Sigma 18-200/3.5-6.3 DC - Sigma 30/1.4 EX DC HSM - Sigma 10-20/4-5.6 EX DC HSM
Sigma 30/1.4 EX DC HSM
This will be a "fast normal" lens for APS-C DSLRs. In an EOS 20D it will give the same field of view as a 48mm f1.4 lens on a 35mm full frame camera. The lens has a Hypersonic motor (HSM) which is Sigma's version of the Canon USM (Ultrasonic motor). It uses SLD (special low dispersion) glass and molded aspheric elements to improve performance. The lens will be available in Canon, Nikon and Sigma mounts.
Sigma 10-20/4-5.6 EX DC HSM
Sigma have had a 15-30 and a 12-24 zoom for a while, but this lens is the first wideangle zoom designed for use on APS-C format DSLRs and so may be less expensive (let's hope so!). The Sigma 10-20/4-5.6 EX DC HSM has the same field of view when mounted on an EOS 20D as a 16-32/4-5.6 would have on a full frame 35mm DSLR. Again this lens uses an HSM motor for fast and quiet focusing. The Sigma 10-20/4-5.6 EX DC HSM uses three SLD glass elements one molded and two hybrid aspherical lenses to better control chromatic aberrations, distortion and spherical aberration. The lens will be available in Canon, Nikon and Sigma mounts.
The Sigma 10-20/4-5.6 EX DC HSM will clearly be a competitor for the Tamron 11-18/4-5.6 lens which is also designed for use only on APS-C format cameras, as well as the Tokina 12-24 and Canon's own 10-22.
Sigma 18-200/3.5-6.3 DC
Sigma's new "superzoom" designed for use on APS-C sensor cameras. When used with an EOS 20D it will have the same field of view as a 29-320/3/5-6.3 lens would on a full frame 35mm camera. Obviously this is an analog of the 28-300 lenses which a lot of consumers seem to like. It's certainly a "one lens" solution for those who hate switching lenses. At f6.3 it's a little slow, but it[s easy to dial up the ISO on DSLRs so that many not be a problem for many users. With such a large zoom range image quality is always a concern, but we'll just have to wait and see how well Sigma have done with this 11x zoom.
The Sigma 18-200/3.5-6.3 DC uses two Special Low Dispersion (SLD) glass elements and two hybrid aspherical lenses to control chromatic aberration and lower distortion and spherical aberration. At 400g (14oz) it's very light and at just over 3" long it's also very small and takes a 62mm filter. The front element of the lens does not rotate, facilitating the use of a polarizer and a zoom lock is included to eliminate "zoom creep" when the lens is being carried.A custom designed "petal" type lens hood is included. The Sigma 18-200/3.5-6.3 DC will be available in Canon, Nikon, Sigma and Pentax mounts.
Sigma DG lensesIn addition to these "DC" lenses Sigma have also announced the introduction of "DG" versions of a number of their existing lenses. The "DG" designation signifies "digitally optimized", but still with full frame 35mm coverage. There are no details of how the "DG" versions of these lenses differ from non-"DG" versions. I suspect perhaps they have new anti-relection coatings - but that's just a guess on my part. The Sigma press release makes no mention of any optical redesign.
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