Intelligent View Cams

Captain, I think you might get a lot from a software simulation of VC
controls. Unfortunately, I have no pointers to such.

I no doubt would. I have no trouble understanding the principles, but I find
that if I know exactly where I want to place the plane of sharp focus, it is
very difficult for me to get it right on the mark, especially at high levels
of swing/tilt.

Often when I swing, the subject moves out of the plane until I can refocus,
whereupon the angle changes, so I adjust the swing, refocus, rinse, repeat
until it's right. I find this a bit cumbersome. Keeping the plane of sharp
focus sharp whilst moving it around would be very helpful.

So I take it that you guys can all place the plane of sharp focus anywhere
you want it with good precision then? If so, pointers on how to pick up the
knack would be appreciated. I've read up on the Scheimpflug and hinge rules,
but I find they're too finicky to predict just by looking at a scene with
any useable accuracy.

Ewan

John McGraw wrote:
"Nicholas O. Lindan" wrote in message link.net...

"Captain Blammo" wrote


Does anyone know of any view cameras out there that would allow you to
adjust the plane of focus directly, as opposed to adjusting the controls
that affect the plane of focus?

Sinar made one 10(?) years ago. All sorts of encoders and stepping motors
and cables and interface boxes all tied into a PC. $35K I think.


BTW, In a discussion of tilts & swings, I read, where someone said
something to the effect: from drawing rays in high school, I know...
(this or that). My question is where can I find the basic topic of
drawing rays? I have no recollection what so ever of "drawing rays"?
Math, physics, & science in general were my best topics in school.
(God knows as any reader of my posts can tell, English wasn't. Thank
god for spell check & computers) And yet I have no familiarity w/
drawing rays. Where can I find this topic?

I don't have a reference handy for ray tracing, but let me briefly
outline how you do it in reference to the tilted lens plane and subject
plane.

Draw a picture with a line representing the lens plane and put a point
on it to represent the lens. Through that point, draw a perpendicular
to the lens plane and proceed a certain distance representing the focal
length on that line on the image side of the lens plane. Put a dot
there for the focal point. Any ray in the scene which hits the lens
plane perpendicular to that plane will be refracted so that it passes
through the focal point. Now consider a point in the scene and draw
two rays from it. The first will be perpendicular to the lens plane and
will then turn so as to pass through the focal point as just discussed.
The second ray should go through the point representing the lens.
That doesn't bend at all but just continues straight through. These two
lines will then meet, and the point they meet in will be the image of
the original subject plane.

Now if you draw any line in the subject representing what is supposed to
be the exact subject plane, the images of points in that plane should
all lie in a plane, which in your diagram will be represented by a line.
If you pick two subject points in the subject plane and perform the
above ray tracing, you will get two image points, which will determine
a line which is the trace in your diagram of the image plane. There is
a theorem in geometry which insures that this line, the line
representing the lens plane, and the line representing the subject plane
will all intersect in a single point. (In space the corresponding
planes will intersect in a line.) That is the Scheimpflug principle,
and if you draw your diagram carefully, it should all work out.

You can also start backwards, choose the image plane and lens plane, and
by tracing rays in the other direction, using the same principle,
determine the subject plane.

There are lots of similar triangles in these diagrams and lots of simple
trigonometry to play with. These relationships give you all the
standard formulas governing what happens.

It is a bit hard to explain this without diagrams, so what I wrote may
not be very clear. But if you were at all good at geometry, you should
be able to puzzle out most of it with some study. If you are still
unclear about some point, let me know, and I will see if I can
straighten it out.

P.S. Ray tracing, in general, is also used to predict what will happen
with a multielement lens. That is much more complicated, and the above
discussion won't help you with that.



Thanks, John


I don't know if they ever sold one. The only application would be table-top
product photography.


What I mean is that instead of applying, say, front swing, you would be able
to rotate the plane of focus 35 degrees left and bring it back 5 feet,
whilst the camera automatically kept the image framed about the same, and
tried to keep the DOF as you set it.

For ordinary subjects you will find you use very little movement. So little
that micrometer drives are a real convenience feature. You will most likely
never need 35 degrees worth.

Setting up a view camera is easy to do and takes almost no experience.
Learn it all in one afternoon.

It would take the same afternoon just to get the above mentioned compu-Sinar
(or whatever it was called) all plugged in and zeroed out.

