basically... to achieve a maximum level of detail, where possibly wanted.
What do stops actually mean? and var questions
- Thread starter weltweit
- Start date
basically... to achieve a maximum level of detail, where possibly wanted.
cybertect
It's grim up north (London)
i'm just thicker than normal today
i get the stops now, sort of, but can you explain the point of exposure compensation and why you would use it when you have the other variables to choose from?
Your camera is probably thicker than you.
Say you're taking a picture of someone stood in a spotlight on a dark stage. The person is considerably brighter than the background.
Your camera's meter is likely to calculate the average exposure across the whole scene, which is mostly darker than the item in the frame you're actually interested in, the person. You may end up with a well exposed stage and an over exposed performer.
To counteract this, you'd dial in some negative exposure compensation (resulting in a faster shutter speed, smaller aperture or a bit of both) to expose correctly for the person and making the background (which you care about less) a lot darker.
leaf, curtain, fore or rear?
I have viddy felch to watch!
A discussion of the merits or otherwise of the various shutter systems in relation to the subject would be expected
Your camera is probably thicker than you.
Say you're taking a picture of someone stood in a spotlight on a dark stage. The person is considerably brighter than the background.
Your camera's meter is likely to calculate the average exposure across the whole scene, which is mostly darker than the item in the frame you're actually interested in, the person. You may end up with a well exposed stage and an over exposed performer.
To counteract this, you'd dial in some negative exposure compensation (resulting in a faster shutter speed, smaller aperture or a bit of both) to expose correctly for the person and making the background (which you care about less) a lot darker.
that makes sense but what if you simply underexposed the scene. Is that doing the same thing?
Also...
would using spot metering create the same effect in this scenario because if i was to shoot what you described, i'd probably set up the metering differently rather than think of the EV settings?
hope i'm making sense... its been difficult doing the basics in real life today
cybertect
It's grim up north (London)
Yes, that's exactly what it does. Exposure compensation allows you to over- or under-expose compared with the camera's built in metering.
I deliberately left out spot metering so it wouldn't confuse, but yes, it would allow you to do the same thing if you have it available on the camera and you can interpret the result correctly.
Even then you may have to dial in some EC unless you happen to have an 18% grey card in the scene - if you take a spot reading on caucasian skin, you'll probably want to increase the exposure by 1 stop.
Taking an incident light reading where the performer is on stage should be the most accurate method.
weltweit
Well-Known Member
That is in effect what you are doing with the exposure compensation.
If you are using matrix metering, the camera meter will try to expose any scene as overall 18% grey.
But in the example used the background (the majority of the scene) was very dark if not black. To compensate for that (exposure compensation) you decide to let in less light than the meter on its own wants to let in. So you compensate perhaps -0.5 or -1.0 to let less light into the camera than the meter intended.
Also...
would using spot metering create the same effect in this scenario because if i was to shoot what you described, i'd probably set up the metering differently rather than think of the EV settings?
hope i'm making sense... its been difficult doing the basics in real life today
Using spot metering (and perhaps manual) is a different way to achieve the same result. If I have time I like to spot meter around a scene and decide my manual exposure based on what I see with the spot meter.
Yes spot metering in manual is fine, just another way to get the same result.
eta: Oh perhaps you mean spot metering in auto .. could use that and meter on the performer I suppose.
I tend to spot meter in manual because (among other things) I can take a reading from the brightest point and set that at the maximum my camera will expose then meter around the rest of the scene and see which parts will go to black.
weltweit
Well-Known Member
Shooting in Manual with a spot meter .. I think gives me most control.
I get a meter (in the viewfinder) that shows me how bright (or dimly) the camera, in its current settings, detects things at the spot.
Then if the meter flies off the scale on the bright side (perhaps at settings f4 1/250) I can whizz either f4 to f6.3 or f8 (or I can change 1/250 to 1/300 or 1/500) and then move the spot meter over the bright spot again and see if it has come down into the realms of brightness which is exposable by my camera (i.e. where there will still be detail and it will not have all gone to white).
So perhaps I decided my settings at f8 1/250, now I can still run my spot meter around the scene and see how dark the darker areas are going to be, those that fall off the dark end of the meter may tend to black but perhaps some details may be recoverable in PS.
I like to spot meter in manual.
It was the first way I learnt to use the camera.
It took me many years before I learnt anything about exposure compensation in matrix.
I get a meter (in the viewfinder) that shows me how bright (or dimly) the camera, in its current settings, detects things at the spot.
Then if the meter flies off the scale on the bright side (perhaps at settings f4 1/250) I can whizz either f4 to f6.3 or f8 (or I can change 1/250 to 1/300 or 1/500) and then move the spot meter over the bright spot again and see if it has come down into the realms of brightness which is exposable by my camera (i.e. where there will still be detail and it will not have all gone to white).
So perhaps I decided my settings at f8 1/250, now I can still run my spot meter around the scene and see how dark the darker areas are going to be, those that fall off the dark end of the meter may tend to black but perhaps some details may be recoverable in PS.
I like to spot meter in manual.
It was the first way I learnt to use the camera.
