Hi Rob Hmmm. Not so sure about how to test lens resolution on film. I'm sure 100 linepairs pr. mm has been occationally achieved on film. In those days the lenses was often setting the limmits. As opposed to todays technology where the CCD are setting the limits. Hav you ever seen digital images blown up to - let's say - 1200 x 1800mm. Like in a slide show. Or a moovie - made with 35mm film.
Simple math tels me that 3000 pixel covering 24mm gives 125 pixel/mm. But you need three to make a PAIR of lines. Gives you appr. 43 line pairs/mm, right. So, using a 6MP body is like using the poorest lens ever made by Pentax - resoluton wise, of cource. Like 100 lp/mm seemed to be "the sound wall" of analog photography, it seems appr. 5000 dpi is "the sound wall" of current digital photography. But I'm sure they'll break throug this sometime soon. SONY is now marketing a 8MP consumer camera - with a 2.0 Carl Zeiss lens - for appr. 1000$ (Sony DSC F-828). Maybe we'll get there earlier than we relly want. My "old" faithful PZ1 has served me well for 12 years. How long do you think my Pentax *ist D will keep up - 2 years, 3 years? By the way - did you ever think about this - the digital photographic technology pretty much works like the human eye? All the best Jens -----Oprindelig meddelelse----- Fra: Rob Studdert [mailto:[EMAIL PROTECTED] Sendt: 11. januar 2004 23:56 Til: [EMAIL PROTECTED] Emne: *ist D resolution (was:Soon to be new istD owners) On 11 Jan 2004 at 11:26, Herb Chong wrote: > i don't know where you read that. there are a few sensors in use as digital > backs that have that kind of dynamic range, but not the sensors in DSLRs. I'll eventually put up a page like I did for my Oly with my findings on this matter, see: http://members.ozemail.com.au/~distudio/contrast/ > as for resolution, the conditions under which you can reliably achieve 100 > line pairs per mm are when shooting resolution charts under high contrast > conditions with very high resolution film on a tripod at high shutter speeds > with a top lens at its optimum aperture and focus bracketed. It's not actually that difficult if you have gear that it well matched. > the reason digital cameras can compete is that under real life conditions, > few people can possibly exceed 40 line pairs per mm worth of resolution and that > a digital SLR has negible amounts of noise compared to film even at higher ISO > ratings. The *ist D sensor provides a theoretical 128 pixels per mm after demosaicing however in practical terms the body can only resolve between 45 and 50 lpmm, which is very close to what I expected. This figure I derived using bracketed focus on a technical target with optics that should provide well over 100lpmm on film. Cheers, Rob Studdert HURSTVILLE AUSTRALIA Tel +61-2-9554-4110 UTC(GMT) +10 Hours [EMAIL PROTECTED] http://members.ozemail.com.au/~distudio/publications/ Pentax user since 1986, PDMLer since 1998
