possibility: real-time Fisheye perspective correction on live view

Discussion in 'Open Discussion' started by Yong, Jan 23, 2016.

  1. Yong

    Yong Mu-43 Regular

    Sep 25, 2014
    While I'm on looking for ultra wide angle prime lens options, I discovered weakest lines of my beloved system. We don't have any prime lenses shorter than 12mm, excluding manual lenses from 3rd party manufacturers. I'm not interested those manual lenses, since AF is too good to be given up. It's so fast, accurate, and not bothersome, especially when it comes to perfectly implemented touch focusing&shutter release of m4/3 cameras. Combined performances and features, AF is a competitive advantage of this system.

    I digressed. Anyway I found some fish eye lenses instead of absenting rectilinear ultra wide angle lenses. But they are, yes, fish eye lenses. Unlike general lenses, they have curvilinear perspective, not rectilinear perspective. I know I can straighten them on computer after shooting, but I can't see straightened lines WHILE I'm shooting. I think I can't imagine straightened pictures seeing curved pictures on camera, and this would weaken composition of my works. That's the thing I can't handle.

    So here comes my suggestion: de-fisheye conversion on fly.
    Every digital cameras are something small computer specialised to image capture.(especially it's the case for mirrorless cameras) Because straightening curvilinear perspective is done by computer, we could do this on computer before capturing. Then we'll see rectilinear perspective with fish eye lens while shooting on flied, not sitting in front of computer.

    Shouldn't this be possible already? So far we're used to shooting with DSLRs, And they inherently don't allow this features. There's no way enable de-fisheye conversion for optical view finders. But mirrorless surely can. If manufactures provide perspective distortion datas for each lenses in their firmware, then they can be corrected on live view. Shooters could have choice for de-fisheyeing or not. If Olympus and Panasonic provide this feature by firmware of introduce with new cameras, we'll have two ultra wide angle lenses instantly. And perhaps it would be easier to introduce new fish eye lenses on the market, since they are no more mere speciality lenses appeals to minority. In short, I want this feature enabled if this is really any possible.

    Maybe I can misunderstanding something. But I believe this can be an one more advantage of mirrorless cameras. Mirrorless concept is a truly digital approach, not like DSLRs. With advances of computer vision technologies, we can exploit its inherit strength better.
  2. wjiang

    wjiang Mu-43 Hall of Famer

    A great idea. Doable, but you probably don't want full rectilinear reprojection. A 180 degree fisheye is so wide that if reprojected to rectilinear you'd see mostly corners. The processing engines might not be able to keep up with live view ATM but I'm sure we'll get there some day.
  3. Phocal

    Phocal Mu-43 Hall of Famer

    Jan 3, 2014
    I have shot with mine so much now that I can predict how it will come out when de-fished, which I actually don't do a lot of......prefer to shoot in a way that takes advantage of the lens attributes, like this shot.......no crop no de-fishing

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  4. Bruce McL

    Bruce McL Mu-43 Veteran

    1. There's the Olympus 9mm body cap lens. Has manual zone focusing. Leaving the focusing switch in the hyperfocal position gives a very deep depth of field.

    2. If focus peaking is possible, then, yes, lens correction should be. Aren't there cameras that have fisheye as one of the art filters? I wonder if the fisheye effect shows up live on those cameras. I do worry about the need for processing power: having the camera get warm, draining the battery. If they didn't try to make the display perfect it might be possible to do it with a lot less processing power.

    My camera has a "Monochrome Live View" setting that saves the images in color while I compose in grayscale. I find this helpful in composing with the 9mm lens. Color is more information than I need.

    Back in the days of film, people used to talk about pre-visualization. With 28mm(equivalent) focal length, I have a pretty good idea of what I will see before I raise the camera to eye level. I'm pretty good at 40mm(e) as well. But with the 9mm BCL, at 18mm equivalent, it's going to take a lot of practice. It's kind of fun going out and trying things to see what they will look like, but I would like to get better at finding good shots.

    3. I agree with your conclusion. Focus peaking is one expression of the strength of mirrorless. I think there are more possibilities.