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18-200mm f/3.5-6.3 11 DC OS HSM Sigma Model: 18-200mm f/3.5-6.3 11 DC OS HSMExtra Description
Style: Sony SLR Camera Product Description 18-200mm F3.5-6.3 II DC OS HSM lens is ideal for travel photography with a compact construction and length of just 87.7mm. This lens features FLD (F Low Dispersion) glass elementsc which have the performance equal to fluorite glass and SLD (Special Low Dispersion) glass elements providing excellent correction of color aberration. From the Manufacturer Compact High Zoom Ratio Lens with OS (Optical Stabilizer) This 11.1x high zoom ratio lens incorporates Sigmas original OS function and offers a broad shooting range from wide angle to telephoto. The latest optical technology enables easy handheld photography with a compact construction and length of just 3.5”c making it ideal for various scenes such as landscapec general photography and sport. This compact construction guarantees excellent mobility. FLD (F Low Dispersion) glass elementsc which have performance equal to fluoritec SLD (Special Low Dispersion) glass elementsc and aspherical lens elements provide high image quality throughout the entire zoom range. The HSM (Hyper Sonic Motor) ensures fast and quiet auto-focusing. Sony and Pentax mounts are not incorporated with OS function. For Pentax mountc if the camera body does not support HSMc auto focus will not be available. Compact whilst keeping high optical performance The SIGMA 18-200mm F3.5-6.3 II DC OS HSM is the successor to the SIGMA 18-200mm F3.5-6.3 DC OS/ HSM which was launched in June 2007. This lens features the latest optical technology including FLD glass elements and aspherical lens elementsc making it compact with a length of just 3.5” whilst keeping high rendering performance. This compact construction guarantees excellent mobility. Superior image quality One FLD (F Low Dispersion) glass elementc which has performance equal to fluoritec and two SLD (Special Low Dispersion) glass elements provide excellent correction for color aberrations. Two glass mold aspherical and a hybrid aspherical lens element ensure excellent correction for all types of aberrations. Together they provide a high level of optical performance throughout the entire zoom range. FLD glass is the highest level low dispersion glass available with extremely high light transmission. This optical glass has a performance equal to fluorite glass which has a low refractive index and low dispersion compared to current optical glass. It also benefits from high anomalous dispersion. These characteristics give excellent correction for residual chromatic aberration (secondary spectrum) which cannot be corrected by ordinary optical glass and ensures high definition and high contrast images. No Super Multi-Layer Coating (left). With Super Multi-Layer Coating (right). Super Multi-Layer Coating The Super Multi-Layer Coating reduces flare and ghosting as well as providing sharp and high contrast images throughout the entire zoom range. All DG and DC lenses in the current Sigma range feature this original technology. In digital camerasc flare and ghosting may also be caused by reflections between the image sensor and lens surfaces. Here tooc Sigmas Super Multi-Layer Coating is highly effectivec assuring images of outstanding contrast. No Optical Stabilizer (top). With Optical Stabilizer (bottom). Sigmas own unique OS technology The OS system offers effective correction of approximately 4 stopsc making it ideal for handheld photography of various scenes such as travelc generalc and sport. Sony and Pentax mounts do not incorporate Optical Stabilization. Hyper Sonic Motor High speed and quiet AF HSM indicates lenses equipped with a Hyper Sonic Motorc driven by ultrasonic waves. The HSM (Hyper Sonic Motor) ensures fast and quiet auto-focusing. For Pentax mountc if the camera body does not support HSMc auto focus will not be available. Rounded diaphragm The polygonal shape of a conventional iris diaphragm causes outo-focus light points to appear polygonal. A rounded diaphragm is designed to produce rounded outo-focus light points when opened to near maximum aperture. This creates attractive bokeh effects in many situationsc such as when photographing a subject against an out-of-focus surface of water from which light is being reflected. Lens Construction In a conventional lensc focusing requires an extension of the entire lens or the front lens group. Howeverc to better accommodate autofocusing mechanisms and closeup photographyc a need has arisen for lenses that do not change their length during focusing or suffer from focus-dependent variation in aberration. Thereforec Sigma has developed focusing systems that only move elements within the lens barrel. These incorporate smaller and lighter moving lens elements which help improve auto-focus speed. With their unchanging barrel length and small variation in the center of gravityc these lenses also enhance balance and stability for the photographer. Furthermorec since the front of the lens does not rotatec polarizing filters can be used with extra convenience. Specifications Lens Construction 18 Elements in 14 Groups Angle of View (for SD1) 76.5 - 8.1 degrees Number of Diaphragm Blades 7 Blades(Rounded Diaphragm) Minimum Aperture F22 Minimum Focusing Distance 45cm / 17.7in. Maximum Magnification 1:3.8 Filter Size Diameter 62mm Dimensions Diameter 75.3mm x Length 87.7mm / 3.0in. x 3.5in. Weight 490g / 17.3oz. MTF Chart View Larger Image MTF (Modular Transfer Function) is one of the measurements that evaluates a lens performancec and it contrasts sensitivity at different