hyperfocal distance

Roland Karlsson wrote:

I hate to tell you that this test is not so interesting

The hyper focal distance cannot be meassured by photographing
rulers and tape meassures. It has really nothing to do with
actual sharpness - at least not at pixel or grain level.

Hyper focal distance is based upon an aesthetical (is it spelled
thus?) meassure; how unsharp are we ready to accept out of focus
parts to be. In practice this has shown to be approx the picture
diagonal divided by 1500-2000.

I'll probably still mess around with this a bit. It has me
intrigued and I want to see some empirical results.
My purpose is to shift the near focal point back to the subject
point, allowing the far focal point to shift to infinity. If I open
the lens wide and reduce DOF to a narrow field, I can mess
around with the N2020 body, holding lens settings constant,
then varying the FL to maintain FOV. I can look at the
sharpness of the markers set up at, say, five meter intervals,
to determine how the hyperfocal distance moves.

And yeah, it's dull as my mother-in-law's stewed tomatoes.

Sorry for the top posting:

The basic idea of DOF that you have to keep in mind is that it's a
perceptual phenomenon that occurs in the mind of the viewer. So it varies
with enlargement and viewing distance.

The CoC at the sensor is back calculated from a given print size, viewing
distance, and assumed visual acuity of a typical viewer for a required DOF
(i.e. we calculate a CoC on the print for a required DOF under given
conditions, and then back calculate the CoC at the sensor required to meet
those conditions).

Note that if you change the viewing conditions, the DOF the viewer will
report seeing will change _for the same image_.

If you hold those conditions constant, then you will find that 1.6x dSLRs
have slightly _more_ DOF than full-frame film or dSLR cameras _for an image
with the same angle of view_, and slightly _less_ DOF if you use the same
lens but print the dSLR image at the same size as you print the full-frame
image.

But the digital age changes the viewing conditions. We inspect and work on
our images at 100% (actual pixels) on the screen, which corresponds to an
enormous magnification. So DOF gets a lot smaller and now depends only on
the focal length, f stop, and pixel pitchg.

David J. Littleboy
Tokyo, Japan

"M Barnes" wrote in message
...
Big Bill wrote:

Question:
Using that formula, does it work for *any* sensor size, or the one the
image size on the focal plane was designed for (in the case of the
lenses in question, 35mm)?
Or, to put it a different way, if you take a 35mm film image at
hyperfocal distance, does cropping that image alter the hyperfocal
distance, or was the HD set when the pic was taken?

I'm wondering, if the CoC formula includes 1525d (and I'm assuming it
does), does d refer to the sensor, or the image on the focal plane,
and the sensor size that image is designed for?
I mean, in a DSLR, the lens uses a smaller part of the image on the
focal plane than 35mm film does. In effect, it crops that image. As I
ask above, does this really change the hyperfocal distance of that
lens?

I think you've asked the relevant question here.
All the formulae I've seen use focal length, focal ratio
and CoC to calculate HD, with a resolution factor
in the CoC that presumes capture area and a diagonal
measure for the other two.

Can you really say a lens is "designed for" 35mm,
or that the image is "cropped" by a DSLR? Wouldn't
it be just as appropriate to say that a cone of clarity
is projected, and that any plane intersecting that
cone is appropriate, whether 35 mm length or shorter?

The question is, does the change in that diagonal
measure of the capture surface slide the HD calculations
the way Tony Spadaro implies?

Has anyone worked this out, or can they show
how this works?

I'm thinking for the HD to change with crop factor,
there must be a constant that pins the calculations
to the focal length regardless of diagonal measure
of the capture area. Is that an oxymoron?

David J. Littleboy wrote:

Sorry for the top posting:

No worries.

The basic idea of DOF that you have to keep in mind is that it's a
perceptual phenomenon that occurs in the mind of the viewer. So it varies
with enlargement and viewing distance.

The CoC at the sensor is back calculated from a given print size, viewing
distance, and assumed visual acuity of a typical viewer for a required DOF
(i.e. we calculate a CoC on the print for a required DOF under given
conditions, and then back calculate the CoC at the sensor required to meet
those conditions).

Note that if you change the viewing conditions, the DOF the viewer will
report seeing will change _for the same image_.

If you hold those conditions constant, then you will find that 1.6x dSLRs
have slightly _more_ DOF than full-frame film or dSLR cameras _for an
image
with the same angle of view_, and slightly _less_ DOF if you use the same
lens but print the dSLR image at the same size as you print the full-frame
image.

