Digital BW, The Print

On 07/25/2012 10:13 AM, Richard Kenward wrote:
> In his posting of Mon, 23 Jul 2012, writes
> snip
>
>  >Plustek OpticFilm 120
>  >Image Sensor CCD
>  >Light Source LED
>  >Hardware Resolution Maximum Input\uff1a 10600 dpi
>  >Maximum Output\uff1a 5300 dpi
>  >Scan Modes Color: 48-bit input, 24/48-bit output
>  >Grayscale: 16-bit input, 8/16-bit output
>  >Dynamic Range 4.8
>  >Infrared Built-in
>  >Scanning Area (W x L) 60 mm x 120 mm
>  >IT8 Target Included for color accuracy
>  >Power Supply 24 Vdc / 0.75 A
>  >Interface USB 2.0
>  >Net Weight Approx. 5.7 Kgs
>  >Dimensions (W x D x H) 210 x 374 x 189 mm
> Snip
>
> When I read scanner manufacturer's claims of 4.8 dynamic range I suspect
> all of their claims! There is absolutely no way this is possible in a
> desktop CCD scanner! A top drum scanner in perfect condition can only
> manage about 4.2 that's the reality guys and nothing beats a drum
> scanner in good hands.
>
> I remember in years past that when all the desktop CCD scanner makers
> were making increasingly exaggerated claims for dynamic range that when
> challenged about their claims for 4.8 the MD of Imacon said that it was
> a marketing statement. I read that as lies.
>
> Cheers
>
> Richard
> --

It depends very much on what is seen as an acceptable signal to noise 
ratio.
Image Engineering did a test on 3 scanners with and without Multi 
Exposure and gives the data they measured and computed:

www.silverfast.com/PDF/TestReport_ME_DWueller.pdf

Dmax and Dynamic range are important, a drum scanner also has less flare 
due to the single beam optical arrangement. In a desktop scanner the 
best light source is still covering the entire length of the linear CCD.

4,8 Dmax for a Plustek is too good to be true IMHO.

-- 
Met vriendelijke groet, Ernst

Dinkla Grafische Techniek
Quad, pi\ufffdzografie, gicl\ufffde
www.pigment-print.com