Miss Demuir Presents: With the Lights Down Low… use ISO!

Tip o’the Morning to you… #2

With the Lights Down Low… use ISO!

In the Good Old Days – the days of Barbara Stanwyck and the Studio System; the Girl from Ipanema or the Italian Job; whatever your decade, in fact, as long as it pre-dates the ‘Nineties – all cameras took film. You knew that, didn’t you?

However, what you may not know was that not all the film these cameras took was equal – and in respect of being able to light up the dark, some film was decidedly ‘more equal than others.’ There were different speeds of film, you see, classified in terms of their ASA. A fast film (that with a higher ASA) could literally ‘capture’ more light during a given shutter duration – and hence better expose a low light situation. Thus, a wedding photographer of old would have used a high ASA film for the ceremony itself to iluminate the dim church interior, whilst physically switching to a different lower ASA film for the group photographs to be taken in the daylight, outside the church after the service itself was over.

Now, we no longer have film or ASA (well, most of us don’t) … what do we do, when light levels alter?

We have ISO instead! It works in exactly the same way (except without the minor inconvenience of having to stop everything and swap actual tangible rolls of film, without inadvertantly exposing them, between the church door and the churchyard in twenty seconds flat).

Now, take this rather pretty (and very conveniently placed) bunch of flowers, resting upon my kitchen table at oh, say 7.55pm. There is a Very Small amount of light from the window to its right (but not a lot, as you can imagine at this time).  Possibly, flash might appear to be called for but that would ruin the effect with which I wish to dazzle you. Also, to keep this a truly scientific experiment and properly controlled, I am going to go into Manual (so the camera does not think for itself, at all) and select shutter speed of 1/250s, an aperture of f3.5 and an ISO 100 (the lowest). These will remain constant, so that the only thing which changes is the ISO, itelf.

And at ISO 100… Tada!

Oh, I am sorry! You cannot see it? It’s there, I promise. Perhaps I can shed some light upon the matter… and, indeed, things do appear to be a little clearer at ISO 1250:

But I believe the honours must go (for shooting with no flash and in troglodytic conditions)… Ladies and Gents, I give you… ISO 6400:

Nice, eh?

And a BONUS…!

Yes, a super one, too. Because higher ASA film – and higher ISO digital – ‘capture’ more light, they can light up dark places… but they can make your capturing of images in light places even better.

1. Firstly, the movement of others – I find that shutter speeds of less than 1/250 s will often result in blurring even in good light – a higher ISO can allow you to use a higher shutter speed, thus solving the issue (especially useful when so many cameras are tied to a max flash sync speed of 1/250 s or less) .

2. Secondly, the movement of you! If you are handholding (and 99% of the time, unless you are doing landscapes or macro, you will be) your camera WILL shake. But raising the ISO, especially where no flash is allowed, will allow you to raise the shutter speed and minimise its effect on your pictures. More on both of these vital areas later!

OK, Miss Demuir, you have convinced me. So, how do I increase / decrease my ISO?

It is simple. On my D50 and my D7000 – in fact on most consumer / prosumer Nikon and non-Nikon DSLRs, there’s a button that says ‘ISO’. Holding this down whilst turning the wheel and the ISO will alter.  In some cameras, though – including most of the sophisticated point and shoots – you will need to go into the menus to do this but the principle is the same. Whichever your camera, a quick shufti at the Instructions will provide your answer.

And now, three (yes, three!) notes of caution:

1. Whack the ISO up rarely and with extreme care. In fact, don’t whack it up at all. Go slowly and you won’t overdo it. Overdoing it will be an Extremely Bad Thing, because your pictures will develop a nasty, blobby condition called Artefaction – best avoided, it’s fatal for a photograph 😦

2. Remember, you won’t be able to alter the ISO if you are shooting on Auto – the camera will decide ISO, as it decides everything else for you – which is why I almost never use it, myself. It will very likely work admirably, though, on P, S, A, M and any and all other modes you may (or may not) possess.

3. And ALWAYS put it back to minimum before you put the camera away. Then you won’t find yourself shooting inadvertantly at ISO 25000 in broad daylight and ruining every shot next time.

That’s all folks… do let me know how you get on – and which other weird and wonderful photographic arcane arts you would like me to cover in future blog entries.

Until next time, pen (and box brownie) at the ready…

Ruby

x

*****

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TQ x

As ever, (c) Miss Ruby Demuir and her mild(er) mannered alter-ego Bryonie Jones – 2011

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