Help w/ Screen Cezanne 5000

[Peter York]

Hi all,

I recently had the opportunity to test a Screen Cezanne 5000 w/ ColorGenius v.2 software that I am considering buying, and the results not what I was expecting.

A Fuji Velvia 100 4x5 chrome was used for the testing. I cannot say if the chrome is critically sharp, but it includes areas that are quite sharp and areas that are out of focus (the shot was at f/32 with a Kodak 100mm wide field ektar). The chrome was placed in the center of the scanning bed (approximately). All tests, wet and dry (w/ an anti-newton overlay), over the entire area of the chrome and with small selected areas of the chrome, at 3000 dpi and 5000 dpi, produced results less sharp than a scan from my Epson 4990 that I used for comparison.

Should I write this scanner off, or are there any adjustments I can make for a re-test to troubleshoot the scanner? The operator had been wet-mounting to an acrylic bed rather than the standard tray. The standard tray looks ok except for some fine scratches, but I can have a glass or acrylic plate made if necessary. Would a sharper chrome, perhaps from a 35mm slide, give any better indication of the scan quality? Can some calibration or diagnostic can be run? Please help! Thank You.

[Pfeiffer Duckett]

'Less sharp' is such a difficult quantification. Do you have the respective images you can post or link us to?

[Peter York]

I'll try to get some images up soon...

[Peter De Smidt]

A scan of a 4x5 inch piece of film with a Cezanne will involve interpolation at 5000 and 3000 dpi. 2100 would give you straight optical resolution, assuming you put the long side of the film parallel to the front of the scanner. (8000 element ccd over 3.75 inches = 2133 spi.)

Make sure that in both cases no sharpening is applied by the scanning software.

[Peter York]

Peter,

My first thought was that with a 3000 dpi scan over the entire chrome, the interpolation might be an issue. The 5000 dpi scans were of a small area on the chrome (they are 3160x3125 pixels). These small sections should (in a properly functioning unit) resolve at 5000 with no interpolation, right?

[Peter De Smidt]

Yep, at less than 1.5" front to back you should get the full optical resolution.

[Joerg Krusche]

Peter,

1. the Cezanne is specified to deliver 5000 dpi actual optical resolution (?) .. provided the scanning area is small enough .. if so has anyone challenged this with for example a scan of an USAF chart 1951 ... and which max number (group and element) of line pairs was obtained ?

2. Which resolution values to enter do you recommend to obtain optical resolution only without interpolation .. does this question make any sense ? ..or does it just not matter ?

The question for actual max. optical resolution does not mean that it is relevant for actual scanning of sheet film .. just would like to know what to expect .. and/or how serious one may take specs ?

best,

joerg

[Peter York]

I'm having image hosting issues... I'll try to have images up later today.

I recall finding the sharpening button accidentially checked in Epson Scan a while ago, and the test scan I used for comparison probably had sharpening applied. I re-scanned the image and the Cezanne is better, but slightly. If my wide field ektar is similar to the sample tested by Christopher Perez/Kerry Thalmann, then at f/32 the lens can only resolve about 2300 dpi in the center. Add in my technique, etc. and the image I tested may be within the capabilities of my Epson 4990.

Since I do not have a USAF 1951 target, I'm planing on re-testing with a 35mm slide and comparing the results against a Nikon Coolscan 5000. This should say much more about the scanner's capability. Any thoughts on if I should shoot some test shots? If so, do you have a recommended procedure?

Thanks all!

[Peter De Smidt]

The Seybold report measured the optical resolution of the a number of professional scanners. I no longer have my copy of the report, but according to them the Cezanne was capable of about 5600 spi.

The Cezanne uses an 8000 element ccd sensor. It is positioned perpendicular to the front of the scanner. Hence, to obtain maximum optical resolution, position the long end of the film parallel to the front of the scanner. To find the optical resolution, measure the image area of the shortest side of the film. Divide that number into 8000. That'll be near the optical resolution that the scanner can produce in one pass. If more resolution is needed, scan slightly overlapping strips.

All of this is complicated since it's positioning system is good enough to give higher resolution in the direction parallel to the front of the scanner. This explains the Seybold Report's findings. The only way to determine what's best with a given film is to do some experimenting. Scanning is a complex interaction between the light source, film, lens, and sensor, and sometimes unexpected results pop up.

With a Cezanne, it's important to mask off non-image areas of the bed. Otherwise flare can cause problems.

[Peter De Smidt]

Peter,

You want an area with fine detail (to test resolving power), an area with smooth tones (to see how the scanner handles grain), and a representative dynamic range (to check noise.) If you shoot both fine-grained film and large grained film. Check both. The Coolscan excels with fine-grained film, but in my experience doesn't do as good a job with grainier film.