Photo Jottings

Here’s a brief look at the Minolta AF 50mm F/3.5 macro lens.  Scroll down for the main review.

Requisite product shots.

Box and contents

Side shot fully drawn in

Side view, fully extended

Deep front element.

Rear mount and contacts.

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.

The Minolta AF 50mm F/3.5 macro was introduced in the mid 1990s, and was a less-expensive alternative to the Minolta AF 50mm F/2.8.  What made it less expensive was the smaller maximum aperture, maximum reproduction ratio of half life size (1:2) instead of full life size (1:1), and lighter build quality, meaning lots of plastic.  It’s put together well though, and functions properly, as it should.

This lens has the typical look of Minolta AF restyled lenses all through the 1990s.  It’s satin black, similar to the original Sony black, with a wider rubber focus grip ring, and also a different type of rubber barrel grip.  It has the standard prime lens focus distance window, with two depth of field hash marks at F/32 and F/16.  The blue numbers around the focusing ring indicate the level of magnification, 1:2 is half, 4 is 1:4, 7 is 1:7 etc.  The EXIF data reads the proper 50mm.  I can’t find any info about “ED” elements or special coatings used.  Official information from Konica Minolta states this lens has a circular aperture, but heptagons (seven bladed aperture) show up in bokeh about one stop down, which indicates the blades do not form a very good circle.  True circular apertures should be round at least one stop down.  Oh well, this is not something to lose sleep over, the bokeh, or background blur is not very smooth anyways.  This lens is multi-coated and has the common for the era purple/green look.

Focusing.  Manual focusing is easy and properly dampened.   Manual focusing takes just over 1/4 turn from Close-in to infinity, but does add about 1″ or 26mm to the length of the lens.  Auto-focusing is not very fast, but adequate, and accurate.  Note; don’t use auto-focus when shooting things up-close, use manual focus and move the camera back and forth to get the proper focus.

Lens flare/ghosting.  Odd blue/green ghost when sun is in shot, otherwise good control.  See sample images below.

Color fringing (CA).  Excellent control.  In normal pictures there is none to be found.

Bokeh.  Fairly harsh looking.  The aperture shape starts to show up about a stop down.  Look below for sample crops.

Color.   Same as other Minolta lenses.

Coma.  No Coma on either APS-C or full frame cameras.

Regular filters cause no additional light fall-off problems on APS-C cameras, but do affect full frame cameras at F/3.5, see example farther down in review.

Filter size is 55mm.  This is the most popular with Sony, and allows you to swap filters with both Sony macro lenses, the Sony 50mm F/1.4, 35mm F/1.4, DT 18-55mm, DT 18-70mm, 55-200mm and the 75-300mm.

Distortion.  Excellent control, and flat with both APS-C and full frame cameras.

Distortion example directly below.

50mm, flat.

 

Lens flare/ghosting examples

 

I see a funny blue/green blob when the sun is inside the image. I’ve never seen this color before, weird!  Other than that, flare and ghosting are controlled quite well, and would not be a concern in normal shooting.

Bokeh, (cropped) looks harsh even wide open.  Heptagons are clearly visible at F/5-5.6.  Sony macros show a somewhat smoother bokeh, see comparisons below the stamp shot.

 

Light loss at high magnification.

 

Here are the approximate F-numbers or light loss you will get as you increase the magnification, assuming the same exposures at each setting in the table below.  The numbers in the table come from simple observation, they will not be indicated on the camera LCD, and will still read F/3.5 even at 1:2 magnification, though when you look at your shutter speeds you’ll notice the loss.  This is for your information only, so just shoot away, the camera will adjust your exposures automatically.  I’m simply providing this in case you’re wondering why your shutter speeds are so low when the LCD says F/3.5.  For instance, if you’re shooting at infinity focus, F/3.5, with a shutter speed of 1/250sec, at full 1:2 magnification your shutter speed would decrease to around 1/100sec, or an equivalent of one and a third stops of light loss.

 

 

See the images below.  Light fall-off or corner shading is not noticeable in real pictures at any focal length or aperture using an APS-C camera.

Center and corner sharpness.

Below are crops from the image centers and corners.

The center crops show slight veiling haze wide open at F/3.5, though sharpen up nicely at F/4.5, and stay sharp almost to F/11, then diffraction shows at F/16, which is normal.  The corners are a different story.  At F/3.5, they’re quite soft, but improve much a little over one stop down, at F/5.6.  Corner sharpness improves up to F/8, where the centers and corners are nearly the same in sharpness.

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

As close as you can get. F/5.6 Click for larger image.

 

 

 

Special bonus section with comparisons to the Sony 50mm F/2.8 macro

 

 

 

The Sony 50mm F/2.8 macro lens is on the left, the Minolta AF 50mm F/3.5 on the right.  The centers and corners are clearly sharper on the Sony at F/3.5, but are much closer in comparison at F/5.6.  This is to be expected, as the Minolta was intended as a less expensive alternative to the fast F/2.8 macro available at the time.  When they make a cheaper or slower version, they usually have to compromise optical and mechanical quality at some point.  The Minolta does a good job, and the sharpness differences would not be noticeable unless cropped and displayed side-by-side at huge sizes as you see here.  In the film days, this lens’ optical quality was probably indistinguishable from the more expensive F/2.8 model, that’s just the predicament with digital.  Test shots done with the Sony A700.

 

Bokeh comparisons next.

 

 

The bokeh characteristics are similar, but the Sony is slightly smoother at the same apertures.  Also, the Sony is a little smoother yet at F/2.8, which is obviously not available on the Minolta.  I thought the Sony bokeh would be much better before I made a direct comparison with the Minolta, and found the differences small.

 

 

Full frame section below.