Scanner Resolution

[Bill Oehlke]

The Catocala relicta image at
http://www.silkmoths.bizland.com/childhood.htm
was done at a resolution of 600 with moth being placed directly on a flatbed
scanner. I also scan larvae on same scanner
by propping the cover up on a slight bridge with larva draped over bridge.
Lapara bombycoides at  http://www.silkmoths.bizland.com/lbombyco.htm was
done on flatbed scanner at resolution of
600 dpi. Most of the butterflies of
http://www3.pei.sympatico.ca/david.fraser
were done by pinning spread specimens to foliage and then putting on flatbed
at resolution of 600. I have a new scanner that will let me do 3200 dpi and
hope to experiment more this summer when larvae and moths are available.
Larvae have to be inactive during scan or you get distortion.

----- Original Message -----
From: "Kondla, Norbert SRM:EX" <Norbert.Kondla at gems3.gov.bc.ca>
To: "lepstalk (E-mail)" <TILS-leps-talk at yahoogroups.com>; "lepsl (E-mail)"
<leps-l at lists.yale.edu>; "altabugs (E-mail)"
<albertabugs at majordomo.srv.ualberta.ca>
Sent: Sunday, January 19, 2003 1:22 PM
Subject: FW: Scanner Resolution


>
> -----Original Message-----
> From: Cris Guppy [mailto:cguppy at quesnelbc.com]
> Sent: Saturday, January 18, 2003 10:14 PM
> To: Kondla, Norbert SRM:EX
> Subject: Scanner Resolution
>
>
>
> This might be of interest to leps-l subscribers.
>
>
>
> Scanners can be used to "photograph" butterflies or butterfly parts
> (genitalia, wings) placed flat on the scanner plate. Quality of image
> decreases with increased distance from the scanner plate. The question is,
> what is the maximum useful scanner resolution for "photographing"?
>
>
>
> Visible light wavelength = (Violet) 0.4 - 0.7 (Red) micrometre
>
> 1 inch = 2.5 cm = 0.025 metres
>
> 1 micrometre  = 0.000001 metres
>
>
>
> A scanner resolution of 1,000 dpi (dots per inch)
>
> = 250,000 dots per metre  = 1 dot per 4 micrometres.
>
>
>
> A scanner resolution of 10,000 dpi
>
> = 1 dot per 0.4 micrometre
>
>
>
> A scanner resolution of 5,700 dpi
>
> = 1 dot per 0.7 micrometre
>
>
>
> So the theoretical maximum resolution of a scanner to obtain the full
range
> of visible colour in the image is 5700 dpi. A US$200 Hewlett Packard
scanner
> these days has a maximum resolution of 2400 dpi, so they are 42% of
maximum
> theoretical resolution. Not too bad!
>
>
>
> The scanners also have an "enhanced resolution" up to 99,999 dpi, the
value
> of which is unclear to me (anyone else?).
>
>
>
> Cris Guppy
>
>
>
>
>
>
>
>
>
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>
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