't possibly push it that high'.

We went through the same conversation several times over the following months, she could not get her head round it – because what we were saying ran totally against everything she had been taught. Camera club wisdom (at least locally) promotes aperture as the only thing that matters. Because of course you'll always be using a tripod won't you...

Aperture governs so much in the style and character of an image. But shutter speed matters in two ways. If you don't happen to be using a tripod (and I suspect that most people here take most of their photographs hand-held), you need a shutter speed that's fast enough to avoid camera movement.

And even if you are using a tripod, if there is any risk of subject movement you need a speed that's fast enough to freeze it. (That's assuming that you're not aiming for motion blur – I'll leave that one to another day).

Hand-holding, first of all. When you are using wide angle, the lens is short and stubby, it doesn't project very far in front of the camera. So the centre of gravity is near to your hands, the camera is well balanced, it feels stable in your hands.

The longer the focal length, the more there is sticking out in front of the camera, the further the centre of gravity moves away from your hands. That's when it gets harder to hold steady. It's particularly difficult to hold horizontally – pointing the camera up or down is easier.

The standard advice is to use the reciprocal of the full-frame equivalent focal length. DON'T PANIC, IT'S REALLY QUITE SIMPLE!

For a full-frame DSLR, if shooting at 40mm aim to go no slower than 1/40 second, at 80mm no slower than 1/80 second.

My Nikon D7000 has a 1.5 crop factor so the calculation would be: at 40mm 1/(1.5 x 40) =1/60 second.

That's just a couple of examples. Check the crop factor for your camera.

Two caveats: Lenses with IS (image stabilisation) have built-in technology that counteracts the effects of wobble. It will help a lot but it doesn't prevent wobble.

And equally important: the above calculations are a rule-of-thumb, everyone is different. I know that on a good day, if I brace myself and concentrate I can hold my 40mm lens acceptably steady at 1/20 second. When I try to use my 55-200mm at full length I sometimes have difficulty in even keeping the subject in the frame... You need to know your own limitations.

Subject movement is totally different. Very few things apart from Still Life in a studio can be relied on to sit totally still. Living creatures, humans or animals, may pose very obligingly but they swallow, blink, twitch. And they have to breathe...

If there's a breath of wind, a flower can move quite a distance on its stem, and can move quite fast.

Every subject is different, the speed needed will depend on a lot of factors. Take people. I reckon 1/80 second works nicely for portraits, it means that both I and the subject can relax and interact. I'll aim for 1/160 or faster if I'm photographing activities, which is what I do most of the time. Most sports will need a faster speed, somewhere between 1/500 second and 1/2000.

This is where I worry about dependence on scene modes. For example a Sports scene mode will be based on high ISO to allow fast shutter speed – typically 800 ISO, 1/800 second, with the aperture as the variable. Now if the light is good and you are not zooming in on the action, you may not need anything like that ISO. Meanwhile some sports, eg bowls, don't need anything like that shutter speed.

Equally I have seen Portrait scene mode give a shutter speed of 1/15 second, which assumes a) use of tripod, and b) a very well-trained model.

It goes back to yesterday's post – Take control of settings. Or at the very least, if you leave the decision-making to the camera, know and understand what it will do in specific modes.

Remember to keep an eye on both sides of the equation, aperture and shutter speed. And remember that in many situations (eg photographing a child, or a pet... ) the difference between say 1/50 second and 1/100 second may be considerably greater than the difference between F5.6 and F8.

Practise and you'll be able to sort the settings as needed in a matter of seconds. If you need to increase ISO to get the necessary speed, then do so. Photography can be a matter of compromises.

Tags: Critique Critique gallery Critique Team


JJGEE 15 7.7k 18 England
9 Jan 2015 2:20PM

Quote:If you need to increase ISO to get the necessary speed, then do so

It has taken me quite a while to get used to that concept, but I am gradually remembering more frequently that it is a feature on digital cameras that is there to be used !

The problem is, I spent so many years ( more than 30 ! ) taking negative & transparencies where you could not really change ISO from frame to frame...the whole roll had to be shot at the same ISO setting and I am still in that mindset Sad

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mrswoolybill Plus
13 1.8k 2149 United Kingdom
9 Jan 2015 2:24PM
I learnt on film, I got my first camera around 1959; and yes digital was a big jump mentally. But film was a great training, it made you think didn't it! Wink

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