hyperfocal distance

When using the concept of hyperfocal distance, do we need to adjust for the
smaller sensor on 300D?

No. It remains the same.

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"leo" wrote in message
k.net...
When using the concept of hyperfocal distance, do we need to adjust for
the
smaller sensor on 300D?

leo wrote:
When using the concept of hyperfocal distance, do we need to adjust
for the smaller sensor on 300D?

No, but good you asked before burning all that film experimenting yourself.
I hate all that waste.

"leo" wrote:

When using the concept of hyperfocal distance, do we need to adjust for the
smaller sensor on 300D?

It took me 10 seconds at www.google.com to find this equation for the
hyperfocal distance:

h = (f*f)/(N*c)

f = focal length, N = f-ratio, c = "circle of confusion" diameter.

'c' is going to be proportional to the size of a pixel, not the
sensor.

eawckyegcy wrote:
leo wrote:

When using the concept of hyperfocal distance,
do we need to adjust for the smaller sensor on 300D?

It took me 10 seconds at www.google.com to find this
equation for the hyperfocal distance:

h = (f*f)/(N*c)

f = focal length, N = f-ratio, c = "circle of confusion" diameter.

'c' is going to be proportional to the size of a pixel, not the
sensor.

Well, give yourself a gold star, then. Anyway, isn't the
circle of confusion a characteristic of the lens, not the
sensor? Also, I believe the OP was asking if it's required
to adjust the "f" in your formula due to the _apparent_ focal
length adjustments required by fractional-frame sensor form
factors, n'est-ce pas?

"M Barnes" wrote in message
...
eawckyegcy wrote:
leo wrote:

When using the concept of hyperfocal distance,
do we need to adjust for the smaller sensor on 300D?

It took me 10 seconds at www.google.com to find this
equation for the hyperfocal distance:

h = (f*f)/(N*c)

f = focal length, N = f-ratio, c = "circle of confusion" diameter.

'c' is going to be proportional to the size of a pixel, not the
sensor.

Well, give yourself a gold star, then. Anyway, isn't the
circle of confusion a characteristic of the lens, not the
sensor? Also, I believe the OP was asking if it's required
to adjust the "f" in your formula due to the _apparent_ focal
length adjustments required by fractional-frame sensor form
factors, n'est-ce pas?


The formula I found was based on 35mm and in fact, I simply use the chart. I
don't think the sensor size matters but I think I better inquire. Thanx.

"Tony Spadaro" wrote in news:dJCEc.85007
:

No. It remains the same.

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.

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.


/Roland

Gisle Hannemyr wrote:
M Barnes writes:

Anyway, isn't the circle of confusion a characteristic
of the lens, not the sensor?

No - it is proportional to sensor size.

Hm. Okay, I think I get it. How is the CoC computed
for lenses then? And for film body/lens combinations?

Also, I believe the OP was asking if it's required to adjust the "f"
in your formula due to the _apparent_ focal length adjustments
required by fractional-frame sensor form factors,

I don't think that was what the OP asked - but if it was, then the
answer is "no". "Adjusting" the focal length to 35 mm equivalent
will result in a wrong answer.

But the crop factor enters in to the formula. You need to use the
correct CoC for the 300D. Which - has it happens - shrink
compared to 35 mm full frame with an amount equal to the crop
factor: 0.025/1.6 = 0.016.

Is it "as it happens" or is it "as a function of?"

I'm not trying to be snarky here, honestly. I have a D100
(that I haven't used all that much yet) body to replace my
N2020, and usehyperfocal focusing a lot in landscape shots
to keep the foreground sharp.

I'm used to using the lens set I have in a certain way,
and am wondering if I need to adjust for the D100,
which of course has the "crop factor" you speak of.

"M Barnes" wrote:
Gisle Hannemyr wrote:
M Barnes writes:

Anyway, isn't the circle of confusion a characteristic
of the lens, not the sensor?

No - it is proportional to sensor size.

Hm. Okay, I think I get it. How is the CoC computed
for lenses then? And for film body/lens combinations?

It's computed for a given print size assuming a given viewing distance and a
viewer with typical visual acuity. DOF is a perceptual phenomenon in the
viewer.

Also, I believe the OP was asking if it's required to adjust the "f"
in your formula due to the _apparent_ focal length adjustments
required by fractional-frame sensor form factors,

I don't think that was what the OP asked - but if it was, then the
answer is "no". "Adjusting" the focal length to 35 mm equivalent
will result in a wrong answer.

But the crop factor enters in to the formula. You need to use the
correct CoC for the 300D. Which - has it happens - shrink
compared to 35 mm full frame with an amount equal to the crop
factor: 0.025/1.6 = 0.016.

Is it "as it happens" or is it "as a function of?"

I'm not trying to be snarky here, honestly. I have a D100
(that I haven't used all that much yet) body to replace my
N2020, and usehyperfocal focusing a lot in landscape shots
to keep the foreground sharp.

I'm used to using the lens set I have in a certain way,
and am wondering if I need to adjust for the D100,
which of course has the "crop factor" you speak of.

To make a long story short, you do have to adjust. A 24mm lens will have
less DOF when used as a 36mm lens on a D100 than when used as a 24mm lens on
an F100, but will have more DOF when used as a 36mm lens on a D100 than a
35mm lens on an F100.

The best thing to do is to test. For each focal length, for each f stop,
shoot a series of images of a scene with both near and far detail at various
distance settings on the lens starting at infinity. For each focal length/f
stop combination, record the closest distance that you find the detail at
infinity to remain acceptable.

Since it's digital, all it costs is your time. And even then, not much of
that since you don't have to scan.

David J. Littleboy
Tokyo, Japan

David J. Littleboy wrote:

The best thing to do is to test. For each focal length,
for each f stop, shoot a series of images of a scene
with both near and far detail at various distance settings
on the lens starting at infinity. For each focal length/f
stop combination, record the closest distance that you
find the detail at infinity to remain acceptable.

Since it's digital, all it costs is your time. And even then,
not much of that since you don't have to scan.

Got it. I'll set up a 20-meter tape measure in my back yard
and put up letter-sized paper sheets labeled with the distance
at 1-meter intervals. That should do it. Thanks.