Image Comparison of the Canon 1DS MK2 and Better Light Super6K-HS™
...Now Including 4x5 B&W Film

.. by Mike Collette, founder of Better Light

Photographer Richard Sexton visited Better Light’s studio in San Carlos this past June to learn more about our large-format digital scanning backs. He also brought along his Canon EOS 1DS MK2 16-megapixel 35mm DSLR, and some 4x5 B&W sheet film, so he could make a comparison among images captured by familiar 4x5 sheet film, a popular DSLR, and a scanning back. Mr. Sexton details the photographic setup in a thorough article that can be found online at the www.luminous-landscape.com web site (full page address at end of paragraph). In the article, he describes how he uses two stages of additional interpolation and sharpening to increase the file size from the 16-megapixel Canon camera to approximately the same size as the uninterpolated file from the 144-megapixel Better Light scanning back. Several sets of “Detail” images are displayed, and the author states “I’ll let the results speak for themselves, i.e., I suggest you look at the pictures first and make some preliminary decisions for yourself before reading my comments.” He later concludes “The Better Light scan clearly has the most detail, though in many areas of the image it’s a subtle difference. Also, the color accuracy of the Better Light scan is the best overall.”  (full article: http://www.luminous-landscape.com/reviews/cameras/better-light.shtml)

Unfortunately, what isn’t stated anywhere is that the image “Details” displayed are not from the full resolution files described in the article. These “Detail” images have all been REDUCED IN RESOLUTION by amounts varying from 50% to 33% of their original size (one-quarter to one-ninth of their original data). Most readers will understand that if we interpolate an image up to several times its initial size, we haven’t added any real information, and if we subsequently reduce it by several times, we are pretty much back where we started. However, if we reduce a large uninterpolated image by several times, three-quarters or more of its original image information is discarded. This puts the scanning back at a significant disadvantage by eliminating its most desirable feature — much higher resolution. After examining the reduced-resolution “Detail” images in Mr. Sexton’s article, some readers might conclude that a Canon DSLR is capable of producing images nearly as good as those from a Better Light scanning back, regardless of what the article says.

Below are similar “Detail” sections from the original 48-bit RGB images described by Mr. Sexton in his article, reproduced at 100% of the finished image size. Because these “Detail” images are much larger than the reduced-resolution versions in the article, only a portion of each “Detail” is displayed. These sections were each cropped from the original images, converted to 24-bit RGB, and saved as high-quality JPEG files. Interested readers can save these image sections, and open them in an image editor where they can be magnified for even closer inspection. Subtle image quality differences often become more apparent at 200% magnification, although JPEG compression adds minor artifacts that also show up more when magnified. Some readers might question the validity of such close examination of an image file, but anyone interested in obtaining the highest-quality images soon learns to appreciate this level of scrutiny. The Canon DSLR image is very well-behaved, but it still only contains a fraction of the information present in the Better Light image — one-ninth, to be exact. Just as it was with film, the improvement in image quality made possible by a large-format scanning back may not be needed for some applications, but photographers pursuing the absolute best should pay close attention.

>> NEWLY ADDED – equivalent-resolution scans of Fuji Acros B&W film, as described in the article. Mr. Sexton mailed these to me from New Orleans just before Hurricane Katrina struck, and they didn’t arrive in time for the original article posting. I was surprised and pleased when his CD-ROM showed up a few weeks later, and we have now added the corresponding “Detail” sections from the 4x5 B&W film to this article, along with a few comments.

Slight differences in size between the two cameras’ image sections are due primarily to differences in perspective — the view camera used swing, tilt, and ample rise to keep the subject square, but the DSLR captured the image without these camera movements. Parts of the subject closest to the DSLR lens are bigger than parts that are farther away, so it’s impossible to exactly scale one entire image to the other. It’s not clear that the view camera lens isn’t introducing some distortion of its own, either — in retrospect, we should have operated both cameras “straight on” for a closer scale match. This would also let the scanning back use the best (center) part of the lens, instead of being well off-axis. The images immediately below have each been scaled down by the same factor from the original 48-bit files described in the article, and the same size rectangle has been drawn on each image to help show differences in scale and perspective. (The B&W film image used the same 4x5 camera and lens, and was scanned and cropped to match the Better Light image size and resolution, so it also has the same perspective and scale.)

