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slip · 11-15-2006, 07:08 PM

when a manufacture claims the lens is for DSLR' and it is for example a 17-70mm, do you still have to multiply it by 1.5x (pentax) or is it applied? 17mm = 17mm?

just want to double check first

joele · 11-15-2006, 07:13 PM

to get the equivelent FOV you still have to multiply by 1.5

Ole · 11-16-2006, 07:16 AM

joele is correct. Focal length is an optical property of the lens. It has nothing to do with the film or sensor.

If you focus parallel rays with the lens (e.g. from the sun) on a piece of paper they will form a point when the paper is held a distance of the focal length from the optical midpoint of the lens. Warning, don't ever look at the sun through the lens!

slip · 11-16-2006, 01:28 PM

Thank you very much for your replies

randy

11-15-2006, 07:08 PM	#1
slip Veteran Member Join Date: Oct 2006 Location: 2 hours north of toronto ontario canada Photos: Gallery \| Albums Posts: 3,535	conversion multiplier for digital designed lenses? when a manufacture claims the lens is for DSLR' and it is for example a 17-70mm, do you still have to multiply it by 1.5x (pentax) or is it applied? 17mm = 17mm? just want to double check first

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11-15-2006, 07:13 PM	#2
joele Veteran Member Join Date: Sep 2006 Location: Melbourne, Australia Photos: Gallery Posts: 1,308	to get the equivelent FOV you still have to multiply by 1.5

11-16-2006, 07:16 AM	#3
Ole Administrator Join Date: Sep 2006 Location: Copenhagen, Denmark Photos: Gallery \| Albums Posts: 4,409	joele is correct. Focal length is an optical property of the lens. It has nothing to do with the film or sensor. If you focus parallel rays with the lens (e.g. from the sun) on a piece of paper they will form a point when the paper is held a distance of the focal length from the optical midpoint of the lens. Warning, don't ever look at the sun through the lens!

11-16-2006, 01:28 PM	#4
slip Veteran Member Join Date: Oct 2006 Location: 2 hours north of toronto ontario canada Photos: Gallery \| Albums Posts: 3,535 Original Poster	Thank you very much for your replies randy

conversion multiplier for digital designed lenses?

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