Love, light and lenses

I love photography, anyone who knows anything about me knows this much. Just recently I have been longing to take more wildlife photographs, crawling around in the undergrowth setting up spy huts to get close to nature isn't my cup of tea frankly. I would much prefer a big telephoto lens that I can just point at my subject at 50 metres away and get an impressive shot.

So time to hunt for a telephoto lens that will fit the bill. I currently have a very tasty Nikon Nikkor 18-200mm Vibration Reduction (VR). It has a 3.5 f-stop maximum aperture which lets in quite a bit of light and allows me to take photos at fairly low level light. But it's just not long range enough. The problem with lenses is that the longer the lens, the wider it has to be to get the same level of light through the lens, which in turn means that more glass is used, which in turn means that it is more expensive.

So why is light so important? Simple, however much you magnify your subject you ALSO amplify the noticeable movement of the lens/camera. The science of exposing a photograph is based on a trade-off between light levels and shutter speed. The lower the light level, the more time it will take to make the exposure, which in turn increases the risk of recording motion blur from shutter bounce, unsteady hands or general vibrations.

So I started looking around, I wanted a good telephoto zoom that also allowed a decent amount of light through without breaking the bank balance. What I found was the Sigma APO 200-500mm F2.8, I'm kind of guessing it's going to break my bank balance. It is HUGE. It weighs in at approximately 16kg and will cost approximately 7000 US dollars. Needless to say, I'm still looking.