Exposure compensation and AF modes (450D users in particular please read!)

S

Set_Nights

Messages
387
Edit My Images
Yes
I think I have mostly grabbed the absoulte basics of using my camera but have a few things to clear up.

How do I change the exposure compensation on my 450D? I can see the exposure compensation scale (currently set to -2!) but I'm not sure how to access it or change it. More importantly when should this be used instead of ISO/shutter speed/aperture?!

What is the difference between AF focussing modes: Oneshot, AI focus and AI Servo?

When should you use any of the metering options other than Evaluative?

Lastly, and this may sound stupid, but what does the button on the bottom left (when holding camera to your eye, ie the opposite side from the grip and shutter button) of the body do?!
 
Without being too cheecky, RTFM - It's all there and explained well.
 
There should be a couple of little buttons marked + and - on the rear top right corner if I remember correctly.

Exposure compensation is used in conjuction with the Av or Tv modes when you want to over or under expose in comparison with the levels automatically determined by your camera.

One shot holds the point of focus while the shutter button is half depressed. It allows you to focus on a subject and then reframe with your subject off centre.

AI servo will keep refocussing while the shutter is half depressed - great for fast moving action.
 
EOS_JD said:
Without being too cheecky, RTFM - It's all there and explained well.
Click to expand...

Cheecky is fine and you're probably right... but what is RTFM?

Livingdeadboy said:
There should be a couple of little buttons marked + and - on the rear top right corner if I remember correctly.

Exposure compensation is used in conjuction with the Av or Tv modes when you want to over or under expose in comparison with the levels automatically determined by your camera.

One shot holds the point of focus while the shutter button is half depressed. It allows you to focus on a subject and then reframe with your subject off centre.

AI servo will keep refocussing while the shutter is half depressed - great for fast moving action.
Click to expand...

Ah, It makes sense to be using it in Av or Tv instead of manual actually! Hmm, I can edit exposure compensation in Av or Tv just by clicking the button you mentioned and moving the dial but I can't do this in manual and in manual I seem to be stuck at -2 (why?) :suspect:?

Regarding AF... so with One shot if you focus on a single point and then move the camera (I assume only left and right and up and down rather than back and forth?) it keeps the focus point where as AI Servo doesn't? What about AI Focus? What would be best to use for panning?
 
Donki said:
Read the £$%@*&% manual :)
Click to expand...

Lol, I guessed it was read the something manual but couldn't figure out what the F was for! I'm obviously far too polite/naive :p. I got my camera back in 2008 (but only recently started shooting out of auto) and I'm not sure where the manual is :(. I've had a quick look on the canon website and they have a brochure for the 450D but I can't find a link to the manual. Any help?

Edit: Nevermind, I have found the manual on a diferent part of the site so I shall search for the function of my elusive button! Any help regarding the above post/problems would be much appreciated though.
 
Last edited:
One shot is for still subjects, AI servo is for moving subjects, AI focus will switch from still to moving subject, if the still subject starts moving, it will track it to keep it in focus.
 
wontolla said:
One shot is for still subjects, AI servo is for moving subjects, AI focus will switch from still to moving subject, if the still subject starts moving, it will track it to keep it in focus.
Click to expand...

Ah, ok :) thank you.

I have answered all my questions now apart from why does it show me -2 exposure compensation when I'm in manual? You can't edit it in manual so I'm not sure why it's showing this :|.
 
Because you need to set the correct exposure - -2 may be correct if you are shooting a subject against a dark black wall!

there is actually NO exposure compensation in nmanual. All the meter is doing is letting you know it "thinks" you are 2 stops under exposed according to the settings you are using and the subject it sees in front of it.

Make sure you set the exposure correctly for what you see not for what the camera does - In many situations the meter is fooled by the light (or lack of it)
 
EOS_JD said:
Because you need to set the correct exposure - -2 may be correct if you are shooting a subject against a dark black wall!

there is actually NO exposure compensation in nmanual. All the meter is doing is letting you know it "thinks" you are 2 stops under exposed according to the settings you are using and the subject it sees in front of it.

Make sure you set the exposure correctly for what you see not for what the camera does - In many situations the meter is fooled by the light (or lack of it)
Click to expand...

Ah, ok :) thank you very much. I just wondered why it was bothering to show me the -2 considering that I can't actually edit the exposure compensation itself but that makes sense :). Thanks a lot!
 
Set_Nights said:
Ah, ok :) thank you very much. I just wondered why it was bothering to show me the -2 considering that I can't actually edit the exposure compensation itself but that makes sense :). Thanks a lot!
Click to expand...

In Manual, if you move one of the exposure controls by +2 stops, the viewfinder indicator will change to zero. It's just telling you how to set (what the camera thinks is) correct exposure, and how far off you are.

