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Canon G15 Strange Behavior

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Persio

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Gentlemen,

I noticed a very strange behavior on my G15.

Camera set to Av, ISO 100, bright day on the beach, aperture set to 2.8

The auto speed setting would not go higher than 1/2000th and I got an overexposed image.

The question is why would it not set to 1/4000th and not overexpose the image?

Has anyone noticed this?

Am I missing something?

Thanks for your comments,

Persio.
 
Just curious why you chose 2.8?

Hope another forum person can answer your question.
 
If you were using fill flash the shutter is limited to 1/2000. Also only 1 stop difference, perhaps dark area in scene influenced exposure.

If no other solution can use ND filter.

Richard Southworth
 
More info:

1. Could not go past 1/2000 in aperture mode aiming at bright light, would go to 1/2000 and then display ss in red, which I assume means over-exposed.

2. Could not go past 1/2000 in manual mode.

3. In shutter priority mode go to 1/3200 with lens at full telephoto and to 1/4000 with lens at full wide.

I believe there are some limitations to the 1/4000 that Canon doesn't specify.

Richard Southworth
 
Richard Southworth said:
Richard Southworth wrote:

I believe there are some limitations to the 1/4000 that Canon doesn't specify.
Click to expand...
Could be. Did you look in the manual? Use the ND filter in the G15 is a good suggestion.
 
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Richard,

Thank you.

Now I know that I do not have a defective unit.

My G15 presents exactly the same behavior you have described.

Furthermore, in Tv, setting speed to 1/4000th I noticed the aperture would not open more than f:6.3.

I wish Canon would describe these limitations in the documentation.

Regards,

Persio.
 
Phil,

Yes, I searched thru the manual on all instances of "shutter", did not find a reference that explained the limitations on 1/4000. The only note I came acaross was the one concerning the 1/2000 limit when using flash.

Richard Southworth
 
This is funny, I just experienced this with my G15 this morning. Taking pictures of my kids in the snow on this sunny morning, Av - 1.8 - 80. Saw the 1/2000 in red on the screen and the pic was way overexposed. I just brought the aperture up a bit and got some decent shots. I thought about the ND filter but didn't try it; might do that in a little bit.

Strange that Canon would restrict the speed in Av mode.
 
JimmyInTheROC said:
JimmyInTheROC wrote:

This is funny, I just experienced this with my G15 this morning. Taking pictures of my kids in the snow on this sunny morning, Av - 1.8 - 80. Saw the 1/2000 in red on the screen and the pic was way overexposed. I just brought the aperture up a bit and got some decent shots. I thought about the ND filter but didn't try it; might do that in a little bit.

Strange that Canon would restrict the speed in Av mode.
Click to expand...
Actually, it makes sense. I don't think they had a choice. With the lens wide open the hole is bigger. If you look deep into the lens with it in AV mode and set at f1.8 and click the camera, you can see a shutter close down for just in instant. (I have a bunch of pictures of my eyeball looking into the lens now with a staring look. LOL)

It looks like it may be somewhere near the rear element of the lens. This blocks the light while the sensor is being read. The camera also employs an on chip shutter, but it is necessary to block light while the read takes place. Since the shutter has further to move with a big hole, it takes longer for transit, and 1/2000 is as fast as it can go. When the hole is smaller, then the transit time is less and it can go faster. At least I think that is what is happening...
 
Dale,

I think you have e very good point.

What bothers me is that Canon has not documented this behavior.

I use my EOS 7D most of the time and my first reaction was to blame my copy of the G15 because I found no reference to this behavior in the user manual.

Regards,

Persio.
 
Persio said:
Persio wrote:

Dale,

I think you have e very good point.

What bothers me is that Canon has not documented this behavior.

I use my EOS 7D most of the time and my first reaction was to blame my copy of the G15 because I found no reference to this behavior in the user manual.

