So far, mine works pretty well. Your lense might have a defect. You need to have it checked.

Hi perppermintpatty

I'm wondering if you're simply expecting too much of the lens, or rather the camera...

Compact cameras do have especially long zoom ranges due to their very small sensors, which multiply the effective focal length of a lens.

Have a look at this chart: http://en.wikipedia.org/wiki/File:Sensor_sizes_overlaid_inside_-_updated.svg

You can see the NEX-5's APS-C sensor has a 'crop factor' of 1.5 - this means it is going to make your 210mm zoom an effective 315mm (210 x 1.5 = 315) - not bad, but not a huge telephoto either.

That chart also shows the typical 1/2.3"-sized sensor in a compact camera is tiny in comparison. The 1/2.3" crop factor of 5.62 would almost make your 210mm into an effective 1200mm... which is why people (and manufacturers) refer to the cameras as 'superzooms': they don't have a super-duper lens, just a tiny sensor chip with a huge crop factor.

The big sensor in your NEX-5 is the reason it produces such good-quality images. In fact the lens you have is probably much sharper than the optics in many compacts, such that if you cropped the centre 30% out of one of your NEX photos you would actually get something approaching the crop/zoom factor of a compact and better image quality to boot.

If you want to zoom in more while using your NEX, you could perhaps consider an adaptor + teleconverter. The NEX system doesn't use a conventional convertor, but it is possible to adapt something like the DH1758 to the front of the 55-210 (using a filter step-up ring) which will double the length of the lens to an effective 630mm.

I hope that makes sense!

Cheers

Mick