On 14 Mar 2004 at 18:14, John Mustarde wrote: > First - where can I get a higher resolution chart, rather one that has > been printed better, at a reasonable price? I only have the pdf > version, printed on my inkjet at (I think) 300 dpi. Most of my lens > tests resolve the tiny Group 2 line pairs, partly due to very long > focal lengths at my standard 4 or 5 meter test subject distance. But > nothing smaller than Group 2 is resolved on my printed chart, and even > the Group 2 lines are a little ragged and unevenly separated when > viewed under 12x magnification.
If you print out the pdf at my site using a decent LASER printer on photo quality paper the resolution should be much better as the file will print to the resolution of the best printers. http://www.edmundoptics.com/onlinecatalog/Browse.cfm?categoryid=289 http://www.appliedimage.com/ > Second - when using Rob's spreadsheet (USAF lens target to lpmm.xls), > does one enter the actual focal length or the actual focal length > times the crop factor? 300/2.8 times the 1.5x *istD crop factor makes > a big difference in the lpmm numbers; using the 450mm instead of 300mm > significantly reduces the lpmm number. Actual focal length (regardless of format) if you want to determine actual lpmm :-) > Finally - at what resolution do lenses start to look better than > average? Much better than average? Much worse than average? Very subjective, depends upon the capture medium and the reproduction size. 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
