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



 
 
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  #41  
Old August 4th 04, 01:25 PM
Argon3
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Default did anyone try this: cheap point-n-shoot on the back of a large format beast?

Does anyone remember that 4X5 or other LF transparencies can be SCANNED and are
then DIGITAL and can be played with accordingly? Are there really folks out
there who have so much time on their hands that they have to find Rube Goldberg
solutions to simple problems or have some folks just become so hung up on
digital that they just can't think in any other terms?


argon
  #44  
Old August 4th 04, 04:09 PM
Leonard Evens
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Default did anyone try this: cheap point-n-shoot on the back of a largeformat beast?

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.


  #45  
Old August 4th 04, 04:09 PM
Leonard Evens
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Posts: n/a
Default did anyone try this: cheap point-n-shoot on the back of a largeformat beast?

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.


  #46  
Old August 4th 04, 04:12 PM
Leonard Evens
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Posts: n/a
Default did anyone try this: cheap point-n-shoot on the back of a largeformat beast?

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.




  #47  
Old August 4th 04, 04:12 PM
Leonard Evens
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Posts: n/a
Default did anyone try this: cheap point-n-shoot on the back of a largeformat beast?

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.




  #48  
Old August 4th 04, 04:22 PM
Dave Martindale
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Posts: n/a
Default did anyone try this: cheap point-n-shoot on the back of a large format beast?

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
  #49  
Old August 4th 04, 04:22 PM
Dave Martindale
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Posts: n/a
Default did anyone try this: cheap point-n-shoot on the back of a large format beast?

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
  #50  
Old August 4th 04, 04:34 PM
Leonard Evens
external usenet poster
 
Posts: n/a
Default did anyone try this: cheap point-n-shoot on the back of a largeformat beast?

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



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



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.


Okay, I knew there was something wrong with this cockamamie idea, but I
temporaily thought there might be something to it. You should go try
it, as I just did. There is an aerial image there, but when you look at
it with another lens, including the lens in my digital camera, you see
the iris diaphragm opening with a clear image of a small portion of the
scene. If you move the viewing lens (or digital camera) around, you
can see the rest of the scene a very small section at a time. This, I
believe, is exactly what geometric optics says you would see. The point
is that if you have something there, such as a gg or film, the
converging rays produce a physical effect in the physical medium.
Otherwise they just continue off into space and it gets much more
complicated as to what you see with a lens placed at the right distance
from the aerial image.


 




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