up: Camera scanning

There are several types of lenses that can be used for camera scanning, each with their own strengths and weaknesses. The main objective when choosing a lens for this purpose is that it must have a flat field of focus. This is essential because you are photographing something flat — a well-mounted negative held securely by a good film holder — and you want the image to stay sharp from corner to corner.

Another important factor is optical quality. A good scanning lens should have minimal chromatic aberration and color fringing, especially since film can contain fine, high-contrast details. For this reason, an apochromatically corrected (APO) lens is ideal. In addition to flatness and color correction, the lens must be sharp enough to resolve the grain of the film, especially for high-resolution scans.

Different lenses perform better at different magnification ratios, so it's crucial to consider the format you're digitizing and the sensor you're using. When scanning 35mm film on a full-frame camera, the area being photographed is exactly the same size as the sensor. This is referred to as a 1:1 magnification ratio. If the object is half the size of the sensor and you want it to fill the frame, you're working at 2:1 magnification. Conversely, if the object is twice the size of the sensor and you still want to fill the frame, you're at 1:2 magnification.

For full-frame cameras:

So, to fill the frame with a small object, you need higher magnification.

Some lenses are designed to work well at both of these ratios, while others are optimized for one and only one.

Most modern Macro lenses, the kind sold by camera manufacturers, are made to perform adequately from 1:1 all the way to infinity. They're versatile, easy to use, and include features like focusing rings and aperture control. However, this versatility can be a disadvantage in scanning because it often comes with design compromises — more lens elements, for example, which can introduce more room for optical errors.

On the other end of the spectrum, you have Scanner lenses. These are highly specialized lenses designed for film scanners, as the name suggests. They’re optimized for one magnification ratio only. Because they're designed for a fixed working distance, they usually contain fewer elements and can achieve incredible optical performance — often APO corrected and tack sharp. But this comes at a cost: they tend to have very wide fixed apertures, which makes the depth of field razor thin. This means it’s harder to get perfectly focused images unless your scanning rig is extremely stable and precise. When you do nail focus, though, these lenses are among the sharpest available — and surprisingly affordable, since they’re often salvaged from old film scanners.

The main advantage of these scanner lenses makes them also challenging to work with. They weren't designed to be mounted to a camera, so they usually lack threads, focusing mechanisms, or aperture control. Mounting them requires DIY adapters, extension tubes, or helicoid focusing systems. Some popular examples — like lenses taken from the Nikon Coolscan 4000/5000 — were designed to scan 35mm film using a line-based CCD sensor. Because this scanner scans the negative in parts of the short side of the negative, these typically perform best at around 1.33:1 magnification. This can lead to vignetting when used with a full-frame camera, because the image circle is too small. They work wonderfully on APS-C sensors, however, or you can crop your full-frame images or use lens correction in software like Capture One to mitigate the vignetting. However, some scanner lenses do cover full-frame — such as certain Minolta or Kodak high-end scanner lenses, especially those used in medium format scanners.

In summary, the perfect lens for scanning depends on your needs. If you value convenience and flexibility, a modern macro lens will get the job done with minimal hassle. If you’re chasing the absolute best image quality and are willing to deal with some DIY setup, a scanner lens can give you truly exceptional results.

Q and A
Q: Do I need an APO lens for good results?
Not strictly, but it's highly recommended. APO (apochromatic) lenses correct for chromatic aberration across red, green, and blue wavelengths, leading to cleaner, sharper scans — especially in the corners or around high-contrast areas.

Q: What’s the best magnification for scanning 35mm film?
You want a lens that performs best at 1:1 magnification when using a full-frame sensor, as 35mm film (36×24mm) is the same size as the sensor.

Q: My scanner lens has no aperture control. What can I do?
Some scanner lenses can be modified to add an aperture or placed behind a manual aperture diaphragm (e.g., an iris in an extension tube). With the help of for example M42 aperture diaphragm.

Q: My scanner lens has no automatic focus, What can i do?
Use a repro stand or macro rail with very fine adjustable settings. Try using live view with focus peaking or tethered capture.

Q: What if my lens vignettes on full frame?
You can:
Crop slightly into the image
Use an APS-C camera
Apply lens light correction (LLC) in Capture One or Lightroom

Try stopping down with an external aperture (if possible)

Q: Are enlarger lenses better than macro lenses?
They can be — especially APO Enlarger lenses (like Rodenstock APO-Rodagon) are optimized for flatness and resolution at scanning distances. However, they need additional gear (e.g., bellows, helicoids) and lack modern conveniences like autofocus or built-in aperture control.

Q: How do I mount scanner lenses to my camera?
Usually with a combination of:
M42 or M39 extension tubes
Helicoid focusing adapters
Custom mounts or 3D-printed holders

Some people cannibalize old lenses or scanners to get the thread mount, while others use third-party mounts from eBay or adapt via step rings.

Q: What are again the main types of lenses suited for camera scanning?

A:
Scanner Lenses
Originally designed for professional drum or flatbed scanners, these lenses (e.g. Rodenstock or Schneider repro lenses) are optimized for extremely flat field sharpness, low distortion, and high resolving power at close distances. Often adapted for digital camera use via bellows or helicoids, they lack focus mechanisms, requiring precise camera-to-film distance control. Ideal for critical, high-resolution film scanning.

Macro Lenses
Made for photographic enlargers, these lenses (e.g. Rodagon, Componon-S) offer excellent optical performance for flat subjects like film. Many perform best at reproduction ratios around 1:5 to 5:1, making them well-suited for 35mm to medium format scanning. Like scanner lenses, they usually lack focusing helicoids and must be used with precise height adjustment.

Enlarger Lenses
Modern macro lenses (e.g. Nikon 60mm Micro, Canon 100mm Macro) feature built-in focusing mechanisms and are optimized for 1:1 reproduction, making them the most user-friendly option for camera scanning. While not always as optically optimized across the entire frame as high-end repro lenses, many modern macros deliver excellent results, especially when stopped down slightly.

Exellent recources:
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