Timeline for What's the formula for f-stop equivalence between different sensor sizes?
Current License: CC BY-SA 3.0
6 events
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| Dec 26, 2013 at 0:14 | comment | added | Michael C | See also photo.stackexchange.com/a/34801/15871 | |
| Dec 26, 2013 at 0:12 | comment | added | Michael C | But if a negative or digital image is printed at twice the standard 8x10 print (16x20) then the largest blur circles on the negative that will be perceived as single pointsare half the size of the blur circles that will be perceived as points in the 8X10 print, so now the perceived DoF is only the part of the print that comes from the parts of the negative that have blurs circles 15µ or smaller. | |
| Dec 26, 2013 at 0:10 | comment | added | Michael C | Normally the amount of acceptable blur is defined by the size of the blur circle. With an image from a 35mm size film/sensor printed at 8X10 viewed from 10 inches by a person with 20/20 vision the accepted blur circle is about 0.03mm (30µ). When the blur circle is smaller than 30µ it is perceived as a point at standard size/distance/vision and any blur that size or smaller is considered within the DoF. | |
| Dec 25, 2013 at 17:26 | comment | added | Olin Lathrop | @Michael: This depends on how exactly you define depth of field. If it's blur relative to the size of the whole image, then you're right. However, if it's some minimum acceptable blur due to off-focus relative to the sharpness of the lens at focus, then image size doesn't enter into it. Either way, depth of field is a somewhat subjective measure relating to how much degredation you are willing to put up with or that you still consider "in focus". There is no hard sudden edge for off-focus, only what you consider acceptable in that particular circumstance. | |
| Dec 25, 2013 at 1:08 | comment | added | Michael C | It is also related to sensor size because you have to magnify an image produced using a smaller sensor by a greater factor to create a print of the same size, such as the standard 8X10 print viewed at 10 inches by a person with 20/20 vision that is the standard applied to most DoF charts. If you change any of those variables (print size/viewing distance/visual acuity of the viewer) the DoF changes for the exact same image file or negative. | |
| Dec 25, 2013 at 0:37 | history | answered | Olin Lathrop | CC BY-SA 3.0 |