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Leaf Valeo 22
Revisited

A Leaf of a Different Colour

This review is part of a larger series of ongoing articles and reviews of medium format digital backs.
If you have not already done so you might wish to begin by reading my Digital Back Survey
and then refer to the other reviews in this series that are linked at the bottom of that page.


Leaf Vaeo 22, Digital Magazine and iPaq

 

As part of my Digital Back Survey which first appeared here in September, 2003 I published the world's first review of the new Leaf Valeo 22, one of only three 22 megapixel medium format backs currently available. My review was necessarily limited because the only sample back available was for the Mamiya 645 AFD, while my medium format reference system is the Contax 645. This meant that while I could work with the back and its files, I couldn't compare them to identical frames shot with my Contax and Kodak DCS Pro Back 645 — again, my personal reference system.

In early November I was visited by Ilan Carmi, Leaf's Product Marketing Manager. He had with him a Valeo 22 back designed for the Contax 645, and we spent one morning filming an interview with Ilan for the Issue #9 (Dec. '03) issue of The Video Journal. In this discussion we examined the Valeo 22 back and discussed its features and capabilities. We also had a broad-ranging discussion about the digital back and camera industry in general, and the future of large-sized imaging chips.

The next day provided us with the opportunity to take some carefully controlled test exposures with the same camera and same lens at the same time. Finally, here was an opportunity to truly compare the $12,000 16MP Kodak back with the $29,000 22MP Leaf back.

Our test consisted of two parts — colour rendition and noise / resolution. All shots were taken with the camera tripod mounted and locked off. Nothing was changed other than switching the backs. Metering was consistent and determined via the camera's meter as well as evaluation of the histograms produced. A Macbeth colour chart and skin tones were one subject, while some fall leaves under overcast conditions was the other. White Balance was set via a Kodak Gray Card.

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Colour Rendition

The frame immediately below shows Illan holding a Macbeth colour chart. The descriptions that I provide here are of what I see on a calibrated and profiled monitor. The comparisons are against the Macbeth colour chart as viewed under an Ott-Light True-Color daylight-balanced fixture. (These sRGB JPGs may or may not show you what I describe, depending as well on the adjustment of your particular monitor. Go by what I say, not by what you see below).

Both frames are crops, but neither has had any adjustment done to them in either RAW conversion or in Photoshop, other than Gray Balance.

Kodak DCS Pro Back
Leaf Valeo 22
Fig. 1

If you've read the original Valeo review and comparison you'll recall that there was not a huge difference between the backs in terms of their colour rendition. The Valeo does a better job with blues and purples while the Kodak does better with greens and yellows. Neither difference is significant for anything except exacting product or scientific work in which case the photographer will custom profile the back in any event.

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Resolution

Below are full-frame reproductions from the two backs. They are reproduced so that the vertical dimension is the same. This shows what the extra chip real estate of the Valeo 22 provides. We did the shots from the exact same position (only the backs were charged), with the same lens. Exposure was according to the camera's average metering but we adjusted each back's exposure based on reviewing a post-exposure histogram. The reason for this is though both cameras were set to ISO 100, this does not mean that both necessarily would want the same exposure. Sensitivity differences between them called for slight variations to get the best exposure in each case.

Kodak DCS Pro Back
Leaf Valeo 22
Fig. 2
Larger versions may be viewed by clicking on each image

The Kodak frame was processed with both Kodak Capture Studio and Adobe Camera RAW, (more on this in a while). The Valeo 22 frame was processed with Leaf Capture V8 software. In both cases we did the RAW file conversion by selecting the wall of the shed as our gray point (it measured almost exactly equivalent to a Kodak Gray Card) and we adjusted Black Point and White Point in each case by eye.

Other than the wider frame from the Leaf's larger chip (almost full-frame 645 vs. the Kodak's square format), it's likely that the first thing to catch your attention will be the difference in the colour rendition, especially the greens. The Kodak back's greens appear more saturated, though we at first agreed that the Leaf's greens were likely more accurate. We then went back outside and were surprised to see that it was the Kodak's greens which appeared more natural. We even took a sprig of the fir tree and brought it indoors and placed in under a 6500K evaluation lamp. Indeed, and much to both of our surprise, the Kodak's green's were more accurate.

Kodak DCS Pro Back
Leaf Valeo 22
Fig. 3

So too were the yellows — more so than the Macbeth chart would have lead us to believe. Above in Fig. 3 is a 100% enlargement of one of the leaves. Again we brought the leaf itself indoors and compared it under a daylight balanced light source with the images on screen. The Kodak back reproduced the yellow / green leaf more accurately than did the Valeo 22, which was quite a bit more yellow than reality. We repeated the test with another Valeo colour profile and did not find a marked difference.

