Sigma EX telephoto zoom lens - 100 mm - 300 mm F/4.0

...tested) this lens with my SIGMA EX APO 1.4x converter and can vouch for the performance being virtually just as good with only the two smallest apertures being POOR. The rest of the range is great and is particularly so when used on APS-C sized sensor cameras where only the central 'sweet spot' of the image circle is utilised.

A truly great lens.

David Chamberlain  ... more

I purchased this lens a little over a year ago and it has never failed to impress me with it's superb image quality.

This is a fairly large and heavy lens and comes with a sturdy rotating tripod collar. This is both useful and in my opinion, essential. Although this lens has a relatively fast maximum aperture of f/4, consistent throughout the zoom range, it IS heavy and has no image stabilisation, making it difficult to hand-hold and guarantee truly sharp results. I always use this lens attached to a sturdy Manfrotto tripod with heavy-duty head.

Whenever possible - obviously only with static subjects - I always try to use mirror lock-up on my Canon 5D and 400D cameras while on a tripod to avoid any chance of vibration. I have carried out extensive testing of this lens and can confirm with confidence, that if unsharp results are obtained, it IS down either to technique or external circumstances - NOT the lens itself.

The lens is really a pleasure to use. With both internal focusing and zooming, it doesn't extend at all with either function. Nor does the front of the lens turn, so using polarisers is easy.

A great advantage when this lens is attached to a tripod via it's rotating collar is that it is extremely easy and convenient to rotate the both camera and lens through horizontal to verticle positions (or anywhere inbetween) with complete accuracy and security.

Optical performance is impeccable. Unusually for long lenses, particulary zooms, it produces superb results even at it's longest focal-length setting. At f/4, image quality is already EXCELLENT in the centre and the edges are just a little behind at VERY GOOD. These improve to VERY GOOD+ at f/5.6 and EXCELLENT by the time you stop down to f/8. It stays this way until diffraction sets in (to be expected) at the two smallest apertures. This is perfectly normal however and the lens delivers quite amazing performance at this or indeed, any price level.

I have used (and tested) this lens with my SIGMA EX APO 1.4x converter and can vouch for the performance being virtually just as good with only the two smallest apertures being POOR. The rest of the range is great and is particularly so when used on APS-C sized sensor cameras where only the central 'sweet spot' of the image circle is utilised.

A truly great lens.

David Chamberlain 

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