Focal Plane Shutter


What makes a high performance shutter? Is it the 1/8000 sec. shutter speed? Is it about the continuous shooting, how many images you can take per second? Perhaps, durability is another important factor.

You can check these numbers on the specification sheet in the catalog. We obviously looked into these spec when we developed the shutter of X-Pro2, but we also gave much consideration into things that are not talked in the spec sheet.

One is the "Shock".

The term "Mirror shock" is getting popular these days. The mirror in the DSLRs moves when you press the shutter. The term refers to the small vibration that is caused by the movement. The vibration makes the images to get blurry. It is not a placebo, the resolution is indeed affected, and you can see it in the measurement score.

So, many of the DSLR shooters use the "Mirror lock-up" feature when it's necessary. The result in the image quality is quite big. If you are using a tripod, this technique is highly recommended. But perhaps many of use mirrorless camera, X-series in particular. You may be happy with the fact that there is no mirror in your camera and that you do not deal with the "mirror shock" dilemma.

You are correct. If the camera is mirrorless, then you will not have the problem. But you also need to be aware that when the shutter curtain moves, there also is the tiny vibration caused by the movement. Of course, the amount of the shake is significantly smaller than that of the mirror, but absorption of the impact is very critical, regardless. The sensor has higher pixel count and is low-pass filter less. The lens has sharp image quality in the high frequency range to go with the sensor. In order to maximize the benefit of the advanced technology, we need to take these little things into consideration if they may have an impact in the result.

Shutter unit

We first study the mechanism of the shake. The front curtain lifts up. runs, the rear curtain runs, then and charges. When does the big shake occur? How can it be minimized? How can it be processed?

Many tests have been conducted with various vibration suppression materials and mounting of the shutter unit. We have good guesses of the outcome, but the process itself requires much patience. We change the parts one by one, and then mount it to the camera. We release the shutter at every speed and measure the result. When one combination is done, we go for the another to find the best combination. The process is not the most efficient, but is a sure one.

Another topic we talk a lot was the "Sound".

FUJIFILM is probably a minority when it comes to shutter sound. We make it to be "quiet", "unoticeable", and "gentle" as much as possible. Our developing parter has once said that "There is no other company that is as picky as FUJIFILM when it comes to sounds". We have even had requests from the users to make the sound more apparent, so that they have better sense of releasing the shutter".

However, if the sound is louder and more obvious, then it may interrupt the shooting. Especially if you are doing reportage or street snap, where the main subject are the people in the street, then you need to be unobtrusive. Becoming unbobtrusive and friendly to the subject is among the goal of the X series cameras.

Photo by Bert Stephani

To achieve the goal, the sound volume and quality were analyzed and then tuned. The rigorous testing of the "shock" showed a positive result for the "sound". We learned that the "good sound" was proportional to the "good image quality". But the final brush-up had much to do with the peripheral rather than the shutter unit itself.  It was a simple test. The sound differed when the lens was attached and when it was not attached. This is because the sound gets muted when the mount is covered by the lens. You can see the big impact that the housing of the shutter unit may have with this. 

The shutter sound also changes depending on the camera body. The sound is an out of the complex combination of the material, form, build, availability of sealing, and other parts installed in the camera body.

It is difficult to change the mechanism just for the sound, but we can look into it upon designing. The design is boring if it's all about the numbers and specs. We believe the important element is hidden in these emotional aspect of things.

Categories:  X-Pro2, Stories, Technology
Tags:   shutter , development story
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