(Auto) P,S,A and M… Huh?
Or..Lions & Tigers & Bears, oh my!
In continuing our discussion about DSLR’s, the above cryptic letters are easy to decipher.
They stand for (Automatic), (Program) (Shutter) (Aperture) and (Manual).
That’s the easy part. Learning how when & why to use them is a little more daunting.
Let’s start with (Auto) or Automatic.
This is by far the easiest mode to use. It is also the most confining to our creative desires.
In (Auto) mode, the camera is making just about every decision concerning exposure.
(Auto) mode sets the shutter speed and the aperture automatically.
This mode will even pop up the little built in flash if it feels there is not enough light to properly expose the subject.
Even some of the most expensive DSLR’s have this mode. (Why I do not know)
Full (Auto) mode does not allow the photographer to intervene with the settings.
To be fair, I suppose this mode is ok if we are just starting out exploring our new DSLR. After some time however, this mode (should) get very little use.
Why?
(Auto) mode attempts to figure out the proper exposure. Most of the time it gets it wrong!
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| AUTO mode misses the mark |
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| Taking control with manual mode |
Why? Every new DSLR has a built in light meter to measure the amount of light falling on the recording sensor.
While these light meters are quite sophisticated, they have no idea how you want to expose the subject unless you intervene in some way.
Ex: Let’s pretend you are photographing your best friend on a bright sunny day at the beach. The waves are crashing ashore, the water color is azure blue and everything is right in the world.
When you look at what you just captured, the scene beyond your best friend looks great! But your best friend is nothing but a dark shadow! Can’t see their face! Hmm? What happened?
1) There are techniques to overcome this problem..see my May blog entry “Use myflash in the day?”
Your friend in the picture occupied a small percentage of the entire image with the brightly lit beach scene occupying the lion’s share.
Your camera metered properly for the bright beach scene and in doing so (Under-Exposed) your best friend!)
Ex 2: You’ve come upon a deep lush green forest with trees so vertical you know this will be a National Geographic winner. The sun streams down beams of pure golden light through the branches.
With your trusty DSLR (set to Auto mode) you snap the picture. Yuck! The entire picture looks way too bright, the color is off and the beams of light have disappeared.
What happened? You guessed it. The dumb light meter didn’t read my mind! The light meter worked properly, but it saw something you didn’t see. The light meter saw a darkly lit subject and attempted
to compensate by allowing too much light to enter the camera.
What’s a photographer to do?
Stop using (Auto) mode. You have a DSLR now, not a point and shoot. It’s time to take control with one of the other modes available to you.
I’m not sure why DSLR manufacturers included (Auto). Purchasing a DSLR and using it on Auto mode all the time is akin to buying a Ferrari
and never getting out of 1st gear.
P is for PROGRAM
(Program) mode is similar to Auto mode in that it does most of the heavy lifting when figuring out a good exposure but with some important differences.
With Program Auto mode, we now have some control over shutter speed or aperture.
If we do not want let’s say f/8, we can choose another such as F/4 while the camera recalculates the necessary shutter speed to give us hopefully a balanced exposure.
The opposite is also true. If we don’t want a shutter speed of 1/250th , we can change it to let’s say 1/125th as the camera will now recalculate the needed aperture.
There are limits to how far a lens will open or how slow a shutter speed you can use before a tripod is necessary.
(i.e) 1) If your lens maximum aperture is f/4 and you select a shutter speed that requires f/2.8, the lens can not physically accomplish this feat.
2) Selecting a 1/1000th shutter speed, the camera may calculate a aperture (lens opening) that is beyond what the lens is capable of.
There are ways around this that I’ll save for another installment.
So, (Program) mode attempts to figure out a good balanced exposure automatically without too much intervention from the photographer.
The neat aspect of program mode is that you have some control over aperture or shutter speed, not both at the same time. That feat is reserved for full manual
which I get too shortly.
S & A Modes
I include these two modes together because they work opposite each other.
They are considered one of the (auto) type modes where the photographer chooses one with the other adjusting itself accordingly.
