Pentax 645Z Preview – Pentax’s ‘affordable’ medium-format digital SLR gets an upgrade

By Paul Carroll - Tuesday April 15 2014

Camera Preview

Pentax have launched the 645Z medium-format digital SLR, featuring a new 51.4Mp CMOS sensor. Priced at £7,699, including a 55mm f/2.8 lens, it doesn’t cost much more than some pro 35mm DSLRs, but does it offer significant benefits? We preview the new Pentax 645Z and look back at Sensor Scores from its predecessor the 645D to help us decide.

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The Pentax 645Z medium-format digital SLR offers a 51.4Mp resolution on a 43.8mm x 32.8mm CMOS sensor that’s 1.7 times bigger than full-frame sensors in 35mm DSLRs.

Pentax 645Z Specification – Improved performance and more resolution

Pentax caused something of a stir back in 2010 with the release of an ‘affordable’ digital medium format SLR in the shape of the Pentax 645D. Nearly four years on, it’s now been updated with the launch of the new Pentax 645Z, featuring a new 51.4Mp CMOS sensor, as opposed to the 40Mp CCD variety used on the 645D. The physical size of the sensor remains the same, which, measuring 43.8x32.8mm, is 1.7 times larger than full-frame sensors of 35mm digital SLRs.

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Featuring a weather-resistant and dust proof magnesium-alloy exterior, together with an aluminium chassis, the 645Z is built to last and Pentax say the updated model “…provides much faster response to the photographers commands”. That means there’s a new 27-point autofocus system, improved from 11-points on the 645D, burst shooting at 3fps up to 10 RAWs or 30 (L) JPEGs and an improved exposure control system. There’s also a 3.2” 1.04m-dot vari-angle LCD, an optical viewfinder with 98% coverage, max ISO sensitivity of 204,800 and HD video at 1920x1080 60i/30p in H.264 format, or 4K (3840x2160) in both Motion JPEG & AVI formats. Medium-format shooting is all about getting the very best image quality however and while we’ll have to wait and see how the new 51.4Mp Pentax 645Z fares, we can look back at the DxOMark Sensor Scores for its predecessor to give us an idea.

With an Overall Sensor Score of 82 the Pentax 645D ranks 4th for medium format cameras on our database. That places it behind three medium-format digital backs from Phase One including the 80Mp IQ80 with 91 points, the 60Mp P65+ with 89 points and 40Mp P40+ with 87 points. As well as greater resolution the IQ 180 & P65+ backs both boast physically larger sensors that measure 53.7x40.4mm, so it’s not really surprising they came out on top. With the Pentax 645Z using the same sized 43.8x32.8mm sensor, but with an increased 51.4Mp resolution, it’ll be interesting to see how the sensor scores are affected as we test the new model in the coming weeks. 

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The 645Z’s predecessor the 645D achieved a Sensor Score of 82, ranking it 21st for all sensors on the database and 4th for medium-format cameras behind 3 digital-backs from Phase One.

Pentax 645Z Specification – Full Frame DSLRs offering comparable image quality

The Pentax and Phase One are completely different systems however with Pentax featuring a ‘built-in’ sensor, as opposed to Phase One’s interchangeable digital-backs. The advantage of the Phase One system is the digital-backs can be used on older medium format film cameras from manufacturers like Hassledlad or Contax, and ‘future proofs’ the system as you can update the digital-back without having to replace the camera. The Phase One system is much more expensive however, with the Phase One IQ180 digital–back only costing around £24,000, with a comparable Phase One system to the Pentax 645Z coming in at around four times the price, at over £30,000. 

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At £7,699, including a 55mm lens, the cost of the Pentax 645Z is more comparable to pro 35mm digital SLRs, such as the Nikon D4s at £5,199 or Canon 1Dx at £4845. Aimed more towards the sports and press markets these cameras aren’t comparable for resolution however, but 35mm digital SLRs with sensors to rival medium-format are becoming available. Take for example the 36.6Mp Nikon D800E or 36.4Mp Sony A7R that offer a similar resolution to the Pentax 645Z, but on a physically smaller sensor. Despite the smaller 36x24mm full-frame format sensor however the DxOMark Sensor Scores from the Nikon D800E & Sony A7R show image quality from both as superior to the Pentax 645D by some margin. Achieving 96 & 95 points respectively, compared to 82 for the Pentax 645D, the Nikon and Sony sensors are some of the best we’ve tested. What’s more with body only prices for the Nikon D800E and Sony A7R at £2,349 & £1,599 respectively these cameras are significantly cheaper too. We’ll have to wait and see if the new 51.4Mp sensor on the Pentax 645Z can trump the DxOMark Sensor Scores for the Nikon & Sony 35mm DSLR.

The 645Z’s predecessor the 645D achieved a Sensor Score of 82, ranking it 21st for all sensors on the database and 4th for medium-format cameras behind 3 digital-backs from Phase One.