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Old Saturday 20th December 2003, 18:25   #1
jose
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Question Convertion mm vs X factor

Does anyone know where can I find a convertion table that will tell me what a lens lenght is relatively in magnification factor?


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Old Saturday 20th December 2003, 22:08   #2
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Generally 1x per 50mm, or 2x per 100mm.

So a camera with a 300mm lens gives approx the same view as a scope with 6x mag; 400mm gives 8x; 500mm gives 10x; 600mm gives 12x.

Same applies if using teleconvertors...

500mm+2x = 1000mm = 20x Mag.
600mm+2x = 1200mm = 24x Mag.

Hope that helps.
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Old Sunday 21st December 2003, 07:56   #3
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Itís exactly what I wanted to know. Many thanks
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Old Sunday 21st December 2003, 08:31   #4
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The factors are different with most digital cameras, though - at least I believe so. The factor is ... er ... I forget already. Roughly a third, so 500mm in a standard 35mm format is the equivalent of about 750 or 800mm if you are using it with a digital SLR.

Doubtless some kind soul will drop by shortly and give us the correct figures.
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Old Sunday 21st December 2003, 09:04   #5
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Sprry...yes, I'm speaking about straight mag on a lens, and would be correct for straight 45mm or a DSLR with a full frame sensor (35mmx24mm).

If your Digicam/camera body has a different sensor size - eg like APS or smaller, then would be a slightly different magnification. EG. the Canon D60/10D has an extra 1.6x increase to those I gave above. Other cameras have different sizes..and yo need to check the manual...

Some will argue it's a crop and not a magnification factor...but the end result is the same.

So for the Canon 10D
a 500mm becomes a 720mm giving 14x
a 600mm becomes 960mm, giving 19x

add a teleconvertor (2x) and you get...

500 + 2x = 1000 x 1.6 = 1600mm = 32x
600 + 2x = 1200 x 1.6 = 1920mm = 38x

If only the world where simple!
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