It's a very useful feature if you're shooting in manual on a cloudy day for example. You have set the exposure just the way you want it, and then you note what the viewfinder pointer reads - say +1.3 stops. Now at any time you can glance at that, and if it's moved to +0.6, it could be becuase a cloud has come over, or the subject has moved into shade, or whatever. Could be all sorts of reasons, but it's a useful warning for you to double check it's still what you want.

If you watch pros at a sports game or maybe a race track, you'll often see them pointing their big long lenses at the ground for apparently no reason. What they're doing is checking their manual exposure setting, by referencing a subject of a known tone. It could be any tone, but grass or tarmac are are always good and handy.
 
EOS_JD said:
there is actually NO exposure compensation in nmanual. All the meter is doing is letting you know it "thinks" you are 2 stops under exposed according to the settings you are using and the subject it sees in front of it.
Click to expand...

This is interesing and I am not sure how Canon's deal with this. But on a D90 leaving EC set does effect manual shooting.

For example.

I took a picture in A and no EC dialed in, picture was fine.

Change EC to -2.0 and then got a darker picture as expected.

Changed to M and centred the meter, picture was the same as A + EC -2.0.

Set EC back to 0.0 and centred the meter again, picture was the same as A with no EC.

So on a D90 you need to remember to set EC back to 0.0 before going to manual.
 
EC is not related to M exposures - It's only required for Av ot Tv (or whatever the Nik equivs are.

I can't see how it can be related to a Manual exposure that you set.

How did you set the EC back? You must Manually change the shutter speed! So you have not added EC you have changed the exposure in M

That is normal.
 
EOS_JD said:
EC is not related to M exposures - It's only required for Av ot Tv (or whatever the Nik equivs are.

I can't see how it can be related to a Manual exposure that you set.

How did you set the EC back? You must Manually change the shutter speed! So you have not added EC you have changed the exposure in M

That is normal.
Click to expand...

I'm not familiar with Nikon, but this is not changing the manual settings in anyway, just the viewfinder indicator of 'correct' exposure. Just a different way of configuring the same thing.
 
Hoppy I'm not used to Nikons either but it can't be different - I've discussed this too many times with others
 
EOS_JD said:
Hoppy I'm not used to Nikons either but it can't be different - I've discussed this too many times with others
Click to expand...

Why can't it be different? Just a different way of showing the same thing. I can see logic in both ways and I know that Nikon does express metering slightly differently, with macro at 1:1 for example.

I don't know, but that's what Leaky is saying :shrug:
 
Because M is exactly that - it's not affected by exposure compensation. Maybe I'm wrong (not the first nor the last) :)
 
EOS_JD said:
Because M is exactly that - it's not affected by exposure compensation. Maybe I'm wrong (not the first nor the last) :)
Click to expand...

It's not the exposure settings that are changed, they are locked in manual - just the viewfinder indication. I think that's what he's saying, the way I read it anyway :)

Basically, if you are using the on-board meter to set the exposure manually, then you need to ensure the compensation dial is set to zero, or when you use the viewfinder indicator and get that centred, it will be out by whatever the compensation dial is set to.
 
Last edited:
In a canon there is nothing like that though - You can't set EC in M.

I see what you mean though and whilst I understand it seems odd that in M something else is affecting the exposure.
 
HoppyUK said:
It's not the exposure settings that are changed, they are locked in manual - just the viewfinder indication. I think that's what he's saying, the way I read it anyway :)

Basically, if you are using the on-board meter to set the exposure manually, then you need to ensure the compensation dial is set to zero, or when you use the viewfinder indicator and get that centred, it will be out by whatever the compensation dial is set to.
Click to expand...

This is exactly what I think it is doing.

It is handy if you know your camera is always slighty under exposing, you can set say -0.3 or -0.7 in EC. Then when you are in manual you can just centre the meter, you don't have to worry about adjusting to the first or second mark to compensate.

But you have to be aware if you have put a bigger EC in, like say -2.0 and remember to change it back.
 
leaky5 said:
This is exactly what I think it is doing.

It is handy if you know your camera is always slighty under exposing, you can set say -0.3 or -0.7 in EC. Then when you are in manual you can just centre the meter, you don't have to worry about adjusting to the first or second mark to compensate.

But you have to be aware if you have put a bigger EC in, like say -2.0 and remember to change it back.
Click to expand...

I assume all of this is in reference to Nikon only?
 
EC is M pretty much. In Av or Tv if you decrease the exposure by one stop using EC then you are either reducing the aperture by one stop or increasing shutter speed by one stop and vice versa with increasing exposure.
 
You must log in or register to reply here.
Back
Top