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-   -   Re: Angle of view instead of focal length (http://www.velocityreviews.com/forums/t953069-re-angle-of-view-instead-of-focal-length.html)

DanP 10-05-2012 09:10 AM

Re: Angle of view instead of focal length
 
On Wednesday, 3 October 2012 23:22:46 UTC+1, Mxsmanic wrote:
> Alfred Molon writes:
>
>
>
> > Given the wide variety of sensor sizes, wouldn't it be better if the

>
> > EXIF of a photo contained also the angle of view information? The focal

>
> > length of the lens is not really that important, actually it is quite

>
> > irrelevant.

>
>
>
> Seems reasonable, although the software would have to know the sensor size and
>
> focal length, and differences in aspect ratio could prevent the parameterfrom
>
> being completely consistent (but it would still be an improvement over focal
>
> length).


I have used a piece of software for Windows that shows statistics for photos. It has shown me an equivalent focal length of 1600mm for a heavy croppedphoto, the lens used was 250mm and my sensor is an APSC x1.6. So it is possible to extract all that from EXIF. It worked well even for photos taken with a P&S.


DanP

DanP 10-08-2012 11:30 AM

Re: Angle of view instead of focal length
 
On Saturday, October 6, 2012 1:03:19 AM UTC+1, Eric Stevens wrote:
> oOn Fri, 5 Oct 2012 02:10:24 -0700 (PDT), DanP <dan.petre@hotmail.com>
>
> wrote:
>
>
>
> >On Wednesday, 3 October 2012 23:22:46 UTC+1, Mxsmanic wrote:

>
> >> Alfred Molon writes:

>
> >>

>
> >>

>
> >>

>
> >> > Given the wide variety of sensor sizes, wouldn't it be better if the

>
> >>

>
> >> > EXIF of a photo contained also the angle of view information? The focal

>
> >>

>
> >> > length of the lens is not really that important, actually it is quite

>
> >>

>
> >> > irrelevant.

>
> >>

>
> >>

>
> >>

>
> >> Seems reasonable, although the software would have to know the sensor size and

>
> >>

>
> >> focal length, and differences in aspect ratio could prevent the parameter from

>
> >>

>
> >> being completely consistent (but it would still be an improvement overfocal

>
> >>

>
> >> length).

>
> >

>
> >I have used a piece of software for Windows that shows statistics for photos. It has shown me an equivalent focal length of 1600mm for a heavy cropped photo, the lens used was 250mm and my sensor is an APSC x1.6. So it is possible to extract all that from EXIF. It worked well even for photos taken with a P&S.

>
> >

>
>
>
> It must have somewhere kept track of the original size of the photo in
>
> adition to the information normally carried over in Exif.
>
> --
>
>
>
> Regards,
>
>
>
> Eric Stevens


Yes, camera model (look up the number of pixels on sensor) and image quality (can lower the number of pixels), both in EXIF, that gives the number of pixels for the uncropped image. Factor in the actual number of pixels (might be cropped), sensor size multiplier, focal length and magic happens.


DanP


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