Fig. 2 is also worth examining for resolution. There is little to choose between them, as both backs have the same vertical pixel count and both have the same pixel size (9 micron). After careful study of these and other images we came to an agreement that there appeared to be very slightly higher resolution to the Valeo 22 images, but we at first weren't sure why. When we came to evaluating shadow detail the reason became apparent.

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Shadow and Dynamic Range

The Valeo 22 is a true 16 bit back, while the Kodak Pro Back is 12 bits. Does this make a difference? Yes, it does and it visually looks to be about a quarter stop or so better.

Kodak DCS Pro Back
Leaf Valeo 22
Fig. 4

In Fig. 4 above we see the extra shadow detail and also what appears to be slightly higher resolution. The reason for the apparent extra resolution became clear when we looked at the separate Red, Blue and Green channels.

Kodak DCS Pro Back — Blue Channel
Leaf Valeo 22 — Blue Channel
Fig. 5

The Red and Green channels showed little variation. But the blue channel told a different story. This channel on the Kodak was very noisy in the shadow areas while on the Valeo there is little noise difference between the Blue and the other two channels. The Blue channel is the least sensitive on most sensors and this difference is the most glaring between these two backs. (I have lightened the Blue channel in Fig. 5 above to better show the differences).

This blotchyness degrades the Kodak image in two ways. It makes the shadow areas appear darker than they otherwise might and also reduces resolution on that channel. The net result is a slight degradation of image quality over that of the Leaf, which is exemplary in this regard.

I mentioned above that the Kodak frame was processed both in Kodak Capture Studio and Adobe Camera RAW. I noticed that Capture Studio did a much better job of minimizing the Blue channel noise than did Camera RAW, but the noise was still there, and noticeable.

Finally, it needs to be noted that all tests were done at ISO 100. The Leaf tops out at ISO 200 while the Kodak can go to ISO 400. On the other hand the Leaf also works at ISO 50 and ISO 25. Indeed ISO 25 is the Leaf's "native" sensitivity and it is safe to assume that this speed will produce the back's highest image quality.

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The Bottom Line

The Leaf Valeo 22 is a very impressive accomplishment. It is currently the only completely self-contained 22 Megapixel back for medium format cameras that doesn't required a tethered computer. Image quality is first rate and I find the use of an Ipaq PDA as a review screen and control device to be worth the hassle. The digital magazine with its 10GB Firewire hard drive and self contained batteries works reliably and smoothly. In the studio the Valeo 22 hooks up to a computer (Mac only at this time) to provide a full-featured tethered solution. The V8 RAW conversion software is as good as it gets.

All of this begs the question — is to worth $29,000 in its mobile configuration, and is it worth more than double the price of a Kodak DCS Pro Back 645, my reference system? Let's look at it this way. If I was a studio photographer doing high-end product or fashion work where the cost difference would matter little over the long run, and the largest image with the highest quality was paramount then, yes, the Valeo 22 would be my choice.

But, I'm not in that category. I shoot almost exclusively in the field, and price is an issue. I want the best possible image quality but recognize that the price / performance curve gets very flat at this end of the spectrum. Even minor improvements in image quality or chip size costs a great deal. For me the Kodak back remains the ultimate medium format digital back for highly mobile field use, and likely for many other applications as well. The Leaf Valeo 22 though shows us what can be accomplished when money is almost no object. It is a device to be coveted.

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Issue #9 (Dec. '03) of The Luminous Landscape Video Journal will contain
an in-depth interview with Illan Carmi, the Leaf Valeo Product Marketing Manager.
In it we discuss a range of digital imaging topics including the future of high-end digital imaging chips.

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This review is part of a larger series of ongoing articles and reviews of medium format digital backs.
If you have not already done so you might wish to begin by reading my Digital Back Survey
and then refer to the other reviews in this series that are linked at the bottom of that page.
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Concepts: Raw image format, Digital photography, Photography, Digital camera, Camera, Color, Phase One, Color chart

Entities: The Kodak, my choice, Capture Studio, ISO, White Balance, Michael Reichmann, Leaf, Illan Carmi, The Video Journal

Tags: Kodak, Valeo, leaf, medium format, image, Leaf Valeo, digital back, cameras, reviews, image quality, Digital Back Survey, colour rendition, Macbeth colour chart, blue channel, Kodak Gray Card, Kodak Capture Studio, format digital backs, Kodak DCS, Adobe Camera RAW, Kodak frame, Product Marketing Manager, new leaf valeo, Valeo 22 frame, Valeo 22 images, chips, Valeo 22 hooks, Leaf Valeo Product, Valeo colour profile, original valeo review, shows, ongoing articles, higher resolution, larger series, Video Journal, imaging chips, better job, RAW conversion, shadow areas, medium format backs, Kodak image