But the digital age changes the viewing conditions. We inspect and work on
our images at 100% (actual pixels) on the screen, which corresponds to an
enormous magnification. So DOF gets a lot smaller and now depends only on
the focal length, f stop, and pixel pitchg.

I'm beginning to understand all this. What it boils down to
for me is this: I can use the D100 body with my customary
lenses, and I don't have to turn the manual focus ring quite
as far to accomplish the same radical foreground/background
shots I like to take. For example, if before I set up a shot on my
N2020 with a rock at 8 feet, and wanted that and the distant
mountains to both be in focus with a low ASA and dusk light,
I'd set the lens to, say, 15 feet, and could count on getting
the shot. Now with the D100, I can set it to 20 feet after
adjusting for the same FOV (using a zoom).

Roland Karlsson writes:

Yes - this is the intuitive answer. But it is not
entirely correct. The formula for hyperfocal distans
is (just as pointed out in another post):

h = (f*f)/(N*c)
f = focal length, N = f-ratio, c = "circle of confusion" diameter.

The crucial factor here is c (circle of confusion). If you search
further on the net you will find that it is 1/1740 of the diagonal
of the sensor. Therefore, h will be bigger for a smaller sensors.

Assuming that you keep the focal length the same.

On the other hand, if you reduce the focal length in proportion to
the sensor size change, to maintain the same field of view, then
the hyperfocal distance becomes smaller not larger. That's because
it depends on focal length squared.

So - the intuitive answer is wrong. The hyperfocal distance
depends on how much you crop your image. Therefore, it is also only
valid for the 35 mm film camera if you don't crop the image.

Yes - if you don't change the lens focal length.

Dave

Viewing distance has NOTHING to do with hyperfocal focusing as .....
Viewing distance cancels out enlargement!!!!
Viewing distance cancels out enlargement!!!!
Viewing distance cancels out enlargement!!!!
Viewing distance cancels out enlargement!!!!
Viewing distance cancels out enlargement!!!!
Got it yet?
hyperfocal distance for a 4x6 is the same as hyperfocal for a 40x60 because
the VIEWING DISTANCE CHANGES.
--
http://www.chapelhillnoir.com
home of The Camera-ist's Manifesto
The Improved Links Pages are at
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A sample chapter from my novel "Haight-Ashbury" is at
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"M Barnes" wrote in message
...
Tony Spadaro wrote:

HEY ACE --- Viewing distance cancels out enlargement!!!!

I've pointed out that once you take into account enlargement you also
have
to take into account viewing distance.

GET IT? Viewing distance cancels out enlargement!!!!

Think Rover think:

Viewing distance cancels out enlargement!!!!

Sing it with me

Viewing distance cancels out enlargement!!!!

If this concept is too difficult for you - forget it.
This won't be on the test and you won't be penalized.

Mm, hmm. And what does enlargement have
to do with hyperfocal focusing? That was the
intent of my question. Do you know what
hyperfocal focusing is? Something tells
me you don't, and you're shouting out the
answers to the wrong question, naked in front
of the church choir, thinking your robes are
peachy keen.

I'm beginning to think maybe you don't
even know what "hyperfocal" means.

Look here, for example:
http://www.outsight.com/hyperfocal.html#hyper

The DOF calculator for hyperfocal focusing
assumes an 8x10 print (notice -- no enlargement,
Ace). It also stipulates focal length, not 35mm
equivalent. See the purpose of this? It's to
focus from a known point to infinity.

I could be impolite, as you, and state my
response in big caps, call you a dogbrain
and all that, but it's easier to simply point out
that I'm not looking to enlarge, but to focus,
using standard hyperfocal techniques you seem
to be unaware of, and which has been under
discussion here for a while as you were ...
shouting in the corner to yourself?

It ain't gonna happen, Duce You cannot simultaneously do macro focus and
hyperfocal focus. Look at a photography book sometime you will see that
there ain't no such beast as hyperfocal macro focus, and there ain't gonna
be one until you can get a sharp picture from a pinhole camera. I won't make
any predictions about it being impossible as I think the day is coming that
it can be done with software -- but not as a film or digital original.

--
http://www.chapelhillnoir.com
home of The Camera-ist's Manifesto
The Improved Links Pages are at
http://www.chapelhillnoir.com/links/mlinks00.html
A sample chapter from my novel "Haight-Ashbury" is at
http://www.chapelhillnoir.com/writ/hait/hatitl.html
"M Barnes" wrote in message
...
Tony Spadaro wrote:

Ok -- let me put it this way, Ace.

