Hello! Not having a test target, I decided to use a 4x5 astrophoto I took of the Sagitarius star cloud using TMax 400 last year and see the closest stars that the scanner could separate. I scanned a one inch square section of the original at 2400 spi, 48 to 24 bit in the scanner. I enlarged the image to 400% and cropped a small section and split the RGB layers.
Given all the variables of this image -problems in the field, lack of extremely fine focus, and that most people can split lines better they than can split stars, this image probably represents the worst case senario of how the scanner can perform.
To my eye, the three images suggest that the red layer is the sharpest.
The two stars in the the mid-field at the left are separated by 5 to 6 pixels. If I understand the math correctly, (2400 pixels per inch)/(6pixels per star pair)/(25.4mm per inch)/(2lines per star pair) = 8 lines pairs per mm.
In other words, it seems to me that, purely from a sharpness aspect, the scanner should give results that print up to 16x20 since this had a 4x enlargement, and most people consider 5 lines pairs per mm good resolution. Since there are obviously other variables involved that will degrade the image, I would think that the scans should produce excellent prints with my 8x10 R220 and MIS inks.
Am I interpreting this correctly, since I am using spot pairs (star images) rather than line pairs? Best regards.
Mike
Bookmarks