calculating focal length with digital point and shoot cameras.
April 22, 2006 2:54 PM Subscribe
I have some pictures taken by somebody else using a digital camera. I am trying to match them up with a digital model to do photomontages. I need to figure out the 35mm equivalent focal distance on the shots.
The camera is a Sony DSC-P52, and their website says: Focal Length 6.3mm - 12.6mm (41mm - 82mm Equivalent)
Can I transform the pic's focal length (FP) to its 35MM equivalent (FE) using: FE=FP/6.3*41? Is the relationship linear?
I don't have access to the original camera or photgrapher, this is all off of the pics' metadata.
The camera is a Sony DSC-P52, and their website says: Focal Length 6.3mm - 12.6mm (41mm - 82mm Equivalent)
Can I transform the pic's focal length (FP) to its 35MM equivalent (FE) using: FE=FP/6.3*41? Is the relationship linear?
I don't have access to the original camera or photgrapher, this is all off of the pics' metadata.
Yes, it is linear. The term is 'multipiplier'. The sensor size is 5.27 x 3.96 mm.
posted by jedrek at 2:59 PM on April 22, 2006
posted by jedrek at 2:59 PM on April 22, 2006
Response by poster: Cool, thanks. Bonus question: can you figure out the multiplier (6.5 and change, in this case, right?) from the sensor size?
posted by signal at 3:02 PM on April 22, 2006
posted by signal at 3:02 PM on April 22, 2006
can you figure out the multiplier (6.5 and change, in this case, right?) from the sensor size?
Absolutely; here is one article that explains it. It is also called the crop factor and is not just applicable to digital sensors; that is why a 300 mm lens on an 8x10 camera is roughly equivalent to a 50 mm lens on a 35 mm camera. Because the proportions of various sensors and film vary somewhat, the diagonal measurement is used to calculate the crop factor.
posted by TedW at 3:14 PM on April 22, 2006
Absolutely; here is one article that explains it. It is also called the crop factor and is not just applicable to digital sensors; that is why a 300 mm lens on an 8x10 camera is roughly equivalent to a 50 mm lens on a 35 mm camera. Because the proportions of various sensors and film vary somewhat, the diagonal measurement is used to calculate the crop factor.
posted by TedW at 3:14 PM on April 22, 2006
You should be warned that if the pictures were cropped or resized the EXIF data about sensor size depends on what software you're using. Photoshop, ImageMagic, and Aperature all write different things in the different-sized file.
posted by aubilenon at 4:26 PM on April 22, 2006
posted by aubilenon at 4:26 PM on April 22, 2006
This thread is closed to new comments.
posted by andrew cooke at 2:59 PM on April 22, 2006