[ptx] panosifter problems & questions

[Pablo d'Angelo]

On Tue, 17 Feb 2004, Terje Mathisen wrote:

> Pablo d'Angelo wrote:
> 
> >Actually, I'm not completely sure what the crop factor really is.
> >the ratio of the diagonals? Or the ratio of width, or height? Have seem
> >different interpretations on the web.
> 
> You're right, I've even suspected PTAsm of getting this wrong for 
> cameras which don't have a 3:2 aspect ratio, i.e. almost all digicams 
> which have a 4:3 TV style chip.
> 
> IMHO, the proper way would be to calculate all crop factors relative to 
> a film/chip plane diagonal, since this diagonal determines the size of 
> the optics, right?

I thought I've implemented it like that in hugin (but it breaks in case of a
missing exif sensor size). but probably, some bugs have slipped through.
Anyway, a proper lens handling is needed sometime.

> So a 24x36 lens has a 43.27 mm diagonal, while a "standard" small 
> digicam uses a 1/1.8" chip which should have an 8.88 mm diagonal:
> 
> 43.27/8.88 = 4.873
> 
> Using Google, I find various sizes given for chips that should all be 
> 1/1.8", but 7.1x5.3 mm seems typical, this corresponds well to the 
> 7.104x5.328 which I get when starting with an 8.88 mm diagonal.

I was quite surprised when I found:
http://www.dpreview.com/learn/?/Glossary/Camera_System/Sensor_Sizes_01.htm

ciao
  Pablo
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