G1 Focus Hocus Part 2: Conclusion

Peter T said:

I agree with your conclusions. But I'm puzzled as to why you feel
it's important for the test object to be raised above the sheet.

Click to expand...

Doug Mick said:

Do you have any theories why the #sign came out focused in Picture
8? I don't buy the theory that "the focusing is based on a central
area" but if it can't focus within that area, it "goes looking
outside that central area".

Click to expand...

Michael W. said:

First off, I don't mean to be redundant in creating this new
thread; I just though this info is so helpful to G1 users that it
shouldn't get lost in the long, long original thread.

From part 1, looks like there is no dispute that position matters,
as illustrated by the original 5 pictures of the cake I posted.

Then the debate is whether the entire frame or just the center is
used by the camera for focusing. To clear this unsettling question
I added 3 more shots to the test, please take a look.

http://www.ofoto.com/I.jsp?m=25101888103&n=569919155

Picture 8 (# sign on paper) clearly indicates that the G1 will
evaluate the entire frame and will focus on the corner if
sufficient contrast cannot be found elsewhere. Any disgreement?

Picture 6, the cake is VERY near edge causing my G1 to shift focus
to the wall. Like Bob W. noticed, the G1 actualy focuses on the
wall texture and not just arbitrarily throws long -- it's darn
sensitive!

Picture 7, the cake is also near edge but closer to center than in
pic 6, and now my G1 shifts focus back on the cake.

Evidently both the cake and the wall texture provide adequate
contrast. The cake has more contrast but is at edge, the wall
texture has less contrast but covers the center. Combining this
information with what we saw in the original 5 pictures, it is so
clear to me that the G1 indeed scans the entire frame, but it also
gives more weight to subjects which are closer to the center and/or
more contrasty. This behavior can be quite properly called
"Center-Weighed" focusing after all. The Canon Rep who talked to
Don T is correct (my personal conclusion); whether he realy knows
or just got lucky is irrelevant.

If I design an autofocus system, I probably would do the same
thing. In otherwords, the autofocus scheme is very good in my
opinion -- if you know how it works. The main problem is that Canon
does not provide adequate documentation, leading to the massive
confusion when your G1 fails to focus on the object you want it to.

One thing bothers me though: there is no spot focus in M mode!

--
Michael

Click to expand...

Ted B. said:

Spot metering in M mode would be pointless. You have taken over
the 'metering' functions and are setting shutter speed and
aperature yourslef. Metering is used to set one or both of these
automatically, so it would be a waste of time. My guess is NO
metering takes place in M mode, spot or center weighted. What
would be the purpose?

Click to expand...

Peter T said:

Michael W. said:

Picture 8 (# sign on paper) clearly indicates that the G1 will
evaluate the entire frame and will focus on the corner if
sufficient contrast cannot be found elsewhere. Any disgreement?

Click to expand...

I disagree.

You can easily do a test to see where the camera looks for
contrast. Take a sheet of blank white paper. Cut out a 1/2" square
from one of the corners. Mark a bold X on the square and then lay
it in the middle of the sheet of paper.

Put the camera in macro mode and zoom in on the X until you can see
it clearly and the entire image consists of only the sheet of
paper. Turn on spot metering to easily determine the center of the
image and center the X there.

You don't have to take any pictures. Gradually move the X in one
direction and see if you can focus on it using the LCD. It helps to
use a tripod if you have one. Do this several times starting with
the X in the center of the image and moving it in different
directions and you will see where the camera is looking for focus.

Peter T44178 said:

One thing bothers me though: there is no spot focus in M mode!

Click to expand...

There is no spot focus in any mode. Using the above test, nudge
your target until it is just out of focus in spot metering mode.
Then turn off spot metering and autofocus. It will still be out of
focus. This must be done with a tripod to make sure the camera
doesn't move.

Click to expand...

Peter T44178 said:

Peter T wrote:
Metering is NOT used to set shutter speed and aperture
automatically. It is used to determine exposure.

Click to expand...

Peter T said:

Ted B. said:

Spot metering in M mode would be pointless. You have taken over
the 'metering' functions and are setting shutter speed and
aperature yourslef. Metering is used to set one or both of these
automatically, so it would be a waste of time. My guess is NO
metering takes place in M mode, spot or center weighted. What
would be the purpose?

