Metering

mattchewone

mattchewone

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Sorry to be ask a bit of a silly newie question, but could someone explain the process of metering. How the different metering modes affect the results.
Also what the benefit is from using custom function 4 using the * to focus and metering seperatly?

Many Many Thanks

Matt
 
Probably one of the most complex subjects but can be broken down into a couple of simple points.

Metering comes in a few flavours:

Evaluative - looks at the scene and compares the light from multiple areas to a database of typical shots. Normally it does a fair job but can also get it very wrong.
Spot - only considers the light from a small section.
Partial - like spot only using a larger section.
Center Weighted - like partial but covers most of the frame but with a bias towards the centre.

The meter tries to average the light it sees to a mid grey, the theory is that mid grey is the average returned light from a typical scene. On an average scene it works well but if you're shooting a bright or dark scene it will get it wrong which is when Exposure Compensation (EC) comes in useful.

If you meter from a white object the camera will try and turn it grey and under expose as a result. Meter from black object and you'll over expose.

Getting the exposure right is a couple of basic decisions.

What part of the scene do you want correctly exposed?
When I meter for that is it brighter or darker than the average grey and is so by how much?

A lot of it will come down to experience of how to handle different situations and what's best to do for the result you want. Often you'll find you have a situation where the difference in light and shade is more than the camera can record so you have to choose between exposing for the light or shaded at the expense of the other or employ some additional solution such as reflector, fill flash, etc.

The best thing to do is get out and practice with as many different lighting situations as you can. Shoot in AV mode and Eval and go with what the camera says, then you'll learn what can fool the camera into making the wrong choices and when to use some EC to compensate. The repeat the process using spot or partial and you'll see how the mid grey system works and again when you need to compensate.

Go out, shoot, make lots of mistakes and then learn from them...
 
Thank you so much, very helpful!! Whats EC and how does it work?

Cant thank you enough!
 
I can't answer your question as well as SP ^^ However, I can say that until I started shooting manual, my light metre got very little use, and metering therefore was wasted on me.

Now when in manual, I am always using the built in light metre, and always actively thinking about aperture and shutter speed. Allows me to capture the shot much closer to what I want, this is especcially true on the Urban shots, where I favour towards the sark side, loads of shadows and deliberate under exposure.

I only started shooting in manaul after reading the first chapter of "Understanding Exposure", and it said, the only way to shoot, is manual. No reason to do otherwise.

I suspect thats not quite true, but to me its far easier in manual than I had imagined.

Gary.
 
mattchewone said:
Thank you so much, very helpful!! Whats EC and how does it work?
Click to expand...

EC = Exposure Compensation. This allows you to shift the exposure brighter or darker. How you set it depends on your camera, check the docs.

Two things to remember - it's not available in Manual mode because you are choosing the exposure setting anyway and the one that catches eveyone out at some point - don't forget to reset it afterwards or you'll carry on using it when you don't want it.
 
I don't have SPOT metering..

Just

Evaluative , Partial Metering and Center-Weighted average metering. One person said to me the other day make sure you have spot metering on for swans to get the right exposure for swans.
 
So in AV or TV mode you can use EC, So basically you ask it to meter to either under or over expose. Got it!! (i think)

Phew!
 
Pirate Neilsouth said:
I don't have SPOT metering..

Just

Evaluative , Partial Metering and Center-Weighted average metering. One person said to me the other day make sure you have spot metering on for swans to get the right exposure for swans.
Click to expand...

Spot helps but you don't need it. Take a reading from something around mid grey and then dial in 1 1/2 - 2 stops of positive EC and you should be about right. Check the histogram to make sure the whites haven't blown, rinse repeat.

Oh, and avoid bright sunshine for swans - you'll get much better results in more overcast conditions as there'll be much less contrast :thumbs:
 
Are there any good guides online on how to understand the histograms?
 
Thats no problem Neil, i dont have spot either so was glad someone asked ;)
 
mattchewone said:
Are there any good guides online on how to understand the histograms?
Click to expand...

I think there's one on here somewhere, hit the search and see.

The histogram is a graph showing distribution of tones.

Horizontal axis is dark to light tones
Vertical axis is the number of that tone used.

If the histogram is all bunched up on the left then you've got a shot with lots of dark tone. The higher each line goes the more of that tone you've got. If the graph reaches the edge and is high you could have under or over exposed the shot depending which side it is.

Ideally you don't want to exceed the edges on either side, a well exposed "average" scene well look a bit like a hill, rising from the left to the middle and back down again. But that doesn't mean every shot should look like that.
 
Your a genius, Thanks ever so much!
 
wow some useful info, thanks :)
 
As I understand it, partial IS spot... just the spot is bigger :)

I too ALWAYS shoot manual. I find this easier to get the results I expect using the histogram afterwards to have a quick check to make sure I haven't blown anything. And if it's too dark, I compensate and reshoot.

