Infinite Focus

[Manichelo]

Maybe this is a dumb question, but I can't find any thread discussing it...
I'm also a total newbie, so be please be kind!

I have read at many place the term "Infinite focus", wich I assume is just what it say, everything near or far is in focus, with no DOF effect. So, I was wondering HOW can I set the G2 lens to infinite focus?!? I think that in some situation, it could be great to set it to "infinit focus" instead of waiting for the camera to focus. I mean, it's better then missing the shot completely... Does someone has an answer to this? There is so many clever people here, surely someone knows this better then me

have a good day everybody!

My second month learning to learn photography...
http://www.pbase.com/manichelo/home

 

[Larrym53678]

I have read at many place the term "Infinite focus", wich I assume
is just what it say, everything near or far is in focus, with no
DOF effect.

I think your assumption is incorrect. And I'll take a whack at this, although I imagine some of the more learned posters will have a better explanation.

Infinite focus is a distance term. A lens can be focused at 10 feet, 100 feet but up to a certain point the numbers are irrelevant. Anything past x feet will be in focus.

The only way you will not have a DOF effect is if your aperture setting gives you a great deal of DOF. For example, if you set your lens at infinite focus and an aperture of f2 and try take a picture of a rose five feet away, I don't think the rose will be in critical focus.

That sounds a little jumbled. So hopefully someone else wil chime in and make everything perfectly clear. ; )

Larrym

 

[Manichelo]

Not your fault, but now I'm all confuse! snif snif...

I tough that DOF was closely related to the aperture setting, well, I've read on luminous-landscape an essay about COF... O well, maybe I should have studied a bit more during my physic course on light and lens hehe

So infinit focus is wich kind of setting on the lens? Does it have any relation with the aperture at all? Is there any essays out there discussing this?

BTW, tks for replying, it's very nice to help a total newbie

 

[Larrym53678]

Not your fault, but now I'm all confuse! snif snif...

join the club ; )

I tough that DOF was closely related to the aperture setting, well,

that's right. a setting of f/16 gives you more depth of field than a setting of f2

So infinit focus is wich kind of setting on the lens? Does it have
any relation with the aperture at all?

It's the setting that measures distance.

Is there any essays out

there discussing this?

I'm sure there is somewhere. Or you could pick up a good basic photography book.

BTW, tks for replying, it's very nice to help a total newbie

Thanks for calling it help! I'm having difficultly explaining it. And no problem.

I understood you to say that by setting the lens to infinite focus you would have "infinite" depth of field as well. If that is indeed what you're thinking, I doubt if it's true in all cases. With the lens set at infinite focus and f2, this probably wouldn't be true. It might not even be true at f16, but you would have more things in focus than at f2.

Man, I'm giving myself a headache with all this. Hopefully someone else can clear this up a bit.

Larrym

 

[Brian D. Schneider]

Not your fault, but now I'm all confuse! snif snif...

join the club ; )

I tough that DOF was closely related to the aperture setting, well,

that's right. a setting of f/16 gives you more depth of field than
a setting of f2

So infinit focus is wich kind of setting on the lens? Does it have
any relation with the aperture at all?

It's the setting that measures distance.

Is there any essays out

there discussing this?

I'm sure there is somewhere. Or you could pick up a good basic
photography book.

BTW, tks for replying, it's very nice to help a total newbie

Thanks for calling it help! I'm having difficultly explaining it.
And no problem.

I understood you to say that by setting the lens to infinite focus
you would have "infinite" depth of field as well. If that is indeed
what you're thinking, I doubt if it's true in all cases. With the
lens set at infinite focus and f2, this probably wouldn't be true.
It might not even be true at f16, but you would have more things in
focus than at f2.

Man, I'm giving myself a headache with all this. Hopefully someone
else can clear this up a bit.

Larrym

The term you are looking for is "hyperfocal distance" An example, (not nececeraly your camere) would be - focus 10 feet, f8 , in focus from 3 feet to infinity. Different lens diff f-stop diff distance will give different results.

