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

Lens

Box contents

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

Cost

Build quality

Good

Additional information

Specifications below

 

Optical configuration

16 elements in 14 groups

Angle of view

75°-32° full frame, 54°-21° APS-C.

Aperture

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

13"  (330mm)

Minimum focus, end of lens barrel to subject

5.95"  (151mm)

Hard stop at infinity focus?

No

Length changes when focusing?

No

Focus ring turns in AF?

Yes

Filter size

67mm

Filter ring rotates?

No

Distance encoder?

Claims "D" compatible on the box.
 

Max magnification

0.26x, or 1:3.9

Min. F/stop

F/32  

Sony teleconverter compatible?

No

Length changes when zooming?

Yes

Dimensions WxL  (my measurements)

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

Maximum  extended length (my measurements)

5.04"  (128mm)                                                    

Weight bare (my scale)

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


Requisite product shots.

Dec09/t2875kit.jpg
Box and contents
Dec09/t2875sd2.jpg
Side view
Dec09/t2875sdex2.jpg
Side shot fully extended
Dec09/t2875ft.jpg
Front element
Dec09/t2875bk.jpg
Backside

 
 
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 Sony 28-75mm F/2.8 SAM and Sony Carl Zeiss 24-70mm F/2.8, go here.
 
The Tamron 28-75mm F/2.8 and Sony 28-75mm F/2.8 are very similar in design and performance, so I've used some of the same text from the Sony review when there is no difference between the lenses, but all crops below are from the Tamron lens.
 
This moderately 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.  A better choice for APS-C users would be the Tamron 17-50mm F/2.8 or Sigma 18-50mm F/2.8, both reviewed here; or better yet, the Sony DT 16-50mm F/2.8 SSM.
 
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. 
 
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.  Slot/screw drive auto-focusing is fairly quick and accurate.  


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 no axial color fringing at any length or aperture.  
 
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.   About the same as Sony.
 
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, and the same as the Sony version of this lens.
 
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.
 

Dec09/tdis28.jpg
28mm, moderate barrel distortion.
Dec09/tdis35.jpg
Almost flat at 35mm.
Dec09/tdis75.jpg
75mm, very mild pincushion distortion.

 
Bokeh crops next.
 

           28mm F/2.8

             28mm F/4

Dec09/tbok2828.jpg
Dec09/tbok2840.jpg

           75mm F/2.8 

             75mm F/4

Dec09/tbok7528.jpg
Dec09/tbok7540.jpg

 

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.     

 

 

Lens flare/ghosting examples

 

28mm F/5.6, ghosting.

35mm F/5.6

Dec09/tgst28mm.jpg
Dec09/tgst35mm.jpg

75mm F/5.6 sun just out of shot.

75mm F/5.6, sun blocked by hand.

Dec09/tgst75unblk.jpg
Dec09/tgst75blk.jpg

 
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. Note; this hood fits the Sony 28-75mm F/2.8 model too.
 
Don't try to compare the ghosting images above with the Sony 28-75mm images, as they were taken at a different time, and slightly different angles.
 

 
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

Dec09/tw28vig.jpg
Dec09/tw40vig.jpg

           75mm F/2.8 

             75mm F/4

Dec09/tel28vig2.jpg
Dec09/tel40vig.jpg


Center and corner sharpness.

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

         F/2.8 center

          F/2.8 corner

Dec09/t2828ctr.jpg
Dec09/t2828cn.jpg

         F/4 center

          F/4 corner

Dec09/t2840ctr.jpg
Dec09/t2840cn.jpg

         F/5.6 center

          F/5.6 corner

Dec09/t2856ctr.jpg
Dec09/t2856cn.jpg

         F/8 center

          F/8 corner

Dec09/t2880ctr.jpg
Dec09/t2880cn.jpg

         F/11 center

          F/11 corner

Dec09/t2811ctr.jpg
Dec09/t2811cn.jpg

 

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/4-5.6, and seem sharpest (just barely) at F/11. 

 

Below are centers and corners from 75mm.

 

         F/2.8 center

          F/2.8 corner

Dec09/t7528ctr.jpg
Dec09/t7528cn.jpg

         F/4 center

          F/4 corner

Dec09/t7540ctr.jpg
Dec09/t7540cn.jpg

         F/5.6 center

          F/5.6 corner

Dec09/t7556ctr.jpg
Dec09/t7556cn.jpg

         F/8 center

          F/8 corner

Dec09/t7580ctr.jpg
Dec09/t7580cn.jpg

         F/11 center

          F/11 corner

Dec09/t7511ctr.jpg
Dec09/t7511cn.jpg

 
The 75mm center crops show a sharp center at F/2.8, but contrast looks better at F/4.  The corners do improve some by closing the aperture, and F/5.6 looks pretty good.
 
 

  
Let's check out the macro capabilities of this lens.

Below, check out the 100% cropped portion (362kb) 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 5.95" (151mm), measured from the front of the lens barrel to the subject.  
 
This lens has a reproduction size of 0.26x which is pretty large, 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.
 

Dec09/t2875mm09mac.jpg
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

Dec09/tw28ff.jpg
Dec09/tw40ff.jpg

           75mm F/2.8

             75mm F/4

Dec09/tel28ff.jpg
Dec09/tel40ff.jpg

 

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.

    

 

Lens flare/ghosting samples.

 

28mm, F/5.6

75mm, F/5.6

Dec09/t28mmgst.jpg
Dec09/t75mmgst.jpg

 

The above samples are the same as the shots used in the comparison review.  The Tamron lens has nearly identical ghosting and flare patterns as the Sony version. 

 

 

28mm corner samples next.

 

     F/2.8

     F/4

Dec09/t2828cncp.jpg
Dec09/t2840cncp.jpg

     F/5.6

     F/5.6 from center

Dec09/t2856cncp.jpg
Dec09/t2856cp.jpg

     F/8

     F/11

Dec09/t2880cncp.jpg
Dec09/1t2811cncp.jpg

 

The 28mm full frame corners look pretty soft wide open, but they do sharpen up gradually, and by F/8-11 they actually look real 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/2.8

     F/4

Dec09/telcn28.jpg
Dec09/telcn40.jpg

     F/5.6

     F/5.6 from center

Dec09/telcn56.jpg
Dec09/tel56.jpg

     F/8

     F/11

Dec09/telcn80.jpg
Dec09/telcn11.jpg

 

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.  

 

The 28mm and 75mm sample crops above were taken directly from the comparison review.

 

Distortion next

 

Dec09/t28d.jpg
Moderate barrel distortion @28mm on A900
Dec09/t75d.jpg
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/4

Dec09/t2875cma28.jpg

Dec09/t2875cma40.jpg

 

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

 

  
 
 
Conclusion. 
 
I'm very impressed with the Tamron 28-75mm F/2.8 lens.  In fact, I'd prefer this lens to the Sony version.  Why you might ask?  Because not only is the Tamron slightly sharper wide open at the long end, it's almost half the money of the Sony! Aside from the sharpness differences, (really minor except at F/2.8-4 at 75mm) this lens is pretty much the same as the Sony 28-75mm F/2.8 SAM.  See that review and the comparison review to see what I'm talking about.



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 Tamron 17-50mm F/2.8, Sony DT 16-50mm F/2.8 SSM, 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.  The Tamron would be a great less-expensive alternative to the Sony CZ 24-70mm F/2.8 as indicated by my comparison review.  See my comparison review here.
 
 

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