Lens: Fuji Fujinon-m 25mm f/2.8
Vintage: Uncertain.
Lens Mount: C-mount, the mount fits onto a C-mount adapter, but the fit is not perfect.
Needed Adapters: I use a C-mount to Nikon F-mount adapter, easily available on eBay.
Preferred Mounting: Reversed. This lens has thread on both sides, works best when reversed.
Filter Thread: None
Street Price: ??, not commonly seen.
Controls: None.
Aperture: Fixed.
Basic Function: Requires a bellows to set focus and magnification.
| Extension | Magnification | Working Distance |
| 5 cm | 2.89 | 22 mm |
| 9 cm | 4.47 | 19 mm |
| 13 cm | 6.08 | 17 mm |
| 19 cm | 8.52 | 16 mm |
| Est. Focal Length: 24.9 mm | ||
Appearance:
Corner Sharpness vs. Magnification:
This lens has not-so-hot corner sharpness at the lowest magnification, that improves as the magnification rises. It is pretty good at the top end of the magnification range.
Sharpness and Resolution vs. Magnification:
This lens has OK sharpness and resolution. Its performance at lower magnification is notquite up to par, but the lens improves significantly at higher magnifications, suggesting that it may be optimized for higher magnifications.
Performance: 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.
This lens is mostly in the poor category although it improves to good at the highest magnification. This again supports the assertion that this lens is optimized for higher magnification.
Performance: 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.
This lens is in the good category across the magnification range.
Resolving 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.
Good reoslution, especially at the high end of the magnification range.
Chromatic Aberration:
This lens shows mild to moderate chromatic aberration in the center of the field and it shows strong lateral chromatic aberration on the periphery as seen on the graph to the right.
This lens shows mild longitudinal chromatic aberration on the image below.
Longitudinal CA:
Image Contrast: This lens shows good contrast, although not as high as microscope objectives or modern macro lenses.
Flare: This lens shows no significant flare during testing.
Distortion: This lens shows no significant distortion during testing.
Image Samples:
About 4.5:1 magnification, f/2.8, focus stack of 30 images, resized:
Pixel level crop from the image above:
There is good pixel level detail, no problems.
About 8.5:1 magnification, f/2.8, stack of 30 images, resized:
Pixel level crop from the image above:
There is good pixel level detail, no problems.
Conclusion:
This is an unusual lens that acts most like an enlarging lens - it works best when reversed. Thankfully it has thread on both sides of the lens that allow it to be reversed easily. It has a fixed aperture at f/2.8 which doesn't cause any signifcant problems and helps improve the performance at the higher end of the magnification range. Its improving performance with rising magnification (sharpness) suggests that this lens is optiized for higher magnifications.
The sharpness and resolution are not particularly good at lower magnifications, although for routine web-sized images it works fine. It has good contrast, no significant distortion or flare. It does have quite a lot of lateral CA, but it doesn't really show on typical images. The mount is nominally a c-mount and will mount OK with a c-mount adapter.
All-in-all this lens works fine, but I wouldn't go out of my way to buy one (if I could even find one). There are other lenses in the same focal length range that perform better, including most bellows lenses and enlarging lenses.