did anyone try this: cheap point-n-shoot on the back of a large format beast?

"IRO" wrote in message
...
In article
,
chibitul wrote:

just to clarify, the image is there regardless if you have the glass or
not. The rays will keep propagating toward the digicam, and they
"emerge" from the real image, no glass needed. as I said, optics.

The problem at this point is that the light rays from the big camera's
lens are radiating outward in a cone, focused on the glass screen (or
film). The P&S can only ever see a tiny fraction of that cone where-ever
you put it, except perhaps very close in behind the camera lens where
its tiny lens can intercept the complete cone. Unfortunately the image
would be wildly out of focus there, plus it would negate all the
features of the large format camera you are hoping to utilise.

A couple of years ago, there was a similarly confused poster here, who swore
endlessly that one could copy slides using a slide project WITHOUT a screen.


--He stubbornly clung to the idea that by pointing a camera directly at the
slide projector from accross the room...and focusing the camera on the same
PLANE where the screen would have been (where the projector was also
focussed)...that one could photograph the entire picture--as though this
created (I guess) some sort of new magical light-radiation point (or some
such thing) in the air at that unreflected point fo focus.

-No amount of explaining would persuade him otherwise.
I finally suggested that he try it.
....I didn't see any posts from him after that.


It's easy to forget, I guess, that some of these basic directional concepts
are not necessarily intuitively understood by everyone. Perhaps it's a case
of too many Star Trek episodes where they have the magically impossible
capability to...from and single point...project an image, and have it show
up with no point or field of reflected light in the middle of the room's
air.

"IRO" wrote in message
...
In article
,
chibitul wrote:

just to clarify, the image is there regardless if you have the glass or
not. The rays will keep propagating toward the digicam, and they
"emerge" from the real image, no glass needed. as I said, optics.

The problem at this point is that the light rays from the big camera's
lens are radiating outward in a cone, focused on the glass screen (or
film). The P&S can only ever see a tiny fraction of that cone where-ever
you put it, except perhaps very close in behind the camera lens where
its tiny lens can intercept the complete cone. Unfortunately the image
would be wildly out of focus there, plus it would negate all the
features of the large format camera you are hoping to utilise.

A couple of years ago, there was a similarly confused poster here, who swore
endlessly that one could copy slides using a slide project WITHOUT a screen.


--He stubbornly clung to the idea that by pointing a camera directly at the
slide projector from accross the room...and focusing the camera on the same
PLANE where the screen would have been (where the projector was also
focussed)...that one could photograph the entire picture--as though this
created (I guess) some sort of new magical light-radiation point (or some
such thing) in the air at that unreflected point fo focus.

-No amount of explaining would persuade him otherwise.
I finally suggested that he try it.
....I didn't see any posts from him after that.


It's easy to forget, I guess, that some of these basic directional concepts
are not necessarily intuitively understood by everyone. Perhaps it's a case
of too many Star Trek episodes where they have the magically impossible
capability to...from and single point...project an image, and have it show
up with no point or field of reflected light in the middle of the room's
air.

In article ,
PGG wrote:

They make digital scanning backs for large-format cameras. $20,000 I
think.

Lower, down to 5.5k.

--
LF Website @ http://members.verizon.net/~gregoryblank

"To announce that there must be no criticism of the President,
or that we are to stand by the President, right or wrong,
is not only unpatriotic and servile, but is morally treasonable
to the American public."--Theodore Roosevelt, May 7, 1918

In article ,
PGG wrote:

They make digital scanning backs for large-format cameras. $20,000 I
think.

Lower, down to 5.5k.

--
LF Website @ http://members.verizon.net/~gregoryblank

"To announce that there must be no criticism of the President,
or that we are to stand by the President, right or wrong,
is not only unpatriotic and servile, but is morally treasonable
to the American public."--Theodore Roosevelt, May 7, 1918

chibitul wrote:
In article ,
Leonard Evens wrote:


chibitul wrote:

Did anyone try to use a large format camera to get an image (with all
the advantages of large format cameras: tilt, shift, etc) and then use a
small digicam instead of film to snap the picture? I imagine if you make
some sort of fixture to attach the digicam to the back of the large
format camera, and focus on the glass plate, you should be able to snap
*that* image. I never used a large format camera and I do not intend to
venture into this field unless I can do it digitally. I am not into high
resolution stuff, I read some of Ansel Adams books and I am impressed
with what you can do with large format when you can tilt/shift the lens
and the negative as you want. Just wondering if I can "piggy-back" a
cheap point-n-shoot on the back of a large format beast?

