今年适马要发布328，428，540和640的OS版镜头了

最近有内部消息称要在2015年CP+上发布更新版的300-800
售价持平目前300-800老版价格，7999美元

估计自然是SLD甚至FLD镜片堆料成的更高分辨率，更低色差，更高对比度的版本
值得期待！

Sigma 300mm & 400mm f/2.8 OS and 500mm & 600mm f/4 OS Prime Lenses Coming in 2014

http://www.dailycameranews.com/2013/08/sigma-300mm-400mm-f2-8-os-500mm-600mm-f4-os-prime-lenses-coming-2014/

The Sigma 300-800mm f/5.6 EX DG HSM is an extreme telephoto zoom lens, and ideal for nature/outdoor or sports photography. This lens provides a relatively large constant f/5.6 maximum aperture at all focal lengths.

The use of Apochromatic design and 2 ELD (Extraordinary Low Dispersion) glass elements give full correction of chromatic aberration and provide a high level of optical performance. The AF drive for the Canon EOS, Nikon and Sigma mounts are equipped with the silent, responsive and high speed Hyper Sonic Motor and provides fulltime manual focus override.

The improved DG lens design corrects for various aberrations. This lens is specially coated to get the best color balance whilst cutting down on ghosting caused by reflections from the digital image sensor. The lens provides the utmost correction against lateral chromatic aberration, which is a serious problem for digital SLR cameras.

It is also possible to use this lens with Sigma 1.4x EX and 2x EX Apo Tele Converters to convert this lens into an ultra tele-zoom lens, effectively converting it into a 420-1120mm f/8 or 600-1600mm f/11 lens. The lens materials used in this new lens are lead and arsenic free ecological glass.

Hyper Sonic Motor provides smooth, silent AF with fulltime manual focus override
The rotating tripod mount can be conveniently detached if required
Apochromatic design and 2 ELD (Extraordinary Low Dispersion) glass elements give full correction of chromatic aberration and provide a high level of optical performance

2015.3

HSM马达速度

机身驱动电压

这些都是问题

从Sport版的120-300 OS表现看，配自家的SD1，AF估计得来回3秒钟才能瞄上。