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  1. #21
    RalphLambrecht's Avatar
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    Quote Originally Posted by rjbuzzclick View Post
    Wow, a Fiesta! I had one of those in the mid 1980's!

    (Sorry...way, way, way, OT...)
    No, you did not have one like this in the 1980s, but you can see and get one like this at a Ford dealer near you right now!

    http://www.ford.com/cars/fiesta/
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    Ralph W. Lambrecht
    www.darkroomagic.comrorrlambrec@ymail.com[/URL]
    www.waybeyondmonochrome.com

  2. #22
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    Quote Originally Posted by RalphLambrecht View Post
    No, you did not have one like this in the 1980s, but you can see and get one like this at a Ford dealer near you right now!

    http://www.ford.com/cars/fiesta/
    I had heard a while ago that they were starting to build them again, but yeah, I suspect they're a bit different now. It was kind of a fun little car, but it really needed a 5th gear, it was really straining at 65 mph.
    Reid

    http://www.flickr.com/photos/rjbuzzclick/

    "If I had a nickel for every time I had to replace a camera battery, I'd be able to get the #@%&$ battery cover off!" -Me

  3. #23

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    I used to drive a VW bug back then.... It didn't even get to 60mph... it was struggling to reach 55mph even...

    Hey, I can hijack my own thread!
    Develop, stop, fix.... wait.... where's my film?

  4. #24
    RalphLambrecht's Avatar
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    Quote Originally Posted by rjbuzzclick View Post
    I had heard a while ago that they were starting to build them again, but yeah, I suspect they're a bit different now. It was kind of a fun little car, but it really needed a 5th gear, it was really straining at 65 mph.
    Ford never stopped making them, just stopped selling them in the US. However, the current Fiesta is no comparison to the old one and goes well over 100 mph without any vibration in the steering as one would expect from >100 hp. 40 mpg are a good selling point too.

    Enough OT, let's go back to DoF, or is everyone satisfied so far?
    Last edited by RalphLambrecht; 04-28-2011 at 02:43 PM. Click to view previous post history.
    Regards

    Ralph W. Lambrecht
    www.darkroomagic.comrorrlambrec@ymail.com[/URL]
    www.waybeyondmonochrome.com

  5. #25

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    Another way to see it (keeping it simple) is that when comparing two different formats and same AOV (angle of view), then the DOF is approximately the same for a given aperture diameter (not the aperture ratio).

    Example:

    4x5 using a 105mm at f/8 will have approximately the same DOF as 8x10 using a 210mm at f/16, since the aperture diameters for 105mm at f/8 and 210/mm at f/16 are the same
    Last edited by fdisilvestro; 04-28-2011 at 02:29 PM. Click to view previous post history. Reason: Format

  6. #26
    njkphoto's Avatar
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    As the focal length of a lens increases the DOF decreases..I believe that stands for the most part with all formats. Switching between formats and lenses one might notice a difference, but if using the appropriate lens for a particular format things should fall into place. You have to test this with the same subject, same distance different formats, same f-stop. As always there is some interesting technical information here but again I believe understanding the basics of this is key.

    Just my thought.

  7. #27
    RalphLambrecht's Avatar
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    Quote Originally Posted by fdisilvestro View Post
    Another way to see it (keeping it simple) is that when comparing two different formats and same AOV (angle of view), then the DOF is approximately the same for a given aperture diameter (not the aperture ratio). ...
    Correct, but who works in actual aperture dimensions? Aren't we all more comfortable with f/stops (aperture values)?
    Last edited by RalphLambrecht; 04-28-2011 at 03:49 PM. Click to view previous post history.
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    Ralph W. Lambrecht
    www.darkroomagic.comrorrlambrec@ymail.com[/URL]
    www.waybeyondmonochrome.com

  8. #28
    RalphLambrecht's Avatar
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    Quote Originally Posted by njkphoto View Post
    ... Switching between formats and lenses one might notice a difference, but if using the appropriate lens for a particular format things should fall into place. ...
    Nope. Given the same f/stop, the 'normal' lens of a smaller format will always produce more DoF than the 'normal' lens of a larger format.

    Quote Originally Posted by njkphoto View Post
    ... You have to test this with the same subject, same distance different formats, same f-stop. ...
    Did it. See post #10.
    Regards

    Ralph W. Lambrecht
    www.darkroomagic.comrorrlambrec@ymail.com[/URL]
    www.waybeyondmonochrome.com

  9. #29

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    Quote Originally Posted by RalphLambrecht View Post
    Correct, but who works in actual aperture dimensions? Aren't we all more comfortable with f/stops (aperture values)?

    Yes, nobody works in aperture dimensions, but you could use an empirical method using the ratio between the focal length of the lenses and adjust the aperture value (f/stops) accordingly.

    Let's say that a 160mm lens on 4x5 gives you the same AOV of a 320mm lens on 8x10, then the ratio 320/160=2. You have to multiply by 2 the aperture in the 320mm to get the same DOF as the 160.

    In the case of the OP, to get the same DOF in 35mm using a 50mm lens and 6x4.5 using a 80mm lens, you need to multiply by 1.6 the aperture in the 80mm lens. Here the results are approximate since the film proportions and angle of view between the two are not the same.

    In the attachment there are two examples with data obtained from the online DOF calculator http://www.dofmaster.com/dofjs.html
    Attached Thumbnails Attached Thumbnails DOF Ex.jpg  

  10. #30
    RalphLambrecht's Avatar
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    Quote Originally Posted by tkamiya View Post
    I'm confused about DOF when different image size AND equivalent focal length is concerned. ...
    I can see why now.
    Regards

    Ralph W. Lambrecht
    www.darkroomagic.comrorrlambrec@ymail.com[/URL]
    www.waybeyondmonochrome.com

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