Tinted glass

(Crossposted from Cameramakers)

I'm working along similar lines - building a camera around a CIS-type
scanner at the film plane. The thought occurred to me that an
interesting test might be made by disabling the scanner light source,
mounting a piece of parchment paper (or translucent film) onto the
scanner glass plate, taking an enlarger and negative as a light source,
projecting it onto the parchment paper and scanning that. I won't be
able to try this personally until the end of next week, so right now,
the experiment is just conjecture.

Regards,

Marv

jjs wrote:
In article ,
Marv Soloff wrote:


There have been a number of "scanner-direct" articles on the net. Most
involve removing the pickup components and using a lens [...]


You guys are a bad influence. It's the dark of winter. Cabin fever sets
in. There's an Epson scanner on the desk, and I have several very large
(wide, fat) lenses. Heh. Revenge. I'll do self portraits as example
pictures.

"Marv Soloff" wrote in message
...
Working on a scanner back for a large format camera (odd sized). Idea is
to use a standard scanner minus the illuminating tube as a pickup at the
focal plane. Static shots only. Wanted to explore the options other than
GG - which I make myself with valve grind compound. I thought I would
have problems with the CCD pickups and ground glass hence the thought to
use a tinted film or glass.

Reading this may be helpful then
http://www.rit.edu/~andpph/text-demo-scanner-cam.html

Guillermo

Had Andrew's piece for several years now. Thanks.

Regards,

Marv

f/256 wrote:
"Marv Soloff" wrote in message
...

Working on a scanner back for a large format camera (odd sized). Idea is
to use a standard scanner minus the illuminating tube as a pickup at the
focal plane. Static shots only. Wanted to explore the options other than
GG - which I make myself with valve grind compound. I thought I would
have problems with the CCD pickups and ground glass hence the thought to
use a tinted film or glass.


Reading this may be helpful then
http://www.rit.edu/~andpph/text-demo-scanner-cam.html

Guillermo

On Sat, 24 Jan 2004 17:37:35 GMT, Marv Soloff
wrote:

(Crossposted from Cameramakers)

I'm working along similar lines - building a camera around a CIS-type
scanner at the film plane. The thought occurred to me that an
interesting test might be made by disabling the scanner light source,
mounting a piece of parchment paper (or translucent film) onto the
scanner glass plate, taking an enlarger and negative as a light source,
projecting it onto the parchment paper and scanning that. I won't be
able to try this personally until the end of next week, so right now,
the experiment is just conjecture.

Regards,

Marv

The lenses on the scanner bar are focused at the upper surface of the
glass where the document lies. Scanning an aerial image should need no
glass as its there mainly as a support medium for the document. You
just need to determine if the image will focus properly if it is at
the scanners plane of focus. I don't have any idea what the
interactions between the lenses on the scanner bar and the camera lens
would do to the image. It may turn out to be as simple as focussing on
the scanners plane, maybe using that sheet of paper, the removing it
for the actual scan.
This reminds me a bit of shooting through the eyepiece of a telescope
with a 35mm camera. Focus the scope and put the lens at the point of
focus from the eyepiece and somehow it works.

Worth a try.

Thanks!

Regards,

Marv

Gary Beasley wrote:
On Sat, 24 Jan 2004 17:37:35 GMT, Marv Soloff
wrote:


(Crossposted from Cameramakers)

I'm working along similar lines - building a camera around a CIS-type
scanner at the film plane. The thought occurred to me that an
interesting test might be made by disabling the scanner light source,
mounting a piece of parchment paper (or translucent film) onto the
scanner glass plate, taking an enlarger and negative as a light source,
projecting it onto the parchment paper and scanning that. I won't be
able to try this personally until the end of next week, so right now,
the experiment is just conjecture.

Regards,

Marv


The lenses on the scanner bar are focused at the upper surface of the
glass where the document lies. Scanning an aerial image should need no
glass as its there mainly as a support medium for the document. You
just need to determine if the image will focus properly if it is at
the scanners plane of focus. I don't have any idea what the
interactions between the lenses on the scanner bar and the camera lens
would do to the image. It may turn out to be as simple as focussing on
the scanners plane, maybe using that sheet of paper, the removing it
for the actual scan.
This reminds me a bit of shooting through the eyepiece of a telescope
with a 35mm camera. Focus the scope and put the lens at the point of
focus from the eyepiece and somehow it works.

