Lens review
Sigma 4.5 mm f/2.8 EX DC CIRCULAR FISHEYE HSM
3. Build quality
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The thing that surprised me was compact physical dimensions of the front element. It is convex but not very much so and relatively small. I’d seen different kinds of Peleng or Zenitar lenses so I expected that such a risky combination of f/2.8 aperture and 4.5 mm focal length would result in a front element the size of a solid saucer; we see nothing of that kind here, though. Generally the lens doesn’t seem to be bulky what can be seen in the picture below, where we put it next to two Sigma lenses: a 10 mm and a 17-70 mm.
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Not so long ago, while testing a Nikkor 14-24 f/2.8, we noticed that the manufacturer didn’t include any possibility of using filters. The more praises deserves Sigma which managed to include such a possibility in an instrument with a very wide angle of view. You simply put a ring on the front part of the lens which allows us to attach 72 mm filters and a protecting cap as well. Additionally, that ring can be used as a mini hood although we must stress the fact that when you shoot with the ring on you will see it for sure in your photos because it limits the field of view at the edges of the circular field.
When it comes to the inner construction the lens sports 13 elements in 9 groups and one element is made of low-dispersion SLD glass. Additionally inside we’ll find a 6 diaphragm blades aperture which can be closed down to f/22.

It is already a standard for the EX series that the buyer gets the aforementioned mini hood and a stylish hard case included in box.
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