It took me many years before I learnt anything about exposure compensation in matrix.
thats alright. Quite glad that i was correct though
I think the main issue with the EV was that there are two types of way to do the same thing. When i under/over expose a scene, i tend to change the aperture or shutter speed in increments of thirds of stops which i can see through the viewfinder. However there is also the +/- button which is the same thing and i didnt realise that.
weltweit
Well-Known Member
It sounds like, like me you are shooting in M (Manual) mode rather than A or S or P modes.
Is that right?
Yep, pretty much all the time.
weltweit
Well-Known Member
Aha. Probably for the first 3.5 years with this camera I just shot manual / spot and got to know how to do that. It is still the most comfortable way for me.
However a couple of things happenned for me.
1) I discovered that a very good photographer who I know never used manual mode at all, everything was in auto (A S or P modes) and he used this thing called exposure compensation. His photos were (are) excellent so I knew it was "another way" to get the same result.
2) I discovered that I often did not have the time to spot around a scene and decide an exposure, sometimes (like photographing fast moving kids) I just wanted to point and click and let the camera make up its mind.
I started to experiment with A S & P modes and for much did not try exposure compensation at all. I found I could shoot kids outdoors with no compensation most of the time.
Slowly compensation started to make some sense and now I know - if the scene is dark compensate negatively (to let less light in and let the scene be dark in the resulting image) and if the scene is light (snow for example) compensate positively to let more light in and let the scene be light in the resulting image.
I am still most comfortable with spot .. but can now use compensation also.
I get it now. SO on A,S or P that's where you would use +/- button. Interesting... I'm gonna start experimenting with this as well, to see if there is any improvement in my shots.
I've read this but havent had the chance to experiment because i havent seen proper snow for aaaages, but it is said, if positive compensation is not applied then the white in the snow will look more of a grey.
Yup. Rollei light meters give readings in EV to, for extra ease.
stowpirate
skinflintish camera nut
no
Lenses normally have an optimum aperture setting which as a rule thumb on prime lenses falls in the f5.6-f8 region. What I mean by optimum setting is lens performance and sharpness is at its best. Not sure if you can apply this to modern zoom lenses as they are a design compromise. Wide open is one extreme setting as is completely stepped down - problems you get at the extreme settings are Vignetting(dark corners), barrel & Pincushion Distortion, not forgetting spectrum bends at slightly diferant rates as it is refracted through each element and reflections etc etc...... I wish I had never tried to get involved in this thread
gentlegreen
I hummus, therefore I am ...
so you need a three dimensional chart in your head - possibly animated. 
stowpirate
skinflintish camera nut
so you need a three dimensional chart in your head - possibly animated.
Yes - they used do a handy little calculator on a bit of card and even in the golden age of photography (1930-60ish) printed a dof chart on the camera body
weltweit
Well-Known Member
Yes, thats exactly what happens.
It actually happens with both light and dark scenes, if you dont compensate the camera (on auto) will produce 18% grey images [1]. So a dark image will come out grey and a light image also, if you don't compensate.
[1] this is kind of assuming you are using matrix metering across the whole image.
[2] If you wanted you could use (in auto) centre weighted or spot and you could auto expose on a part of your scene that you think is 18% grey, lock the exposure, recompose and fire. That is yet another way to get the same result.
cybertect
It's grim up north (London)
Zoom lenses behave in pretty much the same way as primes as far as sharpness across the entire frame is concerned as the aperture changes, usually peaking around f/5.6 to f/8.
This isn't always the case, the Canon 70-200 f/4L IS delivers almost maximum sharpness across most of the frame from the get-go at f/4, for example. You can barely tell the difference in this comparison (the-digital-picture.com's comparisons are a very handy way of eyballing how lenses perform).
It's not always a linear progression. You do get some lenses that deliver higher resolution in the centre of the image when wide open than they do a stop or two down, after which they will usually improve again.
To understand how any lens performs in terms of sharpness, you need to learn to read an MTF chart.
http://www.luminous-landscape.com/tutorials/understanding-series/understanding-mtf.shtml
Zoom lenses will change their distortion characteristics across the range of the zoom.
Aperture shouldn't have any effect on barrel or pincushion distortion, though.
TBH, much of this pixel-peeping for across-the-frame sharpness is likely to be of interest mostly if you're shooting landscapes on a tripod, for example. Sharpness at the frame edges isn't particularly important if you're shooting at f/1.4 and the subject is in the centre of the image, as the edges are probably going to be out of focus anyway. Other factors, such as control of depth of field, quality of bokeh (shooting wide open always produces nice, circular highlights, for example) getting a usable shutter speed and your general style of photography are probably going to play as big a part in your choices as the MTF chart.
e2a: though understanding how the lenses you use actually perform through experimentation can really help with your creative decisions.
weltweit
Well-Known Member
Indeed, I have a nikon 50mm f1.8 which is generally reconned to be pretty sharp. Anyhow, if you shoot into the light stopped down past f8 (perhaps at f11) it produces a purple circle in the middle of the resulting image! Go more open, perhaps to f5.6 and it dissapears!
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