AF 50mm shootout with my Sony Alpha 100...

 

Preface

This is my personal comparison of my MINOLTA AF 1.4 50mm (first generation) and my Minolta AF 1.7 50mm (last generation) lenses. For myself I wanted to know how they compare. Both 50mm primes are often underrated in many ways. May be because they are both really cheap compared to primes of other focal length. Where else can we get a comparable fast lens (f1.7 or even f1.4) for such a bargain price? Here my opinion...

 

Testing conditions

All shots were taken with my Sony Alpha 100 (10,2 MPixel APS-C CCD) on a heavy Manfrotto tripod. 
Super Steady Shot was switched off and I used the mirror lock up mode (2s selftimer).

 

The first scenery taken with the Minolta AF 1.7 50mm

In the next picture you can see the whole frame shot with my Minolta AF 1.7 50mm at f6.3. To compare border sharpness you can easily take the tractors wheel at the left border. In the center you can find a roof top which is good for comparing sharpness too.

 

What can you expect from a Minolta AF 1.7 50mm? 

Excellent sharpness at center from f2.8 to f8 and excellent sharpness at the borders from f6.3 to f8. To convince yourself look at the pictures in the following table.

Here you can download my original jpegs out of the camera for my shots taken at infinity with my Minolta AF 1.7/50mm. It is the latest built version and a selected sample too:

DSC02483_Minolta_AF1.7_50mm_f1.7.JPG acceptable center, very soft border
DSC02484_Minolta_AF1.7_50mm_f2.JPG acceptable center, very soft border
DSC02485_Minolta_AF1.7_50mm_f2.2.JPG good center, soft border
DSC02486_Minolta_AF1.7_50mm_f2.5.JPG good center, soft border
DSC02487_Minolta_AF1.7_50mm_f2.8.JPG very good center, soft border
DSC02488_Minolta_AF1.7_50mm_f3.2.JPG very good center, soft border
DSC02489_Minolta_AF1.7_50mm_f3.5.JPG very good center, acceptable border
DSC02490_Minolta_AF1.7_50mm_f4.JPG very good center, soft border
DSC02491_Minolta_AF1.7_50mm_f4.5.JPG 
DSC02492_Minolta_AF1.7_50mm_f5.JPG excellent center, good at border
DSC02493_Minolta_AF1.7_50mm_f5.6.JPG excellent center, very good border
DSC02494_Minolta_AF1.7_50mm_f6.3.JPG excellent center to border!
DSC02495_Minolta_AF1.7_50mm_f7.1.JPG excellent center to border!
DSC02496_Minolta_AF1.7_50mm_f8.JPG excellent center to border!
DSC02497_Minolta_AF1.7_50mm_f9.JPG 
DSC02498_Minolta_AF1.7_50mm_f10.JPG
DSC02499_Minolta_AF1.7_50mm_f11.JPG very good center to border
DSC02500_Minolta_AF1.7_50mm_f13.JPG
DSC02501_Minolta_AF1.7_50mm_f14.JPG
DSC02502_Minolta_AF1.7_50mm_f16.JPG very good - good center to border
DSC02503_Minolta_AF1.7_50mm_f18.JPG
DSC02504_Minolta_AF1.7_50mm_f20.JPG
DSC02505_Minolta_AF1.7_50mm_f22.JPG good center to border

Imho the lens shows excellent performance at f6.3, f7.1 and f8 over the whole frame. At higher f-stops the sharpness degrades due to more and more visible diffraction.

 

Comparison of the Minolta AF 1.7 50mm against the Minolta AF 1.4 50mm

At apertures f1.7 up to f5.6 my AF 1.4 50mm (a early first version I own since 1986 and bought it together with my Minolta 9000 body) shows clear better border sharpness than my AF 1.7 50mm. 

 

The second scenery is taken with the Minolta AF 50mm 1.7 and 

the Minolta AF 50mm 1.4 and for comparison with my CZ 16-80mm.

