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120520 Stroller wrote: |
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> Zoom lenses were much less common even 2 or 3 decades ago. |
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> For a long time, a 50mm prime was the common kit lens, |
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> rather than the 18-105mm zoom which is sold today. |
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> This was because on a camera using 35mm film, a 50mm focal length |
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> gives a field of view very close to that seen naturally by the human eye. |
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> Wikipedia states that "the first modern film zoom lens was designed c 1950 |
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> by Roger Cuvillier" and Canon's official website (the "Canon Camera Museum") |
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> states that "The history of Canon's zoom lens goes back to 1954." |
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> Since the photos are stated go have been taken in 1953 |
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> it seems highly unlikely that the photographer was using |
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> a highly expensive and cutting-edge zoom lens. I doubt many people |
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> would have been able to afford these zoom lenses when first released. |
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> It seems to me safer to assume that the lens is a 50mm. |
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In fact, looking more closely at the picture of a ZI |
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which I've put up in my I/net 'test' dir (found on the I/net earlier), |
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it says 'F = 7,5 cm', so the lens appears to have been a 75 mm . |
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|
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> I guess focal length may change fractionally during focussing |
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> -- as lenses are moved back and forth during as the focus ring is turned -- |
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> however it may also be that a camera manufacturer designs a lens |
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> with a 48mm focal length because that's easier to construct for some reason |
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> or produces better images and decides to sell it as 50mm |
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> because a 2mm difference makes no difference to the photographer. |
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> Or it may be that the distortion is caused by lens distortion |
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> perhaps Hugin is trying to compensate for that, and straightening up lines. |
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> In any case, I might try re-doing the stitch a few times, |
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> each time telling Hugin the lens is 47mm, 48mm, 49mm, … 51mm, … 53mm. |
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> Perhaps you may find that one of those is perfectly spot on. |
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Thanks for the further lesson ! -- it sb tried at 75 mm . |
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SUPPORT ___________//___, Philip Webb |
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