On 12 Jan 2004 at 22:28, Jens Bladt wrote: > 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.
Hi Jens, Plenty of resources here: http://members.ozemail.com.au/~distudio/lenstesting/ > 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. Sure, the Kell factor in this case appears to be about 0.7 therefore the resolution in lpmm can effectively be calculated as 3008pixels/23.5mm/2pixels*0.7kell factor=44.8lpmm. I used a conventional test chart in conjunction with a very high resolution lens in order to reduce it's effect on the measurement and I calculated an optical resolution of 44.6lpmm and this was before I made any theoretical calculations. > 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. I don't think so, I doubt there will be that much to gain by making smaller pixels, look at the noise generated by the Pentax *istD at higher ISO already. Smaller pixels will reduce the effective exposure latitude, colour accuracy and increase the noise floor. By many accounts the F-828 offers more promises than performance. > 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? You are probably right, 2-3 years, the *ist D isn't an ideal solution, nor is the Canon 1Ds, the Kodak comes closest at 14MP as it offers the same effective lpmm as the Pentax but using the full frame. Unfortunately it was before it's time technology wise however I am sure that it would be all that most photographers would ever require resolution wise. I don't think we'll see 24x36mm sensors with higher densities any time soon. > By the way - did you ever think about > this - the digital photographic technology pretty much works like the human > eye? I think it may be a while before we are doing image capture "Matrix" style :-) 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