FWIW, Even plain-old manual Sinar's have all sorts of scales on them for
figuring tilt and swing and depth of field.
- However -
In contests with two photographers, one with a full-dress Sinar and the other on
a wood-field (or equiv), the one using the uncalibrated camera will be set
up and have the shot made while the one with the Sinar is still examining scales
and scratching his head.

However, when doing table top shots with the camera all in a pretzel, the Sinar
will
be easier to set up.


I'll get over the initial hump of geometric visualization

You will need the geometric visualization, but just to make sure you tilt
or swing in the right direction and put the standards at kinda the right
place - not hard to do.


but I think [a computer] would ease the process even for experienced users.

So far no soap. Maybe sometime in the future with a 3-D digital back ... but
then it wouldn't be a view camera and it won't be large format.

John McGraw wrote:
"Nicholas O. Lindan" wrote in message link.net...

"Captain Blammo" wrote


Does anyone know of any view cameras out there that would allow you to
adjust the plane of focus directly, as opposed to adjusting the controls
that affect the plane of focus?

Sinar made one 10(?) years ago. All sorts of encoders and stepping motors
and cables and interface boxes all tied into a PC. $35K I think.


BTW, In a discussion of tilts & swings, I read, where someone said
something to the effect: from drawing rays in high school, I know...
(this or that). My question is where can I find the basic topic of
drawing rays? I have no recollection what so ever of "drawing rays"?
Math, physics, & science in general were my best topics in school.
(God knows as any reader of my posts can tell, English wasn't. Thank
god for spell check & computers) And yet I have no familiarity w/
drawing rays. Where can I find this topic?

I don't have a reference handy for ray tracing, but let me briefly
outline how you do it in reference to the tilted lens plane and subject
plane.

Draw a picture with a line representing the lens plane and put a point
on it to represent the lens. Through that point, draw a perpendicular
to the lens plane and proceed a certain distance representing the focal
length on that line on the image side of the lens plane. Put a dot
there for the focal point. Any ray in the scene which hits the lens
plane perpendicular to that plane will be refracted so that it passes
through the focal point. Now consider a point in the scene and draw
two rays from it. The first will be perpendicular to the lens plane and
will then turn so as to pass through the focal point as just discussed.
The second ray should go through the point representing the lens.
That doesn't bend at all but just continues straight through. These two
lines will then meet, and the point they meet in will be the image of
the original subject plane.

Now if you draw any line in the subject representing what is supposed to
be the exact subject plane, the images of points in that plane should
all lie in a plane, which in your diagram will be represented by a line.
If you pick two subject points in the subject plane and perform the
above ray tracing, you will get two image points, which will determine
a line which is the trace in your diagram of the image plane. There is
a theorem in geometry which insures that this line, the line
representing the lens plane, and the line representing the subject plane
will all intersect in a single point. (In space the corresponding
planes will intersect in a line.) That is the Scheimpflug principle,
and if you draw your diagram carefully, it should all work out.

You can also start backwards, choose the image plane and lens plane, and
by tracing rays in the other direction, using the same principle,
determine the subject plane.

There are lots of similar triangles in these diagrams and lots of simple
trigonometry to play with. These relationships give you all the
standard formulas governing what happens.

It is a bit hard to explain this without diagrams, so what I wrote may
not be very clear. But if you were at all good at geometry, you should
be able to puzzle out most of it with some study. If you are still
unclear about some point, let me know, and I will see if I can
straighten it out.

P.S. Ray tracing, in general, is also used to predict what will happen
with a multielement lens. That is much more complicated, and the above
discussion won't help you with that.



Thanks, John


I don't know if they ever sold one. The only application would be table-top
product photography.


What I mean is that instead of applying, say, front swing, you would be able
to rotate the plane of focus 35 degrees left and bring it back 5 feet,
whilst the camera automatically kept the image framed about the same, and
tried to keep the DOF as you set it.

For ordinary subjects you will find you use very little movement. So little
that micrometer drives are a real convenience feature. You will most likely
never need 35 degrees worth.

Setting up a view camera is easy to do and takes almost no experience.
Learn it all in one afternoon.

It would take the same afternoon just to get the above mentioned compu-Sinar
(or whatever it was called) all plugged in and zeroed out.

FWIW, Even plain-old manual Sinar's have all sorts of scales on them for
figuring tilt and swing and depth of field.
- However -
In contests with two photographers, one with a full-dress Sinar and the other on
a wood-field (or equiv), the one using the uncalibrated camera will be set
up and have the shot made while the one with the Sinar is still examining scales
and scratching his head.

However, when doing table top shots with the camera all in a pretzel, the Sinar
will
be easier to set up.


