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