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Game changer, a Sony E Mount camera that will AF legacy glass?

Discussion in 'Micro 4/3 News and Rumors' started by lenshoarder, Sep 2, 2013.

  1. lenshoarder

    lenshoarder Mu-43 All-Pro

    Nov 7, 2010
    It's a rumor, but a SR5 rumor which is pretty solid. It must be pretty far along since there's already a user reporting using it. Can this be a Sony slamduck surprise announcement for next week and not just the FF NEX?

    It's a camera that focuses by moving the sensor and not the lens. Thus it can focus any lens including legacy manual focus glass and 3rd party AF glass that can't be electrically controlled.

    (SR5) UPDATED: There is a Sony camera to come…also for Nikon and Canon lens owners! | sonyalpharumors
     
  2. jeffryscott

    jeffryscott Mu-43 Top Veteran

    505
    Jul 2, 2010
    Arizona
    Contax (edit, think it was a Contax film camera from the 90s that moved the film plane) used this concept. People loved the images from the camera, but from what I remember the AF wasn't the best (no surprise since it was a decade or so ago).

    Think it is a great concept and if it works, wow.

    Edit again: had I followed the link I wouldn't have had to say anything about Contax as it was mentioned already there. Doh!
     
  3. napilopez

    napilopez Contributing Editor

    826
    Feb 21, 2012
    NYC Area
    Napier Lopez
    Hard to see why it wouldn't work! Although I'm not familiar with the contax or the intricacies of this technique... would you have to calibrate it for each lens? Or perhaps it will auto-calibrate itself after the first shot or two?
     
  4. spatulaboy

    spatulaboy I'm not really here

    Jul 13, 2011
    North Carolina
    Vin
    Mad props to Sony if they can pull this off!
     
  5. lenshoarder

    lenshoarder Mu-43 All-Pro

    Nov 7, 2010
    There shouldn't have to be any calibration. If it's just contrast detection it'll just go until it thinks it's in focus.
     
  6. Ned

    Ned Mu-43 Legend

    Jul 18, 2010
    Alberta, Canada
    Probably would work, but looking at the video I can't see that mechanism focusing very fast. I'm sure I could still focus much faster by hand!
     
  7. Jonathan F/2

    Jonathan F/2 Mu-43 Hall of Famer

    Aug 10, 2011
    Los Angeles, CA
    Sounds gimmicky.
     
  8. pdk42

    pdk42 One of the "Eh?" team

    Jan 11, 2013
    Leamington Spa, UK
    Its speed will depend a lot on the mass that needs to be moved. How does a sensor's mass compare to the lens elements moved in conventional systems? The Oly IBIS does a similar trick and it clearly moves the sensor pretty quickly. If this new Sony system works well, it'll potentially reduce lens complexity and cost going forward.
     
  9. zap

    zap Mu-43 Veteran

    215
    Jul 23, 2012
    uk

    it does...
     
  10. kevinparis

    kevinparis Cantankerous Scotsman

    Feb 12, 2010
    Gent, Belgium
    I can only see this as being some kind of focus assist... get the focus manually in the right ballpark, and then move the sensor to get precise focus.

    I just had a look at an old Nikkor 105.... the back element of that moves about an inch between closest focus and infinity.

    Maybe my physics is wrong, but cant see how just moving the sensor would allow the full focus range of a variety of lenses

    K
     
  11. I'm thinking non-macro (unless the sensor can move back and forwards about three inches!), unit-focusing lenses only. Actually you could probably use a macro lens but it would need to be assisted manually as well. I'm not sure how this would work with any internally focusing or front-element focusing lens.
     
  12. drd1135

    drd1135 Zen Snapshooter

    Mar 17, 2011
    Southwest Virginia
    Steve
    It's certainly easier to move the sensor than it was to move the film plane in the old system. Here's an old article about the system used in the Contax AX: http://photo.net/equipment/contax/ax Here's the key problem with respect to the lens:

    "The second limitation is a little more complex - the use of lenses with a floating group. Lens designers developed the use of floating groups to maintain sharpness at close focusing distances. As the subject to camera distance decreases, and the lens is rotated to a closer focusing setting, the floating group moves to maintain sharpness. Remember that with the AX, the lens is normally set to infinity, so that the floating group does not have a chance to move to maintain sharpness at closer focusing distances. So.... a lens with a floating group must also be rough focused before allowing the AX's AF to take over."

    This article is from 1998. There are a lot more lenses like this these days. Still, rough manual focus is not that hard.
     
  13. Roterneylastergen

    Roterneylastergen  

    10
    Aug 31, 2013
    Well let's hope it turns out to be another great product from Sony.
     
  14. Ned

    Ned Mu-43 Legend

    Jul 18, 2010
    Alberta, Canada
    Yes, that makes a lot of sense. Even if implemented like that though, I think it would be good! That's the nice thing about manual lenses is that they stay where you put them. Thus, getting within that range manually then finishing off with sensor-AF would be a feasible method and thinking of it that way could be performed quite fast and efficiently. Even if they can make it move through the whole focus range, I'm sure that it will work much more efficiently if you rough-focus first with the lens.
     
  15. Petrochemist

    Petrochemist Mu-43 Top Veteran

    651
    Mar 21, 2013
    N Essex, UK
    Mike
    Your physics is right. To achieve full auto-focus on longer focal length lenses would require huge sensor movement - some of mine move around 100mm between infinity & closest focus.

    However this sort of focus finishing can make a big difference - which is the reason the Pentax teleconverter that does it is so sort after.
    I find mine great but find the light reduction somewhat limiting, losing ~2 stops so it can't reliably AF lenses slower than ~f4.
     
  16. redington

    redington Mu-43 Regular

    140
    Apr 28, 2012
    I love that Sony has seemed to just let their camera division go bonkers with whatever idea they want to. They have some really interesting products out there right now. Honestly, if I could have gotten an NEX for $300 when I got my epm1, I might have a Sony right now.
     
  17. gsciorio

    gsciorio Mu-43 Top Veteran

    636
    Dec 29, 2011
    Miami, FL
    Correct. I remember the Contax that had the moving plane. It was thought of as a game changer back then too but flopped.
     
  18. pdk42

    pdk42 One of the "Eh?" team

    Jan 11, 2013
    Leamington Spa, UK
    This sounds like a fundamental flaw and presumably the reason why every camera maker before and after the Contax AX has been designing lenses with a focus mechanism!
     
  19. emanmirza

    emanmirza New to Mu-43

    1
    Sep 14, 2013
    nice post
     
  20. alex66

    alex66 Mu-43 Top Veteran

    715
    Jul 23, 2010
    I borrowed one of these when it first came out, it was the first AF I tried. It was slow, but it did have a bonus feature in the built in macro function. Contax gave up on the idea soon after and made their own AF lenses and cameras. So if Sony do create something like this it may be good for slow moving subjects but it will give a great macro function if they are sensiable enough to allow it to work with their native lenses.