Front tilt loses middle

I should know this procedure, but my results say otherwise. When I
front tilt for maximum depth of field then check that my forground and
background are sharp, should I then focus the middle ground for final
focus? I am seeking complete all over focus.

I have been losing middle ground sharpness in situations where even a
tilt would probably not have been necessary, i.e. shooting a full ocean
view from a high cliff. I was amazed to find that detail in the middle
of these images was soft. My apertures are always either f/22 or f/32.

There appears to be a critical step here that I am overlooking.

Thanks for your help.

wrote in message
ps.com...
I should know this procedure, but my results say otherwise.
When I
front tilt for maximum depth of field then check that my
forground and
background are sharp, should I then focus the middle
ground for final
focus? I am seeking complete all over focus.

I have been losing middle ground sharpness in situations
where even a
tilt would probably not have been necessary, i.e. shooting
a full ocean
view from a high cliff. I was amazed to find that detail
in the middle
of these images was soft. My apertures are always either
f/22 or f/32.

There appears to be a critical step here that I am
overlooking.

Thanks for your help.


When you tilt either the back or the lens of a camera
you are tilting the plane of focus. Everything in that plane
should be in focus but stuff outside of it may not be.
Imagine a flat plane in front tilted the opposite direction
of the back. If the subject area you want focused lies in
this plane all of it should be in focus simultaneously. Now,
it may be that you are focusing on something that does not
lie in a tilted plane or that the lens has too much
curvature of field. Both can be cured to some extent by
stopping down.
The procedure depends somewhat on how the camera is
made. Some cameras tilt from the center and some from the
base of the back. Those that tilt from the center will tend
to maintain focus at the center of the image as the back is
tilted, base tilt cameras will require re-focusing for the
center. It may take some juggling of tilt and focus to get
it right. Again, if the objects you want to get into focus
do not lie on the same plane the tilting trick will not
work.


--
---
Richard Knoppow
Los Angeles, CA, USA




--
Posted via a free Usenet account from http://www.teranews.com

In article om,
wrote:

I should know this procedure, but my results say otherwise. When I
front tilt for maximum depth of field then check that my forground and
background are sharp, should I then focus the middle ground for final
focus? I am seeking complete all over focus.

I have been losing middle ground sharpness in situations where even a
tilt would probably not have been necessary, i.e. shooting a full ocean
view from a high cliff. I was amazed to find that detail in the middle
of these images was soft. My apertures are always either f/22 or f/32.

There appears to be a critical step here that I am overlooking.

Thanks for your help.

You have to use two hands!


My finding is you do not need a loupe to get general focus-just spot
check after you get every thing more or less in focus. Depending on the
scene f-32 may not be adequate. However 22 is usually quite acceptable.

If your losing the middle something is certainly wrong- Tilting the lens
is not always the cut and dry some times you have the slide the
standards in and out at the same time as you tilt the front standard
back and forth.....thus using two hands.
--
George W. Bush is the President Quayle we never had.

Depends on whether you have on-axis tilt or if you're using base tilt. I'd
bet a nickel that you're also using too much tilt and you're basically
throwing the middle out of focus by doing so.

The most common mistake I see students doing when I help teach workshops is
using too much tilt. For some reason some seem to think that the lens board
has to be tilted at the same angle that they're trying to aim the lens.

You typically only need a few degrees of on-axis tilt to keep the field of
view in focus. If you're using base tilt, you'll want to re-check your focus
every time you use tilt, front or rear.

Another common mistake is people trying to get everything in focus with the
lens wide open, it doesn't work that way, you really need to get under the
focusing cloth with the lens stopped down at your shooting aperture and
check your focus points with a loupe, it's the only way to know for sure
that you've got what you want in focus.

John Emmons
wrote in message
ps.com...
I should know this procedure, but my results say otherwise. When I
front tilt for maximum depth of field then check that my forground and
background are sharp, should I then focus the middle ground for final
focus? I am seeking complete all over focus.

I have been losing middle ground sharpness in situations where even a
tilt would probably not have been necessary, i.e. shooting a full ocean
view from a high cliff. I was amazed to find that detail in the middle
of these images was soft. My apertures are always either f/22 or f/32.

There appears to be a critical step here that I am overlooking.

Thanks for your help.

