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Here's a brief look at the Minolta AF 28mm F/2.8 lens.  Scroll down for the review.

Lens

Minolta AF 28mm F/2.8 

Box contents

Front and rear caps and a users manual.

Cost

No longer available, but eBay prices are substantially less than the full retail Sony version. 

Build quality

Very good

Additional information

Has neat built-in hood, 3/8" (9mm) deep fully extended, but it does no good

Specifications below

 

Optical configuration

5 elements in 5 groups

Angle of view

75° full frame, 50° APS-C.

Aperture

7 blades, straight

Full frame and APS-C

Yes, made for full frame.   APS-C equivalent, 42mm

Depth of field and focus scales?

Yes and yes

Minimum focus, image plane to subject

12"  (310mm)

Minimum focus, end of lens barrel to subject

7.9"  (200mm)

Hard stop at infinity focus?

Yes

Length changes when focusing?

Yes

Focus ring turns in AF?

Yes

Filter size

49mm

Filter ring rotates?

No

Distance encoder?

No

Max magnification

0.13x

Min. F/stop

F/22

Sony teleconverter compatible?

No

Dimensions W x L (my measurements)

2.6" x 1.7"   66mm x 43mm 

Maximum  extended length (my measurements)

1.8"  (46mm), add 3/8" (9mm) for hood extension.                                                    

Weight bare (my scale)

6.5oz  (184g)  7.2oz (204g) with caps


Requisite product shots.

Aug08/m28mmft.jpg
Front with hood retracted
Aug08/m28mmhd.jpg
Front with hood extended
Aug08/m28mmbk.jpg
Backside
Aug08/m28mmsd.jpg
Side shot

 
 
All testing done with the Sony A 700For a better understanding of my review methods and terminology, go here.
 
This page has a copy of the original owner's manual. 
 
This lens is basically the same as the Sony version, so I've used a lot of the Sony 28mm F/2.8 review text where appropriate, but all images and crops are from the Minolta 28mm F/2.8 lens.
 
The Minolta AF 28mm F/2.8 is a compact lens, about as small as you're going to get.  Build quality is very good.  It has a gloss black finish with ribbed rubber inserts around most of the circumference.  It has a focus distance window with ft and m in different colors along with DOF hash marks.  It also has an infra-red focus index mark, the red dot on the aperture scale.  The lens is made in Japan.  Filter size is 49mm.  This lens has a short focus throw, as you can imagine it focuses very quickly and very accurately using the A700.  There's a tiny bit of slop on the focus ring if you wiggle it by hand when engaged, and none in actual MF use.  Manually, the ring is easy to manipulate with a finger and thumb.  Less than a quarter turn gets you from close focus to infinity.  The focus ring turns in auto-focus mode.
 
The Sony version doesn't quite match up with the Minolta as far as area captured, the Sony seems like it has a 1mm longer focal length.
 
The lens is multi-coated and resists flare and ghosting well.  You'll see a couple of small blobs from ghosting along the sun line.  When the sun is close to, but not in the image, you may have a small blob or a pale cone show up depending on your angle and aperture.  It has a very small built-in lens hood that you slide out from around the front element, but it doesn't do anything.  Use your hand for keeping the sun out of the shot if possible.
 
Coma is evident at F/2.8, but mild and cone shaped, not flying bird type.  it's completely gone at F/4.
 
Color looks the same as other Sony/Minolta lenses. 
 
Close-up filter.  Works great, see results here using a +4. 
 
Bokeh is neutral to just so-so in my opinion.  Results look better stopped down slightly.  The more distant the background, the better.
 
Lateral color fringing is present, but not very apparent unless you shoot bright white subjects flanked by dark areas.  I mostly came upon red and cyan, though red seems more noticeable.  Stopping down won't help with this type of CA.  This lens is average in this department.  See the Sony 28mm review for an example of CA.
 
 

Distortion below.
 

Aug08/m28mmdis.jpg
Barrel distortion.

 

Distortion isn't bad at all, and corrects very easily with standard lens correction tools in your photo imaging software.

 

Light fall-off.

 

F/2.8

F/4

Aug08/m28mmlf28.jpg

Aug08/m28mmlf40.jpg


Light fall-off or corner darkening is mild to moderate at F/2.8.  It blends well into the center of the image so it doesn't show in real life.  By F/4 it's gone
 

Aug08/m28mmover.jpg

 

Shot at F/2.8, no adjustments.  Light fall-off in real images is barely noticeable on a cropped sensor camera.

 

I wonder how sharp the corners are?

 

         F/2.8

          F/4.0

Aug08/m28mm28cn.jpg

Aug08/m28mm40cn.jpg

         F/5.6

          F/8

Aug08/m28mm56cn.jpg
Aug08/m28mm80cn.jpg

 

These crops are from the extreme bottom left corner.  Things look ok here at F/2.8, but the corners definitely respond to stopping down.  F/4 is a little better, and I think the sharpest comes at F/5.6 or possibly F/8.  It's obviously not going to matter after F/5.6.

 

How sharp are the centers if the image is enlarged to a staggering size?

 

F/2.8

amin28mm28ctr.jpg

F/4

bmin28mm40ctr.jpg

F/5.6

cmin28mm56ctr.jpg

F/8

dmin28mm80ctr.jpg

F/11

emin28mm11ctr.jpg

F/16

fmin28mm16ctr.jpg


Center sample results.

The center sample crops above show F/2.8 to be a little soft, but sharpens up nicely at F/5.6.  It appears the lens is at its sharpest at F/5.6-8.  There isn't a whole lot of change as you can see, and it's only noticeable cropped and displayed side-by-side.  I think my Sony 28mm F/2.8 version is very similar to the Minolta in sharpness, but maybe a hair sharper at F/4.  I'd say that's probably caused by sample variations as one might expect.  I've heard people say this lens is very soft at F/2.8, but I don't see a problem.  I wouldn't be afraid to shoot at F/2.8, but see my final thoughts below.
 
 

Close focus sample.
 
Below, check out the close focus shot, a 100% cropped portion of the full image.  The sample shot was taken with the Sony A 700 12.2mp camera.  The subject is a standard US stamp, 1"x 3/4" or 25.4mm x 19mm.  Also, note the macro shot was taken as close to the subject as focusing allowed; In this case, 8" or 203mm, measured from the front of the lens barrel to the subject.
 

Aug08/m28mm67mac.jpg
Click for larger image F/5.6


This maximum magnification shot is sharp, but it's small.  If you're using this lens properly, you won't care about macro type shots.  If you want to add a little "zing" to a close up, add a +4 close up lens, like I did in this review.
 
Full frame users go here for the results of the optically identical Sony 28mm F/2.8. 
 
 

My final thoughts. 
 
The Minolta AF 28mm F/2.8 lens turned in a good performance.  Good points are: compact, lightweight, low distortion, quick focusing with a great price.  It has an average amount of color fringing and it's just a little soft at F/2.8, but hits max sharpness at F/5.6-8 in the centers.  The corners sharpen up nicely two stops down.  Overall, I really like this compact lens.  While it makes perfect sense with a full frame body, I can't help but think it isn't the best choice for an APS-C camera, where it's equivalent to a 42mm.  A wider lens would be a better choice with that type camera, of course that's just my opinion since I like wide.  With that said, I'd rather pay the same amount of money for a Minolta 24mm F/2.8, or use the 18-70mm kit lens.  On a full frame camera the Sony 28mm F/2.8 makes sense, on all others, there're better choices.  The Sony and Minolta 28mm lenses are the same, so buy a Minolta on eBay instead of the Sony branded version and save about half off retail.