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  1. #71

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    Quote Originally Posted by maderik View Post
    Here's a thought experiment: Use a 10 second exposure and move the camera up and down? Will the dot be blurred? Of course; it will be a line. Now explain why the physics of motion are different for 10 seconds vs. 1/10th of a second.

    Yes, the dot moves with the camera. That's the point. However the background doesn't move and the path the dot traces on the background will be recorded.
    The point of the test should be to see how a moving camera records a static object in a real world situation...not to see how a moving camera records the movement of an object that is moving just as much as the camera. Photographing the laser attached to the camera will tell you how much the camera moves, but photographing a still object will tell you how a still object will actually be rendered. The first is simply informative. The second gives you actual practical knowledge. For instance, not just how much does the camera move, but how much movement is acceptable in a picture that is shot in a real-world situation.

    Really. This is test is terribly over engineered. Why can't you just shoot the front page of the Times tacked to a bulletin board? Shooting a laser is just a techy way to make some piece of modern technology seem more useful than it really is.

    ...besides, we all know that the ONLY real use for a laser pointer is for playing with cats.
    2F/2F

    "Truth and love are my law and worship. Form and conscience are my manifestation and guide. Nature and peace are my shelter and companions. Order is my attitude. Beauty and perfection are my attack."

    - Rob Tyner (1944 - 1991)

  2. #72

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    ..besides, we all know that the ONLY real use for a laser pointer is for playing with cats.
    That's about the best use I can think of for one.

    Really. This is test is terribly over engineered. Why can't you just shoot the front page of the Times tacked to a bulletin board? Shooting a laser is just a techy way to make some piece of modern technology seem more useful than it really is.
    Maybe because the techie geeks among us are more likely to have a laser pointer than any page of the Times?
    Besides, everyone knows a test using technology is far superior to those that don't.:rolleyes:

  3. #73

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    Quote Originally Posted by bdial View Post
    That's about the best use I can think of for one.
    Yup...and we don't even have to get off of our fat asses to do it! Even better!

    Call me a Luddite, but I buy the paper every week day. $16 per month to support analog circulation (and the local American jobs that go with it) in my local newspaper machines is worth it to me. I get way more information than I would online, in less time. I also get the funnies, the crossword, sudoku, and one of my personal favorites, the obits. Plus I get to take a walk to the machine from work and back. I also don't bug my eyes out or have to sit on my butt to do it. I feel I am lucky to work in a place without a computer or ass sitting on being a necessary part of my job, personally.

    (Any sheet of paper with text on it will do, of course.)
    Last edited by 2F/2F; 02-04-2010 at 06:31 PM. Click to view previous post history.
    2F/2F

    "Truth and love are my law and worship. Form and conscience are my manifestation and guide. Nature and peace are my shelter and companions. Order is my attitude. Beauty and perfection are my attack."

    - Rob Tyner (1944 - 1991)

  4. #74
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  5. #75
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    Here's a thought experiment: Use a 10 second exposure and move the camera up and down? Will the dot be blurred?
    No, it will not be blurred, unless the laser pointer is poorly attached and moves in relation to the camera. Laser pointers do not leave trails on the wall; it just looks like they do. Why don't you try it some time and report back.
    f/22 and be there.

  6. #76

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    Of course mirror vibration exists. Although the areas where it's the most vexing (high magnifications, long telephotos) are situations you can't really use a rangefinder anyway.

    In addition to all the other problems, the order of magnitude is completely off in the laser/penny tests. How much effective (subject space) movement would you need to make newsprint unsharp? 0.25mm maybe? Can you really see an instantaneous movement that small in a fuzzy consumer laser spot? Now translate that to an amount of actual camera movement. Do you really think the penny test is going to show that?

    For handheld shooting at critical speeds I found getting away from the human movement caused by the button press (by using a self timer, a cable release in the other hand, or burst mode on one of Satan's little toys) more important than camera mechanics.

    Although sure, past that point, my Hi-Matic and Mamiya Universal completely smoked my XD-11 at similar critical speeds/angles of view. My DSLR kept up a little better because of burst mode—out of eight shots there'd usually be one or two where human shake and mirror shake mostly canceled out and gave me something decently sharp. The other 6-7 were often even worse than the XD-11, not that it really matters.

  7. #77

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    Quote Originally Posted by BetterSense View Post
    No, it will not be blurred, unless the laser pointer is poorly attached and moves in relation to the camera. Laser pointers do not leave trails on the wall; it just looks like they do. Why don't you try it some time and report back.
    What, your walls aren't covered in slow decay phosphors? Sigh, I guess I get what I deserve when I attempt thought experiments under the influence of cold medicine. Still cameras do not have persistence of vision like cathode ray tubes or the human eye so I was totally off-base.

  8. #78
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    In your defense, the laser spot can blur even if the laser pointer is attached firmly to the camera, because the laser pointer is probably not oriented exactly along the axis of the lens, and thus there will be a small amount of blur from parallax effect if the wall moves closer and farther to the wall during the course of the wiggling.
    f/22 and be there.

  9. #79
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    This stuff is really funny, the bits about laser pointers and pennies. In order for a test to provide any meaningful information there needs to be a context, and "speermints" like these don't really have one. Camera design, exposure time and focal length all play important roles in how a mirror slap will affect sharpness. One combination may yield on result, and a different combination another. You control what you can. When sharpness is critical and the subject allows I use MLU, because it can't hurt, and sometimes it makes a difference, and sometimes not. When it isn't practical I use a better shutter speed if I can, or I takes my chances. In regard to the range finder vs SLR thing, you use the tool that is appropriate. In all my professional life I personally have never chosen to use a rangefinder based on shutter vibration, although the situation might arise where I might. When I have chosen to use a rangefinder it has always been a matter of ergonomics, optics, and noise. MLU is simply a feature on some SLR's that can be used when appropriate, nothing more and nothing less.
    That's just, like, my opinion, man...

  10. #80

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    Quote Originally Posted by Sirius Glass View Post
    The bottom line is what I said may posts ago. Mirror bounce is not a factor for speeds shorter than 1/[focal length]. For longer shutter speeds use a tripod and if you think it is necessary the MLU. Since then this thread has been a great waste of internet bandwidth and time.

    Steve
    And I'll note again that many published experiments have shown this statement to be inaccurate.
    -brian hayden
    http://fed-2.org

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