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Lens: Nikon E Plan 10x/0.25 LWD microscope objective

Vintage: 1990's?

Lens Mount: RMS

Needed Adapters: RMS to T-mount adapter and a T-Mount to Nikon F-Mount adapter, both available on eBay.

Preferred Mounting: Normal, not reversed

Filter Thread: None

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

Controls: None

Aperture: Fixed at an NA of 0.25

Basic Function: Requires a bellows to set focus and magnification

Extension Magnification Working Distance
5 cm 6.94 10.5 mm
9 cm 9.59 10 mm
13 cm 12.36 9.5 mm
19 cm 16.16 9 mm
Est. Focal Length: 15.1 mm

Appearance:

nikon 10x LWD top view nikon 10x LWD side view

corner sharpness graphCorner Sharpness vs. Magnification:

The fuzziness on the periphery of the image is very good for this microscope objective, as long as you are working at about 10:1 or above. At about 7:1 the corner sharpness is just OK. this is about the lower limit of magnification for this objective and at 7:1 it is starting to show some vignetting on the periphery (getting to the limit of image circle). 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 shows the very good sharpness and resolution in the center of the field, almost as good as the 10x MPlan that I have tested previously. Good performance for a bargain objective.

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 E plan LWD is in the outstanding category for sharpness, what you expect from a microscope objective.

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 E plan LWD is in the outstanding category for all magnifications except for the very highest for resolution. Again, what you expect from a microscope objective.

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 losing steam above 12:1.

lateral CA graphChromatic Aberration:

This lens shows fairly mild color fringing on the periphery, best at around 10:1. It varies from 0.020% at 10:1 magnification (minimal) to 0.052% at the highest magnification (mild). This is very good performance for a microscope objective in my experience.

This lens shows moderate to severe axial CA (see image below). It shows a moderate amount of blue fringing at the focus plane. This seems at least partly an undercorrection of blue compared to red and green in the lens design. Blue just doesn't come into as sharp of focus as do red and green. This is a common trait for microscope objectives.

Longitudinal CA:

axial CA

Image Contrast: Image contrast is extremely high 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 10:1 magnification, focus stack of 36 images, resized:

sample image

crop imagePixel level crop from the image above:

There is very good pixel level detail, no problems.

About 14:1 magnification, stack of 36 images, resized:

sample image

crop imagePixel level crop from the image above:

There is good pixel level detail, no problems.

Conclusion:

This is an objective that works very well as a bellows lens. The center resolution and sharpness are about as high as you will see within the magnification range of about 7:1 to 16:1, although slightly less than the Nikon 10x/0.25 M Plan. The performance comes at a bargain price of typically under $100. This lens has minimal color fringes on the periphery, and moderate to severe axial CA on out of focus details. This lens produces high contrast images and has no visible flare.

This lens has a large aperture for the magnification (working f-number of f/2.0 at m=10, equivalent to a f/1.8 lens). 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 very good as long as you are working at about 10:1 or above. The performance drops off a bit below 10:1. 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 good for the magnification. There's not much to dislike about this lens except for the blue fringe at the focus plane and fairly severe axial CA, although both are common traits for microscope objectives.