![]() ![]() For control of focus, a Hyper Sonic Motor (HSM) is used to ensure fast, precise, and quiet focusing capabilities that are well suited to continuous shooting and movie recording. An internal focusing and zooming mechanism also helps to maintain a compact and consistent overall length and non-rotating front ring also better enables the use of circular polarizing filters. The lens barrel design is constructed from a Thermally Stable Composite (TSC) material that is akin to metal in texture and resistance to temperature and environmental changes while also remaining lightweight and compact. A Super Multi-Layer Coating has also been applied to lens elements to reduce surface reflections, lens flare, and ghosting to produce images with higher contrast and color fidelity. The lens integrates four aspherical elements into its construction as well as five Special Low Dispersion (SLD) glass elements to help minimize various aberrations and distortions throughout the zoom range as well as provide greater image sharpness and clarity. It is specifically designed for use with APS-C-sized sensors and provides a 35mm-equivalent focal length range of 28.8-56mm. You can still spot some traces at f/4 although it's not really relevant here anymore.The Sigma 18-35mm f/1.8 DC HSM Art Lens for Pentax is a wide-angle to normal-length zoom lens that features a fast, bright constant f/1.8 maximum aperture. As to be expected the effect is most pronounced at f/1.8 and decreases the more you stop down. Just like most of ultra-large aperture lenses the Sigma is also affected by this. NReverse 4CDmmV CALL' -72)( Mr.' 28-801/35 35-70/35 6089001 80200 V4.5 135mm V2.8. It can show up as purple halos in front of the focus point and greenish halos in the background. Sigma 18-35mm f/1.8 DC HSM Art for Pentax Great for landscape, event, and street photography Excellent image quality, clarity, contrast, and sharpness Fast. ![]() While this may not sound impressive, the quality of the blur in the focus transition zone is actually very good (smooth) for a standard zoom lens - both in the background and foreground.īokeh fringing is an axial color fringing effect. "Cat's eyes" in the image corners are not so much of an issue surprisingly although you can spot a slight deterioration at f/1.8. The Sigma 18-35mm f/1.8 DC HSM A1 is a high quality zoom lens designed specifically for Pentax K-mount DSLRs. The circular shape remains mostly intact till about f/4 (tested at 35mm). Condition - looks brand new External 10/10 Internal 10/10 Only used 3 times. Out-of-focus highlights show a near-circular shape at large aperture settings but the inner zone of these discs is clearly nervous. Buy Sigma (Pentax K Mount) 18-35mm f1.8 DC HSM ART in Singapore,Singapore. ![]() However, to be fair - this applies to most standard zoom lenses. The Sigma is pretty good but it has its issues here. While not a number game, the quality of the bokeh (out-of-focus blur) is a major aspect for an ultra-large aperture lens. They remain below 1px on the average at the image corners at 18mm and 24mm and are negligible at 35mm. Lateral chromatic aberrations (color shadows at harsh contrast transitions) are low and not disturbing. ![]() The Sigma 18-35mm f/1.8 DC HSM Art lens, shown with the lens. If you want to know more about the MTF50 figures you may check out the corresponding Imatest Explanations Its currently available with mounts for Canon, Nikon, Pentax, Sigma and Sony DSLR cameras. The chart shows line widths per picture height (LW/PH) which can be taken as a measure for sharpness. Please note that the MTF results are not directly comparable across the different systems!īelow is a simplified summary of the formal findings. The centering quality of the tested sample was good. At f/8 you may spot a slight downturn due to diffraction but this is still rather irrelevant here. However, the glory doesn't stop here - the borders are easily on a very good level at large apertures and even touch excellent levels at medium aperture settings. The center performance is already excellent at f/1.8 but downright outstanding between f/2.8 and f/5.6. The Sigma 18-35mm f/1.8 DC HSM | A produced nothing short of stunning resolution figures in the MTF lab. However, the issue is mostly resolved at f/2.8 and gone beyond. Ask sellers your product questions in English. This also applies to the Sigma - the vignetting varies around the 1.5EV (f-stop) mark at f/1.8. Buy SIGMA 18-35mm F1.8 DC HSM Art A013 Pentax K Mount APS-C / Super35 online from Japanese stores. Ultra-low aperture lenses tend to show heavy light falloff at max. ![]()
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