On 1/25/2004 2:51 PM Gary Beasley spake thus:

On Sat, 24 Jan 2004 17:37:35 GMT, Marv Soloff
wrote:

(Crossposted from Cameramakers)

I'm working along similar lines - building a camera around a CIS-type
scanner at the film plane. The thought occurred to me that an
interesting test might be made by disabling the scanner light source,
mounting a piece of parchment paper (or translucent film) onto the
scanner glass plate, taking an enlarger and negative as a light source,
projecting it onto the parchment paper and scanning that. I won't be
able to try this personally until the end of next week, so right now,
the experiment is just conjecture.

The lenses on the scanner bar are focused at the upper surface of the
glass where the document lies. Scanning an aerial image should need no
glass as its there mainly as a support medium for the document. You
just need to determine if the image will focus properly if it is at
the scanners plane of focus. I don't have any idea what the
interactions between the lenses on the scanner bar and the camera lens
would do to the image. It may turn out to be as simple as focussing on
the scanners plane, maybe using that sheet of paper, the removing it
for the actual scan.

This is what I suspected but didn't know for sure.

I think the way I'd try to do this would be to use a conventional ground glass
for focusing, then remove the ground glass completely and simply place the
scanner mechanism so it focuses on the focal plane formerly occupied by the
GG. That way you don't need to mess with paper, parchment or tinted glass at all.


--
Focus: A very overrated feature.

- From Marcy Merrill's lexicon at Junk Store Cameras
(http://merrillphoto.com/JunkStoreCameras.htm)

Hello Marv,

It is'nt as easy it initially sounds, you need to remove the lens and
the mirrors of the scanner an need to focus directly on the surface of
the CCD. That's because if you leave the lens of the scanner in the
optical path, you'll get only an visible image when the tree elements
(CCD - lens of scanner - LF-Lens ) are in one line. Think of a very
strong hot spot.
This produces a new problem. Because the CCD's are shorter than the
papers (flatbed) width they scan, you'll get a strong anamorphic effect
if you achive to proyect correctly the image in the CCD of the stripped
down scanner. That's because the scanner sees an image that is strongly
compressed in vertical-to-travelling direction but not compressed at all
at travelling direction. The scanner logic needs to adjust the data to
give you an image with correct proportions.

Does anyone know, if the sensors of the cheapest Canon scanners (LIDE
techonlogy) are as long as the papers are wide? If so, this would be a
perfect candidate! I have been talking with Agfa, forget about their
scanners for such a proyect, the CCD are way too short.


regards

Tadeuz


Marv Soloff wrote:
Working on a scanner back for a large format camera (odd sized). Idea is
to use a standard scanner minus the illuminating tube as a pickup at the
focal plane. Static shots only. Wanted to explore the options other than
GG - which I make myself with valve grind compound. I thought I would
have problems with the CCD pickups and ground glass hence the thought to
use a tinted film or glass.

Regards,

Marv

jjs wrote:

"Marv Soloff" wrote in message
...

Has any one here used a tinted glass like PPG's Solexia (with a 77%
transmission rate) instead of ground glass for large format focus?



Strange. May I ask Why? Most of us want all the light we can get, and
besides GG is inexpensive, quite available and bright. In fact, if you
put a
drop of oil right in the center of the ground side, you have a brilliant
point for aerial focus.

On 1/31/2004 10:52 PM Tadeuz Jalocha spake thus:

Does anyone know, if the sensors of the cheapest Canon scanners (LIDE
techonlogy) are as long as the papers are wide? If so, this would be a
perfect candidate! I have been talking with Agfa, forget about their
scanners for such a proyect, the CCD are way too short.

I don't know if this applies to current scanners or not--I suspect it still
might--but I took apart an old scanner (Microtek?) once, and pulled out the
optics and CCD. The actually sensor element was nowhere near the width of the
paper; the lens reduced the width of the scanned image to the width of the CCD
(less than half the width, I seem to recall). But maybe wide enough for a
scanning-back project.


--
It's stupid, moronic and too fcuking obvious, as obvious as counting your
fingers, so TELL ME SOMETHING I DON'T KNOW or just shut the fcuk up.

- "jjs" in extremis on rec.photo.darkroom

Tadeuz:

The scanner was a Digital Research flatbed made by some outfit called
Spot Technologies. The scan before disassembly was marginal by any
measure of quality. The scanner was opened, and the moving scanning
section removed from the guide rail. After the paper cover was pulled
off, the folded optical path was exposed - some 5 mirrors - and the CCD
assembly removed from the plastic housing.