A tele lens will have less depth than a wide. A smaller f-stop (larger #) will give more depth than a large stop (small #)

 

[Jeff Brunt]

Hi all,

First I would like to appologize if I get this wrong, I don't have the manual with me.

I believe what you are looking for is the "pan focus mode"? I think it's the icon of the person in front of the mountains. This mode basically disables your zoom (forced to 34mm) sets the aperture to something like f/5.6 and the focus locked at somewhere around 12ft.

The effect of all of these settings, is a large DOF. The manual claims everything from 4 feet? to infinity will be in focus. Again, I could have the numbers wrong but it is all in the manual.

As for the threads you probably see here on infinity focus is discussing when the focus messes up and focuses to infinity and not on the subject you want. Unless you have the camera set to f/8, it comes out very fuzzy. Personally I have only noticed this happen once so I don't see it beging a real problem as I have taken about 1000 pics.

I hope this long winded explanation helps

Jeff

Not your fault, but now I'm all confuse! snif snif...

join the club ; )

I tough that DOF was closely related to the aperture setting, well,

that's right. a setting of f/16 gives you more depth of field than
a setting of f2

So infinit focus is wich kind of setting on the lens? Does it have
any relation with the aperture at all?

It's the setting that measures distance.

Is there any essays out

there discussing this?

I'm sure there is somewhere. Or you could pick up a good basic
photography book.

BTW, tks for replying, it's very nice to help a total newbie

Thanks for calling it help! I'm having difficultly explaining it.
And no problem.

I understood you to say that by setting the lens to infinite focus
you would have "infinite" depth of field as well. If that is indeed
what you're thinking, I doubt if it's true in all cases. With the
lens set at infinite focus and f2, this probably wouldn't be true.
It might not even be true at f16, but you would have more things in
focus than at f2.

Man, I'm giving myself a headache with all this. Hopefully someone
else can clear this up a bit.

Larrym

The term you are looking for is "hyperfocal distance" An example, (not nececeraly your camere) would be - focus 10 feet, f8 , in focus from 3 feet to infinity. Different lens diff f-stop diff distance will give different results.

A tele lens will have less depth than a wide. A smaller f-stop
(larger #) will give more depth than a large stop (small #)

--Jeff

 

[Manichelo]

Tks a lot, I will do some test with this. If it turns out to do this (everything in focus from x feet to infinity), it could be very valuable to use in some condition... And if it is so, it sould also be reproduce in manual mode

Well, I have so much left to learn that I wonder when I'll actually get out to shoot lol, probably next summer, when temperature will get a bit better!

(it begins to be really cold here in montreal, don't want to get my G2 outside hehe)

 

[jr]

Focusing to infinity with G2 is focusing to 62 meters (which
is close enough ...).
You can use pan focus, but that disables tele, if I remember correctly.
Other option is to use manual focus. Just press the manual focus button
long enough so It'll focus to above mentioned 62 meters.
You can use tele as well.
I often use manual focus to infinity when I'm shooting in the night,
usually combined with Tv or manual mode.

Jouko--Jouko

 

[Manichelo]

AAaaaaaa, you are my man! So, actually, focus to infity, is really focussing to the maximum point wich the camera can focus. Tks again, using it in manual mode will also be very interessting. I'll use it when the focus lag will be to long to be usable, and then, with the help of photoshop, i'll be able to blur the background as needed...

Thanks again to all of you,
Ciao!
Daniel

 

[mikecol]

You can set the focus the max (with manual focus) if you want; but you may want to use a hyperfocal technique to maximize the depth of field as the pan mode does. See http://www.cliffshade.com/dpfwiw/exposure.htm for description of hyperfocal. The pan mode is nice but you may want to use more zoom or other Aperture settings (for limited lighting).

My experience in setting the hyperfocal point on the G2 is:

zoom setting Aper Focus Dist DOF Range

for pan mode - (fixed at Wide) f5.6 4.6' 2.2' -> infinity

Manual Wide f8 6' 3' -> infinity

Manual Wide f2 24' 12' -> infinity

Manual Max Tele f8 54' 27' -> infinity
Manual Max Tele f2 ? ?

