# AEB - change shutter speed?



## qwertyjjj (Dec 3, 2012)

With the AEB on my camera it takes 3 different shots at specified exposures, let's say -2, 0 and +2 for this example.

1/ If I wanted to do HDR but need 3, 5, or 7 exposures, how can I do that on a Canon 400D? Do I have to do it manually for each one? If so, idn;t there a chance that by moving the buttons, I will move the camera on the tripod and mess up the HDR sync.
2/ To get a correct exposure at the 3 different brackets, doesn;t the shutter speed have to be changed for each one? Say I picked f/8 and a shutter speed of 1/60, then for an exposure of -2 (2 stops down), doesn;t the shutter speed need to be changed to 1/250? I don't think my camera does this automatically when in AEB mode.


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## KmH (Dec 3, 2012)

Refer to pages 76-77 of your XTi User's Manual - http://gdlp01.c-wss.com/gds/7/0900000357/01/EOSDRXTi400DIM-EN.pdf


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## kundalini (Dec 3, 2012)

qwertyjjj said:


> With the AEB on my camera it takes 3 different shots at specified exposures, let's say -2, 0 and +2 for this example.
> 
> 1/ If I wanted to do HDR but need 3, 5, or 7 exposures, how can I do that on a Canon 400D? Do I have to do it manually for each one? If so, *idn;t* there a chance that by moving the buttons, I will move the camera on the tripod and mess up the HDR sync.
> 2/ To get a correct exposure at the 3 different brackets, *doesn;t* the shutter speed have to be changed for each one? Say I picked f/8 and a shutter speed of 1/60, then for an exposure of -2 (2 stops down), *doesn;t* the shutter speed need to be changed to 1/250? I don't think my camera does this automatically when in AEB mode.



On the QWERTY keyboard, the apostrophe (used to indicate the omission of letters in a word) is just to the right of the semi-colon.


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## qwertyjjj (Dec 4, 2012)

kundalini said:


> qwertyjjj said:
> 
> 
> > With the AEB on my camera it takes 3 different shots at specified exposures, let's say -2, 0 and +2 for this example.
> ...



yeah, I sometimes hit both at the same time


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## qwertyjjj (Dec 4, 2012)

KmH said:


> Refer to pages 76-77 of your XTi User's Manual - http://gdlp01.c-wss.com/gds/7/0900000357/01/EOSDRXTi400DIM-EN.pdf



It says nothing about the shutter speed being changed.
In the books I've read of HDR, the shutter speed is changed for each of the 3 exposures, the camera only changes the exposure setting to decreased, normal, and increased.

Or does an exposure of +1 and -1, mean one stop up and one stop down?
stopping up and down could be done by either the shutter speed or the aperture couldn't it, so which does it change when doing AEB?


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## Overread (Dec 4, 2012)

The AEB takes one shot above and one shot below the exposure you've set - the above and below are always at equal points and you set that value (eg one stop, two stops etc..).

If you want to day more shots with more exposure differences you'll have to do this manually yourself by changing the shutter speed to each setting. Manual mode will be needed. Just set the aperture, ISO and shutter speed - take the shot and then repeat changing only the shutter speed for the rest of the shots.


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## qwertyjjj (Dec 4, 2012)

Overread said:


> The AEB takes one shot above and one shot below the exposure you've set - the above and below are always at equal points and you set that value (eg one stop, two stops etc..).
> 
> If you want to day more shots with more exposure differences you'll have to do this manually yourself by changing the shutter speed to each setting. Manual mode will be needed. Just set the aperture, ISO and shutter speed - take the shot and then repeat changing only the shutter speed for the rest of the shots.



But why do I need to change the shutter speed?
Can't I just roll the exposure on 5 shots from -2, -1, 0, +1, +2?


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## Overread (Dec 4, 2012)

Auto Exposure Balance only takes 3 shots for canon (far as I recall). So you can only use it for a batch of 3 shots. One on the exposure setting, one below and one above. 

If you want more shots you have to either use AEB with a different base exposure to get the other 3 shots or just do the whole process manually yourself by selecting the shutter speed each time.


Remember exposure wise the camera only has aperture, ISO and shutter speed. Nothing else in the camera affects the overall exposure. If you want to change the exposure in any way one of those 3 settings has to change (either hte camera does it automatically or you change it yourself).


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## qwertyjjj (Dec 4, 2012)

Overread said:


> Auto Exposure Balance only takes 3 shots for canon (far as I recall). So you can only use it for a batch of 3 shots. One on the exposure setting, one below and one above.
> 
> If you want more shots you have to either use AEB with a different base exposure to get the other 3 shots or just do the whole process manually yourself by selecting the shutter speed each time.
> 
> ...



I suppose the reason for changing shutter speed is that is doesn't affect the DOF or grainyness, it only affects the amount of light coming in?


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## Dao (Dec 4, 2012)

The Canon camera that I had experience with XTi, 40D and 7D take 3 shots for AEB.

What you can do is set the AEB such as -1 and +1, dial the exposure compensation to 0 and then take 3 burst shots.  Now while the camera still mount on the tripod, change the exposure compensation to -1/2 (or +1/2) and take another 3 shots.  And that should give you 6 different exposures with 1/2 stop difference between shots.


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## Overread (Dec 4, 2012)

Changing the shutter speed is normally the default most go with because it has the least amount of effect upon image quality provided that the slowest shutter speed you'll use is still fast enough to freeze motion. That said I suspect that ISO could also be used to good effect and that its oft not suggested as much possibly because of the history of film (with film ISO/ASA was basically fixed unless you had a high end removable back camera or more than one camera to use).


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## KmH (Dec 4, 2012)

qwertyjjj said:


> KmH said:
> 
> 
> > Refer to pages 76-77 of your XTi User's Manual - http://gdlp01.c-wss.com/gds/7/0900000357/01/EOSDRXTi400DIM-EN.pdf
> ...


Exactly.

It says it does AEB by doing Exposure Compensation.

The implication is - your XTi isn't capable of doing *AEB* by changing the shutter speed.

However, you can bracket exposures by changing the shutter speed manually.


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## Overread (Dec 4, 2012)

KmH said:


> qwertyjjj said:
> 
> 
> > KmH said:
> ...



I wait - here - what? 
Exposure compensation has to change either shutter speed, aperture, ISO or a combination of two or three. If the mode selected is (for example) aperture priority then only the shutter speed or the ISO could be changed and the ISO only if its set to auto and not manual. 
So it should be possible to make the camera change only the shutter speed?


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