It appears that the scanner CCD now only operates correctly when the
traversing motor is attached and will not produce any type of usable
image without it. The CCD assembly and circuit boards have been removed
from the plastic shrouds and body of the scanner. The glass plate has
been salvaged. I will get some more time this week to play with the
sensor which is about 2 1/4 inches long by 1/2 wide. Results thus far
are not encouraging, but I am about ready to set up a small optical
bench to test the CCD strip with a series of lenses. This is too good
an idea to let drop.

Regards,

Marv

Tadeuz Jalocha wrote:
Hello Marv,

It is'nt as easy it initially sounds, you need to remove the lens and
the mirrors of the scanner an need to focus directly on the surface of
the CCD. That's because if you leave the lens of the scanner in the
optical path, you'll get only an visible image when the tree elements
(CCD - lens of scanner - LF-Lens ) are in one line. Think of a very
strong hot spot.
This produces a new problem. Because the CCD's are shorter than the
papers (flatbed) width they scan, you'll get a strong anamorphic effect
if you achive to proyect correctly the image in the CCD of the stripped
down scanner. That's because the scanner sees an image that is strongly
compressed in vertical-to-travelling direction but not compressed at all
at travelling direction. The scanner logic needs to adjust the data to
give you an image with correct proportions.

Does anyone know, if the sensors of the cheapest Canon scanners (LIDE
techonlogy) are as long as the papers are wide? If so, this would be a
perfect candidate! I have been talking with Agfa, forget about their
scanners for such a proyect, the CCD are way too short.


regards

Tadeuz


Marv Soloff wrote:

Working on a scanner back for a large format camera (odd sized). Idea
is to use a standard scanner minus the illuminating tube as a pickup
at the focal plane. Static shots only. Wanted to explore the options
other than GG - which I make myself with valve grind compound. I
thought I would have problems with the CCD pickups and ground glass
hence the thought to use a tinted film or glass.

Regards,

Marv

jjs wrote:

"Marv Soloff" wrote in message
...

Has any one here used a tinted glass like PPG's Solexia (with a 77%
transmission rate) instead of ground glass for large format focus?




Strange. May I ask Why? Most of us want all the light we can get, and
besides GG is inexpensive, quite available and bright. In fact, if
you put a
drop of oil right in the center of the ground side, you have a brilliant
point for aerial focus.

On Sun, 01 Feb 2004 03:52:37 -0300, Tadeuz Jalocha
wrote:

Hello Marv,

It is'nt as easy it initially sounds, you need to remove the lens and
the mirrors of the scanner an need to focus directly on the surface of
the CCD. That's because if you leave the lens of the scanner in the
optical path, you'll get only an visible image when the tree elements
(CCD - lens of scanner - LF-Lens ) are in one line. Think of a very
strong hot spot.
This produces a new problem. Because the CCD's are shorter than the
papers (flatbed) width they scan, you'll get a strong anamorphic effect
if you achive to proyect correctly the image in the CCD of the stripped
down scanner. That's because the scanner sees an image that is strongly
compressed in vertical-to-travelling direction but not compressed at all
at travelling direction. The scanner logic needs to adjust the data to
give you an image with correct proportions.

Does anyone know, if the sensors of the cheapest Canon scanners (LIDE
techonlogy) are as long as the papers are wide? If so, this would be a
perfect candidate! I have been talking with Agfa, forget about their
scanners for such a proyect, the CCD are way too short.


The Canons use CIS (contact image sensor) technology,
where the sensor is indeed as wide as the scan bed -- but
relatively low resolution. There is no "optical" system to
speak of - no lens, no mirrors. Illumination of the target is
by red/green/blue LEDs that also run the width of the
target. Amazingly this is cheaper to build than the typical
CCD scan bar. The sensor itself is monochrome; color is
obtained by illuminating the target successively with the
red/green/blue LEDs (as in the Nikon film scanners also.)

The other type of scan head uses a CCD sensor that
typically has only 30-40 mm optical width. In this kind of
scan head there is an array of folded mirrors and a lens
right in front of the CCD sensor. The CCD system yields
much higher resolution, even though the sensor is much
smaller. Illumination in this case is via cold cathode
(fluorescent) embedded in the scan head. The sensor
is "color" ie, there are three photosites per pixel, one
each for red, green, and blue.

CIS sensors are cheap, and allow for a very shallow
scanner design. They are typically used in card readers,
and fax machines. The majority of flatbed scanners use
CCD scan heads.


rafe b.
http://www.terrapinphoto.com