Resolution: This is an interesting one and of course noise, contrast (including micro-contrast from lenses) and optical factors all influence perceptions, but this is my take: I believe that Michael Reichman’s view on Luminous Landscape that the 51MP 645Z resolves one solid school grade above the D800/810/A7R is about right under non-demanding conditions, but in practical terms often a bit conservative. He shoots fairly straight colour files and at mild wide to telephoto focal lengths, so I can see why he concluded what he did. It is accurate if you compare top quality mid to telephoto lenses of each and in straight file comparisons roughly adjusted for format i.e. 645Z & 75mm FA at f9/10 vs A7R & 55mm Sonnar at f6.3/7.1. In such situations the A7R will come as close as you would expect from the pixel counts. Heavily process them for B&W, however, and the 645Z pulls ahead further, simply because the files hold together better with less noise and noticeably more apparent resolution.
Head into wide-angle land and you may be looking at two school grades under some circumstances. I will talk you through my perception of this scrutinising my own photos from the field, taken under varied circumstances i.e. different apertures, distances, different final processing. This is not test charts stuff, but what I see in real use when using the Pentax HD 28-45 f4.5 DA SR (which I will review in due course). At 45mm, the Pentax zoom is noticeably superior to the 35mm Sonnar on the A7R (both equating to the same angle of view). The latter is very good actually, but the huge Pentax zoom looks the same at the edges as it does on centre. It’s so good that I regard it as a ‘giant Leica 24mm f3.8 Elmar-M’ at middle apertures. I thought the Canon 24-70 f2.8 L II was impressive (and it is) but I did not think that performance could be significantly better on an even wider (albeit slower) zoom. Its not a perfect lens, but the end result is that the 645Z combo is way ahead of the Sony. Looking at the wide end (28mm on the 645Z being roughly 21 to 22mm on the FF format), the Pentax is markedly superior to the Sony Zeiss 16-35mm f4 OSS / A7R RAW samples I have worked over in Adobe Lightroom. While I recognise that the Sony 28mm F2 offers a strong performance when stopped down and that the 25mm Batis is likely to be superb, there is no escaping the fact that the 28-45mm on the 645Z provides an output with a level of perfection I have never see on the 35mm Sonnar and the Pentax-HD lens will do it every single time I focus in the right place and stop it down to between f8 and beyond. It is this sort of consistency that build immense confidence that in turn can fuel creative ambitions.
It’s worth noting that this sort of wide-angle performance is not restricted to the giant and expensive Pentax 28-45mm. The second-hand 35mm f3.5 A that I bought (28mm equivalent) also performs to a higher standard around the image margins than the 35mm Zeiss FE, despite the Pentax being much older, wider and covering a larger sensor. Will this be meaningfully visible on an A2 print? Not a chance. Will it make a difference if you are aiming for the top with 40” prints? Yes, it will: the print will appear more uniform and detail at the edges and corners will be noticeably better defined. But hey, I am guessing very few people reading this are doing so because they are looking for better A2 prints.
The end result is that the 645Z feels like a ‘no excuses’ set up with a consistent perfection to the images that I only ever saw with longer than 35mm lenses on the A7R. On top of this we have the better high ISO performance, incredible retention of detail up the ISO range, more DR, more robust files and some incredible lenses (that as I will get onto later, can be had for surprisingly low prices).
Its great. Typical Pentax colour is present in the RAWs, I’d say: not overly saturated (but realistic) and very accurate in my experience. While I know some like to have a particular fingerprint on their colour files and ‘love Olympus colour but hate Nikon’ or similar, I’m a bit of a simpleton in this department I am afraid. If it looks natural and accurate, I could not be happier. After all, this is a useful place to start. I did not notice any odd white balance issues and think the camera did a stunning job with lots of white snow and blue skies. On the other hand, My Sony A7 has decided to make everything yellow and I have absolutely no idea why!
I will shoot some skin tones when I have a suitable guinea pig and put up some examples, but from what I am seeing the camera is what you would expect from a top end Sony sensor souped in sensible Pentax/Ricoh sauce. Use the latest Pentax HD lenses and you’d think you were using a giant Ricoh GR. With older A series lenses, you will see a noticeable drop in contrast and colour saturation and it isn’t always subtle. Lenses like the 75mm FA are closer to the HD lenses, but don’t quite have the pop. This is hardly an issue and its subtle, but the difference is there.
It works perfectly. I had no problems whatsoever, although it will select an exposure that will also give very blown highlights on the histogram (such as caused by bright cloud); however, the negative compensation required is much less than the histogram suggests. It takes a bit of experimenting to get to know the camera, but its easy enough.
Next, I will get onto Part 3: 645z + Lenses = samples….