Filter Kit Canon

Filter Kit Canon
Should I get a polarized lens filter for my camera?

I have a Canon xti with the standard 18-55mm lens that came in the kit. The guy at the camera store tried to sell me a polarized Tiffen filter, which I didn’t buy. Now I’m considering it. Is it necessary, and if so, what are the benefits? What are negative things that can come from using it? Can it be left on at all times for all shooting conditions? Right now I just have a hood, but am considering returning it for the filter. Any advice on what to do and what positive and negative effects the filter could have would be great.

Short answer: You don’t need it.

A CPL (Circular Polariser) allows you to filter out polarised light. Effectively this lets you do several useful things:

It can make a sky turn a darker blue.
It can take the reflections off water, glass and reflective surfaces.
It also limits your light gathering ability so it can be used as a makeshift ND filter if you need one in a pinch.
It can also sometimes slightly alter the colour of other things such as foliage.

When using a CPL to darken skies, the effect is greatest when shooting at 90degrees from the sun. A word of warning: do not use a CPL to darken skies when using a lens any wider than your kit lens. This rarely gives anything other than a very uneven effect as the angle of view is too wide.

In some cases a CPL is a MUST, like when you need to reduce reflections but it’s not an essential piece of kit unless you have the specific needs mentioned above.

I definitely wouldn’t recommend leaving it on the lens all the time. All filters cause glare and ghosting, which can degrade your images and even show up as bright lights in your shot, especially when you have a strong light source in the shot.

If you want something to leave on your lens as protection, buy a good quality multicoated UV filter. Hoya are good. However, even very expensive filters can cause some glare, etc.

One thing you should know if you decide to get a CPL is that it won’t totally remove strong reflections from flash. Flash is pure non-polarised light and isn’t affected until it’s been polarised. If you do ever need to do such things then a second polariser can be fitted over your flash at 90 degrees to the one on your lens to give a flash lit picture with very little reflections, even when photographing things such as water.

Out of all these uses for a CPL, reducing reflections is the only one that can’t be done in post processing. For this reason, the CPL (along with ND filters) are amongst the few filters that are still useful in the digital age.

Goodluck!

EDIT: Holly9’s answer is partly incorrect. All filters, especially cheap filters and especially in bright sunlight can and will harm image quality. So even if you keep a UV protection filter on your lens, it is wise to remove it for important shots where there are bright light sources.

Also, Holly9s comment about UV filters filtering out UV light is also incorrect. Unlike in the film days, modern digital sensors are built with filters which block out almost all UV light. So a UV filter does nothing, at least not to UV light.

Clubbed to Death (Canon Rebel 550D T2i *6 Minute 1st Test Shoot*) kit lens only — 1920×1080 / 24P