Canon Zoom

[Wozzy]

I just purchased a Canon EF 70-200mm F4L IS USM 70-200.

I have only used it for about a week and noticed the pictures were not very sharp and in fact pretty crappy. Today I took some wildlife shots and altered aperture and shutter etc and still crap pics.

I decided to try something else and took off the Polarizer lens off and the ictures are about 100% better and look OK.

Is this a common problem? Have I bought a cheap Polarizer lens?

Any thought,

Woz

[inkista]

A polarizer is not the type of filter you leave on a lens 100% of the time, like a UV.

But that said, what's probably the culprit is your shutter speed. A polarizer can act like a neutral density filter/sunglasses for your camera and cuts down the amount of light coming in. That's why you don't want it on unless you need it.

Without IS, the rule of thumb for handholding and eliminating camera shake is to use a shutter speed of 1/focal_length or faster. So, with a 200mm lens, that means 1/200s or faster. Some folks will also throw in the crop factor.

AND that "rule" supposes you know how to hold your camera. If the majority of the weight of your camera/lens combination is not being supported by your left palm 100% of the time while you shoot---you're doing it wrong.

[NicoleScraps]

You know, I was wondering about the same thing the other day. I have QuantaRay Skylight 1a filters on all of my lenses. I put them there to protect against dust and scratches, but now I am wondering if they have an affect on the quality of my photos.

[inkista]

Most filters can affect image quality in one way or another--you've put a piece of glass in front of your lens. Depending on the quality of that filter, light transmission, flare resistance, color, etc. can affect your photo. A skylight, for example, is tinted to warm the image (essentially the old-tech version of the "daylight" white balance).

Cheaper filters are typically uncoated or single-coated which makes them more liable to exhibit flare than multi-coated filters.

This is why whenever someone asks, "should I have a UV filter on the front of my lens" heated arguments pop up. On one side are the "physical protection at all costs!" camp, and on the other are the "why pay $1000+ for great light transmission, only to cut it back down again?" or "Just use a hood" camps. Personal preferences and tolerances play a part.

I have UV filters on all my lenses for front-element protection. I shot outdoors in dusty situations a lot. I shoot at the beach. I tend to be careless and wipe things off with a shirt tail. While I don't think a UV filter is going to be much use against smashing the end of the lens against something, I do think it protects the coatings on my front element really really well. And if I run into flare, I can always take the filter off. I'm a klutz, and I'm careless, so I prefer having the peace of mind to know that if I lose a lens cap, the front element of my lens is still protected.

Someone who works in a studio or has better care for their equipment could probably go without.