Learning at home

Discussion in 'Photography Beginners' Forum' started by Raeanne06, Mar 8, 2007.

  1. Raeanne06

    Raeanne06 TPF Noob!

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    I already tried to post this or whatever but I don't know if it worked. Thanks

    1) Is a 50mm lens and good choice to use with a 35mm camera in order to avoid perspective distortion?

    2) Is a 50mm lens regarded as a normal for all cameras regardless of film size?

    3) If you are using a 35mm camera and you are taking a photograph of a tall building should you position the camera so that the face of the lens is parallel to the face or side of the building, in order to aviod linear distortion?
     
  2. fmw

    fmw No longer a newbie, moving up!

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    1. That depends on the camera to subject distance as noted in my response to another of your posts. You can read about it there.

    2. No. On a medium format camera with an appropriate image circle it would be a wide angle lens. On an APS sized digital it would be a modest telephoto. However, it will still be a 50mm lens with every format. The difference is in the angle of view.

    3. Yes, unless you have a camera (like the one in my avatar) capable of rise and fall movements or a shift lens on a camera that does not provide for movements.
     
  3. Innocence

    Innocence TPF Noob!

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    haha i'd like a go too.

    1/ In short - yes. (if it's a non zoom lens)

    2/ Yes (in terms of magnification), it's similar to what the human eye is - regardless of the angle of view talked about above.

    3/ As per fmw. :) Although mind you tilt shifts can only do so much correction.

    By the way, good on you learning at home and keep your questions coming! Plenty of folk here ready to help :D
     
  4. fmw

    fmw No longer a newbie, moving up!

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    Innocence, angle of view is what makes a lens considered to be wide angle, normal or telephoto, not focal length. A 50mm lens is a 50mm lens on any format but the angle of view varies depending on the format, not the focal length. The "magnification" is the same with any 50mm lens regardless of film format. But put a 50mm lens (with the appropriate image circle) on a medium format camera and you will have a modest wide angle of view. On a 4X5 camera would have a super wide angle of view. On the APS digital (with the "crop factor"} you would have a modest telephoto angle of view. Same focal length, very different angle of view.
     
  5. Innocence

    Innocence TPF Noob!

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    Yes. Don't disagree with you...?

    Maybe I have a misunderstanding of perspective distortion. =)

    I was thinking more along the lines of 50mm gives the same perspective as our eyes ie "normal".
     
  6. Alex_B

    Alex_B No longer a newbie, moving up!

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    Well it is considered to do so for 35mm film or full frame digital sensors, if you further assume a certain final print size and viewing distance.

    However for medium format or large format, or also for smaller format, this does not hold true (as already said above).

    you will be causing some confusion with the original poster here
     
  7. Innocence

    Innocence TPF Noob!

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    Sorry!

    haha i stand corrected, please disregard everything i've said~
     
  8. Alex_B

    Alex_B No longer a newbie, moving up!

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    don't worry, happens to everyone once in a while ;)
     
  9. fmw

    fmw No longer a newbie, moving up!

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    Innocence, perspective is a confusing topic because it is a broad subject.

    Perspective in a photographic sense is really a comparison of how the lens sees things when compared to the way the eye sees things. The perspective distortion the OP referred to would be the perspective one would get by using a wide angle lens on a head and shoulders portrait close enough to fill the frame. The nose would be elongated and the features distorted from what the eye would see. The distortion is corrected by moving away from the subject. The frame is then filled by using a longer lens.

    Long lenses create a perspective distortion of their own called foreshortening. It brings distant subjects closer relative to closer subjects than shorter lenses do. It tends to flatten the view of the subject when compared to the way the eye sees.

    Linear perspective distortion is often called keystoning. It is caused by receding lines coming together with distance from the lens. If we shoot up at a building, for instance, the top of the building will be more narrow than the base. Our eye sees this as well but our brains tend to correct for it while lenses do not - or at least most lenses do not.

    So lenses have a perspective or view of the world and our eyes have a somewhat different perspective or view of the world. We use different photographic techniques to make the lens perspective appear more like that of the eye in the photograph. Or, sometimes we even exaggerate perspective differences for one reason or another. Changes in perspective coupled with the distance to the subject is why we have lenses of varying focal lengths.
     
  10. Innocence

    Innocence TPF Noob!

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    thank you for the education. =)
     
  11. Torus34

    Torus34 No longer a newbie, moving up!

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    An old 'rule of thumb' is that the 'normal' lens for a film size has a focal length approximately equal to the diagonal of the film image size in mm.
     

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