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Janet
24th January 2010, 10:27 PM
Help!

Apologies if this has been posted before, but I need the information in a hurry!

I started a photography course today, and one of the rules is that we are only allowed to use manual mode.

Now whilst I can change the shutter speed and aperture, I couldn't figure out how to alter the exposure compensation. Looking at the manual, it says...

Exposure compensation is not available in M and SCENE modes....

This isn't right, surely?

Does anyone know a way round this?

Many thanks!

Janet

meach
24th January 2010, 10:50 PM
You don't need a way round it in manual mode - by changing either the shutter or aperture only (i.e. one but not the other) you are effectively compensating manually. If you want to under expose by a stop either close the aperture by a stop or reduce shutter speed by a stop. To over expose open the aperture or increase shutter speed. Therefore you can't automatically compensate exposure in manual mode - the camera won't know which of the two to change. In aperture priority it will change the shutter - in shutter priority it will change the aperture. Hope this makes sense!

Kiwi Paul
24th January 2010, 10:59 PM
In manual mode the dial can adjust aperture or shutter speed and as you look through the viewfinder the exposure bar will show if you are under or over exposed, you move the dial to adjust the degree of under or over exposure by changing the aperture or shutter speed, when the exposure bar is centred the exposure is correct.

Paul

photo_owl
24th January 2010, 11:00 PM
wot Paul says - but looking at it another way......

exposure compensation is the application of a compensating adjustment to an automatically selected, or programmed, exposure setting.

in M mode there isn't one - so you can't

there is an argument that you should be able to dial an adjustment into the exposure meter reading, from which you may (or may not) be working but this is somewhat flawed.

there is another case for having EV adjustment available when in M mode but using Auto ISO setting. Here you are effectively using auto mode and this should be available (and is on some (non-Oly) DSLRs

Janet
24th January 2010, 11:05 PM
Thanks for such quick responses guys.

It makes a lot more sense now. I'll get to grips with this camera eventually!

Janet

JohnGG
25th January 2010, 12:32 AM
Other replies have mentioned adjusting shutter speed or aperture to achieve exposure compensation when in manual mode but, now that we are not stuck with a constant film speed associated with, say, a 36 exposure roll of Velvia in a film camera, we are also free to vary the ISO sensitivity of the sensor from shot to shot. This feature can also be used for exposure compensation.

Suppose that for a given scene you set the aperture to f/5.6, the shutter speed to 1/250s and the ISO to 400 in order to centre the meter bar in the viewfinder and achieve a "perfect" exposure. Now, to apply 1 stop of under-exposure (-1 stop) you can do one of three things: you could stop the aperture down to f/8 to halve the amount of light passing through the lens; you could reduce the shutter speed to 1/500s to halve the time the sensor is exposed to the light; you could reduce the ISO to 200 to halve the sensitivity of the sensor. These things are additive, do any two of the above and you will have -2 stops, do all three and you've applied -3 stops of compensation.

I hope this explanation makes sense and is helpful. Best of luck with your course :)

Cheers,

JohnGG

Ian
25th January 2010, 08:51 AM
My take on it - exposure compensatiion is for overriding an automatic exposure setting. These modes are P (program auto - the camera adjusts both shutter speed and aperture itself), A (Aperture priority - you set the aperture and the camera takes care of the shutter speed), and S (Shutter priority - where you set the shutter speed and the camera adjust the aperture by itself).

In all these cases the camera determines the exposure. If you don't trust the camera's decision in certain situations, then you can bias the exposure up or down by over or under compensating, in plus or minus Exposure Values (EVs).

In manual mode, the camera will indicate what it thinks the correct exposure should be, but you are in complete control of both the aperture and shutter. The camera will suggest you are plus or minus EVs away from correct exposure. This, in effect, can be used as a compensation method if you need it. Simply adjust the shutter and/aperture until the plus or minus EV bias is acheived and indicated.

Ian

photo_owl
25th January 2010, 02:35 PM
My take on it - exposure compensatiion is for overriding an automatic exposure setting. These modes are P (program auto - the camera adjusts both shutter speed and aperture itself), A (Aperture priority - you set the aperture and the camera takes care of the shutter speed), and S (Shutter priority - where you set the shutter speed and the camera adjust the aperture by itself).

In all these cases the camera determines the exposure. If you don't trust the camera's decision in certain situations, then you can bias the exposure up or down by over or under compensating, in plus or minus Exposure Values (EVs).

In manual mode, the camera will indicate what it thinks the correct exposure should be, but you are in complete control of both the aperture and shutter. The camera will suggest you are plus or minus EVs away from correct exposure. This, in effect, can be used as a compensation method if you need it. Simply adjust the shutter and/aperture until the plus or minus EV bias is acheived and indicated.

Ian

Absolutely - except that M with Auto ISO is also a situation where the camera determines the exposure (you just set the aperture and shutter speeds you want)

It would be appreciated if you could pass on to Olympus the real need to enable EV adjustment to be dialed in when shooting in this mode - it is one of the most useful modes available, taking advantage of a 'digital' feature.

Cheers