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This comparison review will involve the Sony 28-75mm F/2.8 SAM, and the Tamron 28-75mm F/2.8 using the A900 full frame camera.  Be sure to check out the bonus section at the bottom, where I compare both of the above lenses with the much more expensive Sony Carl Zeiss 24-70mm F/2.8 SSM lens.
 
 

Lens

Tamron SP AF 28-75mm F/2.8 XR Di LD aspherical IF Macro Model A09

SAL-2875  Sony 28-75mm F2.8 SAM

Box contents

Front and rear caps, user's manual, and hood.

Front and rear caps, user's manual, and hood.

Cost

Street price around $459

$799

Build quality

Good

Good

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

16 elements in 14 groups

Angle of view

75°-32° full frame, 54°-21° APS-C.

75°-32° full frame, 54°-21° APS-C.

Aperture

7 blades, curved

7 blades, curved

Full frame and APS-C

Yes, full frame and APS-C.   APS-C equivalent, 42-112.5mm

Yes, full frame and APS-C.   APS-C equivalent, 42-112.5mm

Depth of field and focus scales?

Focus distance indicators.

Focus distance indicators.

Minimum focus, image plane to subject

13"  (330mm)

15"  (380mm)

Minimum focus, end of lens barrel to subject

5.95"  (151mm)

6.65"  (169mm)

Hard stop at infinity focus?

No

No

Length changes when focusing?

No

No

Focus ring turns in AF?

Yes

Yes

Filter size

67mm

67mm

Filter ring rotates?

No

No

Distance encoder?

?
 

Yes
 

Max magnification

0.26x, or 1:3.9

0.22x, or 1:4.5

Min. F/stop

F/32  

F/32  

Sony teleconverter compatible?

No

No

Length changes when zooming?

Yes

Yes

Dimensions WxL  (my measurements)

2.9" x 3.7"   74mm x 95mm.   Add 1mm in width for zoom lock.

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)                                                    

5.04"  (128mm)                                                    

Weight bare (my scale)

17.9oz  (507g)  18.9oz (537g) with caps

19.6oz  (557g)  20.7oz (587g) with caps

 

Requisite product shots.

 

Dec09/2875cpsd.jpg
Tamron 28-75mm F/2.8, Sony 28-75mm F/2.8 (with Sigma rear cap)
Dec09/2875cpbk.jpg
Tamron, Sony backside
Dec09/2875cpft2.jpg
Tamron and Sony front elements.

 

You can see the Tamron lens is a little slimmer, I guess the Sony design needs more room for the SAM.  In the second image I notice the metal mount on the Sony is very much like the Carl Zeiss mounts, with a smooth and shiny machined surface, as opposed to the slightly duller regular Sony models, and the Tamron too.  The mounting screws are located differently also.  The front elements look identical.  In the front shot you'll notice by looking in the very center that the Tamron rear cap doesn't open the aperture when fully installed like Sigma and factory Minolta/Sony caps (which use a tab to move the aperture lever).

 

Distortion below

 

Dec09/t28d.jpg
Tamron at 28mm, moderate barrel distortion.
Dec09/t28d.jpg
Sony at 28mm, moderate barrel distortion
Dec09/t75d.jpg
Tamron at 75mm, moderate pincushion distortion.
Dec09/s75d.jpg
Sony at 75mm, moderate pincushion distortion

 

Distortion is the same on both lenses, though my crops are slightly off.

 

Light fall-off next

 

           Tamron, 28mm F/2.8

             Sony, 28mm F/2.8

Dec09/tw28ff.jpg
Dec09/ffvigw28.jpg

          Tamron, 28mm F/4

             Sony, 28mm F/4

Dec09/tw40ff.jpg
Dec09/ffvigw40.jpg

          Tamron, 75mm F/2.8

             Sony, 75mm F/2.8

Dec09/tel28ff.jpg
Dec09/ffvigt28.jpg

          Tamron, 75mm F/4

             Sony, 75mm F/4

Dec09/tel40ff.jpg
Dec09/ffvigt40.jpg

 

Light fall-off is the same for both lenses, although there are minor exposure deviations. 

