How to determine magnification ration?

[coralnutz]

I've been searching trying to figure out magnification ratios and how to calculate what it is? Is there an easy way, like take a picture of a ruler or something to determine what magnification your shooting in?

My issue is that I don't have a dslr so the calculations for lenses and crop sensor size, etc aren't matching what I have. (Canon S3 with Raynox DCR-250 macro lens) I don't need to know exactly, but it would be nice to know ballpark area of what I'm shooting at so i can understand when people are talking 1:2 or 1:2, etc...

Sorry if this doesn't make any sense. Pleaes tell me if not and I'll try to explain better.

Thanks in advance. :)

[LordV]

You can work out the magnification ratio by doing exactly as you suggest - take a pic of a mm scale of a ruler across the width then the mag ratio = sensor width/mm across pic.

This tells you the mag ratio of the lens which is the normal quoted figure. For your camera because the sensor is smaller, the Picture magnification on a normal sized print is higher (it has to be blown up more) so a Mag ratio of about 0.3:1 will give the same print magnification compared to a 1.6 crop camera with a lens at 1:1 at the same print size. Think your sensor width is 7.2mm compared to 22.5mm of a 1.6 crop camera

Brian V.

[coralnutz]

So I took a picture at full zoom and it was 11 mm across the frame. Does this meen that my magnification ration is aprox 0.6:1?

Thanks for the help...

[LordV]

So I took a picture at full zoom and it was 11 mm across the frame. Does this meen that my magnification ration is aprox 0.6:1?

Thanks for the help...

Yes it means the lens system you were using is giving about 0.65 :1 magnification ratio. That also means though that if you compared a shot taken with your camera to one taken with a 1.6crop DSLR at 1:1 with the same screen size (ie print size) then your would actually be twice as magnified on the screen or in print.

Brian V.