Archived posting to the Leica Users Group, 2000/10/31
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]> I started with a 24x36mm negative of silverbased emulsion and used standard > calculations to find the number of picture elements (pixels) or in classical > terms "image points" for a given resolution in lines per mm. So on the > assumption of 40 lp/mm (80 lines) as an industry standard (BTWthis > resolution gives salon quality exhibition prints of size 40 x 50cm 400 x 500 mm, from a 24 x 36mm is a 16.66x enlargement. That gives you 4.8lines/mm or 122 lines/inch... I really don't know what you mean by 'salon quality exhibition prints' though...but 122 lines/inch is only 1.5 times more than your computer monitor, but it certainly isn't 'bad'. > a 35mm > negative capturing 24 x 80 x 36 x 80 lines has a number of pixels or image > points of 5.5 million. This figure is independent of whatever grain size. That's a different story, as you mentioned M bytes before...which relates to amount of data... but that is certainly an entirely different subject than what resolution you need to scan film at...or how many grains on film...etc. > Now a new CMOS chip with 16.8 million pixels needs 4 pixels to repesent one > image point. The 16.8 million divided by 4 gives more than 4 million true > image points. 4 picture elements gives you four true image points. It only gives you one color point. They are different information, and you can interpolate the four points into one point, or you can keep the four image points and extrapolate the color information from all four over all four. > So what I intented to note is that with a CMOS of size 16.8 Million pixels > the overall image resolution is close to if not equal to the film resolution > needed for a high quality image and that with such a convergence it could > become difficult to see the differences in print (digital or analogue). Film records pseudo randomly, and digital imaging does not. That is absolutely important to image quality, and to comparing/relating the two 'technologies'. I know I can see the difference in print between a common silver print of equal size, and a digitally taken image. I have and have used both the Leaf and the Phase One digital backs for my Hasselblad. The PhaseOne back is 6.2M pixels, and scans three times....so it fits exactly with what you are claiming is 'equal' to film. I suggest you take a look at prints made from these digitally captured images. Here is their claim: "High quality image files can be offset printed in high quality at sizes over A4/8.5" x 11"" That claim leave me not convinced that it is anywhere near what either a darkroom print, or a print made from a scanned negative (at 4000DPI). Don't get me wrong at all, I love these backs, and they give exceptional results...just not as good as scanned film or a darkroom print does... > I think it best to leave this list now. That would certainly be a shame, your contributions have been outstanding. Not everyone has to agree with them for them to be outstanding. I do have one explanation you could really help with. I read (in a link that JD posted) the claim that color film has 1/3 the resolution of B&W film. Is that true? Personal experience tells me it isn't true...but I would certainly like to hear what you have to say on this topic.