Lens Pros I need your help.......

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Lens Pros I need your help.......

Postby Talvan » Jun Thu 30, 2005 5:23 pm

I was reading this thread on another chat board, and they were discussing the normal FOV lenses like the 50mm lens on a 35mm camera. The way I read it, to figure out the normal FOV lens for a given media you measure the diagnol of the sensor or A squared + B squared = C squared. According to this method of thinking, a 35mm(36 x 24mm) film camera would need a 43mm lens. The thread went on to say that since no 43mm lens was available, photgraphers adopted the 50mm lens as the normal view lens. According to this philosphy to get a normal view lens for a Nikon D70(23.7 x 15.6 mm) you would need a 28mm lens, Canon 20D(22.5 x 15mm)a 27mm lens, 6x4.5(56x42mm) 70mm lens, 6x6(56x56mm) is a 80mm lens (79mm actually, rounding up to 80mm), and 6x7(56x67mm) is a 90mm lens (87mm actually, rounding up to 90mm). Here is the thing I need help with. If you use a 50mm lens on a 35mm and you want the same angle of view on a APS-C camera you would use something close to a 35mm lens. If your intention from the begining was to get the angle of view that the normal eye sees, would you use the 28mm lens or still use a 35mm lens? I am not sure on all this math stuff when it comes to Field of View and Circles of Confusion stuff. Infact it can all get kind of confusing to me. Is this formula correct on normal angle of view lenses?

Matt?
Sincerely,
John Talvan
Life, One Frame At A Time
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Postby Watchin » Jul Sat 02, 2005 7:04 pm

The angle of view of a "normal human eye" is not the same as the FOV for a
full frame coverage. For a 35mm camera the full frame coverage with no
distortion is 50mm (nominal) but the "eye" perspective and angle of view is
usually regarded as 70 to 85mm. So don't get apples and oranges confused here.

As for the math stuff... I've never seen a formula on a print!

The 50mm on the D70 will give you the proper angle of view for an
"eye" perspective (strange how that works out ain't it :D)

The real deal is the way the eye see's things. The math stuff is for getting
the "angle of view" for the frame size at nominal distance. As you know
a longer lens not only changes the angle of view but the perspective and
DOF and compresses the distance precieved between objects. That is
why the 85mm gives the "eye" perspective. The problem is that the 50mm
will give the same angle of view but will not completely take in the other
aspects of the effects, so I still like the 70-85mm as a protrait lens even
on the APC frame size. Then again I don't know the math, so I'm only
going by what I see.

Okay, that's what I learned 30 years ago... chew it up guys :D
Greg aka Watchin..."just watchin the world go bye, trying to understand the picture."
"Life is a grand adventure! Not a guided tour." oWo
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Postby Talvan » Jul Sat 02, 2005 10:00 pm

Thanks for the insight there Greg. I guess its all a matter of personal opinion then. When I get chance I will take a llok at what you said with my camera.
Sincerely,
John Talvan
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