9 out of 10 points and recommendedFor extreme macro photography this is *the* lens.Difficult to use. Limited Depth of Field
This lens is one of the more unusual produced. It is not just manual focus, it has no focus ring at all! Instead you have to move in and out to find the right focus.reviewed October 24th, 2005 (purchased for $799)
The ring on the lens is for zooming. In its closed state the lens produces life size images 1:1. Zoomed to its maximum it produces 5:1 images. In essence this is like no other macro lens!
The image is sharp but the depth of field extremely shallow. This is not a general purpose lens, more a specialist optic.
Generally it needs to be used with a flash setup, I use the Canon MR-14 ringflash. The amount of light on the subject is very low at the larger magnifications, so flash becomes essential.
I tend to use Manual Mode on the camera, shooting at 1/160th sec @ f16. On the camera (a 20D) I also set +1 FEC. The Ringflash is set on E-TTL.
One of the great exponents of this lens online is Frank Phillips http://www.beautifulbugs.com/
Here are two examples of a gnat shot with this lens/flash combo: