My powershot G3 lens is 7.2mm at the wide end (equiv of 35mm on 35mmm), if it had f/22, the physical size if the aperture would be 0.3mm, diffraction city! I don't have one of the old mans books around to look up the math (I should really remember it!) but that's the basic reason.
And referring to the original post: >Focal length dictates the depth of field that a lens can achieve. This counts only for the same format of image or even sensor type. Yes, the optics of both systems are the same but, DOF must also take into account the 'circle of confusion'. This differs from format to format on film. Dig-wise it depends on oh-so-many things.... Pixel size, low-pass filters, colour interpolation, software..... Alex Ray > Perhaps due to the resolving power of 35mm film? The small sensors in > most digital cameras will produce soft results at very small apertures > due to diffraction. Same reason you don't find F64 on lenses for 35mm > format. =============================================================== GO TO http://www.prodig.org for ~ GUIDELINES ~ un/SUBSCRIBING ~ ITEMS for SALE