 

Flare and ghosting samples below.

 

 Tamron, 28mm F/5.6

Sony, 28mm F/5.6

Dec09/t28mmgst.jpg
Dec09/s28mmgst.jpg

Tamron, 75mm F/5.6

Sony, 75mm F/5 .6

Dec09/t75mmgst.jpg
Dec09/s75mmgst.jpg

 
Flare and ghosting appears the same on both lenses judging by the full resized images above.
 
 
Center and corner sharpness.

Tamron at 28mm                                                            Sony at 28mm

          F/2.8

          F/2.8

Dec09/t2828cp.jpg
Dec09/s2828cp.jpg

          F/4

          F/4

Dec09/t2840cp.jpg
Dec09/s2840cp.jpg

          F/5.6

          F/5.6

Dec09/t2856cp.jpg
Dec09/s2856cp.jpg

          F/8

          F/8

Dec09/t2880cp.jpg
Dec09/s2880cp.jpg

          F/11

          F/11

Dec09/t2811cp.jpg
Dec09/s2811cp.jpg

 

Center sharpness is nearly identical on the lenses at 28mm.  The Tamron color seems somewhat warmer than the Sony, although the Tamron set was taken after the Sony, when the sun was low in the sky.  All images have the same exposure values.

 
Now for some corner crops.

 

Tamron at 28mm                                                            Sony at 28mm 

          F/2.8

          F/2.8

Dec09/t2828cncp.jpg
Dec09/s2828cncp.jpg

          F/4

          F/4

Dec09/t2840cncp.jpg
Dec09/s2840cncp.jpg

          F/5.6

          F/5.6

Dec09/t2856cncp.jpg
Dec09/s2856cncp.jpg

          F/8

          F/8

Dec09/t2880cncp.jpg
Dec09/s2880cncp.jpg

          F/11

          F/11

Dec09/1t2811cncp.jpg
Dec09/s2811cncp.jpg

 
The 28mm corner crops look slightly sharper with the Sony.  The exposure values are the same as the center crops, but light fall-off makes the corners darker.  You may also notice the color fringing looks about the same too.
 

75mm Center sharpness below.

Tamron at 75mm                                                            Sony at 75mm

          F/2.8

          F/2.8

Dec09/tel28.jpg
Dec09/sel28.jpg

          F/4

          F/4

Dec09/tel40.jpg
Dec09/sel40.jpg

          F/5.6

          F/5.6

Dec09/tel56.jpg
Dec09/sel56.jpg

          F/8

          F/8

Dec09/tel80.jpg
Dec09/sel80.jpg

          F/11

          F/11

Dec09/tel11.jpg
Dec09/sel11.jpg

 

Center sharpness is clearly better at F/2.8-4 with the Tamron, which is a surprise.  In fact, so much of a surprise that I re-shot the entire 75mm test sets three times just to make sure they produced the same images, and differences.  I'm not sure if this difference at 75mm is inherent in all Sony 28-75mm lenses, or my sample may be on the low end in the quality control acceptance scale.  I see some axial fringing in the Sony crops at F/2.8-4 too, and none in the Tamron.  All images have the same exposure values.

 
Now for some corner crops.

 

Tamron at 75mm                                                            Sony at 75mm 

          F/2.8

          F/2.8

Dec09/telcn28.jpg
Dec09/selcn28.jpg

          F/4

          F/4

Dec09/telcn40.jpg
Dec09/selcn40.jpg

          F/5.6

          F/5.6

Dec09/telcn56.jpg
Dec09/selcn56.jpg

          F/8

          F/8

Dec09/telcn80.jpg
Dec09/selcn80.jpg

          F/11

          F/11

Dec09/telcn11.jpg
Dec09/selcn11.jpg

 

The corner crops on both lenses produce the same moderately soft corners.  It seems the Sony shows a little more lateral color fringing than the Tamron, in this case, purple and yellow fringing.

 

In a nut-shell...

 

Both lenses focus with the same speed and accuracy using the A900.

Distortion, light fall-off and ghosting are identical.

