Lens: Minolta 50mm f/3.5 Rokkor-X auto bellows
Vintage: uncertain
Lens Mount: Minolta MD mount
Needed Adapters: This was a tough lens to adapt to a Nikon mount. My inital though was to get a
cheap 5-piece extension tube set off of eBay and since these are modular, I could screw the Nikon
male portion onto the Minolta female portion (This works well for many lens mounts). When I bought
a Minolta version of the extension tubes, I found that the threads were reversed and the male Nikon
portion and the female Minolta portion have the same threads. I then found a 57-58mm step-up ring
and screwed that into the Minolta side. Then you get a 58-52 mm step down ring and then that can
be screwed into a reversing adapter. Not the easiest adapter, but it works.
cheap 5-piece extension tube set off of eBay and since these are modular, I could screw the Nikon
male portion onto the Minolta female portion (This works well for many lens mounts). When I bought
a Minolta version of the extension tubes, I found that the threads were reversed and the male Nikon
portion and the female Minolta portion have the same threads. I then found a 57-58mm step-up ring
and screwed that into the Minolta side. Then you get a 58-52 mm step down ring and then that can
be screwed into a reversing adapter. Not the easiest adapter, but it works.
Preferred Mounting: Normal.
Filter Thread: 34 mm on the lens. Has a screw-on lens hood that is 55 mm.
Controls: This lens only has an aperture control.
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Resolution vs Aperture:
The sharpest aperture is f/8 and the most
resolving aperture is f/6.7. There is a good
argument for using f/6.7 since the sharpness is
very nearly the same as F/8 and the resolution is
superior. The only problem with that is a loss in
depth of field at f/6.7. I would suggest that f/8 is
adequate at lower magnification and f/6.7 is good
for higher magnification.
The sharpest aperture is f/8 and the most
resolving aperture is f/6.7. There is a good
argument for using f/6.7 since the sharpness is
very nearly the same as F/8 and the resolution is
superior. The only problem with that is a loss in
depth of field at f/6.7. I would suggest that f/8 is
adequate at lower magnification and f/6.7 is good
for higher magnification.
Corner Sharpness vs Aperture:
The corner performance of this lens is extremely
good, even at large apertures. The interesting
part is that the corners outperform the center at
larger aperture - i.e. The corners are sharper
than the center. This results in negative corner
sharpness numbers. i haven't seen this before
with a lens.
At smaller apertures, the lens shows virtually the
same sharpness and resolution in the far corners
compared to the center. Overall the best corner
performance that I have com across to date.
(Testing done at 1.31:1 magnification. Numbers
at each aperture setting will tend to improve as
the magnification is increased and worsen as the
magnification is decreased.)
The corner performance of this lens is extremely
good, even at large apertures. The interesting
part is that the corners outperform the center at
larger aperture - i.e. The corners are sharper
than the center. This results in negative corner
sharpness numbers. i haven't seen this before
with a lens.
At smaller apertures, the lens shows virtually the
same sharpness and resolution in the far corners
compared to the center. Overall the best corner
performance that I have com across to date.
(Testing done at 1.31:1 magnification. Numbers
at each aperture setting will tend to improve as
the magnification is increased and worsen as the
magnification is decreased.)
Sharpness and Resolution vs Magnification:
This lens shows good sharpness and resolution
across its usable magnification range of 0.5x - 4x.
Compared to similar 50 mm lenses such as the
nikon El-Nikkor 50mm f/2.8 and the Nikon 50mm
f/1.8 reversed, it has less resolution and
sharpness although the difference is pretty small.
It significantly outperforms these lenses in the
corners.
If you want corner to corner sharpness, this is a
very good lens.
You will notice that the corner performance starts
to suffer at a magnification of 0.50:1. This
magnification is achieved when the lens is
mounted directly on the camera body. I think that
0.50:1 is starting to get out of the design range
of this lens. It works best at 1:1 and above.
This lens shows good sharpness and resolution
across its usable magnification range of 0.5x - 4x.
Compared to similar 50 mm lenses such as the
nikon El-Nikkor 50mm f/2.8 and the Nikon 50mm
f/1.8 reversed, it has less resolution and
sharpness although the difference is pretty small.
It significantly outperforms these lenses in the
corners.
If you want corner to corner sharpness, this is a
very good lens.
You will notice that the corner performance starts
to suffer at a magnification of 0.50:1. This
magnification is achieved when the lens is
mounted directly on the camera body. I think that
0.50:1 is starting to get out of the design range
of this lens. It works best at 1:1 and above.
Street Price: ~$150 - $200 in good used condition, hard to find.
