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Review by Klaus Schroiff, published April 2007
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 In the meanwhile the lens has been
replaced by the Zeiss ZA 85mm f/1.4 - not exactly a cheap lens so used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 length | 127.5 mm (full format equivalent) |
| Equiv. aperture | f/2.1 (full format equivalent, in terms of depth-of-field) |
| Optical construction | 7 elements in 6 groups |
| Number of aperture blades | 9 (rounded) |
| min. focus distance | 0.85 m (max. magnification ratio 1:7.8) |
| Dimensions | 73 x 78 mm |
| Weight | 550 g |
| Filter size | 72 mm (non-rotating) |
| Hood | barrel shaped, snap-on type |
| Other features | Lens 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.
Please note that the MTF results are not directly comparable across the different systems!
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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