Here's a brief look at the Sony 16-35mm F/2.8 SSM zoom lens.  Scroll down for the main review. Lens SAL-1635Z  Sony Carl Zeiss Vario-Sonnar T* 16-35mm F2.8 ZA SSM Box contents Front and rear caps, users manual, hood and soft case. Cost $1998 retail. Build quality Very good Additional information New Carl Zeiss Sony design introduced in 2009. Specifications below   Optical configuration 17 elements in 13 groups Angle of view 107°-63° full frame, 83°-44° APS-C. Aperture 9 blades, curved Full frame and APS-C Yes, full frame and APS-C.   APS-C equivalent, 24-52.5mm Depth of field and focus scales? Focus distance window, and focal length index marks at 16mm, 20mm, 24mm, 28mm, and 35mm. Minimum focus, image plane to subject 11"  (279mm) Minimum focus, end of lens barrel to subject 4.35"  (110mm) Hard stop at infinity focus? No Length changes when focusing? No Focus ring turns in AF? No Filter size 77mm Filter ring rotates? No Distance encoder? Yes   Max magnification 0.24x, or 1:4.2 Min. F/stop F/22   Sony teleconverter compatible? No Length changes when zooming? No Dimensions WxL  (my measurements) 3.27" x 4.5"   83mm x 114mm.   Add 2mm in width for AF/MF switch. Maximum  extended length (my measurements) 4.5"  (114mm)                                                     Weight bare (my scale) 30.4oz  (863g)  31.7oz (899g) with caps Requisite product shots. Side view Box and contents Backside Front element drops 6mm @24mm Front element Sony X-ray view and MTF chart     The Sony A700 and A900 were used for this review.  For full frame results, go to the bottom of the page.  For a better understanding of terms and methods used in this review, go here.   Check out a comparison review that includes this lens.    This expensive Carl Zeiss super wide-angle zoom lens (made in Japan) features a constant fast aperture of F/2.8 with an very good build quality.  A professional photographer or advanced amateur may benefit from those features, and most importantly, be able to justify the high cost.  This lens was designed for a full frame camera.  If you have an APS-C camera, consider the much less expensive, (but much wider on that type of camera) Sigma 10-20mm, or Sony 11-18mm.  Other less-expensive full frame options include the Konica Minolta AF 17-35mm F/2.8-4, and the Minolta AF 17-35mm F/3.5 G.    The Sony Carl Zeiss Vario-Sonnar T* 16-35mm F/2.8 ZA SSM has a long and interesting name, that's for sure.  Fortunately, this lens has other interesting features and characteristics as well.  On the outside, there is the usual Zeiss-type black finish, with the texture being different between the metal parts and the plastic parts.  Speaking of which, most of the outer barrel components are plastic, but the portion in front of the focus ring appears to be metal.  This lens sports an integrated AF/MF and focus hold button, which can be changed to DOF (depth of field) on select camera bodies.  There's a focus distance window with readings for feet and meters.  Inside the lens, Sony claims the use of three aspherical elements, super ED glass¹, and of course the T* coatings.  ¹This is the first Sony lens that gets the "super" ED designation.   The zoom action is somewhat stiff, but it holds its position well, so there is no zoom creep.  Focal length index marks come at 16mm, 20mm, 24mm, 28mm and 35mm, and the EXIF data matches those lengths, except 28mm, which reads 26mm.  I also notice the EXIF data jumps quickly to 17mm at just a hair past 16mm, you almost have to hold the zoom at the full wide position to get the data to read 16mm-weird.  The zoom movement is internal, meaning the lens doesn't change length when zooming.  It gradually drops the front group to a maximum depth of 6mm, coming at 24mm focal length, then rising gradually until reaching 35mm, (see photo above).  This is a different type of movement than the Minolta 17-35mm F/3.5 G lens, which drops farther, and is fully down at 35mm.     In the box is the lens, petal shaped plastic hood with a nice felt-type anti-glare covering on the inside, black vinyl softcase, owner's manual, warranty card, and an inspection sticker signed by the inspector, in this case, H Hirano.    Focusing.  The focusing ring is at the front of the lens, and does not turn during auto-focusing.  You can override the auto focus at any time by just turning the focus ring.  All SSM have an over-drive type manual focusing system, that is, if you turn the focusing ring a certain amount, the distance numbers in the window will turn a lesser amount.  This allows for more precise manual focusing.  Manual focusing takes about 1/4 turn from Close-in to infinity, and doesn't add any length to the lens.  Auto-focusing is quick and very accurate, but when used in the super wide lengths with close-in framing, you may have to override AF, as the focusing system may not be able to determine what you want to focus on since some items may be very close, and others farther away, that's the nature of using a super-wide angle lens.  Note; don't confuse SSM with SAM.  SSM (super sonic wave motor) is a very good focusing system designed by Minolta in the late 1990s.  SAM (smooth auto-focus motor) is a cheap (less effective) focusing system developed by Sony for use in less-expensive lenses, starting in 2009.  They both feature a focus motor inside the lens, instead of the camera body motor turning a coupled slot/screw to focus the lens. Lens flare/ghosting.  Average to above average control for a super-wide angle zoom.  I see multi-color ghosts if the sun is at the edge, or inside the image.  The ghosts change shape and color with focal length and aperture.  Look below for examples.  Veiling glare seems a little strong as you zoom out, so prepare to block the sun or other super-bright light source with your hand to keep the contrast up in your shots, if the sun isn't actually in the shot.   Color fringing (CA).  Above average control, when used on an APS-C camera.  Look for mild amounts of lateral color fringing at and near 16mm, diminishing to almost nothing at 35mm.  Full frame coverage shows more at the widest lengths.  See full frame section for sample crop. I see no axial color fringing at any aperture.   Bokeh.  Somewhat smooth looking at the wide end, with very light edges around the highlights, stopping down to F/4 looks about the same.  As you zoom out, the bokeh starts to become harsh when used at F/2.8, but looks better one stop down.  The aperture shape starts to show up around F/5.6.  Look below for sample crops.   Color.   Same as other Sony lenses.   Close up filter.  N/A       Coma.  No problems with APS-C cameras, full frame shows a small amount at F/2.8, see below.   Regular filters cause no additional light fall-off problems on APS-C cameras, but do affect full frame cameras at 16mm, see example at bottom.     Filter size is 77mm.  This is the standard size for all Minolta and Sony super-wide zooms.  Other Sony lenses that use 77mm filters are; CZ 24-70mm F/2.8, 70-200mm F/2.8 G, CZ 135mm F/1.8, 11-18mm F/4.5-5.6, and the 70-400mm G.   Distortion.  You'll notice moderate barrel distortion at the wide end, becoming flat around 26-28mm, then very light pincushion distortion out to 35mm using an APS-C camera.  Of course, full frame coverage shows more distortion.  Check out the cropped samples below.   Distortion examples directly below.   16mm, moderate barrel distortion. Flat at 26mm. 35mm, very mild pincushion distortion.   Bokeh crops next.              16mm F/2.8              16mm F/4            35mm F/2.8               35mm F/4   The 16mm crops show fairly smooth out-of-focus highlights wide open.  At 35mm, bokeh looks less harsh one stop down at F/4, and F/5.6 starts to show the nine bladed aperture shape.          Real bokeh shot below.     The full image directly above shows the real world background blur focused close at F/5.6, 28mm, and looks smoother when viewed in this way, instead of the 100% crops.  Super-wide angle lenses have a huge Depth of field, (as observed), especially stopped down, and getting any background blur is tough, unless focusing on close subjects.      Lens flare/ghosting examples   16mm F/5.6, ghosting. 16mm F/5.6 sun centered. 16mm F/5.6, sun just out of picture. 16mm F/5.6 sun just out of shot, using hand to block sun. 24mm F/5.6 sun just in shot. 35mm F/5.6, sun in shot. 16mm F/16, sun in shot. 16mm F/11, sun centered.   I see multi-colored blobs when the sun is near, or inside the image. This lens produces an average amount of veiling glare, especially zoomed out, but overall control of glare and ghosting is better than the average super-wide angle zoom.  