Chromatic Aberration: This lens show minimal color fringing in the center
(about 0.30 - 0.80 pixel) and even better on the periphery (0.05 - 0.80 pixels).
Anything below 1.0 pixel is good.
(about 0.30 - 0.80 pixel) and even better on the periphery (0.05 - 0.80 pixels).
Anything below 1.0 pixel is good.
Image Contrast: Image contrast is good across the magnification range.
Flare: No significant flare is evident during lens testing
Conclusion:
This is an unusual and hard to find lens. I have only ever seen two of them, and I own one. Across
all brands, there are very few bellows lenses in the 50 mm range. Not sure on the reasoning behind
this.
This lens has good resolution and sharpness, but it does get slightly outperformed by other lenses
in its focal length range. This is probably related to having f/8 as the sharpest aperture. Most
lenses that I have tested in this focal length range are sharpest in the f/4 to f/5.6 range.
Where this lens shines is in its corner performance. There is virtually no loss in resolution or
sharpness even in the extreme corners of the frame. This combined with an almost total lack of
distortion suggests that this lens should be very good if you plan on stitching images together
(doing micro panoramas).
I would suggest that its usable range is really from 1:1 to 4:1 and that means either using a little
extension or a bellows. Mounting it straight onto the camera is OK, but the corner performance
suffers a bit.
This is an unusual and hard to find lens. I have only ever seen two of them, and I own one. Across
all brands, there are very few bellows lenses in the 50 mm range. Not sure on the reasoning behind
this.
This lens has good resolution and sharpness, but it does get slightly outperformed by other lenses
in its focal length range. This is probably related to having f/8 as the sharpest aperture. Most
lenses that I have tested in this focal length range are sharpest in the f/4 to f/5.6 range.
Where this lens shines is in its corner performance. There is virtually no loss in resolution or
sharpness even in the extreme corners of the frame. This combined with an almost total lack of
distortion suggests that this lens should be very good if you plan on stitching images together
(doing micro panoramas).
I would suggest that its usable range is really from 1:1 to 4:1 and that means either using a little
extension or a bellows. Mounting it straight onto the camera is OK, but the corner performance
suffers a bit.
Basic Function: Requires extension tubes or bellows to focus.
Appearance:
Aperture: 6 blades.
Image Samples:
About 1:1 magnification, f/8, resized:
About 1:1 magnification, f/8, 1 to 1 crop:
Good pixel level detail.
Good pixel level detail.
About 2.9:1, f/8, focus stack of 22 images, resized:
About 2.9:1 magnification, f/8, 1 to 1 crop of a
single source image from above:
Again, good detail, no problems. A little light leakage
from the outside window in the room can be seen on
the left edges of the relief. This can be sured by
placing a dark sheet next to the copystand to block
that light.
single source image from above:
Again, good detail, no problems. A little light leakage
from the outside window in the room can be seen on
the left edges of the relief. This can be sured by
placing a dark sheet next to the copystand to block
that light.
Distortion: The is virtually no distortion with this lens. Straight lines on the
edge of the frame are straight on the image.
edge of the frame are straight on the image.
Performance: Sharpness vs Magnification:
This is a new graph that I recently constructed. I
have 4 lines that represent levels of performance
from outstanding (top) to fair (bottom). This
shows where this lens fit into the hierarchy that I
have created.
The Minolta 50mm shows sharpness that varies
from very good on the low-end of magnification to
fair/poor on the high-end.
This is a new graph that I recently constructed. I
have 4 lines that represent levels of performance
from outstanding (top) to fair (bottom). This
shows where this lens fit into the hierarchy that I
have created.
The Minolta 50mm shows sharpness that varies
from very good on the low-end of magnification to
fair/poor on the high-end.
Performance: Resolution vs Magnification:
This is a new graph that I recently constructed. I
have 4 lines that represent levels of performance
from outstanding (top) to fair (bottom). This
shows where this lens fit into the hierarchy that I
have created.
The Minolta 50mm shows resolution varying from
very good at low magnification to poor at the
high-end. Its resolution performance is hampered
by having f/8 as its sharpest aperture. This could
be improved a little by shooting at f/6.7 at high
magnification.
This is a new graph that I recently constructed. I
have 4 lines that represent levels of performance
from outstanding (top) to fair (bottom). This
shows where this lens fit into the hierarchy that I
have created.
The Minolta 50mm shows resolution varying from
very good at low magnification to poor at the
high-end. Its resolution performance is hampered
by having f/8 as its sharpest aperture. This could
be improved a little by shooting at f/6.7 at high
magnification.
