Program mode and inconsistant exposure

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baz gimson

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baz
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I took these pics using the program mode, all I did was change the f number. I thought the camera would produce consistant exposure. The majority of my pics came out darker than I expected. The screen on the back of the camera showed the pics to look quite bright. Any ideas what has happened? Cheers.


155_5527 by baz gimson, on Flickr


155_5526 by baz gimson, on Flickr


155_5537 by baz gimson, on Flickr


155_5536 by baz gimson, on Flickr
 
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It looks like you're changing the F number (aperture) by altering the exposure compensation.

You'd probably be better of switching to aperture priority mode (I think that's Av on a Canon), choosing the F number yo want. And then using the exposure compensation to adjust if needed. Bare in mind that as you increase the aperture the shutter speed will become slower. You might need to increase ISO.

EDIT: Are you metering from the same spot in both photos?
 
Yes, you've used exposure compensation, which has changed the aperture but left the shutter speed unaltered because that's what you've asked it to do.

If you use program shift instead (see handbook) it will change the aperture, but also adjust the shutter speed to rebalance the exposure. You can use the shift facility to get any combination of shutter speed and aperture you want, just like using Av or Tv, and on top of that you can also apply compensation (as you have accidentally been doing) to adjust the overall brightness of the image. It's just a different way of doing the same things.
 
Cheers chaps, I wasn't aware that I was using exposure compensation. In fact I have no idea how to switch it on!

The handbook describes Program AE as a general purpose shooting mode with fully auto shutter speed and aperture. I thought that by turning the dial I was changing the f stop, whilst maintaining correct exposure. I obviously misunderstood the handbook.

The exif for the pics show

Pic 1: 1/50, f4.5, exposure mode: auto, iso 200

Pic 2: 1/125, f 7.1, exposure mode: auto, iso 200

Pic 3: 1/100, f 7.1, exposure mode: auto, iso 200

Pic 4: 1/125, f 8, exposure mode auto, iso 200

I have used AE aperture priority mode since I took these pics. They also came out quite dark and under exposed.

As to metering in the same spot, well I just point the camera at what I want to photogragh, compose the shot, hold the button halfway down and then take the pic after focusing/composing the shot. I thought the camera did the metering automatically. From reading the handbook it seems like I cant select metering modes manually.

thanks for the info.
 
Sorry I dont understand this. The exif shows in pics 1 and 2 the OP has narrowed the aperture from f4.5 to f7.1 as he said and the camera has upped the shutter speed instead of slowing it?
I thought exposure comsenation was done digitally in the camera rather than making a difference to shutter/aperture?

Baz, you saying what you changed between pics 1 and 2 was done using exposure comp or by altering shutter/aperture?
 
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Hi Chris, I turned the dial to alter the f stop number I could see in the view finder. The shutter speed changed at the same time. I thought that the exposure was automatically adjusted to give the correct exposure. I dont know anything about exposure compensation or how to switch it on. It maybe that I had switched it on by accident, but I dont know.
 
Strange, if you changed the aperture using the rotary dial then the camera should adjust shutter speed accordingly to maintain the correct exposure.
maybe someone more knowledgeable can explain!
 
I'm confused now. My Exif reader won't open on those images so I kinda just assumed from what was written. It seems like the OP probably did use program shift, if the shutter speed altered at the same time, and not compensation.

So, next guess is the metering has been skewed by the area of bright sky, and/or quite likely by some element of user error by way of inadvertant focus-lock exposure-recompose. What mode are you in? Re-set to evaluative metering mode.

Assuming that there's nothing wrong with the camera, it can only be one thing really... ;)
 
Just to clarify, would I be correct in saying exposure compensation adjusts the image digitally rather than using shutter/apert/ISO?
 
Hi Hoppy, according to the exif the metering mode was evaluative. The handbook says that evaluative is used in all modes apart from in manual when the camera automatically uses centre weighted average or AE lock when it uses partial metering. So it looks like I can't choose what metering to use.

The sky looks bright, but it wasn't a sunny day, just dull with cloud and bits of blue sky showing through.

I'm not trying to imply that that because the pics are crap it must be the camera, I'm well aware that I'm no photographer. But a lot of the pics I took that day were very similar to this and i wondered why that might be.
I've used Av mode since this to adjust the f stop and a lot of the pics also came out under exposed. But when they appear on the review screen they look quite bright so I think they are ok, but when I get them home they look dull and under exposed.
 
Chr1stof said:
Just to clarify, would I be correct in saying exposure compensation adjusts the image digitally rather than using shutter/apert/ISO?
Click to expand...

No. It adjusts shutter speed and/or aperture. In P, it adjusts both alternately, in Av it adjusts the shutter speed, in Tv it adjusts the aperture, and in M it just moves the viewfinder indicator so that when you realign it manually you will have under/over exposed by the appropriate amount.

baz gimson said:
Hi Hoppy, according to the exif the metering mode was evaluative. The handbook says that evaluative is used in all modes apart from in manual when the camera automatically uses centre weighted average or AE lock when it uses partial metering. So it looks like I can't choose what metering to use.

The sky looks bright, but it wasn't a sunny day, just dull with cloud and bits of blue sky showing through.

I'm not trying to imply that that because the pics are crap it must be the camera, I'm well aware that I'm no photographer. But a lot of the pics I took that day were very similar to this and i wondered why that might be.
I've used Av mode since this to adjust the f stop and a lot of the pics also came out under exposed. But when they appear on the review screen they look quite bright so I think they are ok, but when I get them home they look dull and under exposed.
Click to expand...

Not sure what's happening here Baz, but you can't really use the LCD for exposure estimation at the best of times. It can be hard to see in bright light, and the brightness also varies. LCD on the 300D is also very small by modern standards.

However, you have the histogram and blinkies (highlight over exposure warning - in the menu) and they are both very accurate guides to correct exposure. Much more accurate than any metering system. Learn to read the histogram here http://www.sekonic.com/images/files/HistogramsLightmetersWorkTogether.pdf
 
HoppyUK said:
No. It adjusts shutter speed and/or aperture. In P, it adjusts both alternately, in Av it adjusts the shutter speed, in Tv it adjusts the aperture, and in M it just moves the viewfinder indicator so that when you realign it manually you will have under/over exposed by the appropriate amount.
Click to expand...

Thanks for clarifying
 
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