spacial frequencies. The horizontal axis is in millimeters and shows the distance from the center of the image toward the edgesc and contrast value (highest value is 1) is shown in the vertical axis. The readings at 10 lines per millimeter measure the lens contrast ability (red lines)c repeating fine parallel lines spaced at 30 lines per millimeter measure the lens sharpness ability (green lines)c when the aperture is wide open. Fine repeating line sets are created parallel to a diagonal line running from corner to corner of the framec are called Sagittal lines (S) and sets of repeating lines vertical to these lines are drawnc called Meridional (M) line sets. Distortion View Larger Image effective distortion: When you take a picture of a lattice patternc it will appear as the blue dotted line shows. the red line illustrates how the lattice pattern will appear in the actual picture when any lens distortion is taken into account. relative distortion: In this chartc the horizontal axis shows the ideal image height (the distance from the center to the edge of the image mm). The vertical axis shows the extent of distortion. The extent of the distortion is represented by how much Yc which is the actual image heightc grows (or shrinks) against Y0 which is the ideal image height. Extent of distortion: D%(Y-Y0/Y0)x100 When you take the picture of a square objectc if the distortion amount show a minus valuec the image will be seen as expanded (Barrel distortion). If the distortion amount is a plus valuec it will be seen as a recessed (pincushi on distortion). When the distortion value is close to 0c the appearance of distortion is very minimal. Vignetting View Larger Image The horizontal axis shows the image height (the distance from the center to the edge of the image mm). The vertical axis shows the amount of light in the image (based on the amount of light in the image center being 100%). If the peripheral amount of light is lower than the centerc the four corners of the image will be darker (vignetting).
I bought this lens with a little trepidationc b/c of so much Sigma bashing going on out therec and its extended aperture to 6.3. Howeverc I have other good lenses for specialized situations for my D7000c and didnt want to spend the money on Nikons 18-200 just for what I considered to be a generalc walk around lensc so I tried the Sigma. (Just so you know I am not cheap per se when it comes to lensesc I also have the Nikon 16-35 VR; 24-120 VR; 105mm DC; 105mm VR macro; 50mm 1.4; 85 mm 1.8; and 80-200 2.8.) br brThe first time I used it was for a train event yesterdayc which involved a whole lot of shooting variety: outdoor garden trains; train sets set up in basements; a toy train museum; a real train museum; and a real train ride. And I came home and pored over the imagesc trying to find fault. I did find a few minor faults in sharpness in some picturesc butc not having a Nikon 18-200 to compare it againstc I dont know if those were any different than the Nikon would put outc or just the way it is with a 18-200 lens in that situation (for examplec some of the shots were in a basement shooting at iso 6400c no flash. Some were of moving toy trains outside. So some of the lack of sharpness in some of the shots could very well be what you are going to get with a do it all lens zoomed out to 200mm in that situation.) br brButc other shotsc like in daylightc at reasonable isosc were tack sharp. And going through the picsc there was not one that I could say was unusable (at least b/c of the lens). br brThen todayc I did a test shot against my Nikon 25-120 VR in the kitchenc with one of the Department 56 buildings above the cabinetc at 120 mmc no flash. And side by side in LIghtroomc I could not tell the difference. And even 100% zoomed inc I could tell only the tiniest differencec and only b/c I was looking for it (which I actually hoped I wouldc with a $400 lens vs a $1000 lens!) br brSo basicallyc I have looked for every reason to send this lens back and buy a Nikonc but so farc I just cant find onec other than that nagging feeling in the back of my mind of missing out by not having the Nikon. I seriously think that sometimes peoplec like mec get caught up in fretting whether a third party lens is good enoughc and end up buying a Nikon just for peace of mindc if nothing else. br brBut I have had to remind myselfc I only bought this lens not for absolute perfectionc but just so I could have a decent lens without having to change lenses for basic shotsc and that sometimes (and maybe even most of the time)c when it comes to travelc family shotsc etc.c good enough really IS good enough. After allc once I send these pictures to Walgreens to be printed out as 5x7 printsc and they come back and go into an album and they get looked at maybe 2 or 3 times in the next 50 yearsc does it really matter which lens I had Probably not. br brAlsoc this new found consideration. The D7000 was to replace my D700/28-300VR combo which was stolen a few weeks ago in Seattle. (BTW - I hope the people who stole my camerac and anyone who buys it knowing it is hotc die a slow and painful death. But I digress.) But never again am I traveling anywhere with my very best equipment just for taking glorified snapshots. So if something happens to a $400 Sigma lens instead of a $900 Nikon lensc I know I will sleep much better that night than I did after I found thousands of dollars worth of equipment gone from the trunk of my car. br brSo bottom line to me isc is it perfect No. Do I expect any 18-200 zoom to be perfect No. But for a very good lens of convienencec I cant see spending over twice as much for the Nikon.