This thread sort of relates to my one discussing the * button and AI-Servo.

Reading between the lines, am I right in assuming that in tricky lighting (ie: moving object coming in and out of shadow), I would HAVE to shoot either AV or TV (probably TV to control motion blur/movement) as there is no way I could anticipate the correct manual settings. I say this, because in the other thread the benefits of using the * mention sperarate focus/metering point, which tbh doesn't really bother me. Am I just being niaive and getting into bad habbits that will need to be broken if I ever want to shoot enything other than stationary or studio?

Hope this isnt thread hijack... seems to be carrying on down the right path i think :)
 
Shooting manual solves a lot of problems but does introduce a few others.

I tend to shoot manual when the light is fairly constant. I take two readings, one for light, the other for shade. Then depending on where the subject is I flip between the two - it's just a case of remember how many clicks on the quick dial to turn. This way I avoid all the problems of constantly changing meter readings, etc. and can just shoot away knowing the exposure is right for the subject.

Remembering to switch between the two settings and periodically checking the reading are the main things you need to remember or it can all go horribly wrong, not that ever happens to me :lol:
 
68lbs said:
As I understand it, partial IS spot... just the spot is bigger :)

I too ALWAYS shoot manual. I find this easier to get the results I expect using the histogram afterwards to have a quick check to make sure I haven't blown anything. And if it's too dark, I compensate and reshoot.

This thread sort of relates to my one discussing the * button and AI-Servo.

Reading between the lines, am I right in assuming that in tricky lighting (ie: moving object coming in and out of shadow), I would HAVE to shoot either AV or TV (probably TV to control motion blur/movement) as there is no way I could anticipate the correct manual settings. I say this, because in the other thread the benefits of using the * mention sperarate focus/metering point, which tbh doesn't really bother me. Am I just being niaive and getting into bad habbits that will need to be broken if I ever want to shoot enything other than stationary or studio?

Hope this isnt thread hijack... seems to be carrying on down the right path i think :)
Click to expand...



I think sports etc will be difficult with manual, as you say, fast moving subjects. Shutter Priority surely the way forward in this case...

Gary.
 
EdinburghGary said:
I think sports etc will be difficult with manual, as you say, fast moving subjects. Shutter Priority surely the way forward in this case...

Gary.
Click to expand...

No, as long as the light isn't changing manual is better for sports. It's one situation where the meter is easily and often fooled. The changing background and team colours mean the meter will get confused. If the light is the same then you should be using the same settings anyway :thumbs:
 
Ok, stupid time :D

Up until recently, I've avoided the whole metering thing.
I've basically just composed and fired, and hoped for the best!
But now I'm starting to realise that if I want to take better shots, I need to understand this metering lark!!

So PLEASE forgive me, but I'm starting right at the beginning here, and going to ask a few daft questions :nuts:

When you say you take a reading, what do you mean?
How do you take a reading?
Are you pressing the shutter button halfway???

And what is a meter?!?!?
I'm guessing it's something inside the camera that determines the correct aperture/shutter speed (depending on mode used I spose??!)

Sorry - I know I should know these things, but I'm still learning!!!!

Thanks
 
sony_dslr_500px_dslr-a350_back_lg.jpg


I'm hoping I got this right but the built in meter is the scale from -2 to +2 and should also be seen through the view finder. If the pointer is away from the 0 mark then you can adjust the shutter speed or aperture to get the light setting correct.

I tend to knock the adjustment wheel down a notch to very slightly under expose on my Canon 400D as I find this gives a richer colour and guards against blowing highlights.
 
andy_fozzy said:
Ok, stupid time :D

Up until recently, I've avoided the whole metering thing.
I've basically just composed and fired, and hoped for the best!
But now I'm starting to realise that if I want to take better shots, I need to understand this metering lark!!

So PLEASE forgive me, but I'm starting right at the beginning here, and going to ask a few daft questions :nuts:

When you say you take a reading, what do you mean?
How do you take a reading?
Are you pressing the shutter button halfway???

And what is a meter?!?!?
I'm guessing it's something inside the camera that determines the correct aperture/shutter speed (depending on mode used I spose??!)

Sorry - I know I should know these things, but I'm still learning!!!!

Thanks
Click to expand...


:withstupid:
Someone must have taken pity with me!!
Any help on this would be very much appreciated..... :nuts:
 
Andy,

When you look through the viewfinder of the camera you will see a bar like in the picture, which has -2 -1 0 1 2
sony_dslr_500px_dslr-a350_back_lg.jpg


That is the meter. When its a 0 its perfectly exposed. When at -2 its under exposed, and when at +2 its over exposed.

