Lens: Rodenstock APO-Rodagon D 75mm f/4 1:1
Vintage: Current
Lens Mount: M39
Needed Adapters: I use a M39 to Nikon F-mount adapter, easily available on eBay
Preferred Mounting: Normal, not reversed
Filter Thread: 40.5 mm
Street Price: $200-$500 in good 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 |
| 5 cm | 0.39 | 233 mm |
| 9.6 cm | 1.00 | 118 mm |
| 13 cm | 1.46 | 90 mm |
| 19 cm | 2.27 | 73 mm |
| Est. Focal Length: 74.5 mm | ||
Appearance:
Resolution vs. Aperture:
This lens is at its sharpest between f/4 and f/5.6 at both m=1 and m=0.4. F/4 as a sharpest aperture is good for the focal length.
The most detailed aperture is f/4 at both magnifications.
Corner Sharpness vs. Aperture:
The field is virtually flat across the aperture range at m=1. Performance is worse at m=0.4 although the field flattens significantly by f/6.7.
Sharpness and Resolution vs. Magnification:
This lens produces very sharp and detailed images across the typical macro magnification range. This lens slightly outperforms its fixed aperture brother around 1:1 and is slightly outperformed by same at about 2.3:1
The corner sharpness is extremely good at 1:1 and deteriorates above and below this magnification.
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 Rodenstock 75mm shows sharpness performance that varies from outstanding at the low-end to fair at the high-end of its magnification range.
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 Rodenstock 75mm shows resolution performance that varies from outstanding at the low-end to very good at the high-end of its 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.
No problems here, compatible with the resolution performance. Also very similar to the fixed aperture version of this lens.
Chromatic Aberration:
This lens show minimal color fringing in the center (about 0.08 - 0.15 pixel) and minimal to moderate on the periphery (0.006 - 0.083%), with the minimal seen at 1:1. . There is mild axial CA on out-of focus details (see image below) as shown by a slight red fringe on the left and a slight green/cyan fringe on the right of the image. This has more long CA than I would like for an apochromatic lens - similar to the fixed aperture version.
Longitudinal CA:
Image Contrast: Image contrast is very good, although not as high as a modern macro lens.
Flare: This lens shows no significant flare during testing.
Distortion: This lens shows no significant distortion during testing.
Image Samples:
About 1:1 magnification, f/4, cropped and resized:
Pixel level crop from the image above:
There is very good pixel level detail, no problems.
About 2.3:1 magnification, f/4, stack of 9 images, resized:
Pixel level crop from the image above:
There is good pixel level detail, no problems.
Conclusion:
This is a lens that performs very well as long as you plan on shooting images at 1:1 magnification. Above and below this magnification, performance is not as good. This is because the lens is optimized for use at 1:1 magnification. It is a little expensive, but comparable to a typical bellows lens. The sharpness and resolution are extremely good at the lower end of the magnification range - comparable to a modern macro lens. The field is extremely flat at 1:1 and OK above and below that. The chromatic aberration is minimal at 1:1 and mild to moderate above and below, again showing its tuning for 1:1. The contrast is very good, but not quite that of a modern macro lens.
Overall this lens performs well, but its optimization for 1:1 somewhat limits its utility for general use. It slightly outperforms its fixed aperture brother around 1:1 - newer, modified design, sample variation? The advantage it has over the fixed aperture version is a variable aperture. It performs very nearly as well at f/4.7 and f/5.6 with only a slight loss in resolution. This will give a little more DOF and likely a little less long CA in the images.