Last week, we pointed you to a piece by the New York Times on how Fujifilm is attempting to kill moiré without killing sharpness by designing its sensors in a way that eschews the traditional anti-aliasing filters used in digital cameras. Photographer Martin Doppelbauer disagrees with Fuji’s claims: he has published a piece arguing that, “digital cameras without aliasing filters are cameras with a built-in design flaw“:
To omit an alias filter in front of a digital image sensors is like building a sports car with no brakes. Of course, the car accelerates a little faster due to the lower weight and the cornering ability is also better due to the smaller unsprung weight – but ultimately it lacks an essential functional element.
For analog cameras, an alias filter is not required: Film has no sharply defined limit of resolution. It loses contrast and resolution gradually with increasingly higher frequencies. You could say, the low-pass filter is already incorporated in the film itself.
[...] By omitting the alias filter, the recorded image information [...] does not increase! Even though images of cameras without aliasing filters may appear sharper and crisper: Images of cameras with a proper alias filter can easily be re-sharpened to achieve the same visual impression – without side effects.
So according to Doppelbauer, the recent fascination with removing anti-aliasing filters is more based in marketing rather than science.
Alias-filters: Yes or No? [Martin Doppelbauer]
Fujifilm’s new X-Trans sensors diverge from the traditional way CMOS sensors are designed by using an irregular pattern of red, green, and blue pixels. This allows the sensors to eschew the standard anti-aliasing filter, eliminating moiré patterns without putting an extra component in front of the sensor. Roy Furchgott over at The New York Times has an interesting piece on how the new tech is inspired by Fujifilm’s glory days in the film photography industry:
Old fashioned analog photographs didn’t get a moire pattern because the crystals in film and photo paper aren’t even in size and placement. That randomness breaks up the moire effect.
So Fuji built a new sensor employing what it knew from the film business. Instead of using the Bayer array, it created a pattern called the X-Trans sensor which lays out the red green and blue photo sensors in a way that simulates the randomness of analog film.
Furchgott does a good job of explaining the new sensor design (and its benefits) in an easy-to-understand way.
Old Technology Modernizes a Camera Sensor [NYTimes]
Reviews of the new entry-level full-frame Canon 6D DSLR are starting to make their ways onto the Web. While most reviewers seem to agree that the still image quality of the camera is quite good, the camera appears to suffer from a horrible moiré pattern problem. Gizmodo created the comparison test above pitting the 6D against the 5DMk3, and writes in their review:
All signs pointed toward the 6D sharing the same great video quality of the 5D MK3. The thing that the 5D3 does so well—that no other DSLR has accomplished—is reducing moire patterns (rainbow-like bands along detailed surfaces). But the 6D fails where the 5D3 prevailed. Moire is rampant. This single failure ruins the 6D as a viable alternative to the 5D3 for professional video.
If you’ve been eyeing the 6D, you might want to look elsewhere if solid video recording performance is a must-have for you.
Canon EOS 6D Review: Beautiful Full-Frame Stills, Crummy Full-Frame Video [Gizmodo]
P.S. You can find some other sample videos captured using the 6D here. The camera performs quite well in low light at high ISOs.