I don’t normally write about equipment in this blog but I’m making an exception in the hope that someone might find this interesting.
I recently compared the 80Mpx Leaf Aptus II 12 single-shot digital medium format back and the 312Mpx Anagramm Production2 5 x 4 inch scanning back. My employer has owned an Anagramm Production2 scanning back for several years. This has a resolution of 13,000 x 8,000 pixels and is used for digitising larger books, maps and artwork from our collections. (Each pixel records R, G & B colours hence the 13 x 8 x 3 Mpx count). We currently use Phase One P45+ backs (7,216 x 5,412px, i.e. 39Mpx) to digitise smaller items. Leaf recently released a back of 10,320 x 7,752 px, i.e. 80Mpx, and I recently spent an afternoon evaluating the Leaf back against the Anagramm. I was impressed by the quality of the Leaf to the point where I would advise anyone looking to invest in a scanning back to seriously consider the new 80Mpx backs from Leaf (since Phase One are releasing an 80Mpx back based on the same chip, this would also be worth evaluating, though the additional sophistication of the Phase One back will be largely wasted on the digitisation applications I am mostly involved with). In the time available I could only evaluate the fidelity of resolution, not colour. I used the same camera and lens, column stand, lights and original artwork, which ranged in size from roughly A4 to A3. The camera was a Linhof RD-1 with 180mm f5.6 lens. This lens had a built-in infra-red filter though this was only necessary for the Anagramm scanning back, since the Leaf has an infra-red blocking glass as part of its construction. It was necessary to adjust and re-focus the camera for each image and, since the Leaf has a much smaller sensor area than the Production2, I was more restricted on the size of original I could copy with the Leaf. I cropped much more tightly with the Leaf than the Anagramm, which had the effect that 100% enlargements were about the same size from both backs.
I chose 3 Japanese woodblock prints from our collections. These had a lot of detail right down to the paper grain and the inker’s wiping marks, so these should be a good test. All test shots were exposed so that the brightest highlight fell substantially under the 255 saturation point. The dynamic range of all medium and large format backs is well able to cope with the reproduction of the works of art we normally digitise, though I made sure I included an item with reflective gold on it just to make sure the Leaf could rise to this challenge (it did, with ease). I also white balanced all images against a Qpatch included in each shot. The Leaf back was set to its native ISO50 setting. The Anagramm back is not calibrated to ISO film speeds: instead I set the scan speed to Fast (1 notch down from Very Fast) and the fine control, or amplification, came out at 96% to achieve good exposure. I used well-ballasted continuous lighting for the tests. The ballasting reduces flicker, which is significant when the Anagramm back is scanning on fast and very fast settings. The ballasting won’t be of practical significance for the Leaf back.
So here are some results, full frame image and 100% enlargement:
The results amazed me when I saw them side by side on the monitor: I had previously seen a significant difference between the 39Mp back and the Production2 back, but this time the ability of the 80Mpx Leaf and the 312Mpx Anagramm backs to distinguish detail was very similar. No sharpening was applied to the images, however the process of down-resolving to create the above JPEGs has reduced the quality noticably. Remember that the backs were not colour-profiled so you cannot judge the colour quality in this test.
I timed the process of composing, focusing, setting exposure and white balance and capturing the image. Both Anagramm and Leaf took 4 minutes 30 seconds. If subsequent images could be taken without further adjustment, the scan time of the Anagramm was a minute whereas the shutter speed for the Leaf was 1/30th of a second. So from a production point-of-view the Leaf would win hands down – this productivity is worth a lot of money. In practice we use Mamiya cameras with P45+ backs for their speed. We find that we can digitise 5 times as much material with the P45+ compared to the Production2, so we reserve the Production2 for large items such as maps. The Leaf Aptus II 12 and the Production2 both have a “live view” refreshed at several frames per second, which makes focusing so much easier and safer than using the Mamiya’s viewfinder a long way up a column stand – another reason to trade up to the Leaf, but this time from the P45+.
There is a tendancy for digital copying processes to enhance the contrast of the image in comparison to the original, and the Leaf did just that. Although a custom ICC profile would help (I will do this if I can get my hands on the back for a bit longer), it is still necessary to adjust the final image, from whatever source, manually alongside the original to get the ultimate fidelity to the original. I don’t normally have the budget to do this so it is important to me that the calibrated workflow gets as close as possible to the original without manual adjustment. The indication from my testing so far is that the Leaf will do an excellent job. The Leaf seems to come so close in quality to the Production2, with the advantage of speed and smaller file size, that it is hard to see the justification for the 312Mpx scanning back.
The quality achievable from high megapixel cameras needs scrupulous attention to detail in lens quality, rigidity of support and quality of lighting. Accurate focusing is also essential. But get these right and the Leaf Aptus II 12 can produce exceptional results.
My thanks go to Andy Quiney of Peartree Rental Ltd., and Yair Shahar, Product Manager at Leaf Imaging Ltd For their time, interest and equipment in making this test possible. The School of Oriental and African Studies provided its digitisation facility and equipment for the test.