For some reason, the Sony seems to produce slightly more color fringing.

The Sony has marginally sharper corners at 28mm.

The Tamron has much sharper centers at 75mm, F/2.8-4.

The Sony is slightly larger and heavier.

Build quality is the same.

 

 

Bonus section below that includes the same center and corner crops above, but now I've added the Sony Carl Zeiss 24-70mm F/2.8 to the mix!

 

Centers.

Tamron 28-75mm @28mm                                             Sony 28-75mm @28mm                                                Sony Carl Zeiss 24-70mm @28mm

          F/2.8

          F/2.8

          F/2.8

Dec09/t2828cp.jpg
Dec09/s2828cp.jpg
Dec09/cz2828cp.jpg

          F/4

          F/4

          F/4

Dec09/t2840cp.jpg
Dec09/s2840cp.jpg
Dec09/cz2840cp.jpg

          F/5.6

          F/5.6

          F/5.6

Dec09/t2856cp.jpg
Dec09/s2856cp.jpg
Dec09/cz2856cp.jpg

          F/8

          F/8

          F/8

Dec09/t2880cp.jpg
Dec09/s2880cp.jpg
Dec09/cz2880cp.jpg

          F/11

          F/11

          F/11

Dec09/t2811cp.jpg
Dec09/s2811cp.jpg
Dec09/cz2811cp.jpg

 
By golly the Carl Zeiss seems a tad soft at F/2.8, the other two look sharp.  The Carl Zeiss has a slight advantage as it covers less area at the indicated 28mm, that's no big deal though.
 
 
Corners.
 
Tamron 28-75mm @28mm                                             Sony 28-75mm @28mm                                                Sony Carl Zeiss 24-70mm @28mm

          F/2.8

          F/2.8

          F/2.8

Dec09/t2828cncp.jpg
Dec09/s2828cncp.jpg
Dec09/cz2828cncp.jpg

          F/4

          F/4

          F/4

Dec09/t2840cncp.jpg
Dec09/s2840cncp.jpg
Dec09/cz2840cncp.jpg

          F/5.6

          F/5.6

          F/5.6

Dec09/t2856cncp.jpg
Dec09/s2856cncp.jpg
Dec09/cz56cncp.jpg

          F/8

          F/8

          F/8

Dec09/t2880cncp.jpg
Dec09/s2880cncp.jpg
Dec09/cz2880cncp.jpg

          F/11

          F/11

          F/11

Dec09/1t2811cncp.jpg
Dec09/s2811cncp.jpg
Dec09/cz2811cncp.jpg

 
In my original review of the Sony Carl Zeiss 24-70mm, I thought the corners were pretty decent, and they are, it's just that the other two lenses produce excellent corners, and were unavailable at the time.  This kind of stuff isn't noticeable all that much unless cropped and displayed side-by-side as I'm doing here.
 
 
Centers.
 
Tamron 28-75mm @75mm                                             Sony 28-75mm @75mm                                                Sony Carl Zeiss 24-70mm @70mm

          F/2.8

          F/2.8

          F/2.8

Dec09/tel28.jpg
Dec09/sel28.jpg
Dec09/zel28.jpg

          F/4

          F/4

          F/4

Dec09/tel40.jpg
Dec09/sel40.jpg
Dec09/zel40.jpg

          F/5.6

          F/5.6

          F/5.6

Dec09/tel56.jpg
Dec09/sel56.jpg
Dec09/zel56.jpg

          F/8

          F/8

          F/8

Dec09/tel80.jpg
Dec09/sel80.jpg
Dec09/zel80.jpg

          F/11

          F/11

          F/11

Dec09/tel11.jpg
Dec09/sel11.jpg
Dec09/zel11.jpg

 
The Carl Zeiss seems to pull plenty of detail at 70mm, and is probably as sharp as the Tamron.  I see the Carl Zeiss is sharp at F/2.8, but does have a little axial color fringing. 
 
 
Corners.
 
