December 2012

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Since I know people who take photos for money and stuff, I’m a bit reluctant to be HERE’S HOW IT’S DONE BITCHEZ! but since I’m very experienced at not knowing what I’m talking about and a few desperate lucky ducks got cameras for christmas and had to resort to me as some kind of authority, here is my explanation I can point to.

Actually before I do, a couple of disclaimers. Firstly, I realise this may qualify as a ‘here you are’ shot and to deflect any criticism, it was shot live so it is in fact ‘un moment decisif’. As an experienced adult educator, I feel the need to come across as incredibly patronising. OK we’re good.

If you’re Ansell Adams and you’re at Yosemite Park and you see a nice cliff, you may want to see everything. When you take photographs of food there are bits you want to see like a prawn; and bits you don’t want to see so much like boring lettuce, or a wall; or you want to hint at like a contextual saucepan, the bottle of wine you’re incidentally having, or the KitchenAid you’re a bit embarrassed about but still want everyone to know you’re got.

So you can signify this hierarchy of importance in you photo by using focus. The things which are important are in focus and the ones that aren’t so important are out of focus. How much is in or out of focus is called depth of field. The above photo has a shallow depth of field – you’ll see the spoon, index finger, and narrow line of almonds are in focus. Watch, wineglass, elbow, etc are out of focus. This picture would therefore be for Spoon Monthly or Pudding Almanac rather than Elbow!

So, how can you get this shallow depth of field thing?
First you’ll need to change your camera to aperture mode. This is usually indicated by an A.
Then you’ll need to understand aperture. Aperture is how much light is let in by the camera. A large aperture lets in lots of light and a small aperture lets in a little bit of light. Aperture is represented by an f-stop e.g. f/2.8

Here is the mind bending bit: small numbers mean a large aperture and big numbers mean a small aperture. f/2.8 large aperture. f/22 small aperture.

In an olden days camera you’d adjust the aperture to get the photo exposure right. Bright and sunny – less light in; bit dark – more light in.  A by-product of this is that aperture also affects focus. A pinhole camera will be in focus from the pinhole to infinity and then as the aperture increases from the size of a pinhole, you have increasingly less depth of field.

Lets recap: A larger aperture, represented by a smaller f-stop, will let more light in and also give you a shallow depth of field which will mean less of the picture is in focus such as in the above photo.

Other things: 

Shutter Speed
In low light situations you increase the aperture so shallow depth of field is a great double bonus for food shots, which are often indoors. Eventually you’re going to get to the other side of the light trade off – as the light decreases your shutter (opening) speed has to decrease to allow more time for light to get in. 1/60 of a second is usually seen as the point to stop for good hand held shots and the 1/30 second and below for resting your hands or something or a few hand-steadying pints.

Film Speed
I love you digital film speed. In the olden days you could get slow film, which was beautifully detailed and enlargeable but needed lots of light. If you were shooting say, Herman’s Hermits at an indoor ‘gig’, you’d use a fast film, which needed less light but looked ‘grainier’ when enlarged. To do both you’d have to swap film or have two cameras.
With digital cameras you can just find the ISO setting/button and increase the ISO until you get the exposure right. ISO 200 is the standard slow and ISO 1600 is fast.
The trade off is there’s more noise and grain but if you’ve got a good new camera or a digital SLR, the pictures are large enough to not worry about grain too much. If you do want to take the perfect shot that’ll be 6 feet high in MOMA, you’re not going to do it with a flash on top of your camera anyway, so use ISO.

Do I need to tell you you need to have the right thing in focus? No. But if you’re not aware that your camera has a grid of focus sensors and you can choose which one to use, then you are now. There are other ways but journey of self discovery begins now.

To summarise: Depth of field can be used to emphasise parts of a photo and this can be exploited by using your aperture setting.

Merry Christmas