Secrets of direct digitizing

Pierre Zagatti zagatti at
Mon Sep 29 04:46:57 EDT 1997

>         I have received no new information in response to my earlier
> posting re digitizing, but I gather there is some interest in how this
> may best be done. So here are some hints:

Sorry, but I just changed my computer and had no possibility to reply.

>         Definition: Direct digitizing = making digital images without
> going through the 'normal' procedure of making a photograph and then
> scanning the slide or print (or making a PhotoCD).
>         Methods: 1) flatbed scanners, 2) digital cameras. There is a
> third method, using single frames from video cameras--I have nothing to
> offer regarding that approach.

I have: our database on Lepidoptera of the French Antilles
( is totally based on images digitized
from a video camera.
Now we have approx. 500 _photographic_ images in this database (including
the Geometridae and Amphipyrinae not yet available on the net),
and we expect more than 1200 soon.

The camera is a tri-CCD JVC KY-F50 with a C-mount. With the C mount you may
use all cinematographic lenses or (via an adaptator) photographic lenses.
We use a Nikon Micronikkor (60 mm) to take our pictures. The video camera
is connected to a Macintosh Quadra 650 (40 Mo RAM) via an Image Grabber 24
digitizing card. The max. resolution of the camera is the same than the card:
768 x 576 pixels, in 24 bit colors. The image is then reduced to 400 pixels
wide to be included in the web catalog.

to take a picture of a moth:

The light is provided by 4 incandescent bulbs on a reproducing stand (4 x 150
The moth is placed at the tip of a glass rod, above a grey cardboard
background to avoid shadows. I am currently building up a web page
dealing with these technical aspects.
The video camera device certainly represents the best choice for
immobile objects. An adaptor for the C mount allows us to take
pictures under the microscope (the male genitalia slides of small
Noctuidae were done under the microscope).
A 3-ccd camera is rather expensive, but there are big differences
with mono ccd cameras. We began our catalogue with a mono ccd camera,
but replaced these old pictures, except for one species (we lose our
unique specimen !), so compare the mono ccd picture of Disphragis delira:
with a 3-ccd image of a similarly sized notodontid:

Costs (approx. from prices in French francs without taxes,
on the basis of 1 US$ = 6 FF).

Camera: 7500 $
Digitizing Card + software: 1400 $

A digital photo camera with interchanging lenses is more expensive
(12 000 $ for the Kodak DCS 420 with Nikon F90 body), but gives larger
images: 1524 x 1012 pixels.
The digitizing devices without interchanging lenses (photo or video)
are considerably cheaper but difficult to use in Entomology.

The main advantage of video (against flatbed scanning of prints) is the
immediate evaluation -and correction- of the result, in terms of
focusing, shadows and general color balance. The main problem relies
on the obligatory computer (or professional recorder) link. If you visit
a museum and want to take pictures of the type specimens hosted, you
must use photography.

BTW, to make pictures of large male genitalia, we obtained very good results
by inserting the microscopic slides into the slot of a Nikon scanner for
color slides.

Pierre Zagatti
INRA Unite de Phytopharmacie et Mediateurs Chimiques
78026 Versailles Cedex
Tel: (33) 1 30 83 31 18
e-mail zagatti at

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