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Fujifilm X-Trans CMOS sensor

Fujifilm has along history in designing its own unique sensors which don't use conventional Bayer-pattern colour filter arrays. The X-Trans CMOS is the latest design to emerge from its out-of-the-box thinking, and while it uses a conventional square-grid pixel layout (unlike the company's EXR compacts), the colour filter array over the pixels has been completely redesigned. The result, according to Fujifilm, is minimal susceptibility to colour moiré, which in turn allows the company to dispense with the anti-aliasing filter that's used by almost all other cameras. In principle, this means the X-Pro1 should be able to resolve more detail than Bayer-array cameras with a similar pixel count.

The color filter array

Almost all digital cameras use what it called a Bayer color filter array, named after the Kodak engineer who developed the pattern. Over the years it's proved to be an excellent way of capturing both color and detail in a scene. Essentially, it consists of a simple repeating pattern of four pixels, two of which are sensitive to green light, one to red and one to blue, in a square RGGB layout.

However, one problem with the Bayer array is its susceptibility to false colour artefacts when faced with an image that contains finely-repeating patterns (such as textiles), caused essentially by interference between these patterns and the regular grid of photosites. This results in unsightly bands of color, and in most digital cameras is suppressed by the addition of an optical low pass (or 'anti-aliasing') filter in front of the sensor that blurs away the finest image detail. This reduces any moiré patterns, but with an inevitable loss of resolution.

Film never showed an analogous effect due to its random grain structure, and Fujifilm's engineers reasoned that modifying the sensors' colour filter array to make it look more irregular would have a similar effect. The result is the X-Trans CMOS's 6x6 colour filter array, with red, green and blue photosites on each row and column (diagrams courtesy of Fujifilm):

The common 2x2 'Bayer' pattern used in most digital cameras The 6x6 color filter array pattern of Fujifilm's X-Trans CMOS sensor

Use of an unconventional CFA is not without its complications, though; most obviously, it demands a completely different demosaicing algorithm for RAW conversion, which complicates third-party RAW support. The more-complex demosaicing also demands an upgraded in-camera processor, which Fujifilm calls the 'EXR Processor Pro'.

The elimination of the low-pass filter has knock-on benefits - it allows the shutter to be set closer to the sensor, which in turn enables more flexibility in lens design as the 'back focus' distance from the rear lens element to the sensor can be shorter. This is reflected in the lens mount specifications for the all-new 'X' mount, which allows a back focus distance of a mere 10.2mm.

All-electronic X mount

A new camera system requires a new lens mount, and Fujifilm has duly complied with the 'X' mount. It offers few surprises to anyone who's been following recent developments in mirrorless camera systems, being an all-electronic bayonet mount with ten contact pins for communication between the camera and lens. The lenses released alongside the X-Pro1 have traditional-looking aperture and focus rings, but these have no direct mechanical coupling, and do nothing when the lens is dismounted from the camera.

The X-mount's claim to fame, though, is an extremely short flange distance (from mount surface to sensor) of 17.7mm - shorter even than Sony's E-mount for its NEX system. The lenses themselves feature unusually short backfocus distances from the rear element to the sensor, and use large rear elements to maximise the illumination of the corners of the frame. The diagram below (again supplied by Fujifilm) illustrates this principle, here with the 18mm lens:

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Comments

Total comments: 13
bootsofspanishleather

I am a rather new member and I must say that the few dopey questions I have asked have usually been answered with great information and a lack of sarcasm and judgement. They were not dopey on purpose. If anyone would like to visit the images in my portfolio you will at least know that I am not just obsessed with cameras but sing them to shoot, share, publish et. So without further ado, just purchased a new Fuji X Pro1 and bam I read the rumor page and it says Fuji X Pro2 verified rumor will be introduced this year. Besides offering the advice, "just shut up and shoot', What would you do? Is this even the right spot to leave my qesriom

1 upvote
Gerardjan

Don't worry too much about it.I also just bought the X Pro 1,well aware of the rumors. It's all about IQ right?I can assure you,you wont be disappointed! Far away from it.And I really wonder whether the IQ(mind you, IQ!)will be very different from this one.
All else, yes for sure.

1 upvote
Don Sata

It will take you a bit of effort getting used to the AF of this camera but it's very engaging to use, the VF is great and images are great too.

If you don't shoot action (like sports, pets or running children) you will be ok.

1 upvote
theprehistorian

I bought an X-Pro1 a week or so ago - I've got a use for it (I wanted a compact 50 that's not too demanding) and they can be had new for £350 in the UK! Happy days. No doubt a new flagship X-Pro2 will be announced soon, but it'll be a very expensive camera, presumably sitting above the X-T1 in the range.

0 upvotes
BobFoster

Fujifilm has fixed most of the reported issues (like slow AF) with incremental updates. I got a chance to review it recently

6 upvotes
optofonik

What is the seemingly insurmountable problem with studying a traditional 35mm film rangefinder and re-engineering it into an equally capable digital rangefinder instead of trying to re-invent the wheel? The idea that you cannot accurately use manual focus is absurd. The whole focusing by wire thing is absurd. Again, why is everyone trying to re-invent the wheel?

Comment edited 1 minute after posting
0 upvotes
LightCatcherLT

things what you are asking do exist and they are called Leica.

1 upvote
paul simon king

looking at these RAW examples the fuji x Pro looks softer nad less saturated than the Fuji X100s

Comment edited 3 minutes after posting
0 upvotes
Dave Chilvers

After using one for a while and with the latest firmware I find the camera to be quite superb. Lets face it, most of us are looking for IQ firstly and has been said in the review lenses like the 35 1.4 are second to none in my book.

3 upvotes
bootsofspanishleather

I just purchased a used X-_pro1 like new in box and I am very curious about the firmware updates that seem to address its previous shortcomings. Should I ask the seller about these because I am naive and no nothing about these on her camera is it a simple fix to update the firmware Your recommendation I don't even know the latest and best ones. or are they available fre e or can they be user updated. and again what is the latest firm ware and how would you perceive this as situation.

0 upvotes
Nikonhead

The latest firmware update as of May 2015 is version 3.4 and can be downloaded from Fuji's website for free. Also check to see if your lenses are also up to date.

2 upvotes
bootsofspanishleather

Firstly I really would like to thank almost everyone for the generous and non combative input. So as long as I am curious about one further issue, any gracious input will be devoured with great enjoyment. Some lenses, whether short, medium or full on zooms have O.I.S and some don't. So any other advice on gaining sharpness and stability that works well for you, hardware wise , please let me know because I am well aware of the great impact shutter speed and stillness etc. have. And please take a moment to take a look at my gallery just so you understand that it is images and not equipment I am really hungry for. Thanks in advance, and yeah thanks Light Catcher LT for the real corn on the cob. "things what you are asking do exist and they are called Leica..Really??

1 upvote
darngooddesign

OIS helps when the shutter speed gets below 1/60.

Use as wide an aperture as possible and push the ISO up to 6400.

Brace the camera against your face with your left hand under the lens to steady it. A thumb-grip, like the Lensmate, helps as well.

Set the camera to continuous low and learn to fire off two or three shots. many times one will be sharper than the other.

After that, just practice being as smooth as possible while gently pressing the shutter release, I find a screw-in soft release button helps. Also, use a faster SD card like the Sandisk Extreme Pro 95 Mb/s.

1 upvote
Total comments: 13