Ooh, touched a nerve, have we?

If you wish to find out exactly what size
you can enlarge you (sic) P&S stuff to ---
get it enlarged and LOOK at it.

Well, evidently you haven't been paying
attention. I don't use a point-and-shoot.
And I'm not looking for enlargement
resolution. I'm looking to use hyperfocal
focusing to keep foregrounds sharp while
focusing to infinity. That way, I can stretch
the hyperfocal boundary with a semi-wide
prime on my D100 and get those stunning
closeups of bugs sitting on smoky quartz while
the Costa Mesa range is still in focus. Ace.

Formulas don't tell you anything.

Well, let's put it this way. Evidently they don't
tell _you_ anything. They've told me a lot
through the years. If you knew how to use
them, they'd tell you things to. Evidently you're
too busy busting spammers and making threats
to learn a little basic math. And basic math is
what we're talking here. It's not calculus.
It's not even analytical geometry. It's just a tad
of elementary school albegra.

If you think that is not serious enough for your
scientifical mind go talk to other anal retentives
and leave the real world to people who are
not obsessive compulsive.

Right. Like the anal retentives at JPL who
computed the VVJ swings to Saturn, using formulae,
by the way. Last time I looked, they exist. They're
real.

And the wackos who computed range tables that
allowed Grandpa to factor in the Coreolis force
to correct his artillery shells firing north-by-northwest
in France, so as not to take out B Company coming
in from Omaha. They were real. At least my Grandpa
was. Can't testify to yours. Ace. Maybe he left
you inside a fairy ring. Stranger things have happened.

Oh, let's not forget the dim bulbs at Canon and Nikon
who use formulae to design those lenses you try to
use from time to time. Or did you think they sketched
them out on napkins with #2 Ticonderogas, as you
seem fond of doing. Ace. They're real. At least my
D100 is, and the lenses I use are.

I guess in your limited reference frame, there are
10 kinds of people (binarily speaking, of course):
those who shoot from the hip and speak from the
cuff (I'm being polite -- another extremity came to
mind, and I don't mean your hat), and those who
retain their feces, love it, plate it with bronze, save
it in little file drawers for posterity.

Something tells me that the anger you express at
having your first glib answer challenged and a mild
request for explication put forth tells more about
which side of the fence you're on than it does about,
say, the effect of sensor size on computing hyperfocal
distance.

And by the way, Ace, blowing up my prints isn't the
point. It's where to set the manual focus ring when I
have a 17mm prime loaded with a 2/3 frame sensor,
and I'm trying to edge off on a subject at 1.5 meters
stopped down to 22. I'm accustomed to doing this
with an N2020 body, and just entered the discussion
to see if anyone had definitive info about any changes
I might need to make, and why.

But since you don't seem to even comprehend the
question, I can safely disregard your "real world"
snerk responses, since they're informed not by
"scientifical" reasoning but voices from, it would
seem, your bunghole, a place where your head
seems to have been residing while most of the rest
of us were learning how to use simple formulas
to resolve technical matters. And Ace, it resides
there still.

Tony Spadaro talked to himself in the dark:

Viewing distance ... Got it yet?

crickets

Tony Spadaro wrote:

It ain't gonna happen, Duce ...

Yawn

"Tony Spadaro" wrote in news:Eh5Fc.93833
:

Viewing distance has NOTHING to do with hyperfocal focusing as .....
Viewing distance cancels out enlargement!!!!
Viewing distance cancels out enlargement!!!!
Viewing distance cancels out enlargement!!!!
Viewing distance cancels out enlargement!!!!
Viewing distance cancels out enlargement!!!!

Entirely right - but viewing does not cancel out cropping.

All things you say does not become right because you write
one true thing 5 times. How old are you? 5? Time to grow up?


/Roland

(Dave Martindale) wrote in news:cc2lhd$lgt$1
@mughi.cs.ubc.ca:

So - the intuitive answer is wrong. The hyperfocal distance
depends on how much you crop your image. Therefore, it is also only
valid for the 35 mm film camera if you don't crop the image.

Yes - if you don't change the lens focal length.


Ahhh ... but as you yourself said, the hyper focal distance
varies as the focal length squared.

If you crop only - the hyper focal distance is proportional to the
__inverse__ of the cropped image size.

If you crop and compensate with a shorter focal length - the hyper
focal distance is proportional to the cropped image size.

In neither case it is constant - as Tony claimed.


/Roland