Try it out and let me know of corrections to above.

Mike

AAaaaaaa, you are my man! So, actually, focus to infity, is really
focussing to the maximum point wich the camera can focus. Tks
again, using it in manual mode will also be very interessting. I'll
use it when the focus lag will be to long to be usable, and then,
with the help of photoshop, i'll be able to blur the background as
needed...

Thanks again to all of you,
Ciao!
Daniel

 

[mikecol]

Sorry my columns didn't post clearly. The columns are mode, zoom setting, aperture, focus distance, range of acceptable focus.

Mike

My experience in setting the hyperfocal point on the G2 is:

zoom setting Aper Focus Dist DOF Range
for pan mode - (fixed at Wide) f5.6 4.6'
2.2' -> infinity
Manual Wide f8 6'
3' -> infinity
Manual Wide f2 24'
12' -> infinity
Manual Max Tele f8 54'
27' -> infinity
Manual Max Tele f2 ?
?

Try it out and let me know of corrections to above.

Mike

AAaaaaaa, you are my man! So, actually, focus to infity, is really
focussing to the maximum point wich the camera can focus. Tks
again, using it in manual mode will also be very interessting. I'll
use it when the focus lag will be to long to be usable, and then,
with the help of photoshop, i'll be able to blur the background as
needed...

Thanks again to all of you,
Ciao!
Daniel

 

[jhaze]

I don't agree with your calculations for hyperfocal distance, but it is based on perception so you used a different COC (circle of confusion...yes, don't worry about what that means...) value. I used a COC=0.005150...after doing research on the size of the CCD and checking with 3 or four sites dealing with COC on digital cameras.

Now, without explaining all the big words, here's what you do. Decide what aperture you are using or the aperture the camera has selected. It will be between f2 and f8. Also, either set the zoom at full wide or full tele to make things simple. If you push the zoom lever forward you will get full wide at 7mm. Now, MANUALLY set the focus using the scale on the screen as a guide. Set the focus to the following, IF at full wide zoom:

If aperture is at f8 set focus to 3.9 feet; if f5.6 set to 5.6 feet; if f4 set to7.8 feet; if f2.8 set to 11.1 feet; if f2 set to 15.6 feet. You will only get it approximately to the focus point since the manual focusing is a little poor on these cameras, but don't worry. Keep your focus locked onto this value. Time to do some simple math next...

Now remember the distance you focused to? Divide it in half in your HEAD, DON"T reset the focus on G2. If your aperture is f8, divide 3.9 feet by 2= 1.95 feet. Everything from 1.95 feet to the horizon should be in focus. If your aperture is f2, focus to 15.6, and everything from 8.8 feet to infinity will be in focus. Aperture makes a BIG difference huh? So does what zoom length your at, f8 and full wide giving you the most in focus.

These distance values (3.9, 5.6,7.8, 11.1. 15.6) are called hyperfocal distances...they give maximum amount of picture in focus (Depth of field).

BTW here are the numbers for 21mm zoom or full telephoto: if f8 focus to 35.1 ft; if f5.6 focus to 50.1 feet, if f4 focus to 70.2 feet; if f2.8 focus to 100.3

....yes I know you can't focus using the scale on the G2 to any of these values, even 35.1 feet is a large number- you see the DOF is much more shallow and farther away at telephoto...even at f8 only from 17 feet to infinity will be in focus. But anyway these are my calculations for the 21mm tele position for what it's worth.
Jim H.

Mike

You can set the focus the max (with manual focus) if you want; but
you may want to use a hyperfocal technique to maximize the depth of
field as the pan mode does. See
http://www.cliffshade.com/dpfwiw/exposure.htm for description of
hyperfocal. The pan mode is nice but you may want to use more zoom
or other Aperture settings (for limited lighting).

My experience in setting the hyperfocal point on the G2 is:

zoom setting Aper Focus Dist DOF Range
for pan mode - (fixed at Wide) f5.6 4.6'
2.2' -> infinity
Manual Wide f8 6'
3' -> infinity
Manual Wide f2 24'
12' -> infinity
Manual Max Tele f8 54'
27' -> infinity
Manual Max Tele f2 ?
?

