Apologies for the "newbie" question, but can someone explain to me the basics of filters, and perhaps while you're at it, metering!?!

I recently purchased a 400D (& Kit Lens) having wanted to take the plunge into "proper" photography for quite some time. I had previously read up on a lot of the theory on exposure/apertures/shutter speeds etc, but am quickly finding that real world experience is far more valuable and am enjoying playing around with various settings to achieve different results.

One thing I haven't the foggiest on, is filters, and the results that can be achieved through using them. I was advised to purchase one to protect my lens, but am aware that not only are their several types, but also sizes. Which one do I need, and where do I start when it comes to looking at others?! I'd also appreciate some tips on metering - both an explanation on what it is, and what can be done with the various types of metering available on the 400D.

Any advice gratefully received!

Kelvin.

The sticky by Hoppy is a good starting point:

http://bbs.scoobynet.com/photography-360/543761-understanding-photography.html#post6159604

400D standard kit lens takes a 58mm filter size...everything else refer to Hoppy :D

For normal day to day lens protection you would either use a Skylight or UV filter - doesn't really matter which. Metering should automatically adjusted via the cameras TTL system.

Circlular polariser should work in the same way.

Other filters may require you to meter first, set exposure manually, then fit filter and take the photo.

For graduated filters, meter (using spot or centre weighted) off the part odf the frame where you will not have the filter, set your exposure in manual, add filter (if you have DOF preview, use that to get a better feel for where the darker bit starts) et voila!

Some people say only use polarisers when it's sunny, but they do more than give you great skies, unless you really need fast shutter speeds (and you lose about 2 stops with a CPL) you can use them in any conditions, especially where you have reflections to contend with.

A UV filter should not affect your metering at all. If you get a polariser, make sure it's a ciruclar one as your camera AF may be affected otherwise.

Those are pretty much the commonly used ones, all the others just play around and see what happens! You can replicate lots of filters in PS to see what type of effects you would get before buying, or even prevent you buying but most people like to get it right on the shot. The effect of a polariser cannot be replicated however.

Geezer