Megapixel war just beginning with DSLRs

acl wrote:
On Jan 29, 8:44 am, Paul Furman wrote:

I wonder what the '35mm equivalent f/stop' of a stitched pano would be?

The same: stitching amounts to using a larger sensor with the same-
sized pixels, if you think about it. The focal length and aperture
diameter also don't change.

OK yes, that makes sense, Doh. The DOF does increase though.

Chris Malcolm wrote:
Paul Furman wrote:
Jeremy Nixon wrote:
RichA wrote:

So, what specifically can we say ...is the smallest practical pixel size
for a DSLR?
The tricky one is that, at this size, you have a practical minimum
aperture of f/11 before you start losing resolution to diffraction.
With smaller pixels this will get worse, and I wouldn't want to use
an APS-size camera that can't go below f/8. You can't really solve
this one with better lenses.

Interesting point. f/11 or 16 is where a 12MP D300 or D2x becomes
diffraction limited so for 15MP maybe f/16 isn't worthwhile (for that
type of tripod landscape/studio work anyways).

Isn't worthwhile if using the full resolution. But if you have 12MP
you might well be content with say a close-up product photograph of
3MP resolution, for which you could either use in-camera or editor
resizing. In that case would you gain anything, such as increased DoF,
by being able to stop down further than the 12MP diffraction limit?

Yes there are going to be situations where it's useful: where you don't
need a big print but do need the DOF.

On Jan 29, 2:29*am, acl wrote:
On Jan 29, 8:44 am, Paul Furman wrote:



I wonder what the '35mm equivalent f/stop' of a stitched pano would be?

The same: stitching amounts to using a larger sensor with the same-
sized pixels, if you think about it. The focal length *and aperture
diameter also don't change.

But he was asking about the '35mm equivalent f/stop'. Since in effect
we are using a much larger sensor the equivalent f/stop is smaller,
poor DOF but very good resolution.

But a easier way to look at it is your way, a large sensor at the same
FL and f/stop that the photos to be stitched were taken at. In many
ways stitching is like having a LF camera, great resolution but poor
DOF.

Scott

Scott W wrote:
acl wrote:
Paul Furman wrote:

I wonder what the '35mm equivalent f/stop' of a stitched pano would be?
The same: stitching amounts to using a larger sensor with the same-
sized pixels, if you think about it. The focal length and aperture
diameter also don't change.

But he was asking about the '35mm equivalent f/stop'. Since in effect
we are using a much larger sensor the equivalent f/stop is smaller,
poor DOF but very good resolution.

But a easier way to look at it is your way, a large sensor at the same
FL and f/stop that the photos to be stitched were taken at. In many
ways stitching is like having a LF camera, great resolution but poor
DOF.

It would have more DOF on the print. Maybe the question was too strange
to answer: the f/stop doesn't care about sensor size but the DOF matters.

Let's see, if you take a 4/3 sensor & stitch 4 shots at 8mm f/3.5 that's
going to make the equivalent of a 16mm field of view on full frame. But
wouldn't it take something like f/5 for the same DOF? And the 8mm lens
probably only stops down to f/8 (doubles to f/11 stitched) where the
16mm lens goes 2 more stops to f/22 and opens up another half stop to f/2.8.

On Jan 29, 7:39*am, Paul Furman wrote:
Scott W wrote:
acl wrote:
Paul Furman wrote:

I wonder what the '35mm equivalent f/stop' of a stitched pano would be?
The same: stitching amounts to using a larger sensor with the same-
sized pixels, if you think about it. The focal length *and aperture
diameter also don't change.

But he was asking about the '35mm equivalent f/stop'. *Since in effect
we are using a much larger sensor the equivalent f/stop is smaller,
poor DOF but very good resolution.

But a easier way to look at it is your way, a large sensor at the same
FL and f/stop that the photos to be stitched were taken at. *In many
ways stitching is like having a LF camera, great resolution but poor
DOF.

It would have more DOF on the print. Maybe the question was too strange
to answer: the f/stop doesn't care about sensor size but the DOF matters.

Let's see, if you take a 4/3 sensor & stitch 4 shots at 8mm f/3.5 that's
going to make the equivalent of a 16mm field of view on full frame. But
wouldn't it take something like f/5 for the same DOF? And the 8mm lens
probably only stops down to f/8 (doubles to f/11 stitched) where the
16mm lens goes 2 more stops to f/22 and opens up another half stop to f/2.8.- Hide quoted text -

4 shots stitched, assume no overlap, witha 8mm lens will have the same
field of view (or close to it) of a full frame camera with a 8mm
lens.

