| 1 |
On 19 May 2012, at 20:28, Michael Mol wrote: |
| 2 |
> … |
| 3 |
> Worse, if the photographer was not using a prime lens[1], and was |
| 4 |
> instead using a lens with variable zoom, you can't easily know what |
| 5 |
> the real focal length was, as this will change depending on how far |
| 6 |
> the photographer has zoomed in. |
| 7 |
|
| 8 |
Throughout everything else you said I was thinking something like this. |
| 9 |
|
| 10 |
Zoom lenses were much less common even 2 or 3 decades ago. |
| 11 |
|
| 12 |
For a long time, a 50mm prime was the common kit lens, rather than the 18-105mm zoom which is sold today. |
| 13 |
|
| 14 |
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. |
| 15 |
|
| 16 |
Wikipedia states that "the first modern film zoom lens was designed around 1950 by Roger Cuvillier" and Canon's official website (the "Canon Camera Museum" pages) states that "The history of Canon's zoom lens goes back to 1954." |
| 17 |
|
| 18 |
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 they were first released. |
| 19 |
|
| 20 |
It seems to me safer to assume that the lens is a 50mm. |
| 21 |
|
| 22 |
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 in focal length makes no difference to the photographer. |
| 23 |
|
| 24 |
Or it may be that the distortion is caused by lens distortion - perhaps Hugin is trying to compensate for that, and straightening up lines. |
| 25 |
|
| 26 |
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. |
| 27 |
|
| 28 |
Stroller. |
Archives