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Thread: Lens calculations

  1. #1
    Member DanTidswell's Avatar
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    Lens calculations

    Can anyone help me out with a calculation.

    I have a 5D3 with a 200mm lens. What is the equivalent lens using my P40+ with 645DF body.

    It's the 1.3 crop factor of the sensor that really got me stuck.

    Thanks,

    Dan

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    Re: Lens calculations

    calculate the diagonal of the format, Canon: sqrt(24*24+36*36) = 43.2mm, and the P40+ 44x33 yields 55mm diagonal, so the difference is 55/43.2 = 1.27, so the equivalent would be 200 * 1.27 = about 250mm.

    Note that the format is 3:2 on the Canon and 4:3 on the P40+, so rather than comparing the diagonal you can compare horizontal or vertical if you want to crop to 4:3 or 3:2 format. You'll end up roughly at 250mm anyway though.
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  3. #3
    Member DanTidswell's Avatar
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    Re: Lens calculations

    Hi torger

    I won't embarrass myself further by showing you how I was trying to calculate this :-)

    I've used your calculations to fill-down in a spreadsheet and - bam! - I have a lens conversion chart.

    Thank you very much indeed.

    Dan

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    Re: Lens calculations

    Feel free to use our free lens equivalency utility which would also help you understand te impact of the different aspect ratios:

    Tech Camera, Image Circle, Focal Length Equivalent
    Doug Peterson , Digital Transitions | Email
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    Member DanTidswell's Avatar
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    Re: Lens calculations

    Quote Originally Posted by dougpeterson View Post
    Feel free to use our free lens equivalency utility which would also help you understand te impact of the different aspect ratios:

    Tech Camera, Image Circle, Focal Length Equivalent
    Hey that's really cool! Love it.

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    Re: Lens calculations

    What is even better (if you have an iPhone) is Viewfinder Pro, which allows you to configure almost any type of format/lens combo and then see how it frames things in real time on the iPhone. You can take a picture with multiple frame lines present.

    The biggest drawback is that since the iPhone itself is about a 30-ish-mm equivalent in 35mm film terms, it won't be able to handle wide angle focal length demos without a wide angle adapter. Still, if you are someone who mainly shoots 28mm(equivalent) and longer, it is a VERY useful tool when scouting locations.
    Last edited by John Perkins; 16th August 2013 at 20:36.
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    Member DanTidswell's Avatar
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    Re: Lens calculations

    Hey John, sounds interesting, ill check it out.

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    Senior Member Stefan Steib's Avatar
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    Re: Lens calculations

    if you have an iPhone get AngleofView app. by far the best and easiest way to calculate this and compare it with up to 5 formats that you can set up for a permanent info.

    https://itunes.apple.com/us/app/angl...452946973?mt=8

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    Workshop Member Wayne Fox's Avatar
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    Re: Lens calculations

    Another app which I really like which has this capability is PhotoPills. this app has everything, such as tools like TPE (the photographers ephemeris), all types of calculations such as FoV and DoF, viewfinder assistants (it even has a way to see where your crop is if your lens is wider than the iPhone lens can handle by moving it around).

    It also has a augmented reality mode, where you can view a scene and then move through time to see where the sun or moon will move through the scene, allowing you to position yourself pretty accurately for sunrise/sunset shots.

    very useful app.
    wayne
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    Member DanTidswell's Avatar
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    Re: Lens calculations

    Quote Originally Posted by Wayne Fox View Post
    Another app which I really like which has this capability is PhotoPills. this app has everything, such as tools like TPE (the photographers ephemeris), all types of calculations such as FoV and DoF, viewfinder assistants (it even has a way to see where your crop is if your lens is wider than the iPhone lens can handle by moving it around).

    It also has a augmented reality mode, where you can view a scene and then move through time to see where the sun or moon will move through the scene, allowing you to position yourself pretty accurately for sunrise/sunset shots.

    very useful app.
    I'll check it out, sounds like a swiss army knife. :-)

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    Re: Lens calculations

    Formats are different shapes, so the right answer really depends on how you use the frame and how you see things. For some people basing conversions on the diagonal makes the most sense. I use the horizontal. It just works better for the way I see space in a photograph.

    The difference can be significant, so it's worthwhile to do some comparisons to figure out what works for you.

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    Subscriber and Workshop Member MGrayson's Avatar
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    Re: Lens calculations

    Speaking of iPhone viewfinders, what is the auxiliary lens of choice? The Olloclip is cheaper than the iPro (Schneider), but last time I looked, it had severe barrel distortion on the wide.

    So far, I've avoided any viewfinder on the Cambo. Is the iPhone route with Viewfinder app still a thing? Or has the novelty worn off? I'm not looking for an on-camera viewfinder. Just something to poke around and try different Points of View.

    Thanks,

    Matt

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