Pablo said:
Hello trigger happy folk,
Can someone explain to me what a camera changes when you change exposure compensation ?
It doesn't change the aperture, shutter speed nor (I believe) the ISO.
So, what does it do to achieve the result ???
Ther reason I ask is that my D70 manual page 86 states that the aperture and shutter setting remain.
Out of curiosity I happened to be using my 20D and thought, "ok I will look and see"... it altered the fstop......
Excuse my ignorance as I don't use the function, just like I don't use the settings for the head,hills,tulip etc
Do I deserve a flame for not doing tests :cry:
Cheers
Damn hell you should get flame and be told to go RTFM!!!! Shame on you...using a D70 and a 20D and still not sure! heheheh....tsk tsk tsk..
Gee...no reply at all till this early evening....heh.okay here's my rant on it..take it how you like with it. Say you caught me in a good mood and since I just finish my work at the office and feeling abit too free for my own good, let me spin you a tale of what I think should explain away the mystery of the exposure compensation dial as best I can.....if I got it all wrong,..... I should get flame too I guess..heh
Okay, as plain as I could make it...the exposure compensation mode is the means for you to "trick" your camera into thinking the scene or subject you are shooting is too bright or too dark. In a way you could say you are recalibrating your lighting meter to read the lighting brighter or darker. Confuse still?
Normally I would say we ( or maybe I should just speak for myself and say "me") use this more often with automatic program mode, Speed Priority or Apeture Priority. Yes you could use it with manual mode too but let's yak about manual mode in the last bit if I am in the mood still.
Let's yak about the Auto Modes first. Take Apeture priority as an example. As you know Apeture priorty means if you set the F-stop at F8 to get the best DOF you prefer for the shot, it will be at the expense of whatever shutter speed is selected by the camera to correspond to your (pre-set) F8 and light intensity of the scene or subject you are photographying. Thus depending on what you shoot...the shutter speed could be the slowest to the fastest speed your camera has to offer. But the apeture stays at F8.
Problem is, say you are shooting a snow scene where there has alot of bright areas due to the snowbeing everywhere. (could also be a sun reflected sparkling water pond) With a scene like that you know what will happen right? Your camera meter matrix will try to computate and adjust for the intense brightness of the scene and selects a higher shutter speed since your fstop is fixed at F8. Well add to that you have a friend standing in foreground with the bright snow in background? Result? The picture will have your friend looking dark as a shadow and you can hardly make out his/her face but the snow looked well exposed. This is because the meter is compensating for the rather bright background when it average out the exposure of the entire scene. Meters are not all that smart sometimes especially under difficult lighting. So human need to intervene. How do you get around it and create a longer shutter time to capture more details of your friend while still retaining your f8 in apeture priority mode? Well you use the compensation dial. By adding, 2 stops (you turn the dial till you get +2 reading in your viewfinder) you are tricking the camera to change the shutter speed by +2 stops slower. Slower means longer exposure thus you have an even brighter background scene but then your friend's form and face would have enough light to register on film or the CCD. Thus you have a picture that more balance out with your friend's face being more clearly seen.
The reverse is true too if say you are taking a picture of a group of people wearing black robes with only their face shown.(Llke those graduation gowns) Now if you try to take a picture of them, head to toe and the scene is made up of 80% black robe then light tones, the camera's overall metering might select too slow a shutter speed to compensate for too much dark tones. The camera does not know the difference between a dark under expose scene or a piece of dark cloth. So, if we just take the shot base on the camera selected choice, you will find the picture will be abit over exposed. The robes will not look black but more like dark grey and the face tone will be abit too light and looks over exposure. In that case, we need to use the compensation dial to get the camera to fire at a higher shutter speed. ( remember this is apeture priority so the fstop is at F8) thus we will choose to shoot the shot at 2 stops faster for example. So we dial it to -2. Now when you do this in Apeture priority mode you will notice the shutter speed will jump by two stops lower or faster depend on both scenarios I mentioned. ( In shutter priority it changes the f-stops)
To test this exposure compensation thing in real life, just put your camera on a tripod. Aim it at a scene with some light and dark stuff and do all your shooting from this one visual point. Just take the first shot as it is with the compensation dial set to +/-0. then turn then at incremental of +1 and fire off one shot after each turn. Then do the reverse setting of -1 -2 -3..etc. Now look at the pictures and you will understand what I mean. And what the compensation dial is for.
And if you set it up to shutter priority..well that is the opposite. A fixed shutter speed means a varying f-stop. I am not going to get into it but suffice to say it is very similar in concept to apeture priority. Just think it over and do your own homework and I think you know what I mean.
Another use? The most common use for the compensation as I see it is with DSLRs. Every once in a while you see newbies asking in this forum why D70 camera's exposure seem to be under exposured. Well that is because, it is easier to SALVAGE a underexposed shot then an overexposure one. By default Nikon set their camera to capture scene abit darker. If you don't like that, you can do what me and other folks do. We use the compensation dial to dial in +0.3 and keep it there all the time. In so doing, we are tricking the camera to always take the picture abit brighter by +0.3. There is abit of a difference just by adding that bit. Some would add +0.5. (Nikon D70 allow you to set the dial to change in incremental of 0.3 or 0.5 in the setting mode) So thats another use for the exposure compensation.
Of course there will be days if you are shooting the in a bright seaside with white shimmering sand which can effect your camera metering like snow does, so you set that compensation to +1,+1.5 or +2 or +3..etc. depending on how bright it is, keep to that setting for as long as you keep shooting the same kind of scene.
Btw.... I call it tricking the camera okay. I better state that now as there are some very anal retentive indivdual here who would nitpick rules, law or term used for the heck of it. In any case, I am sure some other folk here will have other way of describing it but for me it a more "visual" way of helping me remember it.
I also use the compensation dial for tricky product shots although the D70 have a auto bracket mode all built in the camera. You can set your D70 to auto bracket. Autobracketing , if you are not aware is about take a shot as the exposure meter sees the scene and lighting but it will also take two more shots with the second being over exposure by anything from +0.3 to +3 and the third one in -0.3 to -3. You can set that up in the camera setting. Once set, it is real easy, simple fire off 3 shots in a roll and the D70 will take care of the bracketing. Again this depend on which priority setting you choose.
But for me, I like to do the exposure compensation myself so that I can do more then just a 3 shots bracket. The automatice bracking feture in D70 is only for up to 3 shots. So if you want more or less, you have to dial each compensation setting yourself after each shot. I like this as it is good in case I forgot to reset the camera back and carry on shooting other things later on......then accidently end up with the camera taking under, over and normal shots in sequences. heheh..And yes it did happen to me twice..come to think of it. Lucky it was only +1.5 stops difference so can still salvage it with photoshop.
Now with full Program mode,(P mode) this one is sometime abit hard to see if your compensation is only small increment like -/+0.3. You have to turn it one full stop +1/-1 or more either way before you can see a change in the numbers to both shutter apeture setting. In Program mode, it average out the compensation you dial in to both the shutter & apeture!!! It does not do either one ONLY but changes them both together!. Hope you are not confused by that. Me itching to go home now from the office so abit impatient to finish my long winded ranting again heheh..
You can use this in manual mode but I see very little reason to do so since you can manually control how much speed versus apeture to creat an over or under exposed shot. Now if you don't know how to use your camera in full manual mode...that is another lesson for another day and I will flame you like hell before I teach you on that!!!!! heheh.
Re-read some part of this as I do tend to submit and then rework it. A dyslexic curse I am afraid...so I tend to rewrite my stuff all the time. Sorry
Okay time to head on home for din din.