I'll get over the initial hump of geometric visualization

You will need the geometric visualization, but just to make sure you tilt
or swing in the right direction and put the standards at kinda the right
place - not hard to do.


but I think [a computer] would ease the process even for experienced users.

So far no soap. Maybe sometime in the future with a 3-D digital back ... but
then it wouldn't be a view camera and it won't be large format.

John McGraw wrote:
"Nicholas O. Lindan" wrote in message link.net...

"Captain Blammo" wrote


Does anyone know of any view cameras out there that would allow you to
adjust the plane of focus directly, as opposed to adjusting the controls
that affect the plane of focus?

Sinar made one 10(?) years ago. All sorts of encoders and stepping motors
and cables and interface boxes all tied into a PC. $35K I think.


BTW, In a discussion of tilts & swings, I read, where someone said
something to the effect: from drawing rays in high school, I know...
(this or that). My question is where can I find the basic topic of
drawing rays? I have no recollection what so ever of "drawing rays"?
Math, physics, & science in general were my best topics in school.
(God knows as any reader of my posts can tell, English wasn't. Thank
god for spell check & computers) And yet I have no familiarity w/
drawing rays. Where can I find this topic?

I don't have a reference handy for ray tracing, but let me briefly
outline how you do it in reference to the tilted lens plane and subject
plane.

Draw a picture with a line representing the lens plane and put a point
on it to represent the lens. Through that point, draw a perpendicular
to the lens plane and proceed a certain distance representing the focal
length on that line on the image side of the lens plane. Put a dot
there for the focal point. Any ray in the scene which hits the lens
plane perpendicular to that plane will be refracted so that it passes
through the focal point. Now consider a point in the scene and draw
two rays from it. The first will be perpendicular to the lens plane and
will then turn so as to pass through the focal point as just discussed.
The second ray should go through the point representing the lens.
That doesn't bend at all but just continues straight through. These two
lines will then meet, and the point they meet in will be the image of
the original subject plane.

Now if you draw any line in the subject representing what is supposed to
be the exact subject plane, the images of points in that plane should
all lie in a plane, which in your diagram will be represented by a line.
If you pick two subject points in the subject plane and perform the
above ray tracing, you will get two image points, which will determine
a line which is the trace in your diagram of the image plane. There is
a theorem in geometry which insures that this line, the line
representing the lens plane, and the line representing the subject plane
will all intersect in a single point. (In space the corresponding
planes will intersect in a line.) That is the Scheimpflug principle,
and if you draw your diagram carefully, it should all work out.

You can also start backwards, choose the image plane and lens plane, and
by tracing rays in the other direction, using the same principle,
determine the subject plane.

There are lots of similar triangles in these diagrams and lots of simple
trigonometry to play with. These relationships give you all the
standard formulas governing what happens.

It is a bit hard to explain this without diagrams, so what I wrote may
not be very clear. But if you were at all good at geometry, you should
be able to puzzle out most of it with some study. If you are still
unclear about some point, let me know, and I will see if I can
straighten it out.

P.S. Ray tracing, in general, is also used to predict what will happen
with a multielement lens. That is much more complicated, and the above
discussion won't help you with that.



Thanks, John


I don't know if they ever sold one. The only application would be table-top
product photography.


What I mean is that instead of applying, say, front swing, you would be able
to rotate the plane of focus 35 degrees left and bring it back 5 feet,
whilst the camera automatically kept the image framed about the same, and
tried to keep the DOF as you set it.

For ordinary subjects you will find you use very little movement. So little
that micrometer drives are a real convenience feature. You will most likely
never need 35 degrees worth.

Setting up a view camera is easy to do and takes almost no experience.
Learn it all in one afternoon.

It would take the same afternoon just to get the above mentioned compu-Sinar
(or whatever it was called) all plugged in and zeroed out.

FWIW, Even plain-old manual Sinar's have all sorts of scales on them for
figuring tilt and swing and depth of field.
- However -
In contests with two photographers, one with a full-dress Sinar and the other on
a wood-field (or equiv), the one using the uncalibrated camera will be set
up and have the shot made while the one with the Sinar is still examining scales
and scratching his head.

However, when doing table top shots with the camera all in a pretzel, the Sinar
will
be easier to set up.


I'll get over the initial hump of geometric visualization

You will need the geometric visualization, but just to make sure you tilt
or swing in the right direction and put the standards at kinda the right
place - not hard to do.


but I think [a computer] would ease the process even for experienced users.

