Back-Button Auto Focus

I have always half pressed the shutter button on all of my cameras to get a focus lock before fully depressing the button to get a shot (after recomposing more often than not).  However, I recently found a BETTER WAY! :)

On my Canon 50d there is a button on the back labelled AF-ON.  This button can be used to focus the camera, removing the focus function from the shutter button.  On some cameras you can reassign the exposure lock button (labelled *) to be an AF-ON button.  The shutter button is only used for metering and to take the picture when set up the way I have it.  Why would you want to do this?  All is explained very clearly at:

http://www.usa.canon.com/dlc/controller?act=GetArticleAct&articleID=2286

I have to say, it feels really awkward at first.  You soon get used to it though.  My hit rate for in focus pictures has gone up since moving to back-button focus.

For 50d owners go to custom function C.Fn IV-1 and selection option 2.  For more options, or if you have a different Canon camera, check out the link above.

Expose To The Right (ETTR)

In order to minimise noise, particularly when using higher ISO, it is important to expose to the right.  Also, when doing this please remember to shoot in RAW so you can adjust your exposure easily in your RAW conversion software.  Simply look at the histogram and make sure it is biased to the right, although not so far to the right so as to blow the highlights though.  Doing this will minimise noise.  Of course when you look at the pictures on your computer they may seem a little light.  Simply adjust the picture with the sliders in your editing software to get it looking right.  Remember, the point of this is to minimise noise.

Normally the above histogram would indicate a well exposed shot.  When exposing to the right you will adjust your exposure to get something more like the histogram below.

You can find out more at:
http://www.luminous-landscape.com/tutorials/expose-right.shtml

Minimum shutter speed when hand holding camera

There are many factors that can dictate how steady your hands are including the way you hold the camera, your level of experience, and even medical factors.  In addition to this Image Stabilisation technology can compensate for hand movement too.  However, in general a rule of thumb that is often advised for hand held photography where there is no Image Stabilisation being used is to use the reciprocal of the focal length as your shutter speed to avoid blurred pictures.  At a focal length of 50mm you should use a shutter speed of 1/50s.  At a focal length of 200mm you should use a faster shutter speed of 1/200s.  This rule of thumb assumes your subject is not moving.  If your subject is moving you need to increase your shutter speed to take account of the subjects movement if you want a photo without any motion blur.

This rule also assumes you are using a full frame camera (which I am not).  Since my camera has a 1.6 crop sensor I need to multiply the focal length by 1.6 before reciprocating it for the required shutter speed.  At 50mm I need to reciprocate 50 x 1.6 = 80 and therefore my shutter speed should be 1/80s (instead of 1/50s that you might assume if you don't take the crop in to account).  At 200mm I need to reciprocate 200 x 1.6 = 320 and therefore my shutter speed should be 1/320s (instead of 1/200s that you might assume if you don't take the crop in to account).  As you can see, the crop makes quite a bit of difference!