If you mean to use the point and shoot camera to photograph the image on
the ground glass, it won't work. The image is much too dim to record
with such a camera. Also, you couldn't focus close enough unless the
camera had a macro mode, which most likely it wouldn't.



yes, that is what I mean. Most cameras have a macro mode, but you can
also put the camera about 0.5 meters away from the ground glass.

I've bought several point and shoot cameras as presents for children and
grandchildren, and not all of them could focus that close up, but there
certainly are such cameras which can.


Ok, the image is dim, but this is large format camera here, not sports
or action. we're talking landscapes, biuldings, etc, right? what's wrong
with a slow shutter speed?

Well in principle you could do something like that, but there are a
whole host of problems.

For one, I hate to disillusion you, but things move in landscapes, e.g.
foliage blowing in the wind. For architecture, a car may drive past or
someone may walk across your field of view. You can't usually assume
that very long exposures are acceptable. Also, the gg, depending on
what type it is, may have signficantly more drop off in illumination
towards the sides and corners than you would see in a film image.


And do you really need the ground glass? what if you *remove* the ground
glass, the image will act as an object for the digicam. it should work.

Some view cameras don't allow you to remove the ground glass that
easily. But if you have one that does, what you suggest might be
possible if you can focus accurately enough to isolate the image plane.
You certainly couldn't do it by automatic focusing. That requires
some physical object to focus on. I suppose you could focus on the
physical back of the camera, hold that focus and then remove the ground
glass, but I doubt if you could get it to focus precisely enough not to
end up with a very blurred image. I would have to think about the
optics or try it to see if there are any other problems.

As someone else pointed out, the problem of using a digital camera with
a view camera to record the image has already been solved by Cambo. The
package together with the digital camera cost about $11,000 the last
time I looked, but maybe it has come down in price since. I've looked
at it at Calumet Photo in Chicago, and it is a really neat contraption.
Were I a billionaire, I would buy one just to play with it. But I
wouldn't throw out my 4 x 5 view camera yet.

I think the upshot is that you might in fact be able to do what you
suggest with some point and shoot digital cameras, but you would end up
with a pretty low quality image.

If the object is moderately low cost digital capture, you would be
better off making a film exposure and scanning it with a scanner such as
the Epson 4870.

chibitul wrote:
In article ,
Leonard Evens wrote:


chibitul wrote:

Did anyone try to use a large format camera to get an image (with all
the advantages of large format cameras: tilt, shift, etc) and then use a
small digicam instead of film to snap the picture? I imagine if you make
some sort of fixture to attach the digicam to the back of the large
format camera, and focus on the glass plate, you should be able to snap
*that* image. I never used a large format camera and I do not intend to
venture into this field unless I can do it digitally. I am not into high
resolution stuff, I read some of Ansel Adams books and I am impressed
with what you can do with large format when you can tilt/shift the lens
and the negative as you want. Just wondering if I can "piggy-back" a
cheap point-n-shoot on the back of a large format beast?

If you mean to use the point and shoot camera to photograph the image on
the ground glass, it won't work. The image is much too dim to record
with such a camera. Also, you couldn't focus close enough unless the
camera had a macro mode, which most likely it wouldn't.



yes, that is what I mean. Most cameras have a macro mode, but you can
also put the camera about 0.5 meters away from the ground glass.

I've bought several point and shoot cameras as presents for children and
grandchildren, and not all of them could focus that close up, but there
certainly are such cameras which can.


Ok, the image is dim, but this is large format camera here, not sports
or action. we're talking landscapes, biuldings, etc, right? what's wrong
with a slow shutter speed?

Well in principle you could do something like that, but there are a
whole host of problems.

For one, I hate to disillusion you, but things move in landscapes, e.g.
foliage blowing in the wind. For architecture, a car may drive past or
someone may walk across your field of view. You can't usually assume
that very long exposures are acceptable. Also, the gg, depending on
what type it is, may have signficantly more drop off in illumination
towards the sides and corners than you would see in a film image.


And do you really need the ground glass? what if you *remove* the ground
glass, the image will act as an object for the digicam. it should work.

Some view cameras don't allow you to remove the ground glass that
easily. But if you have one that does, what you suggest might be
possible if you can focus accurately enough to isolate the image plane.
You certainly couldn't do it by automatic focusing. That requires
some physical object to focus on. I suppose you could focus on the
physical back of the camera, hold that focus and then remove the ground
glass, but I doubt if you could get it to focus precisely enough not to
end up with a very blurred image. I would have to think about the
optics or try it to see if there are any other problems.

As someone else pointed out, the problem of using a digital camera with
a view camera to record the image has already been solved by Cambo. The
package together with the digital camera cost about $11,000 the last
time I looked, but maybe it has come down in price since. I've looked
at it at Calumet Photo in Chicago, and it is a really neat contraption.
Were I a billionaire, I would buy one just to play with it. But I
wouldn't throw out my 4 x 5 view camera yet.

