Minolta AF 85mm f/1.4G D - LEGACY Test Report
Lens Reviews - Sony Alpha/NEX (APS-C)
THIS IS A LEGACY TEST REPORT BASED ON THE ALPHA 100. AS SUCH IT IS NOT 100% COMPARABLE TO THE CURRENT TESTS BASED ON THE ALPHA 700!

Introduction

The Minolta AF 85mm f/1.4G (D) is one of the old professional grade lenses by Minolta. Obviously it is a discontinued item now because Sony took over Minolta's photo department back in early 2006. In the meanwhile the lens has been replaced by the Zeiss ZA 85mm f/1.4 - not exactly a cheap lens so used Minolta AF 85mm f/1.4 G are in high demand on the used market where they seem to sell around 700 €/US$ vicinity at the moment. On APS-C DSLRs such as the Sony Alpha 100 (used for testing) its field of view is equivalent 128mm so it doesn't really leave its primary scope (portrait photography) here.

The mechanical quality of the AF 85mm f/1.4G is excellent with an outer shell made of metal. The broad, rubberized focus ring operates very smooth. Minolta did also implement a focus-stop button - quite convenient for focus fine-tuning. As you can see below it does extend a little when focusing towards closer distances. However, the front element does not rotate.

Like most (though not all) Sony/Minolta lenses the 85mm G relies on the conventional focusing system driven by the camera (via a slotted drive screw). Consequently the AF produces a moderate degree of noise during operations and the AF is also comparatively slow due to the sheer amount of heavy glass to be moved.

Specifications
Equiv. focal length127.5 mm (full format equivalent)
Equiv. aperturef/2.1 (full format equivalent, in terms of depth-of-field)
Optical construction7 elements in 6 groups
Number of aperture blades9 (rounded)
min. focus distance0.85 m (max. magnification ratio 1:7.8)
Dimensions73 x 78 mm
Weight550 g
Filter size72 mm (non-rotating)
Hoodbarrel shaped, snap-on type
Other featuresLens provides distance (D) information to the camera.

Distortion

The AF 85mm f/1.8 D shows extremely low distortion (0.25%) which are negligible in field conditions.

The chart above has a real-world size of about 120x80cm.

Vignetting

The AF 85mm f/1.4 G (D) is a full-frame lens so it can take advantage of a sweet spot effect on the Alpha 100. Vignetting is very well controlled in this scope even at max. aperture with a relative light loss of 0.6EV - this is rarely relevant in the field. From f/2 the issue is absolutely negligible.

MTF (resolution)

The Minolta AF 85mm f/1.4G produced very good to excellent resolution figures in the MTF lab. Typical for ultra-large aperture lenses the performance is moderate at wide-open aperture although the center, and this is where it counts for such a lens, is already very good, less so the borders. Stopping down improves the performance quite a bit and the results are very good to excellent by f/2.8 and superb beyond.

Below is a simplified summary of the formal findings. The chart shows line widths per picture height (LW/PH) which can be taken as a measure for sharpness. If you want to know more about the MTF50 figures you may check out the corresponding Imatest Explanations

Chromatic Aberrations (CAs)

Lateral chromatic aberrations (color shadows at harsh contrast transitions) are very well controlled and not field relevant.

Typical for ultra-large aperture lenses the lens produces some longitudinal Chromatic Aberrations (LCA) - red and greenish out-of-focus halos - this is no different from the Nikkor 85mm f/1.4D or the Canon 85mm f/1.2L for instance. There's also some purple fringing (PF) although the issue remains relatively moderate.

Sample Shots

Here're some sample shots taken with the Sony Alpha 100 and RAW-converted via ACR 3.7.

Click on a thumbnail to view the original file (opens in a separate window). Please note that the originals are FULL SIZE (=several megabytes) which requires quite some bandwidth for downloading so please don't waste the limited resources here.

Make SONY
Model DSLR-A100
ISO Speed 100
Focal Length 85.0mm
Exposure Data: f/2.0 @ 1/1600s
Size 2592x3872
Make SONY
Model DSLR-A100
ISO Speed 100
Focal Length 85.0mm
Exposure Data: f/5.6 @ 1/500s
Size 3872x2592
Make SONY
Model DSLR-A100
ISO Speed 100
Focal Length 85.0mm
Exposure Data: f/2.5 @ 1/500s
Size 3872x2592
Make SONY
Model DSLR-A100
ISO Speed 100
Focal Length 85.0mm
Exposure Data: f/8.0 @ 1/80s
Size 3872x2592
Make SONY
Model DSLR-A100
ISO Speed 100
Focal Length 85.0mm
Exposure Data: f/2.2 @ 1/4000s
Size 3872x2592
Make SONY
Model DSLR-A100
ISO Speed 200
Focal Length 85.0mm
Exposure Data: f/1.4 @ 1/320s
Size 2592x3872
Make SONY
Model DSLR-A100
ISO Speed 100
Focal Length 85.0mm
Exposure Data: f/1.4 @ 1/2500s
Size 3872x2592
Make SONY
Model DSLR-A100
ISO Speed 100
Focal Length 85.0mm
Exposure Data: f/1.4 @ 1/3200s
Size 3872x2592

Verdict

The Minolta AF 85mm f/1.4G (D) is an excellent lens which plays in the same league high up there with the Canon EF 85mm f/1.2 USM L and Nikkor AF 85mm f/1.4D. From f/2.8 and up the performance of the lens is superb and neither distortions, CAs nor vignetting are something to worry about. At f/1.4 the results are a little soft specifically at the borders but this is not unusual for an ultra-large aperture lens. The AF 85mm f/1.4 is also capable to render a beautifully smooth and buttery bokeh (out-of-focus blur) making it an obvious choice for portrait photography. The mechanical quality of the lens is excellent. If you're nit-picky the AF could be a little faster.

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