I like Nathan's idea of a real world comparison between the two. Another way to do it would be to get a friend or volunteer who does film/darkroom 8x10 to choose his/her best 8x10 equipment and shoot your target and process and print it.
In fact I'd set the two cameras up side-by side an shoot some pictoral scenes rather than test charts. Then let your audience decide which pictures look best.
This is interesting. And it affirms in a different way my own personal testing results of what I think for me is the practical max resolution to scan at on the V750.Originally Posted by Nathan Potter
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EPSONcont-web-1 by hypolimnas, on Flickr[/IMG]
Jim, I think you may be referring to a plot I made recently for the V750 Pro. Plot is above from Flickr. The plot was made from the resolution target after importation into PS and with the full density range from 0 to 256. In other words my interest was in finding the MTF curve for a scan where the linearity and full 0 to 256 density range was preserved during and after the scan.
Nate Potter, Austin TX.
OK - looks like we're on for testing next week (14th October) and will have the best lens for the 10x8 too (Mr CAD are lending us a Sironar S 360 and possibly a 210 - great people who I've dealt with before.
The scene will be one interior in a small studio with window lights and one scene from a large garden. If we get time we may nip up the road for a proper 'scenic' shot.
I've yet to do the maths for appropriate distances but will have it all planned in advance.
I can include a resolution target and was wondering which one is recommended? (something I can print out preferably as the timescales are quite small).
I was thinking of including an 8x10 transparency on a light box as a resolution test as well.. should make for a good known target with very high resolution.
Tim
Still Developing at http://www.timparkin.co.uk and scanning at http://cheapdrumscanning.com
that's great. I cant wait to see the results.
-Noah
Tim,
perhaps take a print-out of Norman Korens testchart ..download from his website .. as a print it is 25cm/10 inches long .. fits nicely in a 8x10 holder fo setting up .. at 50x focal length the chart will be 5mm on the film .. easy to read around the 50 lps/mm section with a 10-16x magnifying glass..
best regards,
joerg
If you include a resolution chart as part of the set up, I would suggest a slanted-edge pattern. It is very easy to print your own, and those can be used to automatically evaluate MTF values with the appropriate software, two things which cannot be said of the USAF chart. See: http://www.imatest.com/docs/sfr_instructions.html
I have an Imatest license, so if you send me the relevant portion of image files, I could run them through the software.
I agree on the use of Norman Koren's charts. They will help you evaluate the critical resolution at 10% and 50% MTF, not just minimum discernible resolution. You can print as many as you need and arrange them however you want (and I agree to put one at a 45-degree angle--very important).
Koren's article on lens testing, but it applies here
His chart can be downloaded and printed. I would use matte-surface paper. Include a big black square on the same print. Also, include a known-good gray card somewhere in the image for calibrating any needed color corrections.
Make sure your film exposures are perfect. That means confirming the shutter, or bracketing if you aren't sure.
Rick "who has done this with medium-format, and used a microscope for evaluation" Denney
From experience with my Epson 2200, semi-gloss or gloss will give better results for printing a target. (Yeah, I ran some tests on my printer. Sniff!)
The guys at Imatest have done me a nice deal on Imatest Master but I couldn't afford to buy a big target from them. Norman Koren has been in touch also and is advising.
I'm currently working out how to print out a very big target but also how to include a still life in the scene (it's expensive and dull to take just pictures of targets and there are lots of other non-resolution things we'd like to assess).
Can we mix parts of the target with parts of still life? can we place them side by side? etc. Can I print test target in 17" wide roll sections and then mount to matt board 60x40 mount board?
Also, Markus and I have been working on the old results and have found that we can compare the 55mm result (which had better focus and even though it had extra resolution from it's f/8 and 10% longer focal length was enough to make a simple comparison). This is the result. The IQ180 has about a 20% advantage here in terms of focal length and depth of field.
This is backed up by the diffraction and depth of field maths.
Still Developing at http://www.timparkin.co.uk and scanning at http://cheapdrumscanning.com
How about an assortment: flowers, fabrics with patterns, some finely detailed items such as wood carvings, perhaps a wine bottle with intricate label?
The megapixel equivalent number varies with f-stop (higher res as you open up) so increased depth of field can be a disadvantage, making it preferable to keep things in the same plane.
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