Internal ND filters on the XH-A1 affecting focus

Discussion in 'Professional Video Production' started by Jacques E. Bouchard, Jul 30, 2008.

  1. Jacques E. Bouchard

    Spex Guest

    jaybee,

    Learn how to use the camera.
     
    Spex, Aug 1, 2008
    #21
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  2. Spex, a "craftsman" shouldn't need the painfully simple explanations for
    such things as DOF that I've been forced to dole out to you.

    Get off your self-righteous indignation.


    jaybee
     
    Jacques E. Bouchard, Aug 2, 2008
    #22
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  3. Admittedly, I've only been doing this for about a year. And yet, *I* have
    no problems understanding such simple things as DOF, near limit and far
    limit...



    jaybee
     
    Jacques E. Bouchard, Aug 2, 2008
    #23
  4. Jacques E. Bouchard

    Toby Guest

    I think that the answer is rather simple: the lens is soft at large
    apertures. This is generally true even of pro lenses (at least to some
    extent), especially out full at tele.

    Toby
     
    Toby, Aug 2, 2008
    #24
  5. Jacques E. Bouchard

    Spex Guest

    You are an ignoramus of the first water and I hope you continue to find
    fault with the XH-A1.

    I, however, will continue to capture beautifully focussed images at any
    aperture, at any position in the zoom range and with any number of ND
    and polarising filters in front of the CCD.

    Bouchard you just demonstrate the downside of the democratisation of the
    media industry namely good cameras find their way into the hands of
    halfwits.
     
    Spex, Aug 2, 2008
    #25
  6. The whole world is out to get you, Spex. It's a conspiracy.
    I'm still waiting for you to disprove anything I've demonstrated about
    DoF. I'm still waiting for you to show how going from 9.5f to 3.7f will
    affect DoF for an object 3,000 feet away enough to throw it out of focus.

    But you won't. You know you can't, and now you're left trying to save
    what little face you have left. And that's why you're resorting to
    insults instead of actual arguments.

    You're an arrogant blowhard, Spex. Do you really think anyone's fooled?


    jaybee
     
    Jacques E. Bouchard, Aug 2, 2008
    #26
  7. Jacques E. Bouchard

    Spex Guest

    Toby

    The lens is soft at small apertures. Anything over F5.6 shows some
    softening and I prefer to stay below F7.3. F9.5 and above can hardly be
    described as HD. Shooting is SD masks this lens diffusion effect to a
    greater degree for obvious reasons. I have a matte box and a selection
    of ND filters that I add in to the in-camera ones to ensure I have my F
    stops around F3.4 as far as possible when shooting.

    The problem the original poster has is that he doesn't understand the
    difference between infinity focus and over infinity focus.

    The XH-A1 keeps focus on a subject when switching NDs in and out. And
    that's a fact...
     
    Spex, Aug 2, 2008
    #27
  8. Perhaps not with "JB's" particular sample, and that is what he is asking
    about.
    I have often found defects in gear that I have bought over the years, which
    is
    why I recommend careful testing upon purchase (when return/exchange is
    usually possible). I'm not a fan of repairs after later discovery of
    problems - I
    have not often had good luck with them, at least with lenses...
    --DR
     
    David Ruether, Aug 2, 2008
    #28
  9. Jacques E. Bouchard

    Spex Guest

    But when jaybee understands the difference between infinity focus and
    over infinity focus he will then understand there is nothing wrong with
    his camera.

    The problem is a focus error on his behalf not the camera.

    When the viewfinder displays 8- (infinity -) this means over infinity
    focus and _not_ infinity focus. Put simply, you're out of focus at the
    far end!!!
     
    Spex, Aug 2, 2008
    #29
  10. True, but the odd thing is that it only seems to happen with his ND-filter
    "in".
    The theory of DoF is unlikely and with these small imagers and given the
    distance, the DoF will still be "huge" around the object.
    Maybe the ND-filter came loose in it's socket, misaligning the backfocus?

    cheers

    -martin-
     
    Martin Heffels, Aug 2, 2008
    #30
  11. True. I was not very bright when I wrote this, as it is a filmlens-theory
    thingy. Apologies! :)

    -m-
     
    Martin Heffels, Aug 2, 2008
    #31
  12. Jacques E. Bouchard

    Bill Fright Guest


    Over infinity? How do you measure over infinity? 35 years in the
    business and this is the first time I've ever heard that. When I was a
    ENG shooter and needed a fast infinity focus I'd go to infinity and back
    off a tad. I always assumed full infinity was meant for the doubler. I
    rarely received complaints from even the most exacting producers.

