On 19 Jan 2004 at 9:08, Jens Bladt wrote: > Hi > Hmmm: 46 lines pr. mm. Kind of poor, right. Especially when a CCD is so > small. The whole picture only is 16x24mm. 24 times 46 lines is just 1104 > lines in the whole length of the CCD. On the other hand - 3008 pixels will > allow for 1504 line pairs. > It means it can utilize appr. 63 lp/mm. Maybe that's not exactly how a CCD > work, but ita can't be totally wrong, can it...
You are right to a degree. To prevent aliasing errors in a sampling system the maximum frequency to which the sampling sensor should be subjected should be below fs/2, to achieve this a suitable low pass filter often needs to be employed. Consider a direct audio analogy; the sample rate on a CD player is 44.1kHz however the absolute maximum reproducible frequency is 20KHz due to the implementation of 20kHz low pass filtering in the record chain. When shooting a high contrast lens test target using various lenses at optimum apertures the best resolution that I've been able to measure for the system (lens + *ist D) is 44.6lpmm. 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
