Sony 28-75mm F/2.8 SAM Review - Photo Jottings

Sony 28-75mm F/2.8 SAM Review

Here’s a brief look at the Sony 28-75mm F/2.8 SAM zoom lens.  Scroll down for the main review.

SAL-2875  Sony 28-75mm F2.8 SAM
Box contents
Front and rear caps, user’s manual, and hood.
$898 retail
Build quality
Additional information
New Sony design introduced late in 2009.  Similar to the Konica Minolta 28-75mm F/2.8 (D) and the Tamron 28-75mm F/2.8.
Specifications below
Optical configuration
16 elements in 14 groups
Angle of view
75°-32° full frame, 54°-21° APS-C.
7 blades, curved
Full frame and APS-C
Yes, full frame and APS-C.   APS-C equivalent, 42-112.5mm
Depth of field and focus scales?
Focus distance indicators.
Minimum focus, image plane to subject
15″  (380mm)
Minimum focus, end of lens barrel to subject
6.65″  (169mm)
Hard stop at infinity focus?
Length changes when focusing?
Focus ring turns in AF?
Filter size
Filter ring rotates?
Distance encoder?
Max magnification
0.22x, or 1:4.5
Min. F/stop
Sony teleconverter compatible?
Length changes when zooming?
Dimensions WxL  (my measurements)
3.1″ x 3.7″   78mm x 94mm.   Add 1.5mm in width for AF/MF switch or zoom lock.
Maximum  extended length (my measurements)
5.04″  (128mm)
Weight bare (my scale)
19.6oz  (557g)  20.7oz (587g) with caps
Requisite product shots.

Box and contents
Side view
Side shot fully extended
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.
For a comparison review of this lens, the Tamron 28-75mm F/2.8 and Sony Carl Zeiss 24-70mm F/2.8, go here.
This mid-level priced wide-angle zoom lens (made in Japan) features a constant fast aperture of F/2.8 with a good build quality, and is made for a full frame camera.  If used on an APS-C camera, the equivalent focal range is a rather unuseful (in my opinion) 42-112.5mm as stated by Sony.  A better choice for APS-C users would be the16-50mm F/2.8 SSM, Tamron 17-50mm F/2.8 or CZ 16-80mm, all reviewed here.
The Sony 28-75mm F/2.8 SAM first went up for sale late in 2009, but appears very similar to the Konica Minolta AF 28-75mm F/2.8 from 2004.
The zoom action is easy and smooth, with appropriate dampening.  This lens has a zoom lock, and can be set only at the 28mm position.  Focal length marks come at 28mm, 35mm, 50mm, 60mm and 75mm, and the EXIF data matches those lengths.  The zoom movement adds another 1.3″ or 34mm to the overall length of the lens.
In the box is the lens, petal shaped plastic hood, owner’s manual and warranty card.  Sorry, no black vinyl softcase this time.
Focusing.  The focusing ring is at the front of the lens, and does turn during auto-focusing, so watch your fingers.  Thankfully, there is no rotation or extension of the lens when focusing, so polarizers and grads will work great.  Manual focusing takes about 1/5 turn from Close-in to infinity, and has a reversed focus direction, that is, infinity is all the way to the left, see pictures above.  SAM auto-focusing is fairly quick and accurate,  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 control for a 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).  Average, to above average control, especially when used on an APS-C camera.  Lateral color fringing is most noticeable at the wide end if you look hard.  I see some axial color fringing at the long end with a wide aperture.  Thankfully, this type goes away as you stop down.  See sample crops lateral color fringing in the full frame section below.
Bokeh.  fair to harsh if you look closely enough, otherwise, it looks somewhat smooth due to the way the outer rings are rendered.  Look below for sample crops.
Color.   Same as most other Sony lenses.
Close up filter.  N/A
Coma.  No problems with APS-C cameras, full frame shows mild to moderate amounts at F/2.8-4, see below.
Regular filters cause no additional light fall-off problems on APS-C or full frame cameras.
Filter size is 67mm.  This is an odd-ball size for Sony, and this lens is the only one so far to use it.
Distortion.  You’ll notice moderate barrel distortion at the wide end, becoming flat around 35-40mm, then very mild pincushion distortion out to 75mm using an APS-C camera.  Of course, full frame coverage shows more distortion.  Check out the cropped samples below.
Distortion examples directly below.
28mm, moderate barrel distortion.
Almost flat at 35mm.
75mm, very mild pincushion distortion.
Bokeh crops next.
           28mm F/2.8
             28mm F/4
           75mm F/2.8 
             75mm F/4


When viewed closely, you can see the multi-rings in the out-of-focus highlights, fortunately, the outer ring is rendered somewhat smooth, and looks decent when viewed at normal screen sizes.



Real bokeh shot below.




The full image directly above shows real world background blur focused close at F/5.6, 75mm, and looks smoother when viewed in this way, instead of the 100% crops.  You can see the aperture shape starting to show up at F/5.6.  This is a shot from the A900.


Lens flare/ghosting examples


28mm F/5.6, ghosting.
28mm F/5.6 sun centered.
50mm F/5.6
75mm F/5.6 
75mm F/5.6 sun just out of shot.
75mm F/5.6, sun blocked by hand.
I see multi-colored blobs when the sun is near, or inside the image at the wide end. This lens produces an average amount of veiling glare at the long end.  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 looks worse, so keep that in mind when incorporating the sun into your picture.  As always, try to use your hand to block any stray light that may fall on the front element.  The supplied hood really isn’t all that effective in stopping ghosting, and of course it won’t do anything if the sun is part of the image.  Sony does not yet list a hood for this lens, so don’t lose it.
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.

