This is a gest post from Vytas Narusevicius originally posted in his blog Superinfocus.com.
From Medium Format Digital to Micro 4/3
There has been a great deal of hoopla created by the announcement of two new medium format mirrorless cameras from Fuji and Hasselblad. Having shot medium and large format film for some time, I too was excited at the prospect of medium format digital in a compact format and at a more reasonable price than the traditional Phase One or Hasselblad offerings. My previous foray into digital was primarily with Sony A7 series cameras that allowed me to use my existing collection of film era lenses as well as some of the new Sony/Zeiss lenses. I hesitated to upgrade my A7r because of the expense of moving to a A7r II and how physically large and expensive the new Sony lenses had become. For a change of pace I decided to dip my toe into micro 4/3s with the modestly priced Panasonic GX85 that came with a compact 12-35mm lens. The quality of the images from that camera really surprised me and I quickly added a Panasonic Leica Summilux 15mm 1.7 and 25mm 1.4. It was a revelation that in some cases there was very little difference between the images taken on the GX85 versus the A7r. Of course if you pixel peeped, you could see more resolution at 100% on the A7r, but the quality of especially the Summilux lenses was equal to the Sony/Zeiss lenses. The major difference, as far as I could tell, was only how large you could print, but more on this later. The GX85 became my preferred walking around camera, and the Sony A7r was relegated to more serious landscape work. However, with the announcement of the new mirrorless medium format cameras I started to think about getting the look that I loved in medium and large format film that was still missing from my 35mm digital experience.
Since I had a film Pentax 645N film camera with some very nice 645 lenses, it dawned on me that I could try out digital medium format in a relatively economical manner. I purchased a Pentax 645D and although it was 5 years old and came with a 40MB CCD sensor, many Pentaxians claimed there was very little resolution difference between it and the newer Pentax 645Z’s 50MB CMOS sensor (the same one that the new Fuji and Hasselblad are using). Additionally there was talk about how the CCD sensor produced better color than the new CMOS sensor. The real big difference between the 645D and Z is better high ISO performance with the Z. But buying a 645D seemed like a good idea since I was going to use it mainly for landscape photos on a tripod, thus high ISO was not an issue and I already owned some highly rated Pentax lenses such as the SMC-A 645 35mm, an A 75mm, and an A 120mm lens. The results I got from the 645D were great, definitely better than the A7r in terms of resolution, color and a more subtle graduated tonality. Nevertheless, while I was in a forest shooting one of my favourite trees, I decided to do a little experiment as I had both my Pentax 645D with a 35mm lens as well as my GX85 with the 15mm Summilux, each having a roughly similar 28mm focal length in 35mm terms. I took some images with each camera using a tripod from the same spot and compared them in Photoshop. To my great surprise, I again did not really see that much of a difference, obviously as one would expect, the 645D image had far more resolution if you pixel-peeped at 100%. However, as you can see below there is little visible difference between the digital images, especially at Internet resolution. Oddly, the GX85 appeared to have more of a 3 dimensional appearance than the 645D image.
Pentax 645D, Pentax SMC-A 645 35mm, ISO 200, f16 and 2 seconds:
Panasonic GX85, Panasonic Leica Summilux 15mm f/1.7, ISO 200, f5.6 and 1/6 of a second: