I ran several tests on my 4900 using Ernst's file. I've posted my horizontal dithering observations between my 4900 and 7880 on John's latest post and will try to keep this post to resolution and my 4900. Please note, all tests discussed herein were printed using PK ink printed at 2880 high speed (my print heads are aligned), finest detail off and printed on Epson Exhibition Fibre Paper with EFP chosen as the output paper within the 4900's printer driver (an option not available with the 7880 driver). Since, like John, I print from Lightroom, I'm interested in a file's output from LR and how changes within LR affect the output so all tests were printed from LR (no out sharpening or other alterations made to the file). When IR is different than print resolution/output resolution ("PR"), LR handled any file processing via its Print Resolution box. While I printed the full chart at an input resolution ("IR") of 180 across a couple of PRs, I decided to focus on Column A differences so other than IR 180, I'll just be discussing Column A output.
Not surprisingly, when IR is 720 and PR is 720, all appears fine. Unless I'm printing a pano, I rarely have a file with an IR 720 so I quickly moved on. With IR 360 and PR 360, there is no vertical banding across any sections. The 720 ppi section, however, appears very dark gray due to line spacing but faint vertical lines can be seen when viewing with a loupe. WIth IR 360 and PR 720, the 180 and 240 sections appear identical to the PR 360 result but the 360 and 720 sections appear lighter to the naked eye--with the 360 section appearing slightly lighter and the 720 section appearing much lighter. No loupe is required to see the vertical lines of the 360 section, but the 720 section appears to have narrower vertical spacing at PR 720 than PR 360. As a result, I'm not quite sure why PR 720's 720 ppi section appears lighter than PR 360's 720 ppi section--unless the driver is actually using a different black for that section.
IR 240. IR 240 and PR 240, all appears fine. While the 720 ppi section's vertical lines are not as clean looking as any of the others, vertical lines are visible with a loupe and evenly spaced. With PR 360, all sections appear lighter than their PR 240 counterparts (though 180, 240 and 360 barely so). Still no banding but the 720 section is not quite as "clean" as the other sections but is much cleaner than PR 240 (resulting in the lighter gray I am assuming). PR 720 produced the nicest results--no visible difference between the 180, 240 or 360 sections and a slightly lighter gray look to the 720 section probably due to "cleaner" vertical lines. This result seems to support Jeff's advice that if your file is below 360 PPI, print from LR with PR 360 for optimum results--at least for IR 240.
IR 180. IR 180 and PR 180, line thickness differences in Column D could be seen across all PPI sections. The 180 and 240 Column A sections looked fine, the 360 section had barely perceptible vertical banding and the 720 section had noticeable vertical banding which, when viewed with a loupe appeared to be due to varying, repeatable differences in vertical line thickness. WIth PR 360, all looks quite fine--no vertical banding of any sections and clearly defined vertical columns of the 720 section. I thought I also printed it at PR 720 but can't find it at the moment---I printed other IRs at PR 720 so I'm not overly concerned at the moment--perhaps I'll reprint.
More often than not, I find I'm printing files at an IR other than 180, 240, 360 or 720. As a result, I ran some additional tests with different IRs and had some surprising and interesting results.
IR 165. IR 165 and PR 165 is painful to view. The 180 ppi section looks fine, the 240 ppi section has vertical banding, the 360 section has vertical banding as well as vertical line convergence and the 720 section has an even greater frequency of vertical banding and vertical line convergence. At IR 165 and PR 360, the 180 section is fine, the 240 section has horizontal banding, the 360 section only has vertical line convergence, though at a much tighter frequency making it look better than PR 165 (and the banding is gone), and the 720 section is similar to the 360 section--no banding but a greater frequency of vertical line convergence, but it is not a painful print to view. Now the most surprising--IR 165 and PR 720-- everything looks perfect. No banding or vertical line convergence across any sections. The 720 ppi section's vertical lines could barely be made out by my naked eye and are clearly visible under the loupe. I was very surprised at this result.
IR 265. IR 265 and PR 265 looks horrible across all sections. The 180 section has vertical banding, the 240 section has vertical banding and convergence, the 360 section has some banding but a greater convergence and the 720 section has quite a lot of vertical convergence. The results are very bad. IR 265 and PR 360 showed vertical frequency banding on both the 180 and 240 sections and vertical line convergence on both the 360 and 720 sections. The 360 and 720 sections were ok to view, but the 180 and 240 sections were painful to view. IR 265 and PR 720--the 180 section was fine, the 240 section still had vertical banding (albeit narrower but more frequent), the 360 section had vertical line convergence, but looked much better than the 360 version. The 720 section had vertical line convergence (or thicker vertical lines at repeating distances), but at a greater frequency than the PR 360 version leading to a "cleaner" look. Overall, the IR 265 sections all looked better at PR 720 than PR 360.
For me, other than making the waters slightly murkier, if my IR is 240 or less, PR 360 should be fine. If IR is greater than 240, I'm going to change my PR to 720. I'd be interested to read other 4900 user results.
