Canon PowerShots not fully manual?

" wrote in message ...
Dogger the Filmgoblin wrote:
wrote in message
...
Dogger the Filmgoblin wrote:
I just discovered that my Canon PowerShot A75 is not *fully*
manual
even when I operate in manual (M) mode.

When pointed at a very bright light source that overwhelms the
frame,
the camera will stop down to f/8.0, even though I am trying to
take
the picture at f/2.8, it won't let me; it insists on trying to
expose
the picture more normally. But that's not what I'm after. I WANT
the
light source to overwhelm the frame (not that it's important, but
I'm
shooting a window and I want the light from it to bloom as much
as
possible for effect). When I put a camera in manual mode, I
really
mean it. I don't want a babysitter.

Just tried this on an A75 here and it works as I would expect. Put
camera on manual mode, set ap to f/2.8, set shutter speed to 5s,
point
at bright sky, resulting picture is overexposed, camera review says
f/2.8 was used.

The shot may not have been bright enough (and there is no need to set
the shutter speed so long, shutter speed has no effect on the
problem,
it will happen even at 1/2000 resulting in severe underexposure) ...
Here's an extreme test to confirm for sure whether you have the
problem. Try pointing the A75 directly at a low-watt lightbulb (not
the sun, some think that can damage your sensor and I can't prove
they're wrong). Zoom all the way out and place the camera close
enough
to make the lightbulb fairly large in the shot. As soon as you press
the shutter, the camera will force your iris to f/8, even in Manual
Mode, even if your shutter speed is as fast as 1/1000 or 1/2000.

I thought that your original point was that the camera will not allow
overexposure of a full bright subject at f2.8, which is why I set the
shutter speed so slow (to ensure overexposure).

You are correct. And that is still my point. However, on a different
forum it was discovered (after my original post here) that this
response from the camera seems keyed to the iris without much regard
to the shutter setting. In fact, it is actually possible on a very
bright day with an extremely high shutter speed for the camera to
shift the f/stop and actually force an underexposure, by several
stops. There is a description of this problem on dpreview.com in the
'Canon Talk' forum (a lot more people piping up about the problem
there than here, and every A75 user has reproduced it but no other
A-series owners). My own original instructions only work if you try to
really blow out all of the detail of a major part of the frame. (And
yes, I was intentionally trying to do this because I wanted that
effect; I wasn't just screwing around.) The other poster was NOT
trying to blow out any of the frame, he was just trying to do very
high speed sports photography on very bright day, and his A75 forced
3-stop underexposures. I have replicated the underexposure on my own
A75 by pointing at a very weak light-bulb (25W but 40 will probably
do) at the highest shutter and f/2.8, taking the shot, and then
looking at the histogram: extremely underexposed, with nothing at all
in the upper half of the scale. Hope this helps you recreate the
problem ... it does take quite an extreme situation to induce but it
is definitely a bug, or at least a very poorly implemented sensor
protection scheme. And if it IS a sensor protection scheme: why only
the A75? I am curious as to whether the A85 will behave the same way.

DB.

" wrote in message ...
Dogger the Filmgoblin wrote:
wrote in message
...
Dogger the Filmgoblin wrote:
I just discovered that my Canon PowerShot A75 is not *fully*
manual
even when I operate in manual (M) mode.

When pointed at a very bright light source that overwhelms the
frame,
the camera will stop down to f/8.0, even though I am trying to
take
the picture at f/2.8, it won't let me; it insists on trying to
expose
the picture more normally. But that's not what I'm after. I WANT
the
light source to overwhelm the frame (not that it's important, but
I'm
shooting a window and I want the light from it to bloom as much
as
possible for effect). When I put a camera in manual mode, I
really
mean it. I don't want a babysitter.

Just tried this on an A75 here and it works as I would expect. Put
camera on manual mode, set ap to f/2.8, set shutter speed to 5s,
point
at bright sky, resulting picture is overexposed, camera review says
f/2.8 was used.