I think the upshot is that you might in fact be able to do what you
suggest with some point and shoot digital cameras, but you would end up
with a pretty low quality image.

If the object is moderately low cost digital capture, you would be
better off making a film exposure and scanning it with a scanner such as
the Epson 4870.

Mark M wrote:
"chibitul" wrote in message
...


yes, that is what I mean. Most cameras have a macro mode, but you can
also put the camera about 0.5 meters away from the ground glass.

Ok, the image is dim, but this is large format camera here, not sports
or action. we're talking landscapes, biuldings, etc, right? what's wrong
with a slow shutter speed?

And do you really need the ground glass? what if you *remove* the ground
glass, the image will act as an object for the digicam. it should work.


How will the "image act as an object" without the glass?

It won't, but there is an aerial image there even without the gg. Take
off your gg if you can and use a magnifier or loupe to look at where it
was. You will see an image. But you have to point the magnifier in
the right direction. If you don't do that, I'm not sure what you get;
probably extremely diminished intensity.

Mark M wrote:
"chibitul" wrote in message
...


yes, that is what I mean. Most cameras have a macro mode, but you can
also put the camera about 0.5 meters away from the ground glass.

Ok, the image is dim, but this is large format camera here, not sports
or action. we're talking landscapes, biuldings, etc, right? what's wrong
with a slow shutter speed?

And do you really need the ground glass? what if you *remove* the ground
glass, the image will act as an object for the digicam. it should work.


How will the "image act as an object" without the glass?

It won't, but there is an aerial image there even without the gg. Take
off your gg if you can and use a magnifier or loupe to look at where it
was. You will see an image. But you have to point the magnifier in
the right direction. If you don't do that, I'm not sure what you get;
probably extremely diminished intensity.

chibitul writes:
In article Q2YPc.18274$Oi.4714@fed1read04,
"Mark M" wrote:

And do you really need the ground glass? what if you *remove* the ground
glass, the image will act as an object for the digicam. it should work.

How will the "image act as an object" without the glass?

optics 101.

Sorry, you failed the course.

The large format lens will form a real image in the plane of the
focusing screen. The digital camera can focus on that real image. But
you'll get an almost entirely dark frame, with a tiny bit of the image
illuminated in the very centre.

The problem is that, except right on the optical axis, the light that
leaves the exit pupil of the large format lens reaches the image plane
at an angle. Without a focusing screen, the light continues in the same
direction and *none* of it reaches the P&S camera lens. No light, no
image. Just try looking into the back of a large-format camera with
your eye when the focusing screen is removed.

The focusing screen takes the incoming light from the first lens and
scatters it in all directions, which gives a dim image of the entire
scene no matter where you place your eye. Sometimes a Fresnel lens just
in front of the focusing screen is used to redirect more of the light
towards some assumed eye position.

In order to photograph an aerial real image like what is suggested here,
it's not sufficient to have the second optical system focus on the real
image formed by the first optical system. You also need to
*simultaneously* form an image of the exit pupil of the first lens onto
the entrance pupil of the second lens, in order to get the light where
it will do some good. And that requires additional optics in between
the first and second lens.

Dave

chibitul writes:
In article Q2YPc.18274$Oi.4714@fed1read04,
"Mark M" wrote:

And do you really need the ground glass? what if you *remove* the ground
glass, the image will act as an object for the digicam. it should work.

How will the "image act as an object" without the glass?

optics 101.

Sorry, you failed the course.

The large format lens will form a real image in the plane of the
focusing screen. The digital camera can focus on that real image. But
you'll get an almost entirely dark frame, with a tiny bit of the image
illuminated in the very centre.

The problem is that, except right on the optical axis, the light that
leaves the exit pupil of the large format lens reaches the image plane
at an angle. Without a focusing screen, the light continues in the same
direction and *none* of it reaches the P&S camera lens. No light, no
image. Just try looking into the back of a large-format camera with
your eye when the focusing screen is removed.

The focusing screen takes the incoming light from the first lens and
scatters it in all directions, which gives a dim image of the entire
scene no matter where you place your eye. Sometimes a Fresnel lens just
in front of the focusing screen is used to redirect more of the light
towards some assumed eye position.

In order to photograph an aerial real image like what is suggested here,
it's not sufficient to have the second optical system focus on the real
image formed by the first optical system. You also need to
*simultaneously* form an image of the exit pupil of the first lens onto
the entrance pupil of the second lens, in order to get the light where
it will do some good. And that requires additional optics in between
the first and second lens.

Dave