I recently bought a Sigma 18-250mm F3.5-6.3 DC HSM Optical Stabilised Lens for my Canon 600D Digital SLR Camera. Some of the reviews on Amazon made it clear that, with such a long zoom range, there would be some compromise on image quality; but overall the lens got a good rating.
I’ve had the lens for a few months now. While I like the flexibility of the zoom range (I’m not serious enough to want to carry around additional lenses), I’m not so happy with the image quality. But I can’t tell if this is due to the fact that the lens is a compromise or that I’ve been been sent a faulty model.
Below are three photos that show the nature of the problem — generally a halo or soft-focus effect around sharp edges. Admittedly it’s mostly apparent when displaying the images at their maximum size in flickr, but I’d like to know if this is typical. If you have any idea, I’d appreciate a comment.
London Eye – vislible ‘glow’ around the struts.(Large size)
Seagull – chromatic aberration around the top of the bird’s head? (Large size)
Roof repairs – again, an unintended soft-focus effect? (Large size)