Intro & SpecificationsThe Sigma AF 105mm f/2.8 EX macro DG is a recent update to the well-known Sigma AF 105mm f/2.8 EX macro. It's not a totally new lens (the new DG (Digital) designation refers to an improved coating optimized for digital sensors), but that's not necessarily a bad sign
because its predecessor had a good reputation. This is a full-format lens so it is usable on film SLRs as well. On APS-C DSLRs such as the Canon EOS 350D, the field-of-view of the lens is equivalent to 168mm on full frame cameras. This macro lens is obviously focuses on extreme close-ups, but it's not limited to that... it has an infinisty focus that makes it usable as a walk-around lens.
Sigma already has established themselves as a quality manufacturer of camera equipment based prior to the DG lenses for the digital revolution. Here we look at one of Sigma's mid-range macro lenses to see how well it performs for the amateur and professional photographer.
Sigma's DG lenses are optimized for digital SLR cameras, who typically have a CMOS sensor smaller than a film camera's 35mm frame. The optical construction of the 105mm macro lens is made of 11 elements in 10 groups without any special elements, and features 8 aperture blades. The lens provides a maximum magnification of a 1:1 ratio with a minimum focus distance of 0.313 meters (A 1:1 ratio means that the image on 35mm film is the exact same size at real-life, which translates to huge magnification when viewed on your computer screen at 75dpi). The lens is rather compact compared to other macro lenses with a size of 74x97mm and weighing 460 grams (although the length grows substantially when focusing towards closer subjects). The lens also features an infinity focus, so it can be used for taking portraits or other fixed-length shots.
Here are some of the features and specifications:
High performance medium telephoto macro lens optimized for digital cameras.
MACRO 105mm F2.8 EX DG allows greater working distance between the lens and subject. High contrast and excellent image quality are made possible in all shooting ranges. This macro lens is ideal for digital SLR cameras as well as film SLR cameras. Super Multi Coating reduces flare and ghosting that tends to occur when using digital SLR cameras.
Reduces flare and ghost
This new medium telephoto macro lens employs a new design concept for digital SLR cameras. Its new lens power layout produces an excellent optical performance and also reduces flare and ghost. This new lens is designed to reduce the influence of harmful light caused by reflections from the digital image sensor.
An easy to use 105mm medium telephoto lens
MACRO 105mm F2.8 EX DG lens is very suitable for taking pictures in nature and it enables to use of natural light conditions or flash.
The greater working distance of this lens is very advantageous when taking the picture of a flower among the branches or an insect. You do not shake your subject when you want to take its precise details without blurring by using a tripod.
The narrow angle of view is a great aid for simplifying backgrounds and shallow depth of field makes it easier to handle the composition. This lens would have an equivalent field of view of a 178mm telephoto macro lens on a digital SLR camera (when used with the SD10).
Minimum aperture of F45
Depth of field of medium telephoto macro lenses is generally very shallow; however, Sigma, Canon and Konica Minolta mounts of this lens have a minimum aperture of F45 (or F32 for Nikon and Pentax mounts) for incredible depth of field.
Screw-in lens hood
A screw-in hood is included, for convenient use of circular polarizing filters. It is possible to attach a 77mm filter in front of the lens hood.
Dual Focus (DF) system
This lens also incorporates a Dual Focus (DF) system that is designed to make the lens easy to hold during auto focusing. The large focus ring offers smooth and positive action whilst focusing manually.
Specifications
- Focal Length 105mm
- Aperture f/2.8
- Construction 11/10 elements/groups
- Closest focus 0.312m (1:1)
- Aperture blades 8
- Filter size 58mm
- Weight 0.45kg
- Dimensions 74x95mm
- Hood Screw in (supplied)
- Mounts Sigma, Canon, Nikon, Pentax, K-M
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