Shutter Priority mode is you the photographer choosing a shutter speed. The camera then calculates the needed (aperture) to provide a good exposure. Aperture Priority as you guessed is the opposite. You choose a aperture and the camera will pick the needed shutter speed.
Once again we need to remember we are limited to some extent by the design of the lens (maximum aperture) or a shutter speed too slow which will require a tripod for in focus images.
Sports photographers often require a fast shutter speed to freeze the action, so you might think they choose shutter priority and let the camera figure out the aperture.
Well hold on Pete; why not choose a wide open aperture? Would that not force the camera to pick a faster shutter speed?
This is one of those “aha” moments! You bet. And this is often what people do who wish to control their Depth of Field while maintaining a fast shutter speed.
We’ll talk about depth of field another time. For now, the basic definition of depth of field is what is in focus in front of the subject and what is in focus beyond the subject.
It is a heavily talked about subject among photographers. The subject gets complex rapidly since DOF depends on the lens focal length, distance to subject and our focus point.
Generally speaking, the more we open our aperture (more light allowed in), the narrower the DOF (less in focus in front of and beyond our subject.
Personally, aperture priority mode is most useful to me and many other photographers for the fact that controlling DOF allows us more creative freedom.
Portrait photographers love this mode since their subjects stand out well against what might be a busy looking background. The background is now nicely out of focus, blurry if you prefer.
So which mode do I use?
It depends on your goal, your subject, your creative expression.
If you MUST freeze the action, you might want Shutter Priority as long as it does not exceed your len’s optical ability.
Although I prefer to have complete control over my camera, there are times when I don’t have time to set it up the way I want. It is in these times I usually choose aperture priority to deal with ever rapidly changing conditions such as street photography where one moment I am shooting a pic of someone is bright sunlight when all of a sudden I see some action taking place in a low light area; maybe an alley.
My aperture remains constant with the shutter speed changing to compensate for the light levels.
So far, all the modes we’ve discussed have a (Automatic) element to them. In other words, the camera is making a decision depending on what we input, be it selecting the aperture or shutter speed or none of those (Full Auto) Remember full auto? Yuck!
With Auto, P, S or A modes, the exposure is being influenced by the camera’s light meter. It’s kinda’ like a traffic cop who holds his hand up and says “you can go, but you must wait”
With a traffic cop intervening, we have little choice unless we break the law. Luckily, with a DSLR, we can break free of ALL control and use….
** Exposure compensation is not included in this article
(M) is for MANUAL
This is far and away my most favorite of all modes. It allows so much freedom I don’t even consider it a mode really.
Full manual control allows the photographer to choose both the shutter speed AND the Aperture independently of each other.
In other words, one does not affect the other. How cool is that?
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| Minimum DOF and full manual w/ flash |
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| More DOF by choosing a smaller aperture |
Why is this a good thing?
Remember that deep lush green forest? Well; now I have choices. I can tell the light meter in my camera to take a hike.
Now I get to choose the aperture AND the shutter speed and never have to worry about the light meter over riding my commands.
If I want the photo to be dark; it will be dark. If I want it really bright; it will be bright.
I get to adjust the shutter speed anywhere I want. Same goes for the aperture.
Adjusting one will NOT cause the other to change.
As one example; if I want a subject in focus, but everything behind blurry; I can do it by choosing a wide open aperture.
At the same time I can choose a shutter speed for any reason I decide. Perhaps I want a slow shutter speed to blur moving traffic beyond my static unmoving subject. No sweat; I just
choose a slow shutter speed.
The next reason we should want to learn to use our DSLR’s in full manual mode is because we know how stupid our light meter is inside the camera.
The light meter thinks I want a normally lit scene..I DON’T!
As good as the built in light meters are in today’s camera’s, they have yet to invent one that knows what I want or how I picture the image in my mind.
Try all the modes.
Eventually you will want to try Full Manual which affords the most control of all the modes.
As always I will try to get to all the emails.
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