Fat Magic Pixie Dust
Ok, so what does this title mean? You have to ask? Well, ok then. There is a term called Fat Pixel Magic(!) that refers to legacy digital backs that had larger photosites than newer backs. These were typically 9 microns (16mp, 22mp backs) versus the 100mp, 150mp digital back models of today, which feature pixel (photosite) sizes from 3.8 microns to 4.6 microns. So what about some of the newer legacy digital backs, like the 60mp – 80mp backs that had 6.0 and 5.2 micron photosites. Nope, not close enough, there is something about the 9 micron photosites that is special. They produce a certain type of look. Terms are thrown about like “smooth”, film-like”, the word “rendering” is used quite a lot. You don’t hear the term rendering being used much when describing output from a 150 megapixel digital back. So the 9 micron legacy backs clearly have something different about them, something special.
Or do they?
Ok, let’s get more direct. I have from day one, been a bit skeptical about this – but just a bit! I don’t know that I ever felt like I noticed Fat Pixel Magic, and I have been involved with high end digital backs going back to the 6 megapixel days. But I do feel like I notice a certain crunchiness with newer digital capture products, whether they are a 46mp Nikon DSLR, or a 150mp IQ4 150. The visual emphasis seems to be on detail. While the visual emphasis with the legacy digital backs is described as smooth, film like rendering by the Fat Pixel Magic Club.
So … yes, I do like to be skeptical, I am an evidence-based person, but at the same time, I am fair, and I do want to believe. But it’s very hard to test, apples to apples, yes, you can shoot a newer digital back with more and smaller pixels and downsize the output, but then it isn’t really apples to apples, it wasn’t captured at the same resolution as the Fat Pixel Backs. But then I was thinking … if they just had a 20 something megapixel digital back with smaller photosites I could do a more direct comparison and see if the size of the photosites is really what is at play here. But sensor sizes have gotten bigger, and pixels have been added so …
But wait! What about the 60mp and 80mp Phase One IQ digital backs? These have Sensor Plus. Sensor Plus combines information from multiple photosites and creates a file that is 25% of the active number of pixels as the normal resolution, while also gaining roughly 2 stops of sensitivity (resulting from the specific manner in which Phase One accomplishes this task). So a Sensor Plus file from a 60mp digital back is 15 megapixels and from an 80mp digital back it is 20 megapixels. And yet, even though the result is 25% of the normal size file, the photosites themselves are still 6.0 and 5.3 microns, respectively.
So I decided this is as close as we can possibly get to analyzing the question. And the question is – is there really any magic or not? And if so, is it because of the size of the photosites, or something else? And so I decided to put the pedal to the pixel and do some testing.
I am going to allow you the viewer to determine what you think you are seeing. But there are a number of potential conclusions that can be produced from this testing.
Scenario One: The Sensor Plus files from the IQ280 still lack the film like smoothness of the P25 Fat Pixel Back. This would mean that in all likelihood, the size of the photosites has something to do with the result.
Scenario Two: The Sensor Plus files from the IQ280 very much resemble the film like smoothness of the P25 Fat Pixel Back. Naturally there are differences, but in terms of the rendering, and whatever is meant by that from Fat Pixel enthusiasts, this would mean that in all likelihood, the size of the photosites has nothing to do with the result.
Let’s take Scenario One first – in that case, guess what, Fat Pixel Magic Believers win. Keep your P20 or your P25 and keep on keeping on. You were and are right!
But let’s look at Scenario Two. In this event, the Fat Pixel Magic potentially becomes a myth! If you are holding onto your Fat Pixel magic digital back because you feel that if you upgrade to enjoy some of the advantages of the newer digital backs you’ll lose your FPM (Fat Pixel Magic), then you are deluding yourself, and more importantly robbing yourself of advantages that are relevant to your photography.
So, out I went. In my bag I had:
- Phase One P25V Mount
- Phase One IQ280V Mount
- Hasselblad 503CXi
- Hasselblad 50mm CF Lens
- Hasselblad 120mm CF Lens
- Arca Swiss Cube Tripod Head, Classic
- Induro CT213 Carbon Fiber Tripod.
That’s right! I used Zeiss lenses, because what could be better at film like rendering??? So the ultimate FPM Kit – P25, Hasselblad 503 Camera, Zeiss glass. Versus the IQ280 and those pathetically puny little 5.3 micron photosites on the same camera, same lenses.
My shooting process was using a Kaiser Locking Release Cable with mirror up.