BETTER LIGHT SUPER6K-HS final image (reduced)
CANON 1DS MK2 final image (reduced)

Big image files like these are typically used for making big prints, or for archiving a large amount of information for future applications. Below are the print sizes that could be made from the original 6,000 by 8,000 pixel Better Light image shown above left, at several common print resolutions (expressed as the number of image pixels per inch of print). Also shown is the equivalent print size for each 480 x 360 pixel “Detail” image section that follows:

          6,000 x 8,000 pixels at 300 pixels per inch would make a 20 x 26.7 inch print    (480 x 360 pixel Detail would be a 1.6 x 1.2 inch section)
          6,000 x 8,000 pixels at 200 pixels per inch would make a 30 x 40 inch print       (480 x 360 pixel Detail would be a 2.4 x 1.8 inch section)
          6,000 x 8,000 pixels at 150 pixels per inch would make a 40 x 53.3 inch print    (480 x 360 pixel Detail would be a 3.2 x 2.4 inch section)
          6,000 x 8,000 pixels at 100 pixels per inch would make a 60 x 80 inch print       (480 x 360 pixel Detail would be a 4.8 x 3.6 inch section)

High-quality computer displays typically have between 80 and 120 pixels per inch, so the Detail sections below are typically being viewed on-screen at the size they would appear in a very large print. Such a large image may not be necessary for this particular subject, but may be more desirable for architecture and landscape photography, where the original subjects are typically much larger than the print.


Super6k-HS_Detail1 Canon_Detail1
BETTER LIGHT SUPER6K-HS at 100% native resolution CANON 1DS MK2 interpolated as described in article

The Better Light image above has considerably more sharpness and detail in dark areas like the black wrinkle-finish lens board and the shutter speed ring around the lens. It also has cleaner highlights with smoother gradations, possibly due to less sharpening. The Canon image shows red edges on bright highlights, and has more noise in the light gray background. The four small cyan-colored spots in the Better Light image (near the knurled shutter-cocking knob) are “echoes” of the very bright specular highlights just above the cyan spots – these are caused by internal reflections in the cyan-colored infrared-blocking filter used with the scanning back. The light producing these cyan spots has been attenuated by over 9 f-stops (and turned quite cyan) by two internal reflections in the filter, indicating just how bright the specular highlights must be. (This is the first time that I’ve ever seen this, by the way...)

The B&W film image used the same camera and lens as the Better Light image, so the difference in sharpness must be due to the film, processing, and/or scanning. Halation makes the white lettering less distinct, and graininess interferes with clarity everywhere else.

FUJI ACROS B&W FILM scanned as described in article
BetterLight_Detail2 Canon_Detail2
BETTER LIGHT SUPER6K-HS at 100% native resolution
CANON 1DS MK2 interpolated as described in article

The Better Light image above has both better definition (detail) and clarity (smoothness) in the wood grain, and less noise in the shadows behind the knurled focus knob and under the wooden rails. One Better Light user, who also has a Canon 1DS MK2, describes his Better Light images as being more “tactile” than others – perhaps another way of describing what you see here. The Canon DSLR does very well, but its image doesn’t have the depth or clarity of the scanning back’s image.

The B&W film image shows good definition in the wood grain details, but has the highest noise (graininess) of the group.

FUJI ACROS B&W FILM scanned as described in article
BetterLight_Detail3 Canon_Detail3
BETTER LIGHT SUPER6K-HS at 100% native resolution
CANON 1DS MK2 interpolated as described in article

There is considerably more fine detail apparent in the Better Light image above, which also has smoother tones in the black leather strap and lower noise in the light gray background.

The B&W film image has detail similar to the Better Light image, but graininess clouds the smoother tones and background.

The uniform-brightness, out-of-focus neutral background gives us an opportunity to measure the RMS noise in the lighter tones:
(from the original TIFF images)
       Better Light image = 0.23% RMS noise
       Canon image = 0.33% RMS noise
       4x5 B&W film image = 1.78% RMS noise

FUJI ACROS B&W FILM scanned as described in article
BETTER LIGHT SUPER6K-HS at 100% native resolution
CANON 1DS MK2 interpolated as described in article

Some of the difference in sharpness between these image sections may be due to differences in focus between the 4x5 view camera and the 35mm DSLR – the view camera used swings and tilts (along with plenty of rear rise) to maintain proper perspective and place the plane of best focus parallel to the side of the subject and midway from front to back, while the Canon was focused on the lens at the front of the subject, so this latch at the rear of the subject was several inches behind the Canon’s best focus. The Better Light image shows superior definition in both the bellows and wood grain, and less noise everywhere. 
This section of the B&W film image doesn’t show quite as much fine detail as the Better Light image, and the metal latch looks like it’s been sandblasted.


FUJI ACROS B&W FILM scanned as described in article

At Better Light, we are accustomed to looking beyond the obvious to evaluate the quality of an image. In addition to examining images at high magnification, we often make exaggerated Levels adjustments to bring out detail in deep shadows or bright highlights, so we can see things that might not ordinarily be visible.

