Tricky shot of an old church

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

The potential for a LF camera is much greater due to its large film
area. But any film camera will start to suffer a loss of resolution
when shooting above f32.

Certainly in theory because no aperture (no stopping down) has the greatest
potential for resolution, all other things being equal - and they never are.

In real life, diffraction is not stricly about F-Stops because F-Stops are
not measures of the absolute size of the aperture - they are relative to the
focal length of the lens. Longer lenses (typical of LF) have larger absolute
aperture sizes than shorter lenses at the same F-Stop. So My F32 is not your
F32 as far as diffraction is concerned.

Consider this mental picture - One of those tiny, consumer digital cameras
with its aperture is set at F8. You could drop that whole camera through the
F8 aperture of one of my LF lenses. (Cool visual, eh?)

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

The potential for a LF camera is much greater due to its large film
area. But any film camera will start to suffer a loss of resolution
when shooting above f32.

Certainly in theory because no aperture (no stopping down) has the greatest
potential for resolution, all other things being equal - and they never are.

In real life, diffraction is not stricly about F-Stops because F-Stops are
not measures of the absolute size of the aperture - they are relative to the
focal length of the lens. Longer lenses (typical of LF) have larger absolute
aperture sizes than shorter lenses at the same F-Stop. So My F32 is not your
F32 as far as diffraction is concerned.

The size of the diffracted spot is only about F-Stop. And it does not
matter what size camera you are using, F/32 is going to give you a
softer image then F1/6, assume a good lens, and F/64 is going to be way
soft compared to F16.

If you shoot F/64 using a 4 x 5 camera you will not end up with much of
an improvement over shooting a 2 x 2.5 inch camera at F32. Shooting a
F/64 brings down the resolution to the level of a MF camera shooting at
a lower f number.

If I am shooting 4 x 5 I am doing do because that size film can capture
more detail then a smaller piece of film, but not if I shoot at F/64.
If I shoot at F/64 I have given up the advantage of using a large piece
of film

And as I said even F/32 is noticeable reducing the resolution of a
image.

Scott

"Lorem Ipsum" wrote:

Certainly in theory because no aperture (no stopping down) has the
greatest potential for resolution, all other things being equal - and they
never are.

In real life, diffraction is not stricly about F-Stops because F-Stops are
not measures of the absolute size of the aperture - they are relative to
the focal length of the lens. Longer lenses (typical of LF) have larger
absolute aperture sizes than shorter lenses at the same F-Stop. So My F32
is not your F32 as far as diffraction is concerned.

This is dead wrong. The f stop predicts the MTF on the film exactly,
regardless of focal length or format. Informally, that's because the airy
disk is effectively enlarged by the focal length of the lens.

Consider this mental picture - One of those tiny, consumer digital cameras
with its aperture is set at F8. You could drop that whole camera through
the F8 aperture of one of my LF lenses. (Cool visual, eh?)

Cool. But irrelevant.

David J. Littleboy
Tokyo, Japan

Lorem Ipsum wrote:


Consider this mental picture - One of those tiny, consumer digital cameras
with its aperture is set at F8. You could drop that whole camera through the
F8 aperture of one of my LF lenses. (Cool visual, eh?)


Yeah. I can just see you down on the ground amongst the shards of the
broken lens glass shouting at him "What the h*** were you doing?" ;-D

David J. Littleboy wrote:

There is no question that for the same size final image, viewed the same
way, and same angle of view, medium format will have more depth of field
than large format.

But that's only because you're probably comparing a medium format with a
'normal' lens with a large format with its 'normal' lens. Mount a 150 or
210mm lens ('normal' for large format) on that medium format or an 75 or
80mm lens ('normal' for medium format) on the large format. View the scene
the same way at the same distance without changing viewing axis and take
exposure with same f/stop with both cameras. Then enlarge to same size
final image without cropping and see if you can still make the same
statement.

That, by the way, is the same reason that the miniature format (aka 35mm)
has more depth of field than the medium format.

"Lawrence Akutagawa" wrote:
David J. Littleboy wrote:

Actually, Leonard Evens wrote:

There is no question that for the same size final image, viewed the same
way, and same angle of view, medium format will have more depth of field
than large format.

