The Sigma 17-70mm F2.8-4 DC Macro lens available in Canon, Nikon, Sony, Pentax and Sigma mounts deserves strong consideration for underwater photography from the higher end amateur to the professional. While zoom rings for the Sigma 17-70mm are hard to find (if you can) the versatility and quality of the lens is such that if you are willing to invest a little time this could be a great lens for a variety of underwater settings. The lens is good for macro shots as seen in this image of a Candy Cane Shrimp in Maui
It also is quite good for wider angel shots such as this photo from Grand Cayman.
I first took the Sigma 17-70 mm for a test drive in Hawaii. Since, I could not get a zoom gear for my Sea&Sea housing, I just made one. 🙂 If you are not intimidated this is not very hard to do especially if you have other zoom rings lying around that can be “modified” or you can also build a very passable zoom gear from PVC pipe from your local hardware store, but I will leave that for another story.
When compared to other similar lenses, the Sigma 17-70 mm is one of the heaviest and largest instruments of all. This is not a surprise, though, because the lens is also the fastest and similar lenses such as the Sony/Zeiss 16-80 mm, which has a better focal range, doesn’t have an ultrasonic autofocus motor.
The Sigma 17-70 mm f/2.8–4.0 DC Macro OS HSM is an optically complex instrument. It has 17 elements in 13 groups. One element is made of low-dispersion ELD (Extraordinary Low Dispersion) glass and three other elements are aspherical (one hybrid element, two made using the “glass mold” technology). It is definitely superior to its predecessor that had just one SLD (Special Low Dispersion) element and two ordinary aspherical ones. Inside the lens we can also find an aperture with seven diaphragm blades which can be closed down at 17 mm to f/22 and at 70 mm – to f/32.
All in all a versatile lens that can deliver great shots in most situations and is great when you are not sure if you will be shooting macro or wider angle shots on a particular dive.
Technical details: Sigma 17-70 mm
Lens Construction: 15 Elements in 12 Groups
Angle of View: 72.4 – 20.2 degrees (Sigma SD format)
Number of Diaphragm Blades: 7 Blades
Minimum Aperture: F22
Minimum Focusing Distance: 20cm/7.9 in.
Maximum Magnification: 1:2.3
Filter Size Diameter: 72mm
Dimensions Diameter: 79mm X Length 82.5mm
3.1 in. X 3.2 in.
Weight: 455g/16.0 oz