Click to expand...

Metering is NOT used to set shutter speed and aperture
automatically. It is used to determine exposure. Any camera I've
ever seen with spot metering has it available in manual mode. It
doesn't set the exposure. It uses a scale like in exposure
compensation to let you know how close the settings are from a
correct exposure.

Click to expand...

Peter T said:

Ted B. said:

Spot metering in M mode would be pointless. You have taken over
the 'metering' functions and are setting shutter speed and
aperature yourslef. Metering is used to set one or both of these
automatically, so it would be a waste of time. My guess is NO
metering takes place in M mode, spot or center weighted. What
would be the purpose?

Click to expand...

Metering is NOT used to set shutter speed and aperture
automatically. It is used to determine exposure. Any camera I've
ever seen with spot metering has it available in manual mode. It
doesn't set the exposure. It uses a scale like in exposure
compensation to let you know how close the settings are from a
correct exposure.

Click to expand...

Michael W. said:

First off, I don't mean to be redundant in creating this new
thread; I just though this info is so helpful to G1 users that it
shouldn't get lost in the long, long original thread.

From part 1, looks like there is no dispute that position matters,
as illustrated by the original 5 pictures of the cake I posted.

Then the debate is whether the entire frame or just the center is
used by the camera for focusing. To clear this unsettling question
I added 3 more shots to the test, please take a look.

http://www.ofoto.com/I.jsp?m=25101888103&n=569919155

Picture 8 (# sign on paper) clearly indicates that the G1 will
evaluate the entire frame and will focus on the corner if
sufficient contrast cannot be found elsewhere. Any disgreement?

Picture 6, the cake is VERY near edge causing my G1 to shift focus
to the wall. Like Bob W. noticed, the G1 actualy focuses on the
wall texture and not just arbitrarily throws long -- it's darn
sensitive!

Picture 7, the cake is also near edge but closer to center than in
pic 6, and now my G1 shifts focus back on the cake.

Evidently both the cake and the wall texture provide adequate
contrast. The cake has more contrast but is at edge, the wall
texture has less contrast but covers the center. Combining this
information with what we saw in the original 5 pictures, it is so
clear to me that the G1 indeed scans the entire frame, but it also
gives more weight to subjects which are closer to the center and/or
more contrasty. This behavior can be quite properly called
"Center-Weighed" focusing after all. The Canon Rep who talked to
Don T is correct (my personal conclusion); whether he realy knows
or just got lucky is irrelevant.

If I design an autofocus system, I probably would do the same
thing. In otherwords, the autofocus scheme is very good in my
opinion -- if you know how it works. The main problem is that Canon
does not provide adequate documentation, leading to the massive
confusion when your G1 fails to focus on the object you want it to.

One thing bothers me though: there is no spot focus in M mode!

--
Michael

Click to expand...

Steve D said:

But since there are so many people having trouble focusing,
parircularly with macros (thank god they are not my major area of
interest).. there simply must be an easier way to set focus
properly than many have discovered... or Canon would never have
sold so many G1. I think I'm lucky because i just havent had that
many way out of focus... but I'm not overly picky either. her's a
shot of some butterflies. Is this in our out of focus to most of
you? I'm curious.



steve D

Michael W. said:

First off, I don't mean to be redundant in creating this new
thread; I just though this info is so helpful to G1 users that it
shouldn't get lost in the long, long original thread.

From part 1, looks like there is no dispute that position matters,
as illustrated by the original 5 pictures of the cake I posted.

Then the debate is whether the entire frame or just the center is
used by the camera for focusing. To clear this unsettling question
I added 3 more shots to the test, please take a look.

http://www.ofoto.com/I.jsp?m=25101888103&n=569919155

Picture 8 (# sign on paper) clearly indicates that the G1 will
evaluate the entire frame and will focus on the corner if
sufficient contrast cannot be found elsewhere. Any disgreement?

Picture 6, the cake is VERY near edge causing my G1 to shift focus
to the wall. Like Bob W. noticed, the G1 actualy focuses on the
wall texture and not just arbitrarily throws long -- it's darn
sensitive!

Picture 7, the cake is also near edge but closer to center than in
pic 6, and now my G1 shifts focus back on the cake.

