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 Re: A stupid question | |
dcains wrote:I\'m not sure what you mean by same viewing distance or same viewer visual acuity, but they don\'t factor into the DOF calculations.
Do the math. They most certainly do factor in. If you make an 8 x 12 inch print and look at it from about 20 inches away, it will appear to have a particular depth of field. However, if you print the same image at 48 x 72 inches size and look at it from 16 to 20 inches away, you will see things blurry that you perceived as sharp in the 8 x 12 inch print from the same viewing distance; that is to say: less depth of field. You have to look at the large print at a distance of 120 inches to perceive the same depth of field.
Similarly, if someone has poor visual acuity due to loss of retinal cells due to disease, then they will perceive a greater degree of blur and because they are used to this, they will have a greater tolerance of blur and thus will perceive a greater depth of field than someone with high visual acuity.
Do the math with a real Depth of Field calculator that accounts for all the factors: melcat wrote:
Do the study to understand all the factors, starting with an overview http://en.wikipedia.org/wiki/Depth_of_field and proceeding to more primary references as needed or desired.
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