So far no soap. Maybe sometime in the future with a 3-D digital back ... but
then it wouldn't be a view camera and it won't be large format.

jjs wrote:
"John McGraw" wrote in message
om...


BTW, In a discussion of tilts & swings, I read, where someone said
something to the effect: from drawing rays in high school, I know...
(this or that). My question is where can I find the basic topic of
drawing rays? I have no recollection what so ever of "drawing rays"?
Math, physics, & science in general were my best topics in school.
(God knows as any reader of my posts can tell, English wasn't. Thank
god for spell check & computers) And yet I have no familiarity w/
drawing rays. Where can I find this topic?


We all learned ray-tracing. And hand-setting type.

I did learn some basic ray tracing in high school, and I also took a
printing shop in junior high school where I did in fact hand set type.
Ah, for the good old days!

Kidding, but I did go
to a school where we used inkwells in the desk and inkpens, and learned
italics - never longhand.

John, I think you want to look into hand ray-tracing which generally went
out with the advent of the affordable computers.

jjs wrote:
"John McGraw" wrote in message
om...


BTW, In a discussion of tilts & swings, I read, where someone said
something to the effect: from drawing rays in high school, I know...
(this or that). My question is where can I find the basic topic of
drawing rays? I have no recollection what so ever of "drawing rays"?
Math, physics, & science in general were my best topics in school.
(God knows as any reader of my posts can tell, English wasn't. Thank
god for spell check & computers) And yet I have no familiarity w/
drawing rays. Where can I find this topic?


We all learned ray-tracing. And hand-setting type.

I did learn some basic ray tracing in high school, and I also took a
printing shop in junior high school where I did in fact hand set type.
Ah, for the good old days!

Kidding, but I did go
to a school where we used inkwells in the desk and inkpens, and learned
italics - never longhand.

John, I think you want to look into hand ray-tracing which generally went
out with the advent of the affordable computers.

"Captain Blammo" wrote in message ...
Captain, I think you might get a lot from a software simulation of VC
controls. Unfortunately, I have no pointers to such.

I no doubt would. I have no trouble understanding the principles, but I find
that if I know exactly where I want to place the plane of sharp focus, it is
very difficult for me to get it right on the mark, especially at high levels
of swing/tilt.

Often when I swing, the subject moves out of the plane until I can refocus,
whereupon the angle changes, so I adjust the swing, refocus, rinse, repeat
until it's right. I find this a bit cumbersome. Keeping the plane of sharp
focus sharp whilst moving it around would be very helpful.

So I take it that you guys can all place the plane of sharp focus anywhere
you want it with good precision then? If so, pointers on how to pick up the
knack would be appreciated. I've read up on the Scheimpflug and hinge rules,
but I find they're too finicky to predict just by looking at a scene with
any useable accuracy.

Ewan


"Often when I swing, the subject moves out of the plane until I can
refocus,
whereupon the angle changes, so I adjust the swing, refocus, rinse,
repeat
until it's right. I find this a bit cumbersome. Keeping the plane of
sharp
focus sharp whilst moving it around would be very helpful."

Ewan,

I suggest picking up Jack Dykinga's book, "Large Format Nature
Photography". He explains how to do the move-focus iteration, which is
a characteristic of symmetric movement view cameras.

But there is an alternative, although few of them. The Sinar P series
view camera, the Ebony "U" series field cameras, and the Wehman 8x10
field cameras have asymmetric movements (Sinar P on both, the Wehman
and Ebony on the rear). Asymmetric movements are much easier to set up
and frequently require only 1 iteration per movement (swing, tilt) for
typical landscape scenes. I'm not talking about using the Sinar
scales, etc, just focusing on the swing or tilt point and moving the
other side of the standard to finish.

Steve

Captain Blammo wrote:
Captain, I think you might get a lot from a software simulation of VC
controls. Unfortunately, I have no pointers to such.


I no doubt would. I have no trouble understanding the principles, but I find
that if I know exactly where I want to place the plane of sharp focus, it is
very difficult for me to get it right on the mark, especially at high levels
of swing/tilt.

Often when I swing, the subject moves out of the plane until I can refocus,
whereupon the angle changes, so I adjust the swing, refocus, rinse, repeat
until it's right. I find this a bit cumbersome. Keeping the plane of sharp
focus sharp whilst moving it around would be very helpful.

So I take it that you guys can all place the plane of sharp focus anywhere
you want it with good precision then? If so, pointers on how to pick up the
knack would be appreciated. I've read up on the Scheimpflug and hinge rules,
but I find they're too finicky to predict just by looking at a scene with
any useable accuracy.

