Lens: Schneider 45mm f/4 APO enlarging lens
Vintage: Current.
Lens Mount: M39
Needed Adapters: This lens works best when mounted reversed. This will require the use of a 43-52mm step-up ring and a 52mm reversing ring to fit your camera.
Preferred Mounting: Reversed.
Filter Thread: 43 mm.
Street Price: $200-$500 in good new/used condition. Prices vary a lot online, shop around.
Controls: Aperture setting.
Aperture: 5 blades.
Basic Function: Requires a bellows to set focus and magnification
| Extension | Magnification | Working Distance |
| adapters | 0.79 | 95 mm |
| 25 mm | 1.33 | 72 mm |
| 5 cm | 1.70 | 63 mm |
| 9 cm | 2.57 | 52 mm |
| 13 cm | 3.45 | 48 mm |
| 19 cm | 4.82 | 44 mm |
| Est. Focal Length: 45.1 mm | ||
Appearance:
Resolution vs. Aperture:
This lens is at its sharpest at f/4.7. For the focal length, this is a typical sharpest aperture.
The most detailed aperture is at f/4, although the slight increase in resolution at f/4 is also accompanied by a slight loss in sharpness. I would use f/4.7 because of the slightly improved corner performance.
Corner Sharpness vs. Aperture:
Fuzziness in the corners is fair at f/4.7 and good to very good above that. The fuzziness is typical for an enlarging lens. If you need sharper corners you can go to f/5.6. You won't lose much sharpness/resol\ution at lower magnification at f/5.6
This testing was performed at the 1.7:1.
Sharpness and Resolution vs. Magnification:
This lens shows very strong center field sharpness and resolution in the lower half of its magnification range. Not many lenses outdo this lens from 1:1 to 2.5:1.
The corner sharpness is not so hot in the lower half of its magnification range. Switching to f/5.6 in this range will improve that performance considerably.
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.
The Schneider 45 mm shows sharpness performance that varies from very good to outstanding below 3:1 to good above 3:1.
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.
The Schneider 45 mm shows resolution performance that varies from very good to outstanding below 3:1 to fair to good above 3:1.
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.
Very good resolution, no problems.
Chromatic Aberration:
This lens shows minimal color fringing in the center (about 0.06 - 0.21pixel). It shows minimal fringing on the periphery (0.004 - 0.012%). Anything below 0.04% is not considered significant. There is mild axial CA on out-of focus details (see image below) as shown by a slight magenta fringe on the right and a slight green fringe on the left of the image. This axial CA is more than I would expect from an APO lens. If you don't pay and arm and a leg for an APO lens, it is probably not as highly corrected (see Nikon 4/0.2 APO and printing-Nikkor 105 for comparison).
Longitudinal CA:
Image Contrast: Image contrast is good, typical for an enlarging lens.
Flare: This lens shows no significant flare during testing.
Distortion: This lens shows no significant distortion during testing.
Image Samples:
About 1.7:1 magnification, f/4.7, focus stack of 16 images, resized:
Pixel level crop from the image above:
There is very good pixel level detail, no problems.
About 3.5:1 magnification, f/4.7, stack of 50 images, resized:
Pixel level crop from the image above:
Good pixel-level detail, although starting to show some weakness.
Conclusion:
This is an enlarging lens that performs very well mounted directly on a camera or onto a bellows across a magnification range from just below 1:1 to almost 5:1. The sharpness and resolution are very good below 3:1 and generally good above 3:1. Above 3:1 it show weakness because of its smallish aperture compared to its betters in this range (f/4.7). The field flatness is fair in the lower half of the magnification range and very good above that, typical for an enlarging lens The chromatic aberration is minimal across the range, although the axial CA is a little more than I would expect for an APO lens. I guess that you get what you pay for.
Overall this bellows lens performs well. The price can be a little steep, typically ranging from $200 to $500 used online. This lens has an M39 mount, but really should be mounted in reverse configuration - easy with a couple of not hard to find adapters.