Evidently both the cake and the wall texture provide adequate
contrast. The cake has more contrast but is at edge, the wall
texture has less contrast but covers the center. Combining this
information with what we saw in the original 5 pictures, it is so
clear to me that the G1 indeed scans the entire frame, but it also
gives more weight to subjects which are closer to the center and/or
more contrasty. This behavior can be quite properly called
"Center-Weighed" focusing after all. The Canon Rep who talked to
Don T is correct (my personal conclusion); whether he realy knows
or just got lucky is irrelevant.

If I design an autofocus system, I probably would do the same
thing. In otherwords, the autofocus scheme is very good in my
opinion -- if you know how it works. The main problem is that Canon
does not provide adequate documentation, leading to the massive
confusion when your G1 fails to focus on the object you want it to.

One thing bothers me though: there is no spot focus in M mode!

--
Michael

Click to expand...

Click to expand...

Steve D said:

But since there are so many people having trouble focusing,
parircularly with macros (thank god they are not my major area of
interest).. there simply must be an easier way to set focus
properly than many have discovered... or Canon would never have
sold so many G1. I think I'm lucky because i just havent had that
many way out of focus... but I'm not overly picky either. her's a
shot of some butterflies. Is this in our out of focus to most of
you? I'm curious.



steve D

Michael W. said:

First off, I don't mean to be redundant in creating this new
thread; I just though this info is so helpful to G1 users that it
shouldn't get lost in the long, long original thread.

From part 1, looks like there is no dispute that position matters,
as illustrated by the original 5 pictures of the cake I posted.

Then the debate is whether the entire frame or just the center is
used by the camera for focusing. To clear this unsettling question
I added 3 more shots to the test, please take a look.

http://www.ofoto.com/I.jsp?m=25101888103&n=569919155

Picture 8 (# sign on paper) clearly indicates that the G1 will
evaluate the entire frame and will focus on the corner if
sufficient contrast cannot be found elsewhere. Any disgreement?

Picture 6, the cake is VERY near edge causing my G1 to shift focus
to the wall. Like Bob W. noticed, the G1 actualy focuses on the
wall texture and not just arbitrarily throws long -- it's darn
sensitive!

Picture 7, the cake is also near edge but closer to center than in
pic 6, and now my G1 shifts focus back on the cake.

Evidently both the cake and the wall texture provide adequate
contrast. The cake has more contrast but is at edge, the wall
texture has less contrast but covers the center. Combining this
information with what we saw in the original 5 pictures, it is so
clear to me that the G1 indeed scans the entire frame, but it also
gives more weight to subjects which are closer to the center and/or
more contrasty. This behavior can be quite properly called
"Center-Weighed" focusing after all. The Canon Rep who talked to
Don T is correct (my personal conclusion); whether he realy knows
or just got lucky is irrelevant.

If I design an autofocus system, I probably would do the same
thing. In otherwords, the autofocus scheme is very good in my
opinion -- if you know how it works. The main problem is that Canon
does not provide adequate documentation, leading to the massive
confusion when your G1 fails to focus on the object you want it to.

One thing bothers me though: there is no spot focus in M mode!

--
Michael

Click to expand...

Click to expand...

nahau said:

In the case of the G1, this works out to be the same thing. Once
metering is completed, the exposure is set, and a simple push of
the shutter will focus and execute the shot at the shutter speed
and apeture determined by the metering. Or, am I misunderstanding
what you are trying to say.

Click to expand...

Ted B. said:

Your method does not prove whether the camera 'intentionally'
focused on the wall, or did so accidentally. According to my
theory, that is where it would focus anyway, on focus lock
failure. My test, using a blank piece of paper with a crosshatch
around the edges of the frame, proves the camera ignored the edges
of the frame, when it failed to focus on the paper. Proves it.
Tell my if you think it does not, and why.

Spot metering in M mode would be pointless. You have taken over
the 'metering' functions and are setting shutter speed and
aperature yourslef. Metering is used to set one or both of these
automatically, so it would be a waste of time. My guess is NO
metering takes place in M mode, spot or center weighted. What
would be the purpose?

Michael W. said:

First off, I don't mean to be redundant in creating this new
thread; I just though this info is so helpful to G1 users that it
shouldn't get lost in the long, long original thread.

