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Lens: Nikon MPlan 10x/0.25 microscope objective

Vintage: 1990's.

Lens Mount: RMS

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.

Preferred Mounting: Normal, not reversed

Filter Thread: None

Street Price: $100-$150 in good used condition. Prices vary a lot online, shop around.

Controls: None.

Aperture: Fixed at about f/1.8.

Basic Function: Requires a bellows to set focus and magnification

Extension Magnification Working Distance
9 cm 8.1 8.5 mm
13 cm 10 7.5 mm
16 cm 11.4 7 mm
19 cm 13.6 6.5 mm
Est. Focal Length: 21.2 mm

Appearance:

nikon mplan 10 top view nikon mplan 10 side view

corner sharpness graphCorner Sharpness vs. Magnification:

The fuzziness on the periphery of the image is mild for this microscope objective, although as microscope objectives go, the corner sharpness is quite good. Looking at typical images, the peripheral fuzziness is not particularly noticeable. Microscope objectives tend to concentrate on sharpness and resolution in the center of the field. As objectives get more expensive, the peripheral sharpness will improve.

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.

resolution graphSharpness and Resolution vs. Magnification:

This lens show very high sharpness and resolution in the center of the field - higher than any other lens that I have tested in this magnification range. This lens can resolve details measuring less than 1um in the center of the field and will "sharply" resolve details a little less than 2 um in size.

These number only apply to a DX format Nikon D200. With a higher megapixel camera, the numbers would be similar because the resolution supplied to the detector by the lens in this magnification range tends to be significantly less than the detector is capable of.

performance:sharpness graphPerformance: Sharpness vs. Magnification:

I have 4 lines that represent levels of performance from outstanding (top) to fair (bottom). This shows where this lens fits into the hierarchy that I have created.

The Nikon 10x MPlan shows outstanding sharpness across its magnification range of 8:1 to almost 14:1.

performance:resolution graphPerformance: Resolution vs. Magnification:

I have 4 lines that represent levels of performance from outstanding (top) to fair (bottom). This shows where this lens fits into the hierarchy that I have created.

The Nikon 10x MPlan shows outstanding resolution across its magnification range of 8:1 to almost 14:1.

resolving power graphResolving Power vs. Magnification:

This graph represents the smallest details that are able to be resolved by this lens at various magnificaitons. If the number doesn't get smaller as the magnification rises, there is little benefit to going up in magnificaiton with this lens. This situation is also called empty magnification.

Outstanding resolution, although the gains above 10:1 are pretty small.

Chromatic Aberration: This lens shows minimal color fringing in the center (about 0.20-0.40 pixel, mainly axial) and moderate on the periphery (2.0-3.0 pixels, mainly lateral). Color fringes are another factor that microscope objectives tend to have depending upon the price of the objective. The most expensive, apochromatic objectives have the least, while the least expensive tend to have quite a lot. This objective falls in the better side of the spectrum for microscope objectives.

Image Contrast: Image contrast is very good for this magnification range. This is another area that microscope objectives tend to excel.

Flare: This lens shows no significant flare during testing.

Distortion: This lens shows no significant distortion during testing.

Image Samples:

About 8:1 magnification, focus stack of 32 images, resized:

sample image

crop imagePixel level crop from the image above:

There is very good pixel level detail, about as good as you will see at this magnification.

About 11:1 magnification, stack of 34 images, resized:

sample image

crop imagePixel level crop from the image above:

There is very good pixel level detail, again about as good as you will see for the magnification.

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 across its usable magnification range. The corner sharpness is good but not as good as most bellows lenses have. The working distance is limited, but adequate. Limited working distance is the price you pay for high-resolution. These are generally plentiful on eBay and can be purchased for a reasonable price.

Not all microscope objectives are suitable for this application. The Nikon CF finite tube length objectives are the best that I have come across (includes MPlan and CFN objectives).

The only lens that I know that may outperform it in this magnification range is Nikon CFN Plan 10x/0.30 160/0. I would like to get one of these to test it out, but have yet to find one at a reasonable price. The currently available Nikon CF Plan 10x/0.30 infinity-corrected objective is also promising but will require a tube lens to work properly (Can just be a telephoto lens in the 200 mm range).