The shot may not have been bright enough (and there is no need to set
the shutter speed so long, shutter speed has no effect on the
problem,
it will happen even at 1/2000 resulting in severe underexposure) ...
Here's an extreme test to confirm for sure whether you have the
problem. Try pointing the A75 directly at a low-watt lightbulb (not
the sun, some think that can damage your sensor and I can't prove
they're wrong). Zoom all the way out and place the camera close
enough
to make the lightbulb fairly large in the shot. As soon as you press
the shutter, the camera will force your iris to f/8, even in Manual
Mode, even if your shutter speed is as fast as 1/1000 or 1/2000.

I thought that your original point was that the camera will not allow
overexposure of a full bright subject at f2.8, which is why I set the
shutter speed so slow (to ensure overexposure).

You are correct. And that is still my point. However, on a different
forum it was discovered (after my original post here) that this
response from the camera seems keyed to the iris without much regard
to the shutter setting. In fact, it is actually possible on a very
bright day with an extremely high shutter speed for the camera to
shift the f/stop and actually force an underexposure, by several
stops. There is a description of this problem on dpreview.com in the
'Canon Talk' forum (a lot more people piping up about the problem
there than here, and every A75 user has reproduced it but no other
A-series owners). My own original instructions only work if you try to
really blow out all of the detail of a major part of the frame. (And
yes, I was intentionally trying to do this because I wanted that
effect; I wasn't just screwing around.) The other poster was NOT
trying to blow out any of the frame, he was just trying to do very
high speed sports photography on very bright day, and his A75 forced
3-stop underexposures. I have replicated the underexposure on my own
A75 by pointing at a very weak light-bulb (25W but 40 will probably
do) at the highest shutter and f/2.8, taking the shot, and then
looking at the histogram: extremely underexposed, with nothing at all
in the upper half of the scale. Hope this helps you recreate the
problem ... it does take quite an extreme situation to induce but it
is definitely a bug, or at least a very poorly implemented sensor
protection scheme. And if it IS a sensor protection scheme: why only
the A75? I am curious as to whether the A85 will behave the same way.

DB.

" wrote in message ...
Dogger the Filmgoblin wrote:
wrote in message
...
Dogger the Filmgoblin wrote:
I just discovered that my Canon PowerShot A75 is not *fully*
manual
even when I operate in manual (M) mode.

When pointed at a very bright light source that overwhelms the
frame,
the camera will stop down to f/8.0, even though I am trying to
take
the picture at f/2.8, it won't let me; it insists on trying to
expose
the picture more normally. But that's not what I'm after. I WANT
the
light source to overwhelm the frame (not that it's important, but
I'm
shooting a window and I want the light from it to bloom as much
as
possible for effect). When I put a camera in manual mode, I
really
mean it. I don't want a babysitter.

Just tried this on an A75 here and it works as I would expect. Put
camera on manual mode, set ap to f/2.8, set shutter speed to 5s,
point
at bright sky, resulting picture is overexposed, camera review says
f/2.8 was used.

The shot may not have been bright enough (and there is no need to set
the shutter speed so long, shutter speed has no effect on the
problem,
it will happen even at 1/2000 resulting in severe underexposure) ...
Here's an extreme test to confirm for sure whether you have the
problem. Try pointing the A75 directly at a low-watt lightbulb (not
the sun, some think that can damage your sensor and I can't prove
they're wrong). Zoom all the way out and place the camera close
enough
to make the lightbulb fairly large in the shot. As soon as you press
the shutter, the camera will force your iris to f/8, even in Manual
Mode, even if your shutter speed is as fast as 1/1000 or 1/2000.

I thought that your original point was that the camera will not allow
overexposure of a full bright subject at f2.8, which is why I set the
shutter speed so slow (to ensure overexposure).