From part 1, looks like there is no dispute that position matters,
as illustrated by the original 5 pictures of the cake I posted.

Then the debate is whether the entire frame or just the center is
used by the camera for focusing. To clear this unsettling question
I added 3 more shots to the test, please take a look.

http://www.ofoto.com/I.jsp?m=25101888103&n=569919155

Picture 8 (# sign on paper) clearly indicates that the G1 will
evaluate the entire frame and will focus on the corner if
sufficient contrast cannot be found elsewhere. Any disgreement?

Picture 6, the cake is VERY near edge causing my G1 to shift focus
to the wall. Like Bob W. noticed, the G1 actualy focuses on the
wall texture and not just arbitrarily throws long -- it's darn
sensitive!

Picture 7, the cake is also near edge but closer to center than in
pic 6, and now my G1 shifts focus back on the cake.

Evidently both the cake and the wall texture provide adequate
contrast. The cake has more contrast but is at edge, the wall
texture has less contrast but covers the center. Combining this
information with what we saw in the original 5 pictures, it is so
clear to me that the G1 indeed scans the entire frame, but it also
gives more weight to subjects which are closer to the center and/or
more contrasty. This behavior can be quite properly called
"Center-Weighed" focusing after all. The Canon Rep who talked to
Don T is correct (my personal conclusion); whether he realy knows
or just got lucky is irrelevant.

If I design an autofocus system, I probably would do the same
thing. In otherwords, the autofocus scheme is very good in my
opinion -- if you know how it works. The main problem is that Canon
does not provide adequate documentation, leading to the massive
confusion when your G1 fails to focus on the object you want it to.

One thing bothers me though: there is no spot focus in M mode!

--
Michael

Click to expand...

Click to expand...

Peter T said:

nahau said:

In the case of the G1, this works out to be the same thing. Once
metering is completed, the exposure is set, and a simple push of
the shutter will focus and execute the shot at the shutter speed
and apeture determined by the metering. Or, am I misunderstanding
what you are trying to say.

Click to expand...

All the various modes except manual combine two steps: determining
and setting exposure.

My point is that the G1 is the only camera I know of with manual
mode that doesn't provide metering in that mode.

Click to expand...

Steve D said:

Steve D said:

But since there are so many people having trouble focusing,
parircularly with macros (thank god they are not my major area of
interest).. there simply must be an easier way to set focus
properly than many have discovered... or Canon would never have
sold so many G1. I think I'm lucky because i just havent had that
many way out of focus... but I'm not overly picky either. her's a
shot of some butterflies. Is this in our out of focus to most of
you? I'm curious.



steve D

Michael W. said:

First off, I don't mean to be redundant in creating this new
thread; I just though this info is so helpful to G1 users that it
shouldn't get lost in the long, long original thread.

From part 1, looks like there is no dispute that position matters,
as illustrated by the original 5 pictures of the cake I posted.

Then the debate is whether the entire frame or just the center is
used by the camera for focusing. To clear this unsettling question
I added 3 more shots to the test, please take a look.

http://www.ofoto.com/I.jsp?m=25101888103&n=569919155

Picture 8 (# sign on paper) clearly indicates that the G1 will
evaluate the entire frame and will focus on the corner if
sufficient contrast cannot be found elsewhere. Any disgreement?

Picture 6, the cake is VERY near edge causing my G1 to shift focus
to the wall. Like Bob W. noticed, the G1 actualy focuses on the
wall texture and not just arbitrarily throws long -- it's darn
sensitive!

Picture 7, the cake is also near edge but closer to center than in
pic 6, and now my G1 shifts focus back on the cake.

Evidently both the cake and the wall texture provide adequate
contrast. The cake has more contrast but is at edge, the wall
texture has less contrast but covers the center. Combining this
information with what we saw in the original 5 pictures, it is so
clear to me that the G1 indeed scans the entire frame, but it also
gives more weight to subjects which are closer to the center and/or
more contrasty. This behavior can be quite properly called
"Center-Weighed" focusing after all. The Canon Rep who talked to
Don T is correct (my personal conclusion); whether he realy knows
or just got lucky is irrelevant.