But that's only because you're probably comparing a medium format with a
'normal' lens with a large format with its 'normal' lens.

The above statement (by L. Evens, not me) is simply correct. Same FOV, same
f stop, and 6x7 has twice the DOF as 4x5. And 645 will have three times the
DOF. If you do the geometry correctly, that is.

Mount a 150 or 210mm lens ('normal' for large format) on that medium
format or an 75 or 80mm lens ('normal' for medium format) on the large
format. View the scene the same way at the same distance without changing
viewing axis and take exposure with same f/stop with both cameras. Then
enlarge to same size final image without cropping and see if you can still
make the same statement.

That's a silly thing to do, those are radically different images. Comparing
DOF is only sensible if you look at identical size prints of identical FOV
images taken at the same point.


That, by the way, is the same reason that the miniature format (aka 35mm)
has more depth of field than the medium format.


Since you've got the point that subminiature (MF is the miniature format)
has more DOF than MF right, I don't see how you can argue that MF doesn't
have more DOF than LF...

David J. Littleboy
Tokyo, Japan

Scott W wrote:
Lorem Ipsum wrote:

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


The potential for a LF camera is much greater due to its large film
area. But any film camera will start to suffer a loss of resolution
when shooting above f32.

Certainly in theory because no aperture (no stopping down) has the greatest
potential for resolution, all other things being equal - and they never are.

In real life, diffraction is not stricly about F-Stops because F-Stops are
not measures of the absolute size of the aperture - they are relative to the
focal length of the lens. Longer lenses (typical of LF) have larger absolute
aperture sizes than shorter lenses at the same F-Stop. So My F32 is not your
F32 as far as diffraction is concerned.


The size of the diffracted spot is only about F-Stop. And it does not
matter what size camera you are using, F/32 is going to give you a
softer image then F1/6, assume a good lens, and F/64 is going to be way
soft compared to F16.

If you shoot F/64 using a 4 x 5 camera you will not end up with much of
an improvement over shooting a 2 x 2.5 inch camera at F32. Shooting a
F/64 brings down the resolution to the level of a MF camera shooting at
a lower f number.

If I am shooting 4 x 5 I am doing do because that size film can capture
more detail then a smaller piece of film, but not if I shoot at F/64.
If I shoot at F/64 I have given up the advantage of using a large piece
of film

And as I said even F/32 is noticeable reducing the resolution of a
image.

Scott

Scott is correct about f/stop. It is all about aperture. But depending on
how you look at it, resolution does or does not change with f/stop.
F/stop is constant in terms of the linear size of the Airy disk in the
focal plane. At 0.53 micron wavelength (green light) and f/64 the Airy disk
diameter is 83 microns in diameter (0.083 mm). This is true for a tiny 10-mm
focal length lens to a 1000-mm focal length lens. But in terms of
angular resolution, the 1000-mm focal length lens resolves 100 times
more detail in the subject than the 10-mm focal length lens.

But Scott, you are wrong in your assumptions about limiting resolution.
At f/64, depending on other requirements for image sharpness, f/64 may be
required, as this one:
http://www.clarkvision.com/galleries...01a2-600b.html
I make 30x40 inch prints at 305 ppi, lightjet cibachrome and fuji crystal archive
prints. f/64 does not limit the print sharpness. If I did this image at
f/32 or f/45, it would have been limited by depth of field.

See this page on sampling:
http://www.clarkvision.com/imagedetail/sampling1.html
The 4x5 image was at f/45 on fuji velvia 50. The 3300 ppi drum scan
is limited by diffraction AND grain. Film is really pretty poor,
so large diffraction spot sizes are not a problem for 4x5 (and larger
film).

Roger

Roger N. Clark (change username to rnclark) wrote:
Scott W wrote:
Lorem Ipsum wrote:

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


The potential for a LF camera is much greater due to its large film
area. But any film camera will start to suffer a loss of resolution
when shooting above f32.

Certainly in theory because no aperture (no stopping down) has the greatest
potential for resolution, all other things being equal - and they never are.