You are correct. And that is still my point. However, on a different
forum it was discovered (after my original post here) that this
response from the camera seems keyed to the iris without much regard
to the shutter setting. In fact, it is actually possible on a very
bright day with an extremely high shutter speed for the camera to
shift the f/stop and actually force an underexposure, by several
stops. There is a description of this problem on dpreview.com in the
'Canon Talk' forum (a lot more people piping up about the problem
there than here, and every A75 user has reproduced it but no other
A-series owners). My own original instructions only work if you try to
really blow out all of the detail of a major part of the frame. (And
yes, I was intentionally trying to do this because I wanted that
effect; I wasn't just screwing around.) The other poster was NOT
trying to blow out any of the frame, he was just trying to do very
high speed sports photography on very bright day, and his A75 forced
3-stop underexposures. I have replicated the underexposure on my own
A75 by pointing at a very weak light-bulb (25W but 40 will probably
do) at the highest shutter and f/2.8, taking the shot, and then
looking at the histogram: extremely underexposed, with nothing at all
in the upper half of the scale. Hope this helps you recreate the
problem ... it does take quite an extreme situation to induce but it
is definitely a bug, or at least a very poorly implemented sensor
protection scheme. And if it IS a sensor protection scheme: why only
the A75? I am curious as to whether the A85 will behave the same way.

DB.

(Dogger the Filmgoblin) writes:

it does take quite an extreme situation to induce but it
is definitely a bug, or at least a very poorly implemented sensor
protection scheme. And if it IS a sensor protection scheme: why only
the A75? I am curious as to whether the A85 will behave the same way.

It certainly sounds like a firmware bug, if all A75s but no other Canon
cameras do it. Have you tried to report it to Canon? Maybe it can be
fixed before the A85 is released.

Dave

(Dave Martindale) wrote in message ...
(Dogger the Filmgoblin) writes:

it does take quite an extreme situation to induce but it
is definitely a bug, or at least a very poorly implemented sensor
protection scheme. And if it IS a sensor protection scheme: why only
the A75? I am curious as to whether the A85 will behave the same way.

It certainly sounds like a firmware bug, if all A75s but no other Canon
cameras do it. Have you tried to report it to Canon? Maybe it can be
fixed before the A85 is released.

Dave

Yes I reported it (and I'm not the first) with links to all the
relevant online discussions of the problem. I got the brush-off with a
standard boilerplate response about how wider f-stops are unavailable
in the telephoto range. Duh. Par for the course, the support rep
didn't bother reading past the first couple of sentences with any
attempt at comprehension. I replied by following up with another email
exactly according to the procedure that they suggested I follow up,
explaining how the telephoto restriction has nothing to do with it.
But now it's been almost a week and no response. I'm going to wait a
few more days and then go ahead and email them all over again about
it. Ah ... running the tech support gauntlet. It's been a while, but I
see that it's the same old circus.

DB.

(Dave Martindale) wrote in message ...
(Dogger the Filmgoblin) writes:

it does take quite an extreme situation to induce but it
is definitely a bug, or at least a very poorly implemented sensor
protection scheme. And if it IS a sensor protection scheme: why only
the A75? I am curious as to whether the A85 will behave the same way.

It certainly sounds like a firmware bug, if all A75s but no other Canon
cameras do it. Have you tried to report it to Canon? Maybe it can be
fixed before the A85 is released.

Dave

Yes I reported it (and I'm not the first) with links to all the
relevant online discussions of the problem. I got the brush-off with a
standard boilerplate response about how wider f-stops are unavailable
in the telephoto range. Duh. Par for the course, the support rep
didn't bother reading past the first couple of sentences with any
attempt at comprehension. I replied by following up with another email
exactly according to the procedure that they suggested I follow up,
explaining how the telephoto restriction has nothing to do with it.
But now it's been almost a week and no response. I'm going to wait a
few more days and then go ahead and email them all over again about
it. Ah ... running the tech support gauntlet. It's been a while, but I
see that it's the same old circus.

DB.