BetterLight_Detail5 Canon_Detail5
BETTER LIGHT SUPER6K-HS at 100% native resolution
enhanced to show shadow detail and noise
CANON 1DS MK2 interpolated as described in article
enhanced to show shadow detail and noise

Above are MODIFIED sections from the deepest shadows of the original full-resolution files described in the article — these sections have been brightened up by aggressive Levels adjustments to more clearly reveal noise and other potential image quality problems.  (Note that JPEG-compressed images don’t take kindly to aggressive Levels adjustments — all you see is JPEG noise — so we adjust the original 48-bit files, convert them to 24-bit RGB, and then save the adjusted sections as high-quality JPEGs.)  The difference is pretty obvious here – the Canon image maintains shadow tone separation fairly well, but it has significantly more noise than the Better Light image, even though the DSLR was operating at about half the ISO sensitivity of the scanning back — ISO 160 for the Canon vs. ISO 300 for the Better Light.  The 1DS MK2 may have good low-light sensitivity, but this is not the same as having a wide dynamic range, where the large pixels of the scanning back provide a decided advantage. 
Except for a few pesky dust spots, the modified B&W film image does pretty well in the darker tones, but graininess becomes apparent higher up the tonal scale.

FUJI ACROS B&W FILM scanned as described in article
enhanced to show shadow detail and noise

BetterLight_Detail6 Canon_Detail6
BETTER LIGHT SUPER6K-HS at 100% native resolution
enhanced to show highlight detail and noise
CANON 1DS MK2 interpolated as described in article
enhanced to show highlight detail and noise

Finally, above are MODIFIED sections of the bright titanium brackets on the front standard of the subject, to which an aggressive contrast boost has been applied to bring out subtle textures and other low-contrast features, along with any noise or other artifacts.  Note the much clearer appearance of a smeared fingerprint in the Better Light image, along with the lack of “interpolation bobble” – that semi-random pattern in the DSLR image that looks a lot like film graininess.  Instead of being sensor noise, I suspect that this “chatter” in the image highlights is being created by the initial color interpolation routines required by nearly all instant-capture digital cameras.  Considering the opposing demands of achieving maximum image detail from an RGB matrix of pixels without introducing obvious interpolation artifacts, I regard this performance as exemplary, although it can never be as good as having real RGB pixel data to begin with. 
The modified B&W film image has good high-contrast detail, but graininess totally obliterates the subtle detail in the metal surface.

FUJI ACROS B&W FILM scanned as described in article
enhanced to show highlight detail and noise

IN CONCLUSION, I agree with everything that Mr. Sexton has to say, but if his article is going to let the images speak for themselves, they should be allowed to tell their entire story. I definitely agree that any comparison like this should be done with more than one type of subject, and we look forward to presenting landscape and architecture comparisons before long. These comparisons are not particularly intended to have a “winner”, in my opinion, but they do benchmark the relative capabilities of two rather different image capture technologies. The Canon EOS 1DS MK2 is an impressive 35mm DSLR that is making everyone familiar with the potential of high-quality digital image capture, while Better Light scanning backs have quietly been producing superior image quality for more than a decade. Large-format B&W film has acquired somewhat legendary status over its long history, but doesn’t have the image quality of its modern digital counterparts.  Nobody uses a scanning back, or a large-format view camera, because they are easy – it’s because the results are often worth the extra effort involved.  The time required for a scanning back exposure won’t appeal to everyone, and they aren’t very effective for moving subjects or low-light photography, but if you understand and appreciate the advantages of large-format photography, perhaps your next DSLR shouldn’t be an SLR…

P.S. Closely inspecting these full-resolution images in their entirety also imparts a tremendous sense of respect for the meticulous craftsmanship evident in our subject, an Ebony SV45U2 4x5 camera — truly a work of art, but also practical in the field, even with a scanning back: www.ebonycamera.com

NEWLY ADDED – Get a closer look at the Ebony SV45U2 in this full-resolution image from the Better Light scanning back.
CLICK HERE to open a Zoomify window on your browser to see the full resolution "up close".  
The original 16-bit per color image was reduced to 8 bits per color, and some of the white background was cropped away to reduce the image file size to 103 Mbytes.  High-quality JPEG compression subsequently reduced this file to only 2.2 Mbytes!  You won’t be able to find subtle highlight details like those shown above in this highly-compressed image, but you’ll be impressed with how well the Ebony view camera is put together, and at how much image detail CAN be conveyed in a 2 Mbyte file.

          CLICK HERE to download a 2.2 Mbyte JPEG file of the Better Light image of the Ebony SV45U2. 
          NOTE:  This file becomes a 103 Mbyte image when opened in an image viewer or editor.

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