![]() Center sharpness is high at f/1.4 and edge sharpness is quite acceptable. Performance: Since most of my testing was done at f/1.4, I was pleased to note that image quality was very decent at this aperture. Naturally, this feature-plus the corner-cut lens hood with internal ribbing-also provides great resistance to flare from external light sources. The use of “super multilayered” coatings on all glass surfaces minimizes flare caused by a highly-reflective silicon sensor and its glass cover. This multi-platform lens is optimized for digital capture but it’s just as suitable for film photography. ![]() However, older (non-current) Pentax D-SLRs do not support ultrasonic AF when used with one of those cameras, only manual focus is available. The HSM autofocus system-also available with the 30mm f/1.4 model-ensures that AF will work with Nikon cameras without an AF motor (D40, D40X, and D60). The latter provide a circular aperture so out-of-focus highlights appear round even at mid-size apertures. ![]() The designers specified an aspherical lens made of molded glass for aberration correction and a diaphragm with nine blades. Neither the ring or the front element rotate during autofocusing. The very rugged oversized barrel contains eight large pieces of glass and a ring-type (ultrasonic) Hyper Sonic Motor (HSM) for high-speed autofocus and full-time manual focus override. The largest/heaviest current lens of this type, the Sigma model features a massive front element to minimize vignetting (darkening at the corners). By comparison, a photo made at f/4 (a typical maximum aperture with a zoom lens) would have required a shutter speed of 2⁄3 sec or an ISO of 800 for a faster shutter speed of 1⁄10 sec.Īll Photos © 2009, Peter K. This JPEG was made at ISO 100 with a handheld Sony A350 in Budapest, using f/1.4 at 1⁄10 sec. The ability to shoot at f/1.4 minimizes the need to use a tripod or a high ISO level to prevent blurring caused by camera shake. The smaller/lighter “normal” lens is more convenient when traveling and far more useful in dark conditions. While a zoom lens is certainly more versatile, an f/1.4 lens offers much wider maximum apertures. That’s why Sigma also makes a 30mm f/1.4 model, providing a 45mm, 48mm, 51mm, or 60mm equivalent depending on the exact field of view crop produced by a D-SLR’s sensor. On the latter cameras, it’s actually a short telephoto with an equivalent focal length of 75-100mm depending on the exact sensor size. The 50mm model is a multi-format lens, suitable for 35mm SLR cameras and for D-SLRs with a full-frame (24x36mm) or a smaller APS-C-size sensor. Sigma offers “normal” f/1.4 lenses with all of the latest optical and autofocus technology. As a bonus, depth of field is also substantially more shallow at f/1.4, useful in situations where you want to blur distracting elements in the background. It’s also easier to focus manually in dark locations because the viewfinder is much brighter at a very wide aperture. ![]() That can allow for available light photography without flash or a tripod at much lower ISO levels where image quality is best with any camera. Select f/1.4 and you can shoot at a shutter speed that’s four times faster than at f/2.8, eight times faster than at f/4, and 16 times faster than at f/5.6. These days, you can still find a 50mm f/1.4 lens (with an even wider aperture) in most brands. ![]()
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