Regards,

Persio.
Click to expand...
I agree with you, Persio. I searched the manual very carefuly (at least I tried to) but could find no mention of this behavior either in the text or in the appendix. And I admit that I am guessing as to what the reason is. But it does seem logical to me...

Oh well... whatever the reason, the camera does behave just as you said. Mine does also. I think the reason is shutter transit time limitations. (The shutter that I am speaking of is an iris at the back of the lens.) You can watch it stop down all the way with the lens at f1.8. The stopping down and return have a finite travel time. I think that is likely the limitation. But it would have been nice to have been documented.

Another possibility is that Canon wrote the manual before all of the performance data was available on the camera, and they missed being aware that would happen. Anyway, it does, and the only solution I can think of for bright light, f1.8 operation, ISO 80 is to switch in the ND filter and let it do its magic. :) Thanks for calling this to my attention.
 
Persio said:
Persio wrote:

Gentlemen,

I noticed a very strange behavior on my G15.

Camera set to Av, ISO 100, bright day on the beach, aperture set to 2.8

The auto speed setting would not go higher than 1/2000th and I got an overexposed image.

The question is why would it not set to 1/4000th and not overexpose the image?

Has anyone noticed this?

Am I missing something?

Thanks for your comments,

Persio.
Click to expand...
With Safety Shift enabled the camera will attempt to adjust aperture or shutter speed to prevent under/over exposure. This feature will be disabled when the flash is enabled, was the flash on?

Also, maximum shutter speed is effected by focal length and aperture. To achieve the maximum shutter speed (1/4000) you'll need an aperture of f6.3 or higher and focal length of 100mm or lower.


This all seems strange compared to DSLR behavior until you realize the shutter and aperture are not two separate pieces of hardware.
 
Thanks much!
 
MisterPootieCat said:
MisterPootieCat wrote:
MisterPootieCat said:
Persio wrote:

Gentlemen,

I noticed a very strange behavior on my G15.

Camera set to Av, ISO 100, bright day on the beach, aperture set to 2.8

The auto speed setting would not go higher than 1/2000th and I got an overexposed image.

The question is why would it not set to 1/4000th and not overexpose the image?

Has anyone noticed this?

Am I missing something?

Thanks for your comments,

Persio.
Click to expand...
With Safety Shift enabled the camera will attempt to adjust aperture or shutter speed to prevent under/over exposure. This feature will be disabled when the flash is enabled, was the flash on?

Also, maximum shutter speed is effected by focal length and aperture. To achieve the maximum shutter speed (1/4000) you'll need an aperture of f6.3 or higher and focal length of 100mm or lower.

This all seems strange compared to DSLR behavior until you realize the shutter and aperture are not two separate pieces of hardware.
Click to expand...
You are correct!

One gets so much used to DSLR technology that forgets that with "rangefinders" the diaphragm and the shutter are combined into a single unit, which imposes some limitations.

Still, canon should have documented such limitations.

My best.
 
I bumped in to the same problem today with my Fuji x10. 1/1000 and no built in nd filter.

Does anyone know if the S110 has any limit on it's shutter speed?
 
Dale Buhanan said:
Dale Buhanan wrote:

Actually, it makes sense. I don't think they had a choice. With the lens wide open the hole is bigger. ...... Since the shutter has further to move with a big hole, it takes longer for transit, and 1/2000 is as fast as it can go. When the hole is smaller, then the transit time is less and it can go faster. At least I think that is what is happening...
Click to expand...
Good analysis, Dale. This is true for many cameras for exactly the reasons Dale describes. Fortunately, the G15 has a built-in ND filter which can remove the need for a fast shutter in bright, lens wide open situations.
 
Just a thought;

When the camera is in Av or Tv mode you can still do some exposure tweaking by using exposure compensation.
While in Av mode setting the exposure compensation to a positive number will slow down the shutter-speed so it might go from 1/4000 to 1/2000 (You are asking for more light with the same aperture so it will choose a slower shutter-speed) This could explain overexposure.
 
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