To look at this another way, I can use a 100mm lens on my camera to
get the same FOV, using stitching, as one shot with a 25mm lens. If I
want the same DOF in a print with the 100mm lens as the 25mm lens at
say f/4 I would need to set the 100mm lens at f/16.

Scott

Scott W wrote:
On Jan 29, 7:39 am, Paul Furman wrote:
Scott W wrote:
acl wrote:
Paul Furman wrote:
I wonder what the '35mm equivalent f/stop' of a stitched pano would be?
The same: stitching amounts to using a larger sensor with the same-
sized pixels, if you think about it. The focal length and aperture
diameter also don't change.
But he was asking about the '35mm equivalent f/stop'. Since in effect
we are using a much larger sensor the equivalent f/stop is smaller,
poor DOF but very good resolution.
But a easier way to look at it is your way, a large sensor at the same
FL and f/stop that the photos to be stitched were taken at. In many
ways stitching is like having a LF camera, great resolution but poor
DOF.
It would have more DOF on the print. Maybe the question was too strange
to answer: the f/stop doesn't care about sensor size but the DOF matters.

Let's see, if you take a 4/3 sensor & stitch 4 shots at 8mm f/3.5 that's
going to make the equivalent of a 16mm field of view on full frame. But
wouldn't it take something like f/5 for the same DOF? And the 8mm lens
probably only stops down to f/8 (doubles to f/11 stitched) where the
16mm lens goes 2 more stops to f/22 and opens up another half stop to f/2.8.- Hide quoted text -

4 shots stitched, assume no overlap, witha 8mm lens will have the same
field of view (or close to it) of a full frame camera with a 8mm
lens.

To look at this another way, I can use a 100mm lens on my camera to
get the same FOV, using stitching, as one shot with a 25mm lens. If I
want the same DOF in a print with the 100mm lens as the 25mm lens at
say f/4 I would need to set the 100mm lens at f/16.

Ah, sorry I got it turned around. What about this: use the same full
frame 16mm lens on a 2/3 camera & stitch to get the same thing, same
f/stop. More pixels though so it's not much use to stop down more than
f/8. But then it has more resolution so is sharper before stopping down
excessively.

Chris Malcolm wrote:

Isn't worthwhile if using the full resolution. But if you have 12MP
you might well be content with say a close-up product photograph of
3MP resolution, for which you could either use in-camera or editor
resizing. In that case would you gain anything, such as increased DoF,
by being able to stop down further than the 12MP diffraction limit?

At 12MP APS-size, anything below f/11 loses resolution, but yes, you
gain the expected DoF.

The best example I have is this shot:

http://www.flickr.com/photos/100mph/522280431/

I shot that at f/22 (Nikon D2x, 10.5mm) knowing I'd be losing resolution,
but with the flower a couple inches from the lens, I needed the DoF. The
resulting shot has about 6MP of useful resolution -- I can reduce the
original to that size without losing any detail whatsoever.

--
Jeremy Nixon | address in header is valid
(formerly )
http://www.flickr.com/photos/100mph/

On Jan 29, 10:12 pm, Jeremy Nixon ~$!~( )@( )u.defocus.net wrote:
Chris Malcolm wrote:

Isn't worthwhile if using the full resolution. But if you have 12MP
you might well be content with say a close-up product photograph of
3MP resolution, for which you could either use in-camera or editor
resizing. In that case would you gain anything, such as increased DoF,
by being able to stop down further than the 12MP diffraction limit?

At 12MP APS-size, anything below f/11 loses resolution, but yes, you
gain the expected DoF.

The best example I have is this shot:

http://www.flickr.com/photos/100mph/522280431/

I shot that at f/22 (Nikon D2x, 10.5mm) knowing I'd be losing resolution,
but with the flower a couple inches from the lens, I needed the DoF. The
resulting shot has about 6MP of useful resolution -- I can reduce the
original to that size without losing any detail whatsoever.

--
Jeremy Nixon | address in header is valid
(formerly )
http://www.flickr.com/photos/100mph/

For static images, this program does a terrific job:

http://www.heliconsoft.com/heliconfocus.html

I couldn't believe it when I saw the result, I was sure it wouldn't
work very well. Here's a macro sample at 50mm f4:

http://www.pbase.com/andersonrm/image/92272575