Try it out and let me know of corrections to above.

Mike

 

[mikecol]

Jim,

Thanks for the reply. I think the only difference is that I was using a COC=.003345.

I think your number is much better after taking another look based on the EXIF data and G2 specs for the PAN mode. If using the EXIF data of Focus Dist=1.39m at f5.6 and fixed wide angle the COC=.006295. The 1.39m (4.6') is just over double the range of 25.6in. (2.2')-> infinity as listed in the G2 manual for Pan Focus so it works out very close (2.2' * 2 focus Dist is COC=.006524).

So it looks like something between your .005150 and .65 is right.

Thanks for your nice description of how to use this in practice.

Mike

Now, without explaining all the big words, here's what you do.
Decide what aperture you are using or the aperture the camera has
selected. It will be between f2 and f8. Also, either set the zoom
at full wide or full tele to make things simple. If you push the
zoom lever forward you will get full wide at 7mm. Now, MANUALLY
set the focus using the scale on the screen as a guide. Set the
focus to the following, IF at full wide zoom:

If aperture is at f8 set focus to 3.9 feet; if f5.6 set to 5.6
feet; if f4 set to7.8 feet; if f2.8 set to 11.1 feet; if f2 set to
15.6 feet. You will only get it approximately to the focus point
since the manual focusing is a little poor on these cameras, but
don't worry. Keep your focus locked onto this value. Time to do
some simple math next...

Now remember the distance you focused to? Divide it in half in your
HEAD, DON"T reset the focus on G2. If your aperture is f8, divide
3.9 feet by 2= 1.95 feet. Everything from 1.95 feet to the horizon
should be in focus. If your aperture is f2, focus to 15.6, and
everything from 8.8 feet to infinity will be in focus. Aperture
makes a BIG difference huh? So does what zoom length your at, f8
and full wide giving you the most in focus.

These distance values (3.9, 5.6,7.8, 11.1. 15.6) are called
hyperfocal distances...they give maximum amount of picture in focus
(Depth of field).

BTW here are the numbers for 21mm zoom or full telephoto: if f8
focus to 35.1 ft; if f5.6 focus to 50.1 feet, if f4 focus to 70.2
feet; if f2.8 focus to 100.3
....yes I know you can't focus using the scale on the G2 to any of
these values, even 35.1 feet is a large number- you see the DOF is
much more shallow and farther away at telephoto...even at f8 only
from 17 feet to infinity will be in focus. But anyway these are my
calculations for the 21mm tele position for what it's worth.
Jim H.

Mike

You can set the focus the max (with manual focus) if you want; but
you may want to use a hyperfocal technique to maximize the depth of
field as the pan mode does. See
http://www.cliffshade.com/dpfwiw/exposure.htm for description of
hyperfocal. The pan mode is nice but you may want to use more zoom
or other Aperture settings (for limited lighting).

My experience in setting the hyperfocal point on the G2 is:

zoom setting Aper Focus Dist DOF Range
for pan mode - (fixed at Wide) f5.6 4.6'
2.2' -> infinity
Manual Wide f8 6'
3' -> infinity
Manual Wide f2 24'
12' -> infinity
Manual Max Tele f8 54'
27' -> infinity
Manual Max Tele f2 ?
?

Try it out and let me know of corrections to above.

Mike

 

[mikecol]

Correction on:
So it looks like something between your COC=.005150 and .0065 is right.

I think your number is much better after taking another look based
on the EXIF data and G2 specs for the PAN mode. If using the EXIF
data of Focus Dist=1.39m at f5.6 and fixed wide angle the
COC=.006295. The 1.39m (4.6') is just over double the range of
25.6in. (2.2')-> infinity as listed in the G2 manual for Pan Focus
so it works out very close (2.2' * 2 focus Dist is COC=.006524).

So it looks like something between your .005150 and .65 is right.

Thanks for your nice description of how to use this in practice.