In real life, diffraction is not stricly about F-Stops because F-Stops are
not measures of the absolute size of the aperture - they are relative to the
focal length of the lens. Longer lenses (typical of LF) have larger absolute
aperture sizes than shorter lenses at the same F-Stop. So My F32 is not your
F32 as far as diffraction is concerned.


The size of the diffracted spot is only about F-Stop. And it does not
matter what size camera you are using, F/32 is going to give you a
softer image then F1/6, assume a good lens, and F/64 is going to be way
soft compared to F16.

If you shoot F/64 using a 4 x 5 camera you will not end up with much of
an improvement over shooting a 2 x 2.5 inch camera at F32. Shooting a
F/64 brings down the resolution to the level of a MF camera shooting at
a lower f number.

If I am shooting 4 x 5 I am doing do because that size film can capture
more detail then a smaller piece of film, but not if I shoot at F/64.
If I shoot at F/64 I have given up the advantage of using a large piece
of film

And as I said even F/32 is noticeable reducing the resolution of a
image.

Scott

Scott is correct about f/stop. It is all about aperture. But depending on
how you look at it, resolution does or does not change with f/stop.
F/stop is constant in terms of the linear size of the Airy disk in the
focal plane. At 0.53 micron wavelength (green light) and f/64 the Airy disk
diameter is 83 microns in diameter (0.083 mm). This is true for a tiny 10-mm
focal length lens to a 1000-mm focal length lens. But in terms of
angular resolution, the 1000-mm focal length lens resolves 100 times
more detail in the subject than the 10-mm focal length lens.

But Scott, you are wrong in your assumptions about limiting resolution.
At f/64, depending on other requirements for image sharpness, f/64 may be
required, as this one:
http://www.clarkvision.com/galleries...01a2-600b.html
I make 30x40 inch prints at 305 ppi, lightjet cibachrome and fuji crystal archive
prints. f/64 does not limit the print sharpness. If I did this image at
f/32 or f/45, it would have been limited by depth of field.

See this page on sampling:
http://www.clarkvision.com/imagedetail/sampling1.html
The 4x5 image was at f/45 on fuji velvia 50. The 3300 ppi drum scan
is limited by diffraction AND grain. Film is really pretty poor,
so large diffraction spot sizes are not a problem for 4x5 (and larger
film).

Roger

Well first off your a bit off on your sampling theory, the Nyquist
limit does not need any given relationship between the signal and the
sampling phase. This gets people all the time because they will show a
sample like yours, where you show what looks like a frequency right at
the Nyquist limit, but in fact it is not. What you showed was a
rectangular pules of a sine wave, this has side bands some of which go
past the Nyquist limit. If this seems like nit picking it is not, if
you shape the sine wave smoothly the side bands will be much closer to
f0, you still need to shift f0 down just a bit to keep everything below
the Nyquist limit. It turns out that if you keep all the energy,
including side band that are cause by modulating the signal, below the
Nyquit limit you will capture all the information there is.

BTW This is not just an intellectual interest of mine, this is what I
do for a living and have been for many years.

Scott

Roger N. Clark (change username to rnclark) wrote:
Scott W wrote:
Lorem Ipsum wrote:

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


The potential for a LF camera is much greater due to its large film
area. But any film camera will start to suffer a loss of resolution
when shooting above f32.

Certainly in theory because no aperture (no stopping down) has the greatest
potential for resolution, all other things being equal - and they never are.

In real life, diffraction is not stricly about F-Stops because F-Stops are
not measures of the absolute size of the aperture - they are relative to the
focal length of the lens. Longer lenses (typical of LF) have larger absolute
aperture sizes than shorter lenses at the same F-Stop. So My F32 is not your
F32 as far as diffraction is concerned.


The size of the diffracted spot is only about F-Stop. And it does not
matter what size camera you are using, F/32 is going to give you a
softer image then F1/6, assume a good lens, and F/64 is going to be way
soft compared to F16.

If you shoot F/64 using a 4 x 5 camera you will not end up with much of
an improvement over shooting a 2 x 2.5 inch camera at F32. Shooting a
F/64 brings down the resolution to the level of a MF camera shooting at
a lower f number.

If I am shooting 4 x 5 I am doing do because that size film can capture
more detail then a smaller piece of film, but not if I shoot at F/64.
If I shoot at F/64 I have given up the advantage of using a large piece
of film

And as I said even F/32 is noticeable reducing the resolution of a
image.

