A filter is a transparent (or semi-transparent) attachment which fits in front of your camera lens. There are a number of different filters available which all serve different functions. Some simply act to protect the len surface that it's covering, some help to reduce reflections, and some reduce the amount of light entering the camera's lens.
This however is a "Sand Spot Filter," it's designed in such a way to allow you to take a picture that's clear in the centre but that's smoky, and gradually fading out towards the edge of the filter where it becomes like a dense fog. It also produces a photo with a Matt like finish.
I've always had several filters at my disposal, mainly a Circular Polarizer, and a UV filter, but recently my photography has hit a dry spell and I've been experimenting with new things to try and reignite my passion for photography, this was one of two new filters I decided to try (the other was an infra-red filter).
Using it creates an interesting effect, especially with landscapes (but it can also be used with portraits and still life). It fun because it can produce some very unexpected results (think about using a fish-eye lens for the first time and the weird and wonderful photos you get.) It aids your creativity but making you see potential photos slightly differently, and making you think about how you can make a photo better or simply different.
This particular model is 55mm is diameter, which simply screws over your existing camera lens. It is available in different sizes both larger and smaller should you need a different size
Hama produce a lot of high quality components for digital cameras and this is definitely one of them. The filter can't be faulted in terms of build quality and arrived in a strong plastic 'petite-dish' like container to help keep it safe.
It wasn't the easiest item to find in the shops, none of the places I usually go to (such as Jessops and UK Digital Cameras) seemed to have any, and it took some time to find a seller on ebay (based in Germany) who had one. And as filter's go - it was a bit expensive.
It's a shame that it isn't easily available in this country, as it's a pretty neat filter, and one I don't think many photographers know about.
But overall a great addition, and an iten I've enjoyed using, one that's helped me get back on track and back behind the camera.