It can be difficult to use ultra-wide lenses, particularly when using a 35mm format camera system. Short focal lengths may cause blurred edges or capture facial features that are exaggerated. This is one area where medium format excels. Phase One Schneider Kreuznach 35mm LSM f/3.5 ($6,490) captures wide fields of view and is capable of capturing images in close quarters.
It also has the ability to take photos with an equivalent field-of-view as a full-frame 23mm lens. Although it is expensive, that is normal when you look at the top-end medium format camera systems like Phase One's. The camera is sharp and clear, although not perfect optically.
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Design
At 4.7x4.4 inches (HD), and 2.7lbs, the 35mm LS f/3.5 lens is large. It's not unusual for medium format lenses be bigger than 35mm format glasses. Wide-angle lenses are often a little larger than those with more limited fields. It's heavy and bulky to the point that I would not want it to be carried for a prolonged period of time.
Front elements can be used with 105mm filters. A reversible lens hood in petal style is also included. It's not the widest lens in the Phase One system—the Schneider Kreuznach LS 28mm f/4.5 ( at Amazon) captures images with a 18mm (equivalent) field of view, but its bulbous front element precludes filter use without an accessory holder.
The 35mm is part of the updated line of Blue Ring lenses—identified by the blue accent on its focus ring. The in-lens shutter syncs with strobes at speeds up to 1/1,600 seconds. The barrel is metal, with a knurled manual focus ring that acts as a clutch—push it forward to set the camera to autofocus and pull it back toward you for manual focus.
A printed depth-of-field scale can be found on the lens. This scale allows for easy focusing when it is stopped down. It can focus up to 1.6ft (0.5m), keeping it out of macro territory. If you wish to blur the background, you can get close enough to your subject.
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Imatest
Imatest was used to test the sharpness and contrast of the lens when it was paired with full-frame Phase One XF 100MP 645. The 35mm produces some impressive numbers when paired with the 101-megapixel sensor. On a center-weigthed sharpness testing at f/3.5, it scores 5,311 lines per image height.
The image quality through the majority of the frame is excellent, however, the outer third drops to 3,283 lines. This gives our test charts squares a soft appearance when they are viewed at their full resolution. The performance is roughly the same at f/4.
The overall score rises to 6,278 line at f/5.6. There are 4,562 lines along the edges, which gives them a crisp appearance, though not quite as crisp in the middle of the frame. The lens' f/8 score is 6,591 lines with edges exceeding 5,000 lines. Image quality is at the absolute best at f/11—the average score is 6,848 lines, with performance that's very strong from edge to edge—even the periphery tops 6,000 lines.
The score drops to 6,009 lines due to diffraction. However, you can still set the fstop as narrowly when necessary. You should avoid f/22 (441 lines) or f/32 (2912 lines), which reduces resolution.
About 2.3 percent of the barrel distortion is visible. Straight lines appear to have an outward curve because of this distortion. It's easy to get rid of with Phase One's Capture One program. You can also correct the corner lighting using Light Falloff.
The corners are 2.4 stops behind the center at f/3.5 (-2.4EV). At f/5.6 this deficit drops to -1.3EV. It is negligible for f/8 or narrower settings. This is an additional step when you edit images. However, you can use a preset user to automate the process.
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Conclusions
The Phase One Schneider Kreuznach35mm LS F/3.5 is an excellent performer. It captures sharp images through the majority of its frame, even at larger apertures. Images are also very crisp from edge to end when it's stopped down.
The 35mm focal length makes it ideal for landscape photography and work in tight places. It's not a perfect lens—edges aren't entirely crisp, corners are dim at wide apertures, and there's some barrel distortion—but it's still an overall strong performer that pairs well with a Phase One system.