subject: Sigma 17-70 F2.8-4 Macro Hsm Review For Underwater Photography [print this page] I first took this lens 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 laying around that can be "modified" or alternatively you can also construct 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 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 1770 mm f/2.84.0 DC Macro OS HSM is an optically sophisticated 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 significantly 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. Sigma's anti shake feature enables the use of shutter speeds approximately 3 to 4 stops slower than would otherwise be possible under normal conditions. This will be especially helpful for night dives or other lower light situations and enables more creative use of strobes.
The lens is good for macro shots and it is also great on wider angle shots. All in all a versatile lens that can provide 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 Review:
Lens Construction: 15 Elements in 12 Groups
Angle of View: 72.4 - 20.2 degrees (Sigma SD format)