Tamron 28-75mm @75mm                                             Sony 28-75mm @75mm                                                Sony Carl Zeiss 24-70mm @70mm

          F/2.8

          F/2.8

          F/2.8

Dec09/telcn28.jpg
Dec09/selcn28.jpg
Dec09/zelcn28.jpg

          F/4

          F/4

          F/4

Dec09/telcn40.jpg
Dec09/selcn40.jpg
Dec09/zelcn40.jpg

          F/5.6

          F/5.6

          F/5.6

Dec09/telcn56.jpg
Dec09/selcn56.jpg
Dec09/zelcn56.jpg

          F/8

          F/8

          F/8

Dec09/telcn80.jpg
Dec09/selcn80.jpg
Dec09/zelcn80.jpg

          F/11

          F/11

          F/11

Dec09/telcn11.jpg
Dec09/selcn11.jpg
Dec09/zelcn11.jpg

 

It looks to me like the Carl Zeiss has slightly sharper corners between F/4-5.6, even when considering the loss of 5mm of length.  All crops from the Sony and Tamron 28-75mm are the same as what you see at the top, I simply added another column, and the crops from the Carl Zeiss, which of course was tested at the same time as the original test sets with the other lenses.

 

Flare and ghosting samples below.

 

 Tamron, 28mm F/5.6

Sony, 28mm F/5.6

Sony Carl Zeiss 24-70mm, @28mm F/5.6

Dec09/t28mmgst.jpg
Dec09/s28mmgst.jpg
Dec09/cz28mmgst.jpg

Tamron, 75mm F/5.6

Sony, 75mm F/5 .6

Sony Carl Zeiss 24-70mm, @70mm F/5 .6

Dec09/t75mmgst.jpg
Dec09/s75mmgst.jpg
Dec09/cz75mmgst.jpg

 

The fancy Carl Zeiss has the most ghosting, I'm not sure why this is, maybe it's the larger front element group.

 

Sum up; the Tamron really showed-up the much higher priced Sony models in this mid-zoom comparison.  I can't help but think most users would be better off with the Tamron, meaning less money, and better overall performance.  The Sony 28-75mm is good, it just couldn't match the Tamron at the long end at large apertures.  It appears both lenses share most, if not all the same optics, so I'm not sure about the differences you see in the crops above.  Maybe this particular Sony lens barely met the quality control standards, and the Tamron exceeded its quality control standards---I'm not going to do this review over with different lenses, so we'll just assume that might be the case.  The Sony 28-75mm was very impressive at the wide end, so I highly doubt there is anything wrong with the lens.

 

The Sony Carl Zeiss 24-70mm seemed pretty good at the long end, but came in last at 28mm, I can't explain why.  If you're a photo journalist, or paparazzi, I'd still buy the Carl Zeiss lens over the other two because of the marginally faster and more accurate focusing with the SSM, better build quality, and slightly smoother bokeh too!

 

 
____________________________________________________________________
 

Additional 75mm crops added 3/7/10.

 

Below are some final crops between the two lenses.  Some people thought the earlier shots of the white block house at 75mm favored the Tamron because of time and sun angle etc.  This time I used a different scene all together, and show the subject and distant background to make it clear there isn't any DOF sharpening going on.  I also took all the shots from start to finish in five minutes and forty two seconds.

 

You can see some axial color fringing in the Sony crops at F/2.8, look along the power lines, transformer and at the bottom edge of the light fixture.  The Tamron is sharper at F/2.8-4 (check out the foliage in the background) although at F/5.6 and smaller there is no real difference.  Remember too these are 100% crops, and this stuff wouldn't be noticeable at normal viewing sizes.

 
Tamron at 75mm                                                            Sony at 75mm

          F/2.8

          F/2.8

March2010/t28ctr.jpg
March2010/s28ctr2.jpg

          F/4

          F/4

March2010/t40ctr.jpg
March2010/s40ctr2.jpg

          F/5.6

          F/5.6

March2010/t56ctr.jpg
March2010/s56ctr2.jpg

          F/8

          F/8

March2010/t80ctr.jpg
March2010/s80ctr2.jpg

          F/11

          F/11

March2010/t11ctr.jpg
March2010/s11ctr2.jpg