If you are good at math and physics, you might look at my essay

http://www.math.northwestern.edu/~le.../dof_essay.pdf

It outlines some ideas about how to do what you want.

There are two methods described there for setting the tilt angle. One
is a variation of the standard method described at

www.largeformatphotography.info

You pick a near point and a far point in the exact subject plane, focus
on them, and note their positions on the rail (or camera bed). There is
a formula due to Bob Wheeler which tells you how far to tilt the lens.
(It also works for swings with appropriate change of language.) It is
not very hard to use and I describe it in the above essay.

But many people don't like to use formulas, so they do it by trial and
error, and that is also not very hard. In any event even if you use
Wheeler's formula, you are not likely to get the tilt just right, so
some correction is necessary, and that is done by trial and error. The
thing to remember in the trial and error approach is that when you are
focused on the far point, and the near point is still out of foucs, if
you have to increase the distance between the standards to focus on the
near point, increase the tilt, and if you have to decrease the distance
between the standards to focus on the near point, decrease the tilt.

The second method is due to Merklinger. You measure the distance (in
mm) below the lens where you want the exact subject plane to go. You
then divide the focal length of the lens by that distance, and that
gives you the sine of the tilt angle. For small tilt angles, which is
almost always the case, the sine of the tilt angle is very close to the
tilt angle itself in radians, and you can convert that easily to
degrees. A very rough calculation would be just to multiply by 60.
However, you can avoid using angles entirely, and just use the sine
directly as noted in my essay.

There is also the related issue of the hinge line, which Merklinger has
emphasized, which is also discussed in my essay. You should make sure
you understand that.


Ewan

Captain Blammo wrote:
Captain, I think you might get a lot from a software simulation of VC
controls. Unfortunately, I have no pointers to such.


I no doubt would. I have no trouble understanding the principles, but I find
that if I know exactly where I want to place the plane of sharp focus, it is
very difficult for me to get it right on the mark, especially at high levels
of swing/tilt.

Often when I swing, the subject moves out of the plane until I can refocus,
whereupon the angle changes, so I adjust the swing, refocus, rinse, repeat
until it's right. I find this a bit cumbersome. Keeping the plane of sharp
focus sharp whilst moving it around would be very helpful.

So I take it that you guys can all place the plane of sharp focus anywhere
you want it with good precision then? If so, pointers on how to pick up the
knack would be appreciated. I've read up on the Scheimpflug and hinge rules,
but I find they're too finicky to predict just by looking at a scene with
any useable accuracy.

Part of your problem is that the focus changes when you tilt. That
would be less of a problem if you had axial tilt. But I don't find it
a significant issue with base tilt because I focus by moving the rear
standard, which makes it easier. After I tilt, I refocus with the rear
standard on the far point. If you are focusing by moving the front
standard, it doesn't make too much difference for distant subjects, but
it can for close-ups. By understanding the basic principles, you ought
to be able to come up with something, and I hope my previous reference
will be of some help. I will give it some thought myself when I get a
chance.


Ewan

Captain Blammo wrote:
Captain, I think you might get a lot from a software simulation of VC
controls. Unfortunately, I have no pointers to such.


I no doubt would. I have no trouble understanding the principles, but I find
that if I know exactly where I want to place the plane of sharp focus, it is
very difficult for me to get it right on the mark, especially at high levels
of swing/tilt.

Often when I swing, the subject moves out of the plane until I can refocus,
whereupon the angle changes, so I adjust the swing, refocus, rinse, repeat
until it's right. I find this a bit cumbersome. Keeping the plane of sharp
focus sharp whilst moving it around would be very helpful.

So I take it that you guys can all place the plane of sharp focus anywhere
you want it with good precision then? If so, pointers on how to pick up the
knack would be appreciated. I've read up on the Scheimpflug and hinge rules,
but I find they're too finicky to predict just by looking at a scene with
any useable accuracy.

Part of your problem is that the focus changes when you tilt. That
would be less of a problem if you had axial tilt. But I don't find it
a significant issue with base tilt because I focus by moving the rear
standard, which makes it easier. After I tilt, I refocus with the rear
standard on the far point. If you are focusing by moving the front
standard, it doesn't make too much difference for distant subjects, but
it can for close-ups. By understanding the basic principles, you ought
to be able to come up with something, and I hope my previous reference
will be of some help. I will give it some thought myself when I get a
chance.


Ewan