Автор: dreamer_xs
Дата: 22-01-07 20:23
Миронски що не вземеш да ми я дадеш тая Сигма...
По долу изчерпателна иформация...
Sigma 28-80mm f/3.5-5.6 HF AF
A great buy in a macro-zoom you may never want to take off the camera.
September 2001
HANDS ON: This is yet another Sigma general-purpose zoom lens that provides an true macro range, in this case, down to 1:2. It is about average in size for this focal-length and aperture range, and quite light, due to considerable plastic construction, including the lensmount. Satin black plastic exterior pieces are very well fitted and finished. Aperture, distance scales (meter and feet), and focal-length numbers are marked in a very legible stark white. (The aperture scale will be obscured by cameras with pentaprism overhang.) Zooming action is smooth and nicely damped, and lens exhibits no zoom creep whatsoever in any position. Ribbed focusing ring also provides good grip, turns very smoothly in manual focus, but is very underdamped.
Aperture ring is detented at full stops, turns smoothly. The AE lock switch on the aperture ring was a bit tricky to reach on our Nikon test camera. Included cut-out type lenshood has convenient bayonet mount, provides good shielding from stray light.
The lens must be turned to the 80mm position in order to engage the macro range, a slight inconvenience. Autofocusing was very fast and quiet.
IN THE LAB: Due to extensive upgrades being made to our SQF optical bench at the time of testing, we were unable to make SQF or field curvature readings. Lines-per-millimeter resolution numbers show that this is a quite sharp lens throughout the focal-length and aperture range, with the exception of minimum aperture, where diffraction knocked resolution down to below average in some cases. Minimal barrel distortion (0.35%) was seen at 28mm; at 50mm, slight pincushion (0.75%) was measured; and at 80mm, noticeable pincushion (1.25%) was seen. Exposure at the film plane was extremely accurate at 28mm, within 1/10 EV at every aperture except f/3.5, where 2/5 EV underexposure occurred because of light falloff. At 80mm, exposure at the film plane was accurate, with about 1/3 EV underexposure at f/5.6 due to light falloff, and overexposure of about 2/5 EV throughout the rest of the apertures. At the 50mm closest focusing distance of 17 inches (1:7.14), center sharpness was excellent from f/4.8 to f/22, and very good at f/32. Corner sharpness was good at f/4.8, excellent from f/8 to f/16, very good at f/22, and good at f/32. Optimum performance was at f/11. At the closest focusing distance of 9 3/4 inches at 80mm (1:1.96), center sharpness was good at f/5.6, excellent from f/8 to f/16, very good at f/22, and good at f/32. Corner sharpness was below average from f/5.6 to f/8, acceptable at f/11, good from f/16 to f/22, and acceptable at f/32. Optimum performance, f/16.
IN THE FIELD: Test slides were very sharp and contrasty from the center to the corners at every focal length at all apertures, except from f/22 to f/32 at 80mm, where both center and corners were slightly soft. Light falloff was gone by f/8 at all three tested focal lengths. Flare was very well controlled at all apertures and focal lengths.
Цитат от: http://www.popphoto.com/cameralenses/281/sigma-28-80mm-f35-56-hf-af.html
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