Technical notes

Technical notes

This page describes the technique I used in making the prints for the 2016 NCAR show. I describe the Sony A7Rii camera I used for the large prints in the show as well as my new Google Pixel phone camera, which makes amazing images, though the maximum high quality print size (roughly 16×24 inches) is smaller than the A7Rii.

Most of the digital images were converted from raw files using RawTherapee ( a great free raw converter) and edited with Picture Window Pro (my old favorite).

SB25The prints are framed with the matte black metal SB25 Shadow Box frame, which has a built-in spacer to separate the artwork from the acrylic cover. This eliminates the need for an overmat, which can add a lot of expense to large framed images, and which (in my opinion at least) doesn’t really improve the appearance.

A variety of cameras was used, including the Canon EOS20D, EOS40D, EOS6D, the Panasonic Lumix G3 and LX100, and the Sony A7Rii (a recent addition– its image quality is truly amazing).

Sony A7Rii full-frame mirrorless camera

The Sony A7Rii deserves special mention. I got it in late 2015. In some ways it represents the “holy grail” of cameras for me. I can make large prints with detail I always dreamed of— much finer than the great master images I saw at the Eastman House when I was young. It’s so good I have a hard time imaging what Sony will do for a follow-up product. It seems that companies have to keep introducing new products; product life is much shorter than when I was young (the superb Leica M3 was around for many years). There isn’t much room for improvement for a number of reasons.

  • The backside-illuminated image sensor has very high quantum efficiency. It’s not far from the theoretical limit. It has outstanding dynamic range and low light performance.
  • The pixels in the 42-megapixel sensor are small enough so that no anti-aliasing filter is needed. This is a bigger deal than most people realize because Digital SLRs with up to about 20 megapixels need these filters, which slightly blur the image, to eliminate unpleasant image artifacts that can appear when lenses are too sharp for the sensor (technically, when there is too much energy above the maximum spatial frequency that can be digitally sampled— the Nyquist frequency). For this reason there is a bigger than expected improvement in sharpness for 36+ megapixel cameras.
  • It’s a mirrorless camera. The absence of mirror slap is especially helpful with long telephoto lenses. Older mirrorless cameras had rather ugly viewing screens, but they’ve gotten really good in the last few years. Competitive Nikon and Canon models have mirrors, albeit with very good damping.
  • The image sensor has built-in image stabilization, which is especially nice with some of my excellent older lenses, like the Canon 70-200 f/4L (available in a newer IS version; but the old lens is awesome). Competitive Canon and Nikon models lack this feature.
  • It can be adapted (with a Metabones adapter) to work with a wide variety of lenses, including my old Canon lenses, some of which are outstanding. Autofocus works extremely well with the Metabones. Because the A7Rii doesn’t have a mirror box it can be used with a huge variety of lenses. There is even an autofocus adapter for old Leica lenses (I have a few; I haven’t tried the adapter).
  • Speaking of lenses, some of Canon’s older lenses are superb, but they couldn’t reach their full potential with older, lesser cameras. I test them with Imatest— a fantastic program for testing camera and lens quality. It lets me quickly map sharpness over the entire images for all apertures so I can determine where a lens performs best. Imatest is the absolute best way to test cameras and lenses. I can assert this with absolute objectivity because I wrote it (well, most of it).   😀
  • The recent Canon 24-70mm f/4L has amazing performance at f/8-f/11. In practice (in the field) it’s far better than any 4×5 view camera. (I’ll save the technical detail for elsewhere.) The National Park Service is looking for a replacement for Ansel Adams to document the National Parks with a large format film camera. In an NPR interview they get the technological comparison totally wrong.
  • With good lenses, the A7Rii is capable of making absolutely stunning razor-sharp 24×36 inch (60x90cm) images and excellent 40×60 inch (1×1.5 meter) images. A 100 megapixel medium format camera may have an edge with 40×60 inch images, but seriously, who has room for many 40×60 images? And medium format cameras and lenses are bulky, heavy, and really expensive. The 23×34 inch images (framed 29×40 inches) I’m making for the show seem gigantic to me. They’re about as large as I’m comfortable framing.

Google Pixel phone

I got the Google Pixel in late 2016 only partly for the camera, which had excellent reviews. It enabled me to move my mobile phone service to Google Fi, which lets me make reasonably-priced calls from anywhere in the world. I travel a lot (four international trips in 2017— a feat I don’t plan to repeat).

Google_Pixel2_videoBefore I rave too much I need to make a disclaimer (well… maybe a boast). I’ve been involved in the development of Google Pixel cameras. There is a very nice video on the technology of the Pixel 2 (I still have the original Pixel): . I was quite thrilled to see our Imatest test charts in the video at 0:55, 7:42-7:49 and 8:00. The image on the right shows the eSFR ISO chart.

I’ve made some wonderful images with the Pixel; its quality is actually better than my old Leica M2 (a great camera in its time). I probably won’t upgrade to the Pixel 2, though I’m tempted.  It has some impressive technology “under the hood”— so impressive I regard it as the beginning of a second digital revolution (the first was when we changed from film cameras). Essentially it takes a number of short exposures (up to 10, I think), then combines them with sub-pixel accuracy for remarkable sharpness. Since each exposure is underexposed, highlight detail is maintained nicely, especially in challenging situations like sunsets that have areas of extreme brightness. It performs tone mapping to maintain highlight detail when combining the images. The results are wonderful. The technology is explained in “Burst photography for high dynamic range and low-light imaging on mobile cameras“.

The Pixel is good for enlargements up to about 16×22 inches; good enough for most of the prints I plan to make.  (I can remember when 8×10 inches was a “big” print.) The Sony A7Rii is good for much larger prints— 30×45 inches or more, but I don’t have enough wall space for many of those. I carry it the Sony only when I’m “serous” about fine art photography.

The picture below is an excellent example (though I don’t have a good “control” image to show how badly the sky would have washed out without tone mapping). There are more on Images mid Images mid 2016 to late 2017.


Recent images and blog posts by Norman Koren