When the sun is in the center of the shot, there is no wagon wheel or ring visible, (at any aperture), as there is on other lenses of this type.  You can see by the crops above the color and intensity of flare and ghosts are different as you zoom out.  Ghosts become more defined and numerous as you stop down the aperture, I use F/5.6 because it's an often used aperture, F/11 and smaller look worse, so keep that in mind when incorporating the sun into your picture.  This lens gives off nice 18 pointed sun-stars when stopped down hard, a result of the 9 bladed aperture.   As always, try to use your hand to block any stray light that may fall on the front element.  The supplied hood is of little use.  If you lose it, and for some odd reason you want to replace it, Sony will drain your wallet of $130, and labeled by me as an obscene profit generator.     Light fall-off. See the crops below.  Light fall-off or corner shading is not noticeable in real pictures at any focal length or aperture using an APS-C camera.                16mm F/2.8              16mm F/4            35mm F/2.8               35mm F/4 Center and corner sharpness. Below are crops from the image centers and corners at 16mm.          F/2.8 center           F/2.8 corner          F/4 center           F/4 corner          F/5.6 center           F/5.6 corner          F/8 center           F/8 corner          F/11 center           F/11 corner          F/16 center           F/16 corner          F/22 center           F/22 corner   At 16mm, F/2.8 shows just a little veiling haze, but has plenty of detail.  One stop down to F/4 gets rid of the veiling haze, and the centers look very sharp all the way to F/11, peaking at F/4-5.6.  The corners are fairly sharp, considering how the corners are rendered at this focal length, and camera position.  See the full frame 35mm crops for an explanation.  Oddly, they corners really don't change much as you close the aperture, and look almost the same at F/16.  You may also notice some color fringing in the crops, which is more noticeable as you stop down.  If you can't see it,  look at the tree limbs, and along the left/middle of the window in the corner crops, then look at the center crop.  This color fringing is very light and should not concern you in any way.      Below, crops from the 24mm centers and corners.            F/2.8 center           F/2.8 corner          F/4 center           F/4 corner          F/5.6 center           F/5.6 corner          F/8 center           F/8 corner          F/11 center           F/11 corner          F/16 center           F/16 corner          F/22 center           F/22 corner   At mid-zoom, the center performance is similar to the 16mm crops, but the wide open corners are soft, though sharpening up some at F/4.  The centers start to degrade slightly at F/8.    Below are centers and corners from 35mm.            F/2.8 center           F/2.8 corner          F/4 center           F/4 corner          F/5.6 center           F/5.6 corner          F/8 center           F/8 corner          F/11 center           F/11 corner          F/16 center           F/16 corner          F/22 center           F/22 corner   The 35mm center crops show improvement by closing the aperture to F/4.  The corners look pretty good at F/5.6, with the corners and centers having almost the same sharpness at F/8.   To sum up the center/corner performance; the centers look quite good at F/2.8, but lose veiling haze at F/4, then sharpness peaks around F/5.6, and drops of slightly at F/8.  F/16 degrades noticeably due to diffraction, and fully stopped down to F/22 shows very soft, which is normal.  The corners seem to peak around F/8, but look good from F/5.6 to F/16, then F/22 goes fuzzy due to diffraction.      Let's check out the macro capabilities of this lens. Below, check out the 100% cropped portion (384kb) of the full image.  The sample shot was taken with the Sony A 700 12.2MP camera.  The subject is a standard US stamp, 0.87"x 1.0" or 22mm x 25mm.  Also, note the macro shot was taken as close to the subject as focusing allowed; in this case a very short 4.35" (110mm), measured from the front of the lens barrel to the subject.     This lens has a reproduction size of 0.24x which is quite large for a super wide-angle lens, and produced a very sharp close shot of the postage stamp.  Contrast is noticeably excellent.  F/8 was the sharpest at close focus, but F/5.6 looked good also.  