NIKON D4Quick Summary: Nikon's flagship pro DSLR, the D4 features a full-frame, 16.2-megapixel CMOS sensor, very quick response and the most rugged construction in Nikon's line. The relatively low pixel count allows for very quick shooting and excellent low-light performance. The D4 can use nearly all F-mount lenses. Nikon currently offers 79 lenses, including 45 AF-S ones from 14mm through 800mm, many with VR optical vibration reduction. There are also three PC-E tilt-shift perspective-control lenses. DX (APS-C) lenses can be used, but the camera will crop to DX format with them automatically to avoid vignetting.
Special Strengths: The D4 excels in action, photojournalism and low-light photography, but is also a great all-around camera. It can shoot up to 92 RAW or 170 JPEG full-res images at 10 fps with AF for each frame (11 fps in DX crop mode). The AF system is Nikon's best, and can function in light levels as dim as EV -2 and with lens/teleconverter combos as slow as ƒ/8. Normal ISO range is 100-12,800, expandable to 204,800. The shutter is rated at 400,000 cycles. The battery is rated (per CIPA testing) at 2,600 shots per charge. There are slots for CompactFlash and superquick XQD memory cards. The D4 also can produce broadcast-quality video and audio, in three crop formats (full-frame, DX/APS-C and 2.7X), including recording uncompressed 8-bit, 4:2:2 video directly to an external recorder. Estimated Street Price: $5,999 (body only).
Also Consider: Nikon D800E. The D800E features a full-frame, 36.3-megapixel CMOS sensor with OLPF deactivated for optimal sharpness. Almost as rugged as the D4, it features essentially the same AF system, with a shutter rated at 200,000 cycles. Normal ISO range is 100-6400, expandable to 25,600. The D800E ranks first overall in DxOMark.com's RAW image-quality ratings, and is well suited to a wide range of shooting needs. Estimated Street Price: $2,999 (body only).
PENTAX 645DQuick Summary: The Pentax 645D is currently the lowest-cost medium-format DSLR, featuring a 40-megapixel 44x33mm CCD sensor.
Special Strengths: The 645D is also a fine outdoor camera, weather-, dust- and cold-sealed. It has a "35mm-DSLR"-type 11-point AF system, an 800-shot rechargeable lithium-ion battery, digital level, sensor dust-reduction, dual SD/SDHC/SDXC card slots and an ergonomic handholdable form factor. It can use a wide range of Pentax 645 lenses, although only the three D FA 645 lenses are designed for digital and are weather-sealed. Pentax has a white paper on its website explaining how to use it tethered to a computer via Phase One Capture One Pro software. Estimated Street Price: $6,995 (body only).
PHASE ONE IQ280Quick Summary: The IQ280 is Phase One's latest 80-megapixel digital back, and can be used with a number of popular cameras. Phase One also offers it in a kit with the Phase One 645DF+ medium-format body.
Special Strengths: Eighty is currently the highest pixel count available in a medium-format back (there are other backs with 80 megapixels, including Phase One's IQ180 and Leaf's Credo 80 and Aptus 80). Sensor+ technology bins four pixels into one for 4X better high ISO performance (up to 3200) at ¼ the resolution (still 20 megapixels). The back houses a 53.7x40.4mm CCD sensor (2.5X the area of a "full-frame" 35mm sensor) and a 3.2-inch, 1.15-megapixel touch-screen LCD. The IQ280 provides tethered and wireless capabilities, 16-bit capture and 0.7 fps shooting (0.9 fps in Sensor+ mode). The 645DF+ camera features a big prism finder, 3-point phase-detection AF and a lithium-ion battery good for up to 10,000 captures per charge. It can use Phase One Digital, Mamiya AF and AFD, and Hasselblad V-system lenses, as well as a number of different backs. With leaf-shutter lenses, maximum flash-sync shutter speed is a fast 1⁄1600 sec. Handholding ergonomics are very good. Estimated Street Price: $47,990 (body with back, 80mm lens and Classic warranty).
Also Consider: Phase One IQ260. This back provides similar features to the IQ280, but with 60 megapixels, the ability to make exposures as long as one hour (vs. two minutes for the IQ280) and 1 fps shooting (1.4 fps in Sensor+ mode). Estimated Street Price: $43,990 (body with back, 80mm lens and Classic warranty).