Photo Jottings

Here’s a brief look at the Minolta AF 135mm F/2.8 lens.  Scroll down for the main review.

Box and lens

Side shot with hood in up position

Front element

Backside mount.

The Sony A580 and Sony A900 were used for this review.  For a better understanding of terms and methods used in this review, go here.

Check out the original owner’s manual here in multiple languages.

The Minolta AF 135mm F/2.8 is a compact lens, with a nice build quality and cool built-in hood.  It has a gloss black finish with ribbed rubber inserts around most of the circumference.  Also included is a focus distance window with ft and m in those colors along with DOF hash marks at F/16 and F/32.  It has an infra-red focus index mark, the red dot at F/16 on the aperture scale.  The lens is made in Japan.

This lens has a medium focus throw, and it focuses a little behind the subject using the A900, I dialed in -11 for the micro adjustment, your focusing may be different.  There’s a little 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 somewhat tough to manipulate with a finger and thumb, especially with the hood all the way retracted.  Just over a third of a turn gets you from close focus to infinity.  The focus ring turns in auto-focus mode, but thankfully, not the filter ring.

In the box is the lens, caps, and owner’s manual with a warranty card, no case or pouch.

Lens flare/ghosting.  Below average control.  Don’t frame your shot with the sun close by or you’ll be sorry.  See samples below.

Color fringing (CA).  Below average control, but typical for a 1980s and 1990s telephoto lens.  I see the typical fast lens, wide-open axial color fringing at F/2.8, but diminishes greatly by F/4.  There is lateral color fringing also, but it’s controlled fairly well.

Bokeh.  A little distracting due to a colored ring around the highlights caused by spherochromatism, see the bokeh samples below.  The aperture shape starts to show up between F/4-5.6.

Color.   Same as other Sony and Minolta lenses.

Close up filter.  +4 tested, which allows you to get much closer, about 8″ or 203mm to subject from end of lens.

Coma.  None.

Regular filters cause no additional light fall-off problems.

Filter size is 55mm.  Sony lenses that use 55mm filters are; 100mm macro, 50mm macro, 50mm F/1.4, 35mm F/1.4 G, 18-70mm, 18-55mm, 55-200mm, 35mm F/1.8, and the 75-300mm.

Distortion.  Very straight on APS-C and full frame.  Check out the cropped samples below.

Distortion example directly below.

No distortion.

Bokeh, or background highlight blur is generally good, although I see a slight ring around the highlights at all apertures.  I see some spherochromatism, meaning green tinged out of focus highlights in the background, and magenta tinged in the foreground.  This isn’t something to worry about.  Crops above were taken from the center of the image, focused about 25′ (7.6m), with the background about 45′ (13.7m) away.

 

 Light fall-off.

When using an APS-C camera, there is no real light fall-off to worry about.  At close focus, the light fall-off is slightly stronger.

 

Focusing accuracy is crucial at F/2.8!

Focused slightly behind the subject

Focused slightly in front of the subject

Focused correctly

Accurate focusing is crucial for telephoto lenses at wide apertures, such as the 135mm F/2.8 here.  In the top crop, the camera focused slightly behind the house, you can see this by looking at the background foliage above the house, it’s sharper than the other two crops.

The middle crop was focused slightly in front of the subject, although this shots appears better because of the lack of magenta color fringing, it’s really not quite as sharp as it could be.

The bottom crop is focused correctly on the house, you can see the foliage out front and the metal window guard on the left is sharper here.

The range of perfect focus is super slim, and the differences in focusing accuracy in these crops highlights the limits of the camera’s AF system.  I used the Sony A580 for this test, but even using the A900 with micro adjustments enabled still isn’t perfect all the time.  The camera’s AF system chose the focus for the above crops, each time slightly different.  The best way to see if you have your subject in perfect focus is to use live view, focus check and magnified to the max.  At smaller apertures, focusing isn’t so critical, that’s why cheap cameras come bundled (kit) with slow lenses, it’s not just the lower cost, it’s because the AF system doesn’t have to be very good to produce sharp shots.

