T.R | Title | User | Personal Name | Date | Lines |
---|
3154.1 | | LEDS::BUSCH | Dave Busch at NKS1-2 | Mon Nov 27 1989 20:58 | 35 |
| -< Digitizing 35mm Slides with DIGIVIEW >-
When I first got DigiView, I tried using my RCA color camera and quickly
realized that the process of first taking a color picture, only to have to
digitize the black and white component through the color wheel, was going to
give inferior results. The "standard" B/W camera you mentioned is "a must".
This camera allows you to adjust the position of the imaging tube within the
camera to allow you to adjust the focus down to an inch or less.
I also tried to make my own color wheel using various colored photographic
filters (the kind used in studios and movie sets for lighting) but found that
the color pallette in DigiView is initially balanced for the filters that THEY
provide. There is even a difference in the filters/balance between my DV and the
next rev up (Gold). DigiView Gold is balanced for use with fluorescent lights.
The best results I've had were with a small light box I built. It is lit
internally with an incandescent bulb. It has a Fresnel (flat) lens near the top
which is covered with a frosted white glass on which the slide sits. The lens is
important because it re-directs the light at the edges of the slide so that it
focuses on the camera lens rather than diverging out to where it will do no
good. This avoids uneven hot spots in the center of the picture since the light
from the edges now ends up at the camera. I haven't noticed any differences in
the results I get when the iris is open or closed, unless the light box is TOO
bright. I usually leave the lens wide open. BTW, since DV allows you to invert
your image to negative, you can also "print" your B&W negatives by simply
putting a negative on the frosted glass and holding it down with another small
piece of glass.
I built a camera stand for less than $10 using plumbing pipes and flanges, etc.
You can also build a "DigiDroid" to automatically rotate the color wheel. John
Bernard posted the plans elsewhere in this conference. It only cost about $10 to
build. I wouldn't leave home without it.
Dave
|
3154.2 | What kind of lens? | AKOV11::SMITH | Reality, just a visible imagination? | Tue Nov 28 1989 13:19 | 14 |
| Thanks for all the input Dave. Perhaps you could answer a few more
questions about the slide box you built.
What size/watt incandescent bulb are you using? Since I have DV Gold
should I use a fluorescent lamp?
Whats a Fresnel lens?
Any suggestions where to purchase a Fresnel lens and frosted glass?
A Camera shop? I guess a glass dealer would have frosted glass.
Thanks Again,
...Ed
|
3154.3 | Also good for cooking hot dogs | MILKWY::JANZEN | Re-invented the wheel | Tue Nov 28 1989 14:29 | 18 |
| When I needed frosted glass I went to Edmund's but it's very expensive.
i couldn't tell from the directions above whether it's for diffusing
light onto the subject, but if it is there are safer ways. Glass in
proximity to a hot light can crack suddenly in a cold draft or no
apparent reason.
Anyway, fresnel lenses are also available from Edmund's, in fact some
of Edmund's stuff is no available from supplusers they sold it to for
less. A fresnel lens is a flat lens with concentric rings of rounded
prisms that bend the light the same way a conventional lens would.
they are used in theatrical spotlights, on overhead projectors (under
the glass that's under the transparency), and in outdoor cigar lights
;-). It is possible to make radio frequency fresnel lenses with
alternating concentric rings of conductors and open space.
Glass Fresnel lenses are expensive, but you can't put plastic next to a
light. The fresnel lenses in spotlights are very thick for dissapting
heat, and deliberating bumpy to diffuse the light a little.
Tom
|
3154.4 | Slide copy box. | LEDS::BUSCH | Dave Busch at NKS1-2 | Tue Nov 28 1989 16:45 | 46 |
3154.5 | plexiglass (tm) | HYSTER::DEARBORN | Trouvez Mieux | Tue Nov 28 1989 18:27 | 8 |
| Why can't you just use a small commercial light table? Most use
white translucent acrylic and provide a very even light source.
You could pick up a small piece of this type of plastic at
virtually any glass shop for next to nothing. The advantage is
that it is colorless.
Randy
|
3154.6 | Light tables are large. | LEDS::BUSCH | Dave Busch at NKS1-2 | Tue Nov 28 1989 20:12 | 8 |
| < Why can't you just use a small commercial light table? Most use
< white translucent acrylic and provide a very even light source.
You could. Trouble is, where are you going to get a light table as small as a
coffee mug (or thereabouts)? I've got one, but it's about 12" x 18".
Dave
|
3154.7 | get clever | HYSTER::DEARBORN | Trouvez Mieux | Tue Nov 28 1989 20:42 | 5 |
| Mask it off with illustration board or mat board. You could even
make a little thing on the board to position the slide out of the
leftover board.
Randy
|
3154.8 | Another Alternative | SHARE::DOYLE | | Thu Nov 30 1989 12:03 | 18 |
| The folowing was extracted from Amiga World Dec 1989
For Full color digitizing, mount a two-foot square piece of rear
projection screen material- (wich can be purchased by the yard from:
Rosco
36 Bush Ave.
Port Chester, NY 10573
914/937-1300
and
1135 North Highland Ave.
Los Angeles, CA 90038
213/462-2233
) - onto a free-standing frame and project an image on it from the rear.
The Digi-View camera records the image from the front of the screen, and
you don't have to worry about even lighting.
Toby
|
3154.9 | | LEDS::BUSCH | Dave Busch at NKS1-2 | Thu Nov 30 1989 16:10 | 22 |
| Re .7
You missed my point. Of course it's easy to mask off the unwanted portion of the
light from a light table. My point was that who wants to have to buy and store a
large (and expensive) item when a small one will do.
Re .8
< For Full color digitizing, mount a two-foot square piece of rear
< projection screen material onto a free-standing frame and project
< an image on it from the rear. The Digi-View camera records the image
< from the front of the screen, and you don't have to worry about even
< lighting.
The problem here is that you DO have to worry about uneven lighting. This is
because the light coming through the center of the screen disperses, but with
the majority going straight through to the camera. At the edges, the light is
diverging from the main axis and a majority of the dispersed light STILL spreads
out away from the camera, thus leaving what appears to be a bright hot spot in
the middle. The fresnel lens serves to redirect the diverging rays so that the
same "number" of rays converges at the camera lens from ALL parts of the image.
Dave
|