Mike

Now, without explaining all the big words, here's what you do.
Decide what aperture you are using or the aperture the camera has
selected. It will be between f2 and f8. Also, either set the zoom
at full wide or full tele to make things simple. If you push the
zoom lever forward you will get full wide at 7mm. Now, MANUALLY
set the focus using the scale on the screen as a guide. Set the
focus to the following, IF at full wide zoom:

If aperture is at f8 set focus to 3.9 feet; if f5.6 set to 5.6
feet; if f4 set to7.8 feet; if f2.8 set to 11.1 feet; if f2 set to
15.6 feet. You will only get it approximately to the focus point
since the manual focusing is a little poor on these cameras, but
don't worry. Keep your focus locked onto this value. Time to do
some simple math next...

Now remember the distance you focused to? Divide it in half in your
HEAD, DON"T reset the focus on G2. If your aperture is f8, divide
3.9 feet by 2= 1.95 feet. Everything from 1.95 feet to the horizon
should be in focus. If your aperture is f2, focus to 15.6, and
everything from 8.8 feet to infinity will be in focus. Aperture
makes a BIG difference huh? So does what zoom length your at, f8
and full wide giving you the most in focus.

These distance values (3.9, 5.6,7.8, 11.1. 15.6) are called
hyperfocal distances...they give maximum amount of picture in focus
(Depth of field).

BTW here are the numbers for 21mm zoom or full telephoto: if f8
focus to 35.1 ft; if f5.6 focus to 50.1 feet, if f4 focus to 70.2
feet; if f2.8 focus to 100.3
....yes I know you can't focus using the scale on the G2 to any of
these values, even 35.1 feet is a large number- you see the DOF is
much more shallow and farther away at telephoto...even at f8 only
from 17 feet to infinity will be in focus. But anyway these are my
calculations for the 21mm tele position for what it's worth.
Jim H.

Mike

You can set the focus the max (with manual focus) if you want; but
you may want to use a hyperfocal technique to maximize the depth of
field as the pan mode does. See
http://www.cliffshade.com/dpfwiw/exposure.htm for description of
hyperfocal. The pan mode is nice but you may want to use more zoom
or other Aperture settings (for limited lighting).

My experience in setting the hyperfocal point on the G2 is:

zoom setting Aper Focus Dist DOF Range
for pan mode - (fixed at Wide) f5.6 4.6'
2.2' -> infinity
Manual Wide f8 6'
3' -> infinity
Manual Wide f2 24'
12' -> infinity
Manual Max Tele f8 54'
27' -> infinity
Manual Max Tele f2 ?
?

Try it out and let me know of corrections to above.

Mike

 

[jhaze]

Mike,

It's really wild, but I initally considered using 0.003345 as well through initial math. Also, working backwards from as much info as I could get from the specs in pan-focus mode, it suggested a COC=0.0065 so I think we indepently arrived at those two extreme limits.

COC is so much based on "eyeball" judgement, it really is a fudge factor, but we have to start somewhere. Canon was absolutely no help to me- a simple hyperfocal distance table in the manual would have been easy, inexpensive, and very usefull.

As it's all relative, I more or less drew the line in the sand at 0.005150...that would be being more conservative than 0.0065. From the site or three I went to it just didn't seem that I could justify using a number lower than 0.005150

I agree, I think we are very close if not right on with a COC between 0.005150 to 0.0065.

I wanted to make the explanation as simple step by step as possible, so I hope I didn't offend anyone that already knows how to use hyperfocal distance.
Jim H.

Jim,
Thanks for the reply. I think the only difference is that I was
using a COC=.003345.

I think your number is much better after taking another look based
on the EXIF data and G2 specs for the PAN mode. If using the EXIF
data of Focus Dist=1.39m at f5.6 and fixed wide angle the
COC=.006295. The 1.39m (4.6') is just over double the range of
25.6in. (2.2')-> infinity as listed in the G2 manual for Pan Focus
so it works out very close (2.2' * 2 focus Dist is COC=.006524).

