I work in archaeoastronomy and was looking EVERYWHERE for a perfectly circular lens for my Micro 4/3 camera. I looked for 4 days and all I found were lenses that cropped the images (so, a no go for me) and one lens that was over $3,500...

It's weird and wonderful, as a fish-eye should be. This is a solid lens offering from Sigma. In spite of the enormous depth-of-field that is inherently available in such a lens, auto-focusing is a useful thing.

MyCircular Fisheye Lens arrived at home without damage one day earlier.

Fantastic lens. One of the best fisheyes I've owned and some of my others have been far more expensive.

Fantastic lens. For an idea of what this lens can do, go on any of the picture social websites.

This lens captures extremely blurry photos and the depth of field is horrible. It is just impossible to have whole frame in focus (Or may be its an issue with the piece I received). I have just raised a return request to seller.

Like the lens, but it took a LONG time to get it.

This Sigma 4.5mm was bought for night star shots, horizon to horizon, and it does that indeed. In other uses, if one can keep one's feet out of the frame, it is wonderful for cityscapes. A walk in the park can be almost magical with this real fisheye.

So I work a lot and photography is my tool for reminding I'm a much more interesting person outside of my work. I was a paid photographer at one point, maybe I might do it professionally in future. So I was interested in this lens since I could finally get this effect on my smaller sensor camera.

I picked this one out for my Sony Alpha 77 from all the other options, because this one has autofocus. I take a lot of self portraits and I needed autofocus for that purpose. It is exactly what I expected, works well in low light, sufficiently sharp, and fun to use.