Lens: Nikon PlanApo 4x/0.20 microscope objective
Vintage: 1990's?
Lens Mount: RMS (20 mm x 0.8 mm)
Needed Adapters: RMS mount adapters come in various forms. Some can be
found to directly connect to a specific lens mount as this mount is also shared by
many small bellows lenses. I use an RMS to T-mount adapter and then a T-mount
to Nikon f-mount adapter. T-mount adapters are available for virtually all camera
lens mounts.
found to directly connect to a specific lens mount as this mount is also shared by
many small bellows lenses. I use an RMS to T-mount adapter and then a T-mount
to Nikon f-mount adapter. T-mount adapters are available for virtually all camera
lens mounts.
Preferred Mounting: Normal (not reversed)
Filter Thread: None
Controls: There are no controls on this objective.
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Corner Sharpness vs magnification: The
fuzziness on the periphery of the image is
moderate for this microscope objective, but within
the range of normal. Microscope objectives tend
to concentrate on sharpness and resolution in
the center of the field.
Testing done on a Nikon D200, a DX format
digital camera (APS-C). On a full-frame camera
the performance would be significantly worse.
Microscope objectives don't tend to produce a
large image circle and don't tend to work all that
well on full-frame digital cameras.
fuzziness on the periphery of the image is
moderate for this microscope objective, but within
the range of normal. Microscope objectives tend
to concentrate on sharpness and resolution in
the center of the field.
Testing done on a Nikon D200, a DX format
digital camera (APS-C). On a full-frame camera
the performance would be significantly worse.
Microscope objectives don't tend to produce a
large image circle and don't tend to work all that
well on full-frame digital cameras.
Sharpness and Resolution vs Magnification:
This lens shows the highest sharpness and
resolution in the center of the field that I have
tested in this magnification range. Much higher
than any other lens that I have yet tested. The
performance is optimised for 4:1 magnification
and falls off on either side.
This lens shows the highest sharpness and
resolution in the center of the field that I have
tested in this magnification range. Much higher
than any other lens that I have yet tested. The
performance is optimised for 4:1 magnification
and falls off on either side.
Street Price: $400 - $900 in good used condition
Chromatic Aberration: This lens shows fairly severe color fringing on the periphery, worst at lower
magnifications. It varies from 0.044% at the highest magnification (minimal) to 0.48% at the lowest
magnification (quite strongly visible in the right conditions). Just because a lens is apochromatic
doesn't mean that there are no color fringes. Microscope objectives are made to work best in the
center of the frame and are not made to cover a large detector.
This lens show very little if any axial CA (see image below). This is where apochromatic correction
shows its stuff.
magnifications. It varies from 0.044% at the highest magnification (minimal) to 0.48% at the lowest
magnification (quite strongly visible in the right conditions). Just because a lens is apochromatic
doesn't mean that there are no color fringes. Microscope objectives are made to work best in the
center of the frame and are not made to cover a large detector.
This lens show very little if any axial CA (see image below). This is where apochromatic correction
shows its stuff.
Image Contrast: Image contrast is extremely high for this magnification
range. This is another area that microscope objectives tend to excel.
range. This is another area that microscope objectives tend to excel.
Flare: No significant flare is evident during lens testing
Conclusion: This is an objective that works very well as a bellows lens. The center field sharpness and
resolution is higher than any other lens that I have tested from about 3:1 to 6:1. This lens is the
standard by which all are compared in this magnification range (hyperbole, but true). This lens has fairly
severe color fringes on the periphery, but not particularly noticeable in real world images. Due to the
apochromatic correction, there is almost no axial CA present. This lens produces extremely high
contrast images and has no visible flare.
This lens has a very large aperture for the magnification (working f-number of f/2.5 at m=4, equivalent to
a f/2 lens since most lenses don't list a working f-number/NA). That means very little DOF in your
images. Image stacking is important and it will take more images for your stack because of the large
aperture.
The corner sharpness is OK but not as good as most bellows lenses. This lens was made to produce
high resolution in the center and is not made to cover a large detector. It works well on a DX D200, but
will have a harder time working well on a full frame detector (like a D700). It should work really well on
the small detector interchangeable lens cameras such as micro 4/3 and Nikon 1 system. Working
distance is adequate. These are hard to find on eBay and tend to be expensive.
resolution is higher than any other lens that I have tested from about 3:1 to 6:1. This lens is the
standard by which all are compared in this magnification range (hyperbole, but true). This lens has fairly
severe color fringes on the periphery, but not particularly noticeable in real world images. Due to the
apochromatic correction, there is almost no axial CA present. This lens produces extremely high
contrast images and has no visible flare.
This lens has a very large aperture for the magnification (working f-number of f/2.5 at m=4, equivalent to
a f/2 lens since most lenses don't list a working f-number/NA). That means very little DOF in your
images. Image stacking is important and it will take more images for your stack because of the large
aperture.
The corner sharpness is OK but not as good as most bellows lenses. This lens was made to produce
high resolution in the center and is not made to cover a large detector. It works well on a DX D200, but
will have a harder time working well on a full frame detector (like a D700). It should work really well on
the small detector interchangeable lens cameras such as micro 4/3 and Nikon 1 system. Working
distance is adequate. These are hard to find on eBay and tend to be expensive.
Basic Function: Requires a bellows for setting focus and magnification.
Appearance:
Aperture: The aperture is fixed at a numerical aperture of 0.20 - corresponds to about f/2.
Image Samples:
About 4:1 magnification, focus stack of 71 images, resized:
About 4:1 magnification, 1 to 1 crop of a single
source image from above:
This is as good as you are going to see at 4:1. You
can see a little of the soft corners on the above
image, not bad though. The strong measured CA in
the corners is not particularly visible in real world
images.
source image from above:
This is as good as you are going to see at 4:1. You
can see a little of the soft corners on the above
image, not bad though. The strong measured CA in
the corners is not particularly visible in real world
images.
About 6.5:1 magnification, focus stack of 45 images, resized:
About 6.5:1 magnification, 1 to 1 crop of a single
source image from above:
Again, as good as you will see at this magnification.
source image from above:
Again, as good as you will see at this magnification.
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 Nikon 4x plan APO is in the outstanding
category for all except the highest magnification
for sharpness.
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 Nikon 4x plan APO is in the outstanding
category for all except the highest magnification
for sharpness.
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 Nikon 4x plan APO is in the outstanding
category for all magnifications for resolution.
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 Nikon 4x plan APO is in the outstanding
category for all magnifications for resolution.