This lens focused correctly when set to the infinity hard-stop, but if you’re at shorter distances, you’ll want to do a focus check to be sure of getting the sharpest shots.  The above 100% crops were taken almost 200 yards (200m) away from the camera, so infinity for this lens at F/2.8 is somewhere beyond that distance.

This comp shows the differences between the Minolta AF 135mm F/2.8, and Sony 70-400mm F/4-5.6.  All crops were taken at F/5.6.  The crops show my boring stamp test chart from a lens to chart distance of about 17′ or 5.2m.

The Sony shows a little more contrast in the centers, and a little more resolution at the mid-sections and corners.  The Minolta holds up well considering it’s over three decades old, and costs about one tenth the price of the new Sony 70-400mm.

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

As close as you can get, F/4. Click for full image.

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

Light fall-off is definitely stronger with full frame coverage.  I see moderate levels at F/2.8, however, by closing the aperture one stop, the dark corners begin to clear up nicely.

 

Full image below illustrating light fall-off from A900.

This full scene shows actual-use light fall-off.  It’s really not noticeable in my opinion.  This bright daylight landscape scene would normally be shot around F/5.6, and light fall-off would begone.  Data for the image is; F/2.8, 1250sec, +0.30eV, ISO 200.

 

Ghosting.

Ghosting control is awful when the sun is near, or inside the image.  Contrast has been wiped out.  Word to the wise; don’t wave this lens around near the sun or any other bright light.  The hood does no good in sunlight.

 

Color fringing.

Axial color fringing is strong at F/2.8, but stopping down the aperture helps tremendously.  The crops are from the center of the image, displayed at 100%.

Center sharpness.

Below are crops from the image centers.

Center sharpness looks very good in a real scene, although many shots showed an abundance of color fringing, (mostly red) and veiling haze, especially test charts.  If you look closely, you can see F/5.6-8 is slightly sharper in the foreground leaves.  Diffraction causes heavy softening at apertures smaller than F/10.  Distance to subject is about 400-500′ or 120-150m.

There is some softness in the mid-sections at F/2.8-5.6, with a noticeable improvement at F/8, at which point the mid-sections are almost as sharp as the centers.

Corners.

The full frame corners are a little soft and dark at F/2.8, but sharpen up nicely at F/8.  I see the corners look almost sharper than the mid-sections, that’s a little unusual, and makes the lens better suited for a full frame camera as there is no penalty for using the lens’ full image circle.

 

Distortion next

Flat on A900

I see almost no distortion with full frame coverage, again, this is a bit unusual, as there is no distortion using an APS-C camera.  No penalty for full frame here either!

 

Here are the full size versions from the Sony A580 APS-C camera.  Disregard the bottom foreground clutter, it is not within the depth of field.  I see a sharp image from one side to the other at F/2.8, but it’s super sharp at F/4, and that’s where it maxes out in resolution through most of the field.  These are handheld shots, so they are not lined up perfectly.  Manual focusing was used.

Click yellow buttons below for full size versions.

F/2.8 F/4 F/5.6 F/8

 

Full size versions from the full frame Sony A900.  Disregard all the foreground clutter, it is not within the depth of field.  Not a great test shot here; this is what I used for the crops above, and had no intention on using these samples like this.  Even with these awful test shots, things look really good here, even at F/2.8.  When stopping down past F/8 diffraction causes softening of the whole image.

Click yellow buttons below for full size versions.

F/2.8 F/4 F/5.6 F/8

The relatively small and light-weight Minolta AF 135mm F/2.8 turned in a very good performance for a thirty-plus year old lens.  Getting a good copy for under $300 would be a steal, and a nice addition to a prime lovers bag of goodies.  On an APS-C camera, this lens is similar to a 200mm F/2.8 lens for full frame.