A Photography forum. PhotoBanter.com

If this is your first visit, be sure to check out the FAQ by clicking the link above. You may have to register before you can post: click the register link above to proceed. To start viewing messages, select the forum that you want to visit from the selection below.

Go Back   Home » PhotoBanter.com forum » Digital Photography » Digital Photography
Site Map Home Register Authors List Search Today's Posts Mark Forums Read Web Partners

hyperfocal distance



 
 
Thread Tools Display Modes
  #1  
Old June 30th 04, 04:01 PM
leo
external usenet poster
 
Posts: n/a
Default hyperfocal distance

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


  #2  
Old June 30th 04, 06:26 PM
Tony Spadaro
external usenet poster
 
Posts: n/a
Default hyperfocal distance

No. It remains the same.

--
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
"leo" wrote in message
k.net...
When using the concept of hyperfocal distance, do we need to adjust for

the
smaller sensor on 300D?




  #3  
Old June 30th 04, 07:42 PM
Paul Cassel
external usenet poster
 
Posts: n/a
Default hyperfocal distance

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.


  #4  
Old June 30th 04, 08:08 PM
external usenet poster
 
Posts: n/a
Default hyperfocal distance

"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.
  #5  
Old June 30th 04, 08:20 PM
M Barnes
external usenet poster
 
Posts: n/a
Default hyperfocal distance

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?


  #6  
Old June 30th 04, 10:33 PM
leo
external usenet poster
 
Posts: n/a
Default hyperfocal distance

"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.


  #7  
Old June 30th 04, 11:27 PM
Roland Karlsson
external usenet poster
 
Posts: n/a
Default hyperfocal distance

"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
  #8  
Old June 30th 04, 11:40 PM
M Barnes
external usenet poster
 
Posts: n/a
Default hyperfocal distance

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.


  #9  
Old June 30th 04, 11:52 PM
David J. Littleboy
external usenet poster
 
Posts: n/a
Default hyperfocal distance


"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



  #10  
Old July 1st 04, 12:10 AM
M Barnes
external usenet poster
 
Posts: n/a
Default hyperfocal distance

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.


 




Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is Off
HTML code is Off
Forum Jump


All times are GMT +1. The time now is 12:41 AM.


Powered by vBulletin® Version 3.6.4
Copyright ©2000 - 2022, Jelsoft Enterprises Ltd.
Copyright 2004-2022 PhotoBanter.com.
The comments are property of their posters.