Understanding manual mode

ruffdog64

ruffdog64

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Harvey
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Here's how I think it is when in manual mode ,when looking through the lens im trying get the exposure on the middle of the meter buy a combinationof shutter speed and apperture and maybe iso ? Have I understood this ok and what makes this so different from say auto
 
Difference is you can control DOF by choosing the f-number, while in auto mode camera chooses aperture for you by 'guessing' what you want to achieve.

However, using M mode the way you described makes little sense - it the same as using AV mode and letting camera choose shutter speed based on your choice of f-number
 
As said you are in controle not the camera.

Also the needle smack bang in the middile is not always the correct exposure, sometimes YOU might feel the need to go one stop up or down etc etc.

Manual lets you decide

spike
 
Sort of, that will give you a good exposure to make whatever you are pointing the camera a mid tone of grey.

Now that's fine if you are pointing at a mid grey, but what if you are not?

If you have a predominantly bright scene, the meter will be fooled into underexposing, conversely if the scene is predominantly dark, the meter will be fooled into overexposing. If either of these two situations occur, you have to take remedial action by altering your exposure to compensate.
 
Wow! So many replies thanks everyone for taking the time to reply, from what's been said I think I need to spend some time in manual, Harvey
 
ruffdog64 said:
Here's how I think it is when in manual mode ,when looking through the lens im trying get the exposure on the middle of the meter buy a combinationof shutter speed and apperture and maybe iso ? Have I understood this ok and what makes this so different from say auto
Click to expand...

If you use it like that, you are only doing what the camera will do for your automatically. Apart from one very important thing - it is locked at those settings until you change it, regardless of what happens to the light, or the subject. Think of manual as a Set & Lock mode.

The other modes are either fully automatic, or semi-automatic. P is full auto and it will set both shutter speed and lens aperture for you, on a sliding scale. The green square is similar, but also sets a few other things and locks you out of changing others - best avoided.

The other modes are semi-automatic. A (or Av for aperture value) is aperture-priority, where you choose the lens aperture (f/number) and the camera matches that with the correct shutter speed. S (or Tv for time value) is shutter-priority where you choose the shutter speed and the camera selects the appropriate lens aperture.

The camera's meter makes assumptions about the nature of the subject, basically that when everything in the scene is scrambled up together it equates to mid grey, though different metering modes have a different twist on this to try to get it right. However, none of them is foolproof and when the subject does not scramble up to mid-grey, becuase it's a snow scene for example, or a black cat in a coal cellar, then it will get it wrong.

This is what the exposure compensation controls are for, to allow you to make corrections, usually after you've looked at the LCD and histogram etc for guidance. They are a kind of manual override, or you can just set everything fully manually yourself, in M mode, which is where we came in :)
 
You are correct about exposure being a combination of all three elements. Think of it as a triangle, if you change one part, one of the other two needs to be altered to maintain the same exposure. Now metering is a different subject altogether. Depending on (a) what metering mode you've chosen (b) what you are pointing at (c) what is the most important part of the frame to get correct.

For example if spot metering and you are shooting a swan then the meter will try and turn the swan 18% grey and underexpose it, a blackbird at the other extreme will be overexposed as the camera tries to make that grey. Using evaluative ie the whole frame, pointing camera at a basic scene will give you a basic guide as to the correct exposure, large areas of black or white will skew this, but you get the idea.

Now suppose you were shooting a plane against a bright sky, evaluative is going to underxpose th plane, this is where you want it to be correct to get the detail in the aircraft, so adjusting the metering to give more exposure to compensate for the camera trying to tone it all down would give a better value for the plane.

Hope that helps.
 
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