High resolution photos from a digital camera.

Lorem Ipsum wrote:
"Scott W" wrote in message
ups.com...

Olin K. McDaniel wrote:
[...] For
this to be done, the entire image captured with the modest camera must
be of a very tiny portion of the overall subject matter. This seems
to demand some special lens that covers only a limited field of the
total image.

This is simply a long lens, nothing really special about it.

In fact, a very long lens presents a couple problems. First, depth-of-field
is remarkably shallow so that if the complete object in question is not at
infinity (or ideal hyperfocal), then it is refocused for some part(s) of the
image, the focal length, thus the image segment(s) change size.
You shoot like you are shooting LF, a pretty large FNumber.

Second, for
a telephoto lens, the nodal point can be VERY far in front of the lens. Of
course, the later can be accomodated using an offset camera mount.

Well the nodal point can't be way in front of the lens, in fact for my
telephoto
the nodal point is way inside the lens. I have made a chart as to
where the
nodal point is on my zoom lens for different focal lengths.

To date I have been leaving the camera in manual focus mode to avoid
some
of the problem with stitching different images that are focused
differently.

I find that getting a photo in the range of 40 MP is like falling off a
log and 100 MP a whole lot of work.

I also have found that taking photos with people in them is not as hard
as you might think.
It takes a bit of adjusting the seams between photos but this is not
hard to do.
I took 16 wide angle panoramic photos at our canoe race this last
weekend, some of them had
so many people in them I was not sure how they would come out, turned
out not to be a problem

Here is one with a lot of people who were on the move, the line to get
food.
http://www.pbase.com/konascott/image/52303782/large
Hit original at the bottom of the photo for more detail, even then it
is half scale of the stitched photo.

Scott

"Scott W" wrote in message
oups.com...

Second, for
a telephoto lens, the nodal point can be VERY far in front of the lens.
Of
course, the later can be accomodated using an offset camera mount.

Well the nodal point can't be way in front of the lens

Perhaps we have a confusion of terms. Are you thinking of the Entrance
Pupil?

Telephoto lenses are, by definition, physically shorter than their focal
length.
The front nodal point can be in front of the lens. Yes, outside the lens.

Lorem Ipsum wrote:
"Scott W" wrote in message
oups.com...

Second, for
a telephoto lens, the nodal point can be VERY far in front of the lens.
Of
course, the later can be accomodated using an offset camera mount.

Well the nodal point can't be way in front of the lens

Perhaps we have a confusion of terms. Are you thinking of the Entrance
Pupil?

Telephoto lenses are, by definition, physically shorter than their focal
length.
The front nodal point can be in front of the lens. Yes, outside the lens.

It can't be very far out. Trace some rays, they have to go through the
nodal point and then hit the main objective lens. The diameter of the
objective lens limits how far out the nodal point can be.

Also paralax is less of a problem with longer lenses in any event, it
is aways the short FL shoots that are tricky.

Scott

"Scott W" wrote in message
oups.com...

Telephoto lenses are, by definition, physically shorter than their focal
length.
The front nodal point can be in front of the lens. Yes, outside the lens.

It can't be very far out. Trace some rays, they have to go through the
nodal point and then hit the main objective lens. The diameter of the
objective lens limits how far out the nodal point can be.

The nodal point is so far from the default tripod mount that one had better
take it seriously.

Also paralax is less of a problem with longer lenses in any event, it
is aways the short FL shoots that are tricky.

And to exacerbate that, there is edge distortion in most wide lenses.

Lorem Ipsum wrote:
"Scott W" wrote in message
oups.com...

Telephoto lenses are, by definition, physically shorter than their focal
length.
The front nodal point can be in front of the lens. Yes, outside the lens.

It can't be very far out. Trace some rays, they have to go through the
nodal point and then hit the main objective lens. The diameter of the
objective lens limits how far out the nodal point can be.

The nodal point is so far from the default tripod mount that one had better
take it seriously.
I use a panoramic head, it rotate the camera around the nodal point in
both axis.


Also paralax is less of a problem with longer lenses in any event, it
is aways the short FL shoots that are tricky.

And to exacerbate that, there is edge distortion in most wide lenses.
The software adjusteds for that fairly well, still wide angle shots
need much more care.

Scott

In rec.photo.equipment.35mm Scott W wrote:

It can't be very far out. Trace some rays, they have to go through the
nodal point and then hit the main objective lens. The diameter of the
objective lens limits how far out the nodal point can be.

Now consider the angle of view of long tele lens...


Scott


--
Sander

+++ Out of cheese error +++

"Perhaps we have a confusion of terms. Are you thinking of the Entrance

Pupil? "

When shooting multi-image panoramas you need to rotate about the
entrance pupil, not the nodal point. This is because the center of
perspective is the entrance pupil. In telephoto lenses the entrance
pupil is almost always either well inside the lens, and in many cases
is *behind* the lens, not in front of it. Offset camera mount? Maybe,
but offset in the opposite direction to what you are thinking about.

Brian

"BC" wrote in message
oups.com...
"Perhaps we have a confusion of terms. Are you thinking of the Entrance

Pupil? "

When shooting multi-image panoramas you need to rotate about the
entrance pupil, not the nodal point. This is because the center of
perspective is the entrance pupil. In telephoto lenses the entrance
pupil is almost always either well inside the lens, and in many cases
is *behind* the lens, not in front of it. Offset camera mount? Maybe,
but offset in the opposite direction to what you are thinking about.

At last, a source of authority. Brian, so many QTVR and other documents
specifiy 'nodal point', but then talk about something else. I confess to
being confused, and I appreciate the clarification.

Lorem Ipsum wrote:
"BC" wrote in message
oups.com...
"Perhaps we have a confusion of terms. Are you thinking of the Entrance

Pupil? "

When shooting multi-image panoramas you need to rotate about the
entrance pupil, not the nodal point. This is because the center of
perspective is the entrance pupil. In telephoto lenses the entrance
pupil is almost always either well inside the lens, and in many cases
is *behind* the lens, not in front of it. Offset camera mount? Maybe,
but offset in the opposite direction to what you are thinking about.

At last, a source of authority. Brian, so many QTVR and other documents
specifiy 'nodal point', but then talk about something else. I confess to
being confused, and I appreciate the clarification.

I have to confess I was also confused about this issue a few years ago,
because I really hadn't thought it through. Like you say, an awful lot
of web sources say you should pivot about the nodal point. Even
sources that should know better, like Kaidan, make the same error.

But then I tried a simple experiment to demonstrate that the correct
rotation point is indeed the entrance pupil. First, I used parallax to
determine the rotation point for my 50mm f/1.4 lens - stopped way down
of course. Then I moved the entrance pupil by moving the aperture
stop: I opened the lens to f/1.4 and placed a piece of tin foil with a
small hole in front of the lens. Sure enough, the new rotation point
(determined experimentally) had moved forward by the same amount the
pupil had shifted. The nodal points are completely independent of stop
location, so the entrance pupil is clearly the correct rotation point.

In a sense it really doesn't matter, and for most people its just
pointless technical semantics. After all, the parallax method commonly
used to find the correct rotation point is very accurate, and doesn't
require that you understand the underlying optical principles.

Brian