Scott

Scott is correct about f/stop. It is all about aperture. But depending on
how you look at it, resolution does or does not change with f/stop.
F/stop is constant in terms of the linear size of the Airy disk in the
focal plane. At 0.53 micron wavelength (green light) and f/64 the Airy disk
diameter is 83 microns in diameter (0.083 mm). This is true for a tiny 10-mm
focal length lens to a 1000-mm focal length lens. But in terms of
angular resolution, the 1000-mm focal length lens resolves 100 times
more detail in the subject than the 10-mm focal length lens.

But Scott, you are wrong in your assumptions about limiting resolution.
At f/64, depending on other requirements for image sharpness, f/64 may be
required, as this one:
http://www.clarkvision.com/galleries...01a2-600b.html
I make 30x40 inch prints at 305 ppi, lightjet cibachrome and fuji crystal archive
prints. f/64 does not limit the print sharpness. If I did this image at
f/32 or f/45, it would have been limited by depth of field.

Well yes, sometime for DOF you need to go to a large FN, but this does
not mean you will no loss detail when you do. You will loose the same
percentage of detail shooting at F64 as someone would who is shooting
35mm at F64, but you start out with a lot more.

The image you show in your test sample is a very soft scan for film at
3300 ppi. I am surprised at how much grain seems to be visible in a
3300 scan.

I am sure you 30 x 40 in print looks great, but if you were to cut a 4
x 6 piece out would it really compare well with a normal 4 x 6 inch
print. Large prints look sharp in part because we expect them to look
soft, since this is the norm. Tonight I had 6 12 x 18 prints made at
Costco, the people at Costco commented on how sharp the prints were. 4
of the 6 were just straight out of the 20D and two were from stitched
photos. Yes the one right out of the 20D looked very sharp, until you
compared them against the one printed from 20MP file from the stitched
photos.

We can look at this another way, for you to make a 30 x 40 inch print
means a magnification of 8. If we scale that to 35mm it would be a
print very close to 8 x 12. Now using a good lens and good film you
can get a pretty sharp looking 8 x 12 from film. But if you do the
same shot at f8 and at f64 the print made from the shot at f64 will
look much softer then the one short at f8. This scales up directly to
your case, since the film would be the same, the diffraction spot would
be the same size and he magnification would be the same. In both
prints the diffraction spot will scale up to 0.8 mm in diameter. And
if we are printing at 300 ppi the diffraction spot is 9.5 pixels in
diameter, that has to hurt the sharpness.

Scott

"David J. Littleboy" wrote in message
...

"Lawrence Akutagawa" wrote:

That, by the way, is the same reason that the miniature format (aka 35mm)
has more depth of field than the medium format.

Since you've got the point that subminiature (MF is the miniature format)
has more DOF than MF right, I don't see how you can argue that MF doesn't
have more DOF than LF...

hmmm...I see I should have been more specific and said:

"That, by the way, is the same reason that the miniature format (aka 35mm)
'normal' lens image has more depth of field than the medium format 'normal'
lens image."

That having been said, no argument from this corner that the shorter lens
has more depth of field than the longer lens at the same f/stop, regardless
of film/camera format. At the same f/stop, the 22mm lens (on my 16mm
camera) has deeper depth of field than the 50mm lens (on my 35mm camera)
than the 80 lens (on my 120 camera) than the 150mm lens (on my 4x5) than the
300mm lens (on someone else's 8x10). By the same token, at the same f/stop
with my 35mm camera the 20mm lens has a greater depth of field than the 50mm
lens than the 85mm lens than 135 lens than the 200mm lens than the 500mm
lens. Likewise, at the same f/stop the 150mm lens on a 35mm camera has the
same depth of field as the 150mm lens on a 120 camera as the 150mm lens on a
4x5.

Gosh-be-darned - "MF is the miniature format". I swear I learn something
new each and every day! And here all these 50 plus years I thought MF is
medium format! hmmmm....if MF is miniature format, makes you kind of wonder
what medium format is. After all, MF can't be both miniature format and
medium format at the same time...can it?