Depth of Field

By Paul Tyler

After covering the proper use of light meters and light metering in general last month, now I am going to cover one of the most basic points of good photography, focus. Since fully automatic focus came into being and cameras had more processing power than the space shuttle, quite a few fundamental basics have been forgotten.

Remember with this series of articles I am trying to answer that age old question, "Why don't my pictures look like what I see through the view finder?" As stated last month it's because camera film cannot see the same way your brain sees. So fully understanding the difference in what you perceive the scene to be and what is actually being seen by your camera goes a long way to improving your pictures. Notice how all the model pictures on this page use selective focusing and create a picture of far greater interest.

Also with fully programmed and automatic cameras they can deal with a great many situations, but wanting to improve your technique means having to do things the programme cannot do. Also understanding what the camera is trying to achieve in certain programme modes will help you to choose better.

When I say we are discussing focus I hope that all your pictures are crisp and sharp from a focus point of view. I will be discussing selective focusing, which really means understanding and using depth of field. You remember we discussed last month, when we used a light meter we are given a selection of shutter speeds matched to aperture sizes. Well when using depth of field we choose the aperture and let the shutter speed take care of itself. (Providing of course it is fast enough not to give camera shake) Normally with glamour photographs aperture will take priority over shutter speed.

So what is and how does depth of field work?

Well depending on the aperture you choose this will directly affect the amount of the scene that is in focus.

Now as you can see from my side on picture above, (Picture A) using f4 and with a subject distance of 2.5mtrs everything is in focus between 2 mtrs and 3.5 mtrs.

Some of you have been complaining there is no pussy in the magazine, so here are 2 pictures of my girlfriend Christinia's pussy!

Now by closing down the aperture to f22 the focus or depth of field grows to be from 1.3 meters to  about 10 meters. How do I know this? Well my camera lens tells me. On top of the lens you will find a scale. By reading off the scale you can see exactly what is and isn't within the depth of field for that aperture. On the left you will see a camera lens and the f-stop and depth of field scale. The focus is set at 4 mtrs and the f-stop is set at 5.6. (This is an old manual camera) Now look at the green scale. Do you see how it shows you the depth of field? Let's pick f11. It is either side on the scale. It shows us that the focus will run from 2.5mtrs on the left to 10 mtrs on the right with a subject distance of 4 mtrs. If you chose f4 then you can see the focus would be from 3.5 mtrs to 5mtrs. Off the subject for a second,  for those of you that are asking about the red R! When using infra red film you would focus and then slip the focus forward so it lined up with the R. Infra red rays have a slightly different wave length which means you have to compensate the focus. Learn something new everyday!!!!!

Making decisions about what you do and do not want in focus will allow you to be far more selective and accurate with you pictures. Does anyone know why Nikon do not provide a depth of field preview button?

Many of you will be saying, but my camera has to be set at maximum aperture and I can only use it manually by using the electronics. That's fine because it doesn't matter how you set the aperture the scale still works.

Whenever I have run training courses for glamour shoots, (usually somewhere hot and sunny) I start day one by giving my pupils old manual Zeniths. I pick them up at camera fairs and boot sales for around a tenner. I usually find the first morning is a disaster, but once the pupils start to understand the fundamentals and begin to use the equipment as it should be used things move along fast. When I present them the next morning with the pictures they took and give them back their cameras, quite often they want to keep the Zeniths. The work they produce is superior to anything they have done before.

This allows me to explain that their cameras, usually Cannons and Nikons are very capable of producing far better work providing they are used correctly. Do not rely on the camera programme, branch out, experiment and once you know the rules, break them.

I hope I have covered why depth of field is important and how knowing what the focus range is gives you a chance to understand better what the picture will look like. How many of you have thought about the scale on the top of your zoom lenses? See how the scale shrinks as your magnification increases. Now that could be a definite advantage.

One last point for the record. You are taking a picture of a beautiful model out in the country. You want her in the nearest foreground with the beautiful views in the distance. You focus at infinity as you want all the background in perfect focus too. You are using f22. Using the scale you see that everything is in focus from 3mtrs to infinity. Hold on a minute. Slide the infinity mark back round to f22 on the scale, and now you have focus from 1.8mtrs to infinity. You have gained a whole 1.2mtrs in the foreground. It may not sound a lot, but when you start to get really tricky with pictures it could be a godsend.

A Zenith purchased for £10.00 at a boot sale.

Take good pictures with this and take excellent pictures with your camera.

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