Glass 72mm Neutral Density ND4 Lens Filter for Digital Camera

[Thaash]

I am using an EOS 50D with a Sigma 17-70 and want to buy an ND filter for it.

I do not want to spend so much on the Hoya version. I saw this:

Glass 72mm Neutral Density ND4 Lens Filter for Digital Camera

Do you think it is enough for my Sigma 17-70 lens? Or can it influence the IQ in a negative way?

 

[tirediron]

There's no link, so I can't tell exactly what you're looking at, but I can make an educated guess, and I believe the answer is 'yes'. Even the cheapest lens has hundreds of thousands of dollars worth of research and development behind it. Putting a sub-par filter on it will definitely hurt you. The multi-coated Hoya and Tiffen filters are pretty much the cheapest decent filters you can get. If you can dig a little deeper in the pockets, you can look for B+W, Heliopan, Singh-Ray and Lee. If you're interested in graduated ND filters, consider the Cokin system.