28mm f/2.8 Ai-S goes head to head with the Minolta MC W.Rokkor-SI f/2.5
The Nikon Nikkor 28mm f/2.8 Ai-S was first on the market in 1981 and
has eight elements in eight groups and seven aperture blades, 52mm
filter size. The Minolta MC W.Rokkor-SI f/2.5 came on the market in
1979 and has nine elements in seven groups with six aperture blades,
55mm filter size. At the time it was the fastest 28mm SLR lens
available. Why for decades was Nikon the only one to get it with seven
aperture blades for nice looking point light source stars? First we'll
take a look at infinity in full
sunlight. Shot with the Sony A7 on a tripod with high enough shutter
speeds to rule out movement. Focus was done in the
center wide open
with no adjustments for focus shift. White balance set to
sunlight in the first image, showing the yellowing of the radioactive
element in the Minolta 28mm f/2.5. Later images are corrected to better
match the Nikkor as that's something we do with raw images every day.
Mouse over images for
Despite the faster aperture the Minolta here is at 1/4000 f/2.5 while
the Nikon is at 1/6400 f/2.8. White balance and vignetting oh my!
After two weeks of UV
treatment the Minolta has improved both in white balance and light
transmission, here it is at 1/6400 with the Nikon.
After adjusting white balance
the Minolta is shockingly similar to the Nikon.
In the corners the Nikon 28mm
f/2.8 Ai-S is superior.
Vignetting on the Minolta 28mm f/2.5 dramatically improves at f/4 but
it's still behind the Nikon 28mm f/2 and 28mm f/2.8 Ai-S
Both look great
in the center at f/4, no difference that will be
noticed in real world use. The shadows make the largest difference
The 28mm f/2.8
AIS is still ahead in the corners.
changed in the overall shot except vignetting is suddenly
gone for the Minolta at f/5.6, so I'm skipping the overall shot. It's
still 2/3 stop
behind the Nikon 28mm.
Both improve at
5.6 in the corners but the 2.8 AIS says ahead, yet I'd say the Minolta
is better than the well known (and much more expensive) Nikkor 28mm f/2
I'd go so far as
to say the $65 Minolta is besting the $1,200 Sony Zeiss 24-70mm f/4 FE
in all but the very extreme corner.
at f/8 for any of the primes; center crops
Both improve a little but the very extreme
corner isn't quite there. They both got some help from the automatic
chromatic aberration fix in photoshop, although the Minolta needs less
Diffraction takes a toll at f/11 and they all look the same in the
center. Both have resolution to the corner.
As for the Sony
Zeiss 24-70mm f/4 FE it's rather embarrassing.
How close can
they focus? Minimum focus distance wide open with the Minolta Rokkor SI
Minimum focus distance wide open with the 28mm f/2.8 AIS.
is a lot more to a lens than sharpness, yet the Minolta MC W.Rokkor-SI
f/2.5 really puts in a convincing performance for a lens that tends to
sell around $50-100 on the used market while the Nikon 28mm f/2.8 AI-S
appears better in all regards, it's also triple the cost without triple
the performance. Yet isn't diminishing returns the story of photography