Shooting close focus subjects at F/2.8-4 shows very soft, and there is a big leap in sharpness from F/4 to F/5.6.  As a side note; the "1996" on the bottom left of the stamp measures a mere 1mm wide.   As close as you can get. F/8. Click for larger image.   Full frame section next.     Full frame results using the Sony A900 below.   Check out the differences when using a film or full frame camera below.  I'm only pointing out the noticeable issues as compared to the APS-C bodies, so if I don't show it here, the results are not significantly different enough to warrant posting an additional set of images in this section.   Light fall-off               16mm F/2.8              16mm F/2.8 with filter            16mm F/4               16mm F/5.6            24mm F/2.8               24mm F/5.6            35mm F/2.8               35mm F/4   Light fall-off is definitely stronger with full frame coverage.  I see moderate to heavy levels from 16mm to around 20mm, and stopping down doesn't really help matters, F/11 shows about the same as F/5.6.  The mid-zoom lengths respond better to closing the aperture, and the level of light fall-off here is not too bad, especially stopped down some.  Out near 35mm, there's mild to moderate light fall-off wide open, diminishing one stop down.  Regular filters cause slight additional light fall-off at the widest focal lengths, but not much.   Additional ghosting with full frame coverage.   16mm F/5.6 24mm F/5.6 16mm F/2.8 16mm F/8  Noticeable above is the additional ghosting with full frame coverage.  This stuff is visible in the viewfinder, so just pay attention, although there's nothing you can do when the sun or other bright light is inside the image.  The red arc and polygon are visible mostly around 16mm-20mm, diminishing greatly as you zoom out.  This red arc is seen in other super wide-angle lenses also.  I actually like the look of the arc in the left lower image, but I can't think of a good way of including it in a real picture.  All samples above show the entire image, and are not cropped.    Full image from A900 below illustrating light fall-off.     This boring full scene shows light fall-off from 16mm, F/2.8.  It's noticeable, but not distracting in my opinion, especially with a bold subject in the center of the image.  If I were to shoot this picture at 35mm, F/5.6-8 there wouldn't be any noticeable light fall-off, and the Orange King bracts would be in focus.       Lateral color fringing.     This full frame 16mm, F/5.6 crop shows color fringing, and was taken from the last 700 pixels of the image on the middle right side.  I'd say it has less lateral color fringing than other Minolta or Konica Minolta lenses at this focal length.  This type of color fringing doesn't go away as you stop down.  Look at the magenta and cyan colors along the wall edges and tree trunks etc.  It's noticeable if you look for it, but not distracting in my opinion.       16mm corner samples next.        F/2.8      F/4      F/5.6      F/5.6 from center      F/8      F/11      F/16      F/22   The 16mm full frame corners look pretty soft wide open, but they do sharpen up gradually, and by F/8-11 they actually look good.  The area covered by corner softness at 16mm, F/2.8 extends about 800 pixels from the very corner, towards the center, and about 300 pixels in at F/8.  I threw in a center shot comparison, just to show you the difference between the centers and extreme corners.  Exposure differences between the center and corners crops are from light fall-off.   If you look carefully, you can see the line of sharpness increasing or extending to the corners by looking at the F/8 shot, the top left area is sharper than the bottom right.  The size differences between the center and corners are not from moving in, they were shot from the same spot, that's just the nature of wide angle lenses, and the changes in camera position from center to corner for comparison purposes.     24mm corners below.        F/2.8      F/4      F/5.6      F/5.6 from center      F/8      F/11      F/16      F/22   Moving on to the 24mm corners, we see the corners sharpen up fairly well by F/8-11.  At F/2.8, the soft corner area covers about 800 pixels in from the very corner.  At F/8, there is no noticeable soft area.    35mm corners.        