           28mm F/2.8
             28mm F/4
           75mm F/2.8 
             75mm F/4
Center and corner sharpness.

Below are crops from the image centers and corners at 28mm.

         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


The centers at 28mm, F/2.8 are pretty sharp, and closing the aperture more doesn’t seem to add much sharpness.  The corners are soft at F/2.8, but sharpen up reasonably at F/4, and smaller apertures don’t help past F/5.6.


Below are centers and corners from 75mm.


         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
The 75mm center crops show improvement by closing the aperture to F/5.6, where maximum sharpness occurs.  The corners look pretty good at F/5.6, but never seem to match the centers.
Let’s check out the macro capabilities of this lens.

Below, check out the 100% cropped portion (308kb) 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 6.65″ (169mm), measured from the front of the lens barrel to the subject.
This lens has a reproduction size of 0.22x which is about average for a wide-angle zoom lens, and produced a very sharp close shot of the postage stamp.  An aperture of F/5.6 produced the sharpest shot at close focus, but F/8 looked nearly as good.  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/5.6. 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


           28mm F/2.8
             28mm F/4
           28mm F/5.6 
             75mm F/2.8
           75mm F/4
             75mm F/5.6


Light fall-off is definitely stronger with full frame coverage.  I see moderate to heavy levels at both the extremes, however, by closing the aperture one stop, things clear up nicely.  Regular filters cause no noticeable additional light fall-off.


Full image below illustrating light fall-off from A900.




This full scene of my backyard shows light fall-off from 28mm, F/2.8, 1250sec, ISO 200.  It’s really not noticeable, and certainly not distracting in my opinion.


Lens flare/ghosting samples.


28mm F/2.8
28mm F/5.6
28mm F/5.6 sun out of shot
45mm F/5 .6 sun out of shot


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 top row shows ghosting when the sun is in the image.  In the bottom row are samples with the sun just outside the image.  All samples above show the entire image, and are not cropped.


Color fringing crops below.


Color fringing at 28mm, far right side
Color fringing at 75mm, far left side


The full frame 28mm, F/5.6 crop (top) shows mild color fringing, and was taken from the last 700 pixels of the image on the middle right side.  Color fringing is most noticeable at the wide end, but isn’t very distracting in my opinion, and remember, this is a 100% crop.  The lower shot is from 75mm on the far left side of the image, (also a 100% crop) and color fringing is fairly mild.  This is lateral color fringing which occurs along the sides of the image, and doesn’t go away as you stop down.  I see no axial CA at any aperture.


28mm corner samples next.


     F/5.6 from center


The 28mm full frame corners look pretty soft wide open, but they do sharpen up gradually, and by F/8-11 they actually look good.  I threw in a center shot comparison, just to show you the difference between the centers and extreme corners.  Notice the color fringing in the crops.  Exposure differences between the center and corners crops are from light fall-off.  Crops taken from the last 300 pixels at the lower left corner.


75mm corners below.


     F/5.6 from center


The 75mm full frame corners are soft at all apertures, but seem best by a hair at F/11.  Crops taken from the last 250 pixels from the lower left corner.  Exposure differences are from light fall-off.


Distortion next 

Moderate barrel distortion @28mm on A900
Almost flat @35mm on A900
Moderate pincushion distortion @ 75mm on A900


I see moderate wave-type barrel distortion at 28mm, becoming flat around 35-40mm.  The full frame barrel distortion never really gets perfectly flat if you try to fix it using standard distortion tools.  As you near 75mm, moderate pincushion distortion shows up, and the curve here is gradual and even across the frame, making it easy to correct in post processing.


Coma results below.


         28mm F/2.8
          28mm F/5.6
Dec09/ffcma28.jpg Dec09/ffcma56.jpg


Coma is mild to moderate in the extreme corners at 28mm, F/2.8-4, and gone by F/5.6.



Overall, I’m impressed with the new Sony 28-75mm F/2.8 lens.  It’s sharp in the centers at F/2.8 at the wide end, and the corners sharpen up reasonably at F/5.6.  The long end is a little soft in the centers at F/2.8, but sharpens up at F/4, the corners look decent, but not great at F/8-11.  Distortion is about average, as is ghosting control and light fall-off.  Color fringing is not very noticeable at the long end, and control at the wide end is about average.  Bokeh looks similar to other less expensive wide zooms from Sony and Minolta, that is to say it looks somewhat harsh if you look very closely, but at standard viewing sizes it appears neutral.

For APS-C users; although this lens works fine on an APS-C camera, the equivalent focal length of 42-112.5mm is a little long for me.  You may be better served with the Sony 16-50mm F/2.8 SSM, Tamron 17-50mm F/2.8, or the one stop slower CZ 16-80mm.

Full frame users; This lens performs quite nicely, and seems to have the quality optics needed to handle the 24+ megapixels of Sony full frame cameras.  I think it would be a great less-expensive alternative to the Sony CZ 24-70mm F/2.8.
A great way to save money is to buy the Tamron version of this lens, which goes for about half the Sony price. See my comparison review here.
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