Some good advice. Thanks. I think I have what you call axis tilt on a
5x7 Linhof and a converted Crown Graphic 4x5, if this means the center
of the board tilts. I do use a tiny amount, but in the case of the vast
ocean taken from a high vantage point I must say I'm mystified. A
little was used to make sharp tiny beach rocks to horizon, yet on the
larger rocks sticking up in the middle of the scene at f/22 with a 180
lens, its soft. I'm going to revert back to middle ground focusing
after my tilting, then see if the aperture brings it all together.

John Emmons wrote:
Depends on whether you have on-axis tilt or if you're using base tilt. I'd
bet a nickel that you're also using too much tilt and you're basically
throwing the middle out of focus by doing so.

The most common mistake I see students doing when I help teach workshops is
using too much tilt. For some reason some seem to think that the lens board
has to be tilted at the same angle that they're trying to aim the lens.

You typically only need a few degrees of on-axis tilt to keep the field of
view in focus. If you're using base tilt, you'll want to re-check your focus
every time you use tilt, front or rear.

Another common mistake is people trying to get everything in focus with the
lens wide open, it doesn't work that way, you really need to get under the
focusing cloth with the lens stopped down at your shooting aperture and
check your focus points with a loupe, it's the only way to know for sure
that you've got what you want in focus.

John Emmons
wrote in message
ps.com...
I should know this procedure, but my results say otherwise. When I
front tilt for maximum depth of field then check that my forground and
background are sharp, should I then focus the middle ground for final
focus? I am seeking complete all over focus.

I have been losing middle ground sharpness in situations where even a
tilt would probably not have been necessary, i.e. shooting a full ocean
view from a high cliff. I was amazed to find that detail in the middle
of these images was soft. My apertures are always either f/22 or f/32.

There appears to be a critical step here that I am overlooking.

Thanks for your help.

wrote in

Some good advice. Thanks. I think I have what you call axis tilt on a
5x7 Linhof and a converted Crown Graphic 4x5, if this means the center
of the board tilts. I do use a tiny amount, but in the case of the vast
ocean taken from a high vantage point I must say I'm mystified. A
little was used to make sharp tiny beach rocks to horizon, yet on the
larger rocks sticking up in the middle of the scene at f/22 with a 180
lens, its soft. I'm going to revert back to middle ground focusing
after my tilting, then see if the aperture brings it all together.

It sounds like you have the situation that Richard referred to: the big
rocks sticking up in the middle of the scene may be outside the plane of
focus you created with your tilt. You can prove that to yourself if the
bases of the rocks (say if there is beach around the bases of the large
rocks in the middle) are sharp. If that's the case, and is the best you can
do, then close down to at least f/32. That may sharpen the middle rocks
some.

Again, if you are properly making your tilt, a beach and ocean scene should
have no trouble being sharp from right up close to the horizon because your
scene is pretty much a flat plane. Anything sticking up out of that plane is
not going to be in focus, and you're limited to correcting that with your
lens' diaphragm.

The plane of focus, the plane of the film and the plane of the lens board
will all intersect at the same imaginary point unless of course they're all
parallel to one another. Stopping down will increase the depth of field of
the plane of focus in both directions away from it.


"John Emmons"
The most common mistake I see students doing when I help teach workshops
is
using too much tilt. For some reason some seem to think that the lens
board
has to be tilted at the same angle that they're trying to aim the lens.

A famous example of what the OP is describing can be seen in Adams'
photograph of the Alabama Hills.

The middle ground is not as sharp as the foreground or the distant mountain
tops.

John Emmons

"Howard Lester" wrote in message
...

wrote in

Some good advice. Thanks. I think I have what you call axis tilt on a
5x7 Linhof and a converted Crown Graphic 4x5, if this means the center
of the board tilts. I do use a tiny amount, but in the case of the vast
ocean taken from a high vantage point I must say I'm mystified. A
little was used to make sharp tiny beach rocks to horizon, yet on the
larger rocks sticking up in the middle of the scene at f/22 with a 180
lens, its soft. I'm going to revert back to middle ground focusing
after my tilting, then see if the aperture brings it all together.

