Pentax 645z Review
The last week was spent shooting a few thousand frames through the Pentax 645z. This is Pentax’s new somewhat-affordable medium format system. We wanted to take a real world approach to how we would shoot the camera, so this review will be less technical and more about how it performed on the job. We took it to a full wedding, a weeks worth of portrait sessions and a night shoot.
Medium format digital cameras have been on our mind lately and this did not let us down. This is one of the many current medium format offerings to use the 51mp CMOS sensor produced by Sony. This new CMOS sensor is a huge deal for the way we shoot, mainly because it allows useable high-iso and live view, this wasn’t possible with the previous generation of medium format digitals.
For lenses we used both the Pentax 55mm f/2.8 and the fastest lens available for the system, the 105mm f/2.4 from the Pentax 67 film camera. The 55mm is equivalent field of view to ~43mm, it performed well offering very little distortion and great sharpness even wide open. Pentax very much needs to come out with a faster ~50mm equivalent lens.
A f/1.4 lens would be great – it would give two more stops of light and f/1.1 equivalent depth of field.
An interesting note about this camera, you can adapt the readily available and affordable Pentax 67 lenses. There are even a few 67 lenses with leaf shutters should you decide to get strobey.
The camera performs amazingly well shooting at night or in low light with high ISO. There was very little noise in the files, and when it was present it remained somewhat pleasing. We’d feel comfortable shooting up to 12,800 iso for color images, no question. 25,600 is doable if there is some light source or if you plan on going black and white.
The downside is that you really need the high iso. The combination of 2.8 apertures, a giant mirror slapping around, and 51MP resolution makes shooting at slower shutter speeds difficult. We needed to be closer to 1/250th to feel confident we’d have a sharp hand held image.
It is amazing how much shadow detail is retained with the Pentax. Even at higher ISOs the files help up remarkably in post, we were able to boost a 12,800 ISO shot over a stop in post with no problem.
(ISO 6400, f/2.8, 1/60th)(ISO 6400, f/2.8, 1/60th)(ISO 25600, f/2.4, 1/125th)
The 27 point system is clustered near the center of the viewfinder, making it somewhat limiting. We did most of our shooting using the center point and recomposing. It was relatively accurate with most of the images we took being tack sharp at 100%. That said, it was fairly slow, difficult to nail focus on anything moving, and autofocusing in a backlit situations felt nearly impossible. The AF is also very slow and difficult when using Live View, but you can turn on focus peaking and manually focus very accurately.
It is good enough for our needs. I’ll never know if it is 13stops or 15stops, not going to take the time to test that. You could spend hours dodging and burning on any image. There is a massive amount of detail in the shadows and the highlight detail is decent. I do recommend using live view for real-time blown highlight warnings, it is actually useful because it doesn’t use the preview jpeg to generate the warning, but the actual raw sensor data.
This is a big camera, weighing in at 1555 grams (50% more than the Canon 5D), but it has a very comfortable grip. It felt like using an oversized full frame dslr. I’d have no problem shooting this all day. The button placements don’t seem to be as refined as Canon/Nikon. I’d love to see a joystick on the back for moving AF points and the zoom box in Live View.
Big and beautiful with brilliant color detail. The reason you get this camera. Viewing the files at 100% revealed sharp detail. The files are large (8256 pixels x 6192 pixels), around 60mb per file, so editing them takes a powerful machine or patience as a file renders a change. I don’t foresee us using this camera for a full wedding day, but more of the way we integrate film by breaking it out for a few portraits and essential parts of the day.
We purposely underexposed many of the images to see what the latitude of the files could handle. To our surprise, we were able to bring up deliverable images 5 stops in Lightroom. It doesn’t work in the opposite direction however, overexposing leads to blowing highlights and poor color retention.
Depth of Field
I want to dispel one point that I see mentioned in almost every digital medium format camera review, the depth of field. I think people are confusing the fact that they are looking at a 51mp image at full size, it looks like the DOF is razor thin.. compare files at normal sizes and you’ll quickly notice how it isn’t crazy at all.
This sensor is not “full-size” medium format, it is not 6×4.5cm, but 44mm x 33mm. This gives you a crop ratio of .7873 from 35mm full frame cameras, you can multiply your aperture by that ratio to get an estimate of equivalent DoF from the same distance. It is only ~2/3rds of a stop difference wide open on the 2.8 lenses.
The 105mm f/2.4 does give you equivalent DOF to f/1.8, making it a nice portrait lens on this system.
This is a real world review, with example images edited how we would our normal work. We shot it how we would shoot our 5D’s, not from a tripod. Instead of a shot of a chart, you’ll see a portrait of our new kitten.
I’ll link to a few full-resolution images at the bottom for you to get a better idea of the resolution this camera is capable of. ISO 6400 | f/2.4 | 1/60thISO 12,800 | f/2.8 | 1/125thISO 6400 | f/2.8 | 1/125thISO 100 | f/2.8 | 5 secondsISO 25,600 | f/4 | 1/160th – pushed 1.5 in Lr to see how files reacted. not bad.10 image Brenizer method panorama with the 55mm 2.8 | This could print life size. ISO 12,800 | f/4.5 | 1/125th ISO 800 | f/5.6 | 1/125100%
645z VS IQ250
This camera works much better for how we shoot than the Phase One IQ250. The IQ250 is great if you’re shooting tethered and has beautiful lenses, but the live view is not workable.
The IQ250 also has only one AF point, it is in the center of the viewfinder.. but it isn’t marked and does not light up when you’ve locked focus. Slightly odd.
Let’s wrap this up
This camera is incredible for high-detail, beautiful portraits. I can’t wait to shoot a few landscapes, especially at night. It isn’t for everything, it won’t replace your 35mm and it shouldn’t. I think we’ll end up adding one to our gear bag and use it along side our other cameras, it will definitely get the call for commercial work, stock photography, and landscapes. Portraits are incredibly detailed and I can’t wait to see some of these files printed huge. This is definitely a game-changing camera and it should prompt a new gear battle in the digital medium format arena. I hope for the rumors of Sony, Fuji, Nikon, and Canon joining in to all come true.
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