 

Here the whole frame taken with my Minolta AF 1.4 50mm at f5.6:

 

Again you can download the original out of the camera jpegs of my shots taken with my Minolta AF 1.7 50mm,
my Minolta AF 1.4 50mm and for comparison a shot taken with my CZ16-80mm at 50mm f8 in the following table:

  DSC05709_Minolta_AF1.4_50mm_f1.4.JPG  
DSC05710_Minolta_AF1.7_50mm_f1.7.JPG DSC05708_Minolta_AF1.4_50mm_f1.7.JPG  
DSC05711_Minolta_AF1.7_50mm_f2.JPG DSC05707_Minolta_AF1.4_50mm_f2.JPG  
DSC05712_Minolta_AF1.7_50mm_f2.8.JPG DSC05706_Minolta_AF1.4_50mm_f2.8.JPG  
DSC05713_Minolta_AF1.7_50mm_f4.JPG DSC05705_Minolta_AF1.4_50mm_f4.JPG  
DSC05714_Minolta_AF1.7_50mm_f5.6.JPG DSC05704_Minolta_AF1.4_50mm_f5.6.JPG  
DSC05715_Minolta_AF1.7_50mm_f8.JPG DSC05703_Minolta_AF1.4_50mm_f8.JPG DSC05716_CZ 16-80mm_f8.JPG

What I can see is: 
The Minolta AF 1.4 from f1.7 up to f5.6 is a sharper lens compared to the Minolta AF 1.7 50mm! Especially at the borders it holds an advantage of about 1 f-stop against the cheaper f1.7 lens. At f5.6 the AF 1.4 reaches nothing but excellent performance over the whole frame! Not to say the 1.7 is a bad lens (no its excellent stopped down to f6.3 too) , but the the AF 1.4 is really a little bit better!

Here in addition you can also download the original Sony Alpha100 raw file of the AF 1.4 50mm f5.6 shot and try to develop it in your own raw converter:

DSC05704_Minolta_AF1.4_50mm_f5.6.ARW 

With the Photoshop Raw converter you can easily develop such raw files to 5120x3427 corresponding to 17,5MPixel files if you need this resolution for printing (try it yourself, they sharpen up very well!). And I really doubt, that if you develop this raw file to 4096x2742 corresponding to 11,2MPixel, anyone has found out that it is coming from a entry level DSRL like the A100! IMHO the Sony Alpha 100 with such a lens delivers fantastic detail resolution!

For my workflow with that sharp lenses I these days most often use dcraw in conjunction with ufraw which delivers excellent 16 Bit TIFF material for postrocessing.

 

My conclusion

The Minolta AF 1.7 50mm is a excellent lens stopped down to f6.3 up to f8. A small part of the picture in center is very sharp beginning at f2.2 but borders are still soft. Each f stop helps to increase border sharpness. Even at f5.6 borders are still not perfect sharp as they are from f6.3 to f8. 

My AF 1.7 50mm example shows a marginal better center sharpness at f6.3 compared to f8, whereas border sharpness at f8 is very slightly better compared to f6.3 - so its a little dilemma with the 1.7/50mm, because in comparison my AF 1.4 50mm shows perfect sharpness over the whole frame at f5.6.

So for me my Minolta AF 1.4 50mm is really a outstanding lens and I prefer it clear over my Minolta AF 1.7 50mm! From f1.7 on this lens is good usable concerning sharpness, much better than the AF 1.7 wide open!

Also concerning Bokeh the AF 1.4 holds a little advantage compared to the AF 1.7 and you should use apertures f2 to f2.8 with the AF 1.4 lens and you will love its smooth and creamy bokeh! Wide open and at f1.7 the bokeh does not look good! 

With my AF 1.7 I get good looking bokeh at apertures f2.5 and f2.8 too. Again here the bokeh does not look creamy at apertures from wide open to f2.2!

Concerning bokeh both lenses do not compare to my modified (many thanks to Pete Ganzel for his adaptor!) MC Rokkor 1.2 58mm! Concerning sharpness the old MC Rokkor is about equal as good as my AF 1.4 50mm on my A100 and that means this lens is nothing but outstanding - but I have to operate it fully manual. 

Hans-Joachim Weber

(c) August 2007

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