F/2.8      F/4      F/5.6      F/5.6 from center      F/8      F/11      F/16      F/22      F/8 corner, same as above, but corrected      F/5.6 center crop, same as above    The 35mm corners show pretty darn sharp at F/5.6-8, though when viewing a picture at F/2.8, you don't notice any softness in the corners, because the sharpness curve from center to corner is very gradual.     I think the lens does a very good job at correcting corner softness at all focal lengths.  When you consider the way the corners are rendered (larger), as opposed to the centers, you can better appreciate the performance of this lens, especially when used with full frame coverage.   The last row of crops illustrates what I've been talking about when I say the corners look good when considering the way they are rendered.  The left bottom crop is the same F/8 corner crop used above.  The image beside it is the same F/5.6 center comparison crop.  I've corrected the F/8 corner crop for size, tilt, and exposure to make it look like the F/5.6 center crop.  Obviously, you wouldn't be able to do this in real world pictures, but it shows you if you equal things out, the corners are actually pretty sharp, and have plenty of detail.     Distortion next.   Moderate barrel distortion @16mm on A900 Almost flat @24mm on A900 Moderate pincushion distortion @ 35mm on A900   There is moderate complex wave-type barrel distortion at 16mm.  This type of distortion is almost impossible to fully correct in post processing, however, you'll only notice it if you shoot straight lines near the image periphery.  Distortion almost flattens around 22-24mm, which is a little sooner than the APS-C samples.  The full frame wave-type barrel distortion never really gets perfectly flat.  As you near 35mm, mild to moderate pincushion distortion shows up, and the distortion curve here is gradual and even across the frame, making it easy to correct in post processing.   Coma results below.            16mm F/2.8           16mm F/4   Coma is very light in the extreme corners at F/2.8, you see some color fringing and light streaks, but the streaks and most of the color fringing nearly disappear one stop down.           Conclusion.    This is the best (and only Sony branded) super wide-angle zoom lens for your full frame camera.  I immediately noticed the nice color and contrast of this very expensive Carl Zeiss lens, and would be well worth the price if you need this focal length, along with the constant fast F/2.8 aperture.  It's sharp in the centers at F/2.8, and very sharp from F/4 to F/8 at all focal lengths, with the corners sharpening up nicely at F/8.  Ghosting can seem a little strong, but is better than all other super-wide Minolta AF mount options for a full frame camera.  See my full frame comparison review here.  Lateral color fringing is controlled well from 16mm-24mm, and is almost non-existent as you zoom out to 35mm.  Focusing is very accurate, but watch out at the super wide focal lengths, where foreground objects may cause focusing misses, which is standard behaviour for a super wide lens.  Build quality is very good, but no better than the Minolta AF 17-35mm F/3.5 G lens.  All in all, a very good lens at a fairly hefty price tag.  Most people probably wouldn't be able to justify the price, but that wouldn't stop most people from buying it, including me.   Important fact; If you use this lens to take pictures of test charts and other close-focus type stuff, you'll find F/2.8-4 to be very soft, but F/5.6-8 looks great.  If you use this lens for taking real pictures, F/2.8 is almost indistinguishable from F/4 or F/5.6 unless viewed side-by-side at huge sizes.  For APS-C users; although this lens works wonderfully with an APS-C camera, the equivalent focal length of 24-52.5 is a little long.  You may be better served with the one stop slower CZ 16-80mm.  If you want real super wide-angle coverage, then I'd consider the Sony 11-18mm, Sigma 10-20mm HSM F/3.5, Sigma 10-20mm F/4-5.6 or the Tokina 11-16mm F/2.8.        Full frame users;  If you want the very best super wide-angle lens for your Sony camera, and have a boat-load of cash, go ahead and get it, you'll be happy.  For those of you on a budget, consider the KM 17-35mm F/2.8-4, or the Minolta AF 17-35mm F/3.5 G lenses, which perform well, but don't offer the constant F/2.8 fast aperture, or SSM focusing.