To take a meter reading, you can use TV or AV mode to help calculate what you need. If in AV choose your aperture you would like (DoF) Half depress the shutter button and you will see the meter stick to 0 as it has automatically calculated the shutter speed to get the perfect exposure.
You can the switch to Manual and then dial in the settings you used for AV mode and then adjust the shutter or aperture to suite the light changes.

As the meter starts moving to the left slow the shutter speed, and vice versa.

Hope this helps its a very basic guide and should help you get to grips with using it in fully manual.
Matt
 
Top tip for new manual metering users.... when you have metered and then start shooting.. IGNORE the meter bar.. it will show under or over exposed... you must ignore that.. this really onfused me when i first went manual.. seems such a silly mistake now but one I did make so presume there are others as daft as me :)
 
mattchewone said:
Andy,

When you look through the viewfinder of the camera you will see a bar like in the picture, which has -2 -1 0 1 2
sony_dslr_500px_dslr-a350_back_lg.jpg


That is the meter. When its a 0 its perfectly exposed. When at -2 its under exposed, and when at +2 its over exposed.

To take a meter reading, you can use TV or AV mode to help calculate what you need. If in AV choose your aperture you would like (DoF) Half depress the shutter button and you will see the meter stick to 0 as it has automatically calculated the shutter speed to get the perfect exposure.
You can the switch to Manual and then dial in the settings you used for AV mode and then adjust the shutter or aperture to suite the light changes.

As the meter starts moving to the left slow the shutter speed, and vice versa.

Hope this helps its a very basic guide and should help you get to grips with using it in fully manual.
Matt
Click to expand...

Ah, ok that's starting to make sense!
I never used this could be used for that purpose :nuts:

Thanks for posting that, nice one.
 
A new skill learn't by me today!!
It works :lol:

Thanks for that, a top tip.

Just one more daft question :bang:
Why use auto mode?
What benefit does it have over AV mode?
 
andy_fozzy said:
I never used this could be used for that purpose :nuts:

Thanks for posting that, nice one.
Click to expand...

That's the only purpose its for, Andy!! What were YOU using it for?? ;) :lol:
 
andy_fozzy said:
A new skill learn't by me today!!
It works :lol:

Thanks for that, a top tip.

Just one more daft question :bang:
Why use auto mode?
What benefit does it have over AV mode?
Click to expand...

None that I can think of... it doesnt enable you to do ANYTHING yourself.
 
*SCREAMS*

SORRY - I didn't mean auto, I really meant MANUAL :nuts:
(I'm in holiday mode today!!)
 
andy_fozzy said:
*SCREAMS*

SORRY - I didn't mean auto, I really meant MANUAL :nuts:
(I'm in holiday mode today!!)
Click to expand...

Good god man.... you couldnt have been further away!!! :D

I personally think that everyone should LEARN & KNOW how to use their camera in manual. If they dont use it like it everyday then all well and good but they should be ABLE to.

AV means aperture priority... you choose the aperture you want.... depending on the depth of field you want for that photo (ie, how much before and behind the subject are in or out of focus) that is what the aperture controls.

The shutterspeed is then automatically set by the camera so you are still using your chosen ap and it will give you a good exposure. You can change your aperture to your hearts content and the camera will alter the shutterspeed accordingly.. keeping the exposure the same. SO far so good????
 
Shutter priority (TV) means you set your chosen shutterspeed for what you want..................fast speed to freeze movement.. or slow speed to make a waterfull blurry with motion blur for instance...... and the aperture is automatically set by camera to expose correctly.
You can change speeds and the camera sets correct aperture.


Exposure compensation = if the camera sets these and you think the picture looks a bit bright... you can set it to -1 for instance and it will be a bit underxposed but just how you want it. (this compensation will stay on though... so watch it for later pics!!)
 
MANUAL. You set your camera to the aperture and shutterspeed that you are sure will give you the outcome you want and it will stay there. With the otehr modes the metering moves as you move the camera about.. but manual it stays where you put it.

For instance. if you meter on a peice of grey pavement it may show the meter at the middle point... as the camera will try to show evverything as 18% grey.

So if there is somethng in that pic that is bright white the camera left to its own devices would tone it down to 18% grey. so you have to tell the camera that the white is supposed to be white which is nearly 2 stops above. So you roll either wheel (ap or shutter) in manual and thenn your resulting pic will be on the white article showing white.
This works the same with other tones. meter from grass/leaves and turn the meter - 2/3 and things will all fall into place etc etc.
 
You're welcome. :thumbs:
 
DiddyDave said:
PS - don't EVER now post a shot that's not perfect exposure without a damn good reason for doing so !!![/I]

:lol:
Click to expand...

b****r!....shot myself in the foot good and proper now then haven't I!!! :D :lol:
 
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