Why aren't the electronic bright lines for framing in the X-Pro 1 viewfinder more accurate?

Question

The Fujifilm X-Pro 1 has a viewfinder which can switch between an electronic mode and an optical mode with an electronic overlay. One of the key features of this overlay is a "bright frame" — the optical finder shows a good deal more than the expected coverage area of the lens, and the bright line is supposed to show the actual frame.

But, in my experience, the frame line is drawn much too small — there's something between 5-10% off each side. Some of this is surely to cover for the parallax error (since it's not a through-the-lens finder in optical mode), but it seems like Fujifilm could have made the tolerances a little closer. As it is, I'm getting used to cropping in post — or switching to the EVF for critical composition, which is annoying, since the optical view is so much nicer for catching fleeting expressions.

I understand why lower-end DSLR viewfinders don't offer 100% coverage, as there are considerable and obvious savings in size, weight, and cost. But in this case the viewfinder shows a considerable margin outside the line: the overall finder is more than 100%. Since the bright frame is drawn electronically, why isn't it drawn to more accurately match the field of view of the mounted lens?

Fujifilm has clearly put a lot of work into the design and photography-focused user interface of this camera, of which the hybrid viewfinder is a centerpiece. So, surely the viewfinder frame lines work this way for some good reason. What is that reason?

Asked by mattdm

Answer

You can move your head around, and the frame will line up differently depending on your exact point of view. And wearing glasses, the frame will seem even smaller than without - because your eye is further away. Cropping is far easier than synthesizing something you thought would end up in frame, but actually didn't.

The viewfinder on a rangefinder camera should not be considered a device for exact framing, but rather choosing the direction of shooting. The bright frame shows you what's certainly covered. The expensive Leica M9 exhibits similar behavior.

Another issue is that the focal length of a lens is only approximate, with 5% variation not too uncommon. To make matters worse, adjusting focusing distance affects focal length on most of photographic lenses.

It would be possible to craft a more exact viewfinder if the human photographers had a standardized viewfinder-to-eye mount and lenses would report their actual focal length all the time. As long as these issues remain, it's better to err on the safer side.

Answered by Imre

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