Mike

 

[Rado]

Here is a nice DOF/hyperfocal calculator for G1 (should work for any camera by setting the appropriate COC/focal length):

http://www.students.tut.fi/~vahonen/computer/digiphoto/DOF/

Regards,

Rado

 

[Manichelo]

Wow, I am really amazed! I bought two photography books a few weeks ago, while they are really great (they explain thing such as good composition, colors, many many things), they're ain't many "maths" in those. I was wondering if there was any books discussing the physics involved in camera? Like COC associated with DOF etc etc, all this information's probably on the web, but it's not very easy to locate it. anyway, any good book on whats going on inside a camera? Math speaking?

Thanks to everyone, I'll have a lot of test to do tonight!
http://www.pbase.com/manichelo/home

 

[jhaze]

Wow, I am really amazed! I bought two photography books a few weeks
ago, while they are really great (they explain thing such as good
composition, colors, many many things), they're ain't many "maths"
in those. I was wondering if there was any books discussing the
physics involved in camera? Like COC associated with DOF etc etc,
all this information's probably on the web, but it's not very easy
to locate it. anyway, any good book on whats going on inside a
camera? Math speaking?

Thanks to everyone, I'll have a lot of test to do tonight!
http://www.pbase.com/manichelo/home

Well the Rado quoted site in this thread I was aware of, and is informative and explains a lot, but I don't agree with the numbers used for the calculations on this site. I also liked this site as being closer to getting it (you need internet explorer 5.0 to run the calculor, netscape won't do it):

http://clientes.netvisao.pt/mapril/dof.htm

and this site is so far the most flexible DOF calculator I've seen in my searches and explains a bit about DOF as well:

http://www.dudak.baka.com/dofcalc.html

Although this last doesn't discuss digital cameras which have much smaller COC values. Still the calculator works for the COC values discussed in this thread. Those three sites will tell you a lot.

There are probably many up-to-date books on photography. I haven't been looking lately. I do think that if you want to learn photography, at some point you have to put everything on manual and slow down the process. Of course it's more frustrating, and you won't get every fast moving shot. Oh well, just my personal prejudice..

My favorite books for learning about photography are the Ansel Adams series of three books: "The Camera", "The Negative", and "The Print". They focus mainly on b&w photography. "The Camera" will tell you a lot about cameras in general though, color or b&w. I have the first editions, all hardcover from 1980, just before he died. I think they are now softcover. I read these three books when I was learning photography.

Some years later, I discovered another series of books by Henry Horenstein ..." Black and White Photography: A Basic Manual" and "Beyond Basic Photography:A Technical Manual"...but it concentrates on b&w and lumps film development and printing together.

These books will be expensive, and out of date since both were written 20 years ago. By that I mean that no digital camera or Epson inkjet stuff is even known about. In at least "The Camera" you'll learn a lot- and then apply it to the G2...you will know about aperture, DOF, flash, tripods, etc, etc.

There is another book that is more detailed than Adams book. It devotes many pages and a diagram or three to Circle of Confusion and how it relates to focusing and aperture/ DOF(page 75-88). But I think it is out of print. Maybe Amazon has used copies or maybe it has been reprinted/updateded(?). It is called "Basic Photography" by M.J. Langford 1973 Focal Press Limited (third edition, it was first published in 1965!) ISBN 0-8174-0640-9 If you want incredible detail about lenses and light, this is it. You want Physics, you got it here in spades!

Anyway, hope all that helped some.
Jim H.

 

[Manichelo]

Wow, for sure this will help a lot! I'll go visit my local bookstore right today!

I am the kind of guy who needs to know how things work inside to be able to make good use of it, and all those technical details involve into photography are no exception! I always shoot with my G2 in Av/Tv or Manual mode, and I get pleasant result very often (well, to my eyes). But I don't feel like I'm "in control" yet, as I don't understand how all those things works in a purely theorycal point of view. I hoper i'll find what I need into those books, thanks again for pointing them out to me. I'll also take a deap look into the web sites you submitted.

Thanks again, Have a nice day!
http://www.pbase.com/manichelo/home