SIGMA 50-500mm f/4-6.3 EX DG APO Nikon AFD

I have had this lens for about a year, and although I initially found it hard to use, I am really glad I stuck with it. You get a lot of zoom for the money, and you also get a great optical performance - as long as you can hold the lens still. As others have already noted, it is heavy and use of firm support is essential. I find a beanbag on a solid wall or branch more useful than a tripod. As long as the lens is well-supported it produces fantastic results, far better than the 500mm mirror lens I had previously. If you want better results up the top end of the zoom range be prepared to pay a lot more for it.

I have only been into photography for about a year so my comments may appear a bit `non techie'. This is a very good value for money lens that feels well made and pretty sturdy. It's not an easy lens to get good shots with but when I have they have been as good as my Nikon 70-300 DX lens. If you are interested then please bear the following points in mind:

The lens is prone to vibration and with a Nikon camera (such as my D80) there is no anti-vibration technology in the loop. I assume that those who buy it for a Canon have an advantage as Canon integrate their anti-vibration technology into the camera and not into the lens like Nikon. Also this lens seems cheaper for a Canon fitting so it's an even better buy.

You must use a good quality tripod and head which needs to be on solid ground. I have found that suspended floors such as those in hides make getting a good shot an even bigger challenge.

Invest in a camera remote control as it will definitely help with the vibration problem.

It would be wise to buy a UV filter to protect the lens and this will cost £50 plus.

Be careful before buying a circular polariser as it will cost an arm and a leg and given the slowness of the lens it could cause difficulties getting the right exposure.

In low light you will have to crank up the Camera sensitivity so if you have a noisy camera at ISO 800 and above your ability to use this lens will be reduced to good light conditions.

It's a good lens for shooting wildlife but is limited to good lighting conditions for action shots.

You will not get good shots without understanding all about exposure and having good shooting technique so don't buy it unless you are a real enthusiast. Having said this I find that this lens is making me improve my knowledge and technique and I am getting better results with every shoot that I do.

I have read reports of people finding it noisy in use. Mine is very quiet so if yours is noisy return it and get a replacement.

The bottom line is that this is a very good lens for the price. Faster lenses are 4 to 5 times the price! This lens is a bargain but you will have to persevere with it and except it's limitations in low light conditions. If you are buying this lens for a Canon camera, then given the price reduction and availability of some vibration reduction it's an even bigger bargain. I would give it 4.5 stars if I could.

When I purchased this lens I couldn't believe the range it offered - but then I came to use it and discovered it limitations.

Firstly, I would only recommend using it in good lighting conditions. You will definitely need a tripod and release cable in lower light - altering the ISO is only going to add noise.

Secondly, there are issues with the sharpness of the images. From 50-100mm there is a slight softness to the images but this is more significant at 420-500mm and there is a slight chromatic aberation at this end too.

I didn't notice any vignetting but with the problems above I had already decided to sell the lens, spend a lot more and get a couple of Nikkor lenses (70-200 and 100-400) and I didn't regret it.