If I design an autofocus system, I probably would do the same
thing. In otherwords, the autofocus scheme is very good in my
opinion -- if you know how it works. The main problem is that Canon
does not provide adequate documentation, leading to the massive
confusion when your G1 fails to focus on the object you want it to.

One thing bothers me though: there is no spot focus in M mode!

--
Michael

Click to expand...

Click to expand...

Click to expand...

Michael W. said:

At full tele the X test shows that my G1 can only focus if some of
the X is within a center area about 1/2 of the screen each way. At
full wide, however, it has no problem focusing near the edge
(confirming my #8 picture). Perhaps Canon engineers anticipated
tele is used more for portrait and wide is used more for landscape,
hence the different behavior. Whatever the reason, this disparity
is a lot easier to live with than that infamous "wide-angle
mistiming".

Click to expand...

Steve D50919 said:

Steve D wrote:
Nahau.. funny line..

Click to expand...

Michael W. said:

Let's take the easy one first... of course there is no purpose for
spot metering in manual mode. I said this because earlier I though
that spot metering also triggers "spot focus" -- but as in my reply
to Peter I now acknowledge that there is no spot focusing in any
mode.

The pictures themselves some times are not conclusive evidence to
focusing, I admit. But gauging the behavior of the camera's
behavior at the time tells me something. When the camera has
problem focusing it'll make two buz sound before beeping, then if
it gets lucky it'll focus on the X and if not lucky it won't.
Peter's X test, full wide, my G1 has no problem locking focus in
one buz; but in telle it always buz twice and then lock (after that
the X may or may not look focused depending on luck).

My G1 had two-buz hesitation while taking any of the 8 pictures I
posted. Picture #8 is the only one in macro. A more elaborate
test as you describe will take the "luck" factor out, but I doubt

Ted B. said:

Your method does not prove whether the camera 'intentionally'
focused on the wall, or did so accidentally. According to my
theory, that is where it would focus anyway, on focus lock
failure. My test, using a blank piece of paper with a crosshatch
around the edges of the frame, proves the camera ignored the edges
of the frame, when it failed to focus on the paper. Proves it.
Tell my if you think it does not, and why.

Spot metering in M mode would be pointless. You have taken over
the 'metering' functions and are setting shutter speed and
aperature yourslef. Metering is used to set one or both of these
automatically, so it would be a waste of time. My guess is NO
metering takes place in M mode, spot or center weighted. What
would be the purpose?

Michael W. said:

First off, I don't mean to be redundant in creating this new
thread; I just though this info is so helpful to G1 users that it
shouldn't get lost in the long, long original thread.

From part 1, looks like there is no dispute that position matters,
as illustrated by the original 5 pictures of the cake I posted.

Then the debate is whether the entire frame or just the center is
used by the camera for focusing. To clear this unsettling question
I added 3 more shots to the test, please take a look.

http://www.ofoto.com/I.jsp?m=25101888103&n=569919155

Picture 8 (# sign on paper) clearly indicates that the G1 will
evaluate the entire frame and will focus on the corner if
sufficient contrast cannot be found elsewhere. Any disgreement?

Picture 6, the cake is VERY near edge causing my G1 to shift focus
to the wall. Like Bob W. noticed, the G1 actualy focuses on the
wall texture and not just arbitrarily throws long -- it's darn
sensitive!

Picture 7, the cake is also near edge but closer to center than in
pic 6, and now my G1 shifts focus back on the cake.

Evidently both the cake and the wall texture provide adequate
contrast. The cake has more contrast but is at edge, the wall
texture has less contrast but covers the center. Combining this
information with what we saw in the original 5 pictures, it is so
clear to me that the G1 indeed scans the entire frame, but it also
gives more weight to subjects which are closer to the center and/or
more contrasty. This behavior can be quite properly called
"Center-Weighed" focusing after all. The Canon Rep who talked to
Don T is correct (my personal conclusion); whether he realy knows
or just got lucky is irrelevant.

If I design an autofocus system, I probably would do the same
thing. In otherwords, the autofocus scheme is very good in my
opinion -- if you know how it works. The main problem is that Canon
does not provide adequate documentation, leading to the massive
confusion when your G1 fails to focus on the object you want it to.

One thing bothers me though: there is no spot focus in M mode!

--
Michael

Click to expand...

Click to expand...

Click to expand...