    I agree with the other posters that there is a problem with the camera.
    I don't know much about these prosumer cameras except that the glass is
    small and cheap - I'd suspect failure there. On the pro gear you simply
    pull the lens and take a peek at the filters with a flash light.

    I wonder if his problem was always there or if it appeared after some use.


    Bill
     
    Bill Fright, Aug 2, 2008
    #32
  13. Jacques E. Bouchard

    Spex Guest

    **** me. What part of "out of focus at the far end" didn't you
    understand?? The lens isn't infinity locked and so it is possible to
    "over" focus or go beyond the focus point at the far end just like it is
    possible to do the same on cheap stills lenses.

    jaybee's test was flawed not the camera.
     
    Spex, Aug 2, 2008
    #33
  14. That's what I figured, and a child of five could understand this. Maybe
    Spex needs to fetch a child of five.


    jaybee
     
    Jacques E. Bouchard, Aug 2, 2008
    #34
  15. Apparently the first time Spex hears of DoF calculators, as well. He;s
    obviously given up entirely on trying to make sense for the sake of saving
    face at this point, so I'm just not responding to him anymore.

    I'd still like to see someone else replicate the experiment with an
    XH-A1, though. I'm not sure about a lens defect, since the image becomes
    blurry only when I engage the ND filter. I'd tend to suspect a poor-quality
    filter.


    jaybee
     
    Jacques E. Bouchard, Aug 2, 2008
    #35
  16. And you demonstrate the problem with arrogant twits who proclaim themselves
    "professionals" in this industry but are unable to understans such simple
    tersm as DoF at 3,000 feet away.


    jaybee
     
    Jacques E. Bouchard, Aug 2, 2008
    #36
  17. Jacques E. Bouchard

    Spex Guest

    Whatever.

    I've told you that you are wrong and why you are wrong. Your test was
    flawed and you don't understand how to focus your camera nor what the
    information the camera is giving you means. Pg 37 in the manual.

    There is nothing wrong with your camera only the fool holding it.

    You might have the support of the other halfwits in this group but that
    doesn't make you right. You are going to have to eat your words because
    I know I'm right. But keep up the digs because you are going to make
    yourself look a bigger fool time after time.

    ** For anyone reading this who interested in purchasing the Canon XH_A!.
    Don't let one imbecile who doesn't know how to work his camera put you
    off buying one. In the right hands this camera is wonderful. Bouchard
    is a ham fisted clod who can't focus a camera and would rather blame his
    equipment rather than learn the necessary craft.
     
    Spex, Aug 2, 2008
    #37
  18. Jacques E. Bouchard

    Greg Melton Guest

    Come on guys. How can DoF be "huge" when the lens is at it's longest?
    Go ahead and zoom that puppy to the hilt and see just how the
    slightest nudge on the focus ring will affect things.

    Simple photography 101. Long lens + wide aperature = shorter depth of
    field. Doesn't matter what imager. I swear the more "automatic" these
    cameras become, the more clueless "professionals" become.

    And just because the mark on the lens says "infinity" it doesn't
    literally mean as much. It's in the close vicinity. The eye behind the
    camera is expected to dial it in. Or as the most recent professionals
    would expect the "auto-focus" feature to relieve them of the
    responsibility

    Greg
     
    Greg Melton, Aug 2, 2008
    #38
  19. Focused on an object 3,000 feet away and zoomed in (90mm), the DoF remains
    huge whatever the f-stop.
    I'm not using the mark on the lens. I'm focusing manually on the object
    3,000ft away, and when the ND is engaged I can't focus anymore.


    jaybee
     
    Jacques E. Bouchard, Aug 3, 2008
    #39
  20. "Jacques E. Bouchard" wrote ...
    http://en.wikipedia.org/wiki/Depth_of_field

    If you focus on 3K ft at f/3.7 and then go to f/9.5,
    (by removing your ND filter, for example) then
    what happens in your camera?

    How do you know you were "in focus" at f/9.5?

    Exactly how are you determining (and monitoring)
    "focus" in your little experiment?
     
    Richard Crowley, Aug 3, 2008
    #40
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