But I had challenges! I had to manually focus the lens. And my manual focus skills have never been tops, ever. It’s perhaps the weak point of my photography (one of many). So for every shot, I would start out with the IQ280 mounted first. Why? Because the screen on the P25 is so bad, there is little hope of being able to tell whether anything is in focus or not. So I would focus and shoot with the IQ280, then I would check my results on the excellent 1.1 million dot, 3.2” touchscreen. Once I had my focus locked down, I would finish the shots, in both 20MP Sensor Plus and 80MP Full Rez, then remove the IQ280, pop the P25 on there and shoot the same shot with the same focus position on the lens. Yes, there might be small differences in focus due to sensor position, etc, but close enough for this test.
The screen was a huge obstacle in numerous ways. Even checking for composition and framing was challenging on some shots when I had the camera up high and at an angle, I could not even see the screen well enough to really know what I was getting in my frame. Now here’s the amazing thing that has to occur to everyone. People are still using these digital backs and getting great results with them. So they manage. And they’ve been managing for years. It’s not the end of the world. But – having the advantage of the IQ screen is an undeniably huge plus, and could certainly make the difference between some shots being successful and others not.
With the low quality of the P25 screen, I resorted to using the histogram, which got me close enough in most cases for a usable exposure. I did find that the P25 when exposed at the same settings as the IQ280 was about 3/4 stop less sensitive, so I could not just copy exposure settings.
In addition, being able to review the images with specialized review tools of the IQ280 like the dual highlight clip tool and the zone exposure tool was a time saver and provided a more accurate assessment of what I had actually shot. What was the exposure on that tree trunk? Is the sky too bright or just right? Much easier to do with the IQ280.
But nonetheless, I was able to get all my shots done with both digital backs. Below are the results. For post processing, file specifications and adjustments were as follows:
- All files shot in Auto White Balance
- All files had the default profile changed from “Flash” to “Outdoor Daylite”
- Spectrally neutral targets were captured, and where the color was improved, these were applied (which covered most but not all scenarios)
- Other than White Balance and Base Characteristic Profile, all settings were at default except as noted below.
- Luminance Noise Reduction set to Zero
- Modest adjustments were made via Exposure Slider if the exposures of the same shots varied too much
So what do you think?
Of course you can’t easily tell differences in detail from the jpgs above. So these files are available to download as raw files at the bottom of the article.These are packed as EIP, but do with them what you will. It would be interesting to downsize the 80MP full rez files and compare. It would be interesting to print them out (though this introduces some additional variables).
There are strong arguments to be made for both capture systems. I did find that the P25 files had a more homogenous rendering in terms of color and tone. The quality of the files overall was outstanding. On the negative side, I found the greens had a slightly unnatural appearance, and could even approach an over saturated glowing sort of effect, particularly when slightly overexposed in strong light. And while the homogenity produced a certain smoothness, it also gave the entire scene a sort of perceptive cast, or global tone.
I do feel like I can pick up that the files from the IQ280 have a bit more punch, a bit more contrast. It’s not always easy to see or assess because the exposures and lighting has just enough variance to prevent a true apples to apples comparison. But I think I can say yes, I see more evenness or smoothness with the P25 files. To my eyes, the files from the IQ280 do appear to have more independent separation of colors. Earth tones (browns, reds, oranges, yellows) are more saturated and accurately display the variations within the subject matter of those tones more effectively than the P25.
And within all this I can’t help but wonder if I can’t get more of that smoothness, just by pulling back a bit on some of the tonal controls I have at my disposal with Capture One. Minus X percent Contrast, minus X percent Clarity, and do I not have a file that is quite similar to the P25 in terms of the feel? But with better color?
My final word is that when we produce comparison tests, we have a hunch of the outcome, but are often surprised by the process and the results. This test was no exception. I’ve been interested in the Fat Pixel Magic phenomenon for some time now, but never have I seen anyone really do a good job of quantifying what the magic is and nowhere have I seen anyone do an apples to apples comparison, which is admittedly very difficult.
So what does all this mean? There’s no loser here. I think that FPM digital back owners have an excellent imaging tool (that is likely paid for) that they have been working with for years and why change? They like the file quality and have a preference for the FPM “look”. Those same owners also have an opportunity now, with CCD-based digital backs at historically low prices, to upgrade their P/P+ digital back to a digital back that provides superior color (at least to my eye), and a very significant enhancement in usability with the much higher quality LCD screen and the image review tools. Not to mention continuing service and support.
And with Sensor Plus, you have a capture device that can continue to capture at similar resolutions to what you’re used to, and perhaps with a bit of tweaking a very similar rendering, while also having the opportunity to shoot at even higher resolution, should the situation call for it. Did I mention that the P25V and the IQ280V that I performed the tests with are both available for sale in our inventory at excellent prices? So will this article lead to more sales of 60mp and 80mp CCD-based digital backs for us, and will we move some of the older P/P+ series backs in our inventory? I don’t know the answer to that, but I sure did enjoy spending several days shooting old school and (sort of) new school digital backs on an old Hasselblad.