It sounds like you have the situation that Richard referred to: the big
rocks sticking up in the middle of the scene may be outside the plane of
focus you created with your tilt. You can prove that to yourself if the
bases of the rocks (say if there is beach around the bases of the large
rocks in the middle) are sharp. If that's the case, and is the best you
can
do, then close down to at least f/32. That may sharpen the middle rocks
some.

Again, if you are properly making your tilt, a beach and ocean scene
should
have no trouble being sharp from right up close to the horizon because
your
scene is pretty much a flat plane. Anything sticking up out of that plane
is
not going to be in focus, and you're limited to correcting that with your
lens' diaphragm.

wrote:
I should know this procedure, but my results say otherwise. When I
front tilt for maximum depth of field then check that my forground and
background are sharp, should I then focus the middle ground for final
focus? I am seeking complete all over focus.

I have been losing middle ground sharpness in situations where even a
tilt would probably not have been necessary, i.e. shooting a full ocean
view from a high cliff. I was amazed to find that detail in the middle
of these images was soft. My apertures are always either f/22 or f/32.

There appears to be a critical step here that I am overlooking.

It appears that you haven't conceptualized correctly what happens when
you tilt. Richard described one important fact, but there is more to
be said.

There is always in principle exactly one plane which is in exact focus.
With no tilt, the front and rear standard are parallel and the plane
of exact focus is parallel to that. But, in addition, there is a whole
region in front and in back of the plane of exact focus where the focus
is adequate under the circumstances. This is called the depth of field.
The DOF region is bounded by two planes, one in front and the other in
back of the plane of exact focus. (The back plane may be at infinity.)

Now what happens when you tilt. The plane of exact focus shifts, and
it is no longer parallel to either standard. Instead, if you extend the
planes in which the standards lie, they meet in a line, and the plane of
exact focus passes through that same line. Its exact position in space
depends on the separation of the standards.

As in the untilted case, there is also a region of adequate focus, but
this time it is bounded above and below the plane of exact focus by
planes which meet in a special line called the hinge line. If the front
standard is tilted, that line lies some distance below the lens. the
DOF region forms a wege which starts at the hinge line and opens up as
you move away from the lens. Near the lens, the vertical extent in
focus is quite limited, but it gets larger the further you move away
from the lens. How open this wedge is depends on the f-stop.

The correct way to focus is to first choose some plane you want to use
as the exact plane of focus. A good place to set that plane is
somewhere such that there is as much above it that you need in focus as
there is below it. Using a near point and a far point in that plane,
you adjust the tilt so the plane of exact focus passes through those
points. After that you stop down far enough so that points above and
below the exact plane come into focus.

In your example it was not true that everything you wanted to be in
focus was in a single plane. So necessarily you had to rely on stopping
down to get everything in adequate focus. You may have chosen your
exact plane of focus to be close to the plane of the ocean. That way
it might have required you to stop down quite far to get the rocks in
the middle ground in adequate focus. It might have been better to
adjust the tilt and separation of the standards so that the plane of
focus passed halfy up to the midground rocks. Then you might have been
able to get both the ocean and the top of the midground formation with a
more modest aperture.

Thanks for your help.

"Leonard Evens" wrote

In your example it was not true that everything you wanted to be in focus
was in a single plane. So necessarily you had to rely on stopping down to
get everything in adequate focus. You may have chosen your exact plane of
focus to be close to the plane of the ocean. That way it might have
required you to stop down quite far to get the rocks in the middle ground
in adequate focus. It might have been better to adjust the tilt and
separation of the standards so that the plane of focus passed halfy up to
the midground rocks. Then you might have been able to get both the ocean
and the top of the midground formation with a more modest aperture.

Great explanation, Leonard, even if I don't understand half of it. ;-) But
you bring up a good, um, point... choosing the points of nearest and
farthest requires some thought for the final composition. Normally I'd do
something boneheaded like choose the very near foreground (good choice for
sharp impact) and the ocean's distant horizon, leaving me with the puzzle
the OP has presented. However, since in this case the far point is an ocean
horizon, which has some "built-in fuzziness," your solution (if I understand
it correctly) is probably better: use the middle rocks as the far point and
let the background fall where it will depending on the chosen aperture. In a
photograph, the eye is much more forgiving of distant softness than either
middle, or near-ground softness.

View cameras allow for solutions to problems that "fixed" cameras cannot
possibly solve. However, it does take some thinking.... ;-) It ain't
snapshooting.