P setting and A setting

[ventodimare]

Hi All,
in my Nikon D90, when I set P, the camera selects the right shutter/diafram combination for that exposure. Rotating the dial allows me to select different combinations of diafram/shutter at the same exposure. Playing with the dial I can change the depth of field.

When I set A in my Nikon, I play with the dial to decide the depth of field and the camera selects the shutter speed accordingly.

If my goal is to work with the depth of field, I don't see any difference between the 2 methods above.
If I set P then I'll play with the dial to change the depth of field.
If I set A, I will play with the dial and the camera will set the shutter speed for me.

Am I missing something here?

Cheers

[Tringa]

In both cases you are altering the aperture so are in effect working in aperture priority, irrespective of whether the camera is set to P or A.

The only difference I can guess at is when set at P the camera may have some inbuilt parameters that either prevent or warn you from taking a shot at too slow a shutter speed, but that is just a guess.

I'm sure others will know.

Dave

[Ken MT]

I am not a Nikon user, but with a Canon, if I select P, then it reverts to its own setting after I take a shot, while with Av, it stays on the same aperture until I change it, even if I turn the camera off.

[Letrow]

Francis, I think you are right. P gives you a number of shutter/aperture combinations that are set by fixed parameters. Some people really like P, because changes are so easy to make. I use manual mainly nowadays on my D7000 and in the past I used A. Manual gives me exactly what I want though and automatic ISO will take care of the rest for me. The combination is pretty flexible as well.
If you want ISO to be fixed I would say P will work pretty well for you.

[revi]

One difference I see is that with the «P» setting, any change in light conditions can change your aperture, and thus your DoF. This won't happen with the «A» setting (shutter speed might drop too much, but that's another problem). Not an issue in studio settings, but it could be important outdoors.

Remco

[rpcrowe]

I definitely use "A" priority when it is important for me to keep the aperture (and thus the DOF) constant. This is especially important when shooting images that are intended for compositing such as in panoramas and HDR imagery. I will pretty well use "A" mode in most other shooting.

IMO, it is really six or one or a half-dozen of another when shooting individual shots whether you use "A" or "P" - as long as you are cognizent of the parameters of your exposure such as ISO, aperture and shutter speed. It is easy to switch the parameters in either of the above modes.

However, when changing the exposure parameters when you have selected the "P" mode, the camera will revert back, in subsequent shots, to what it considered correct parameters before you changed those parameters. When changing shooting parameters in the "A" mode the camera will retain the parameters selected by you in all subsequent shots of the same scene.

This is quite advantageous when shooting multiple shots in the same general venue. For most of my shooting, I like to shoot at the sweet spot of my various lenses (usually 2-stops below maximum aperture). However, when I either need extra DOF or if I want a narrow DOF for selective focus, I will adjust the aperture accordingly. This is also true when I am shooting in dim light and need the fastest shutter speed possible, when I am shooting action and want the fastest shutter speed possible or when I want the slowest shutter speed possible.

However, when I am driving back roads with the high possibility that I will see some wildlife; I keep my camera within grasping distance (my wife is very willing to hold the camera for me when she is a passenger), I have the longest focal length at my disposal mounted, I have the ISO set at 320 (which will give me excellent results but is a bit better in low light than my usual ISO 160) AND... I will have the mode set at "P" because it will give me the highest chance at a usuable image for a quick, off-the-cuff, shot.

[William W]

If my goal is to work with the depth of field, I don't see any difference between the 2 methods above.
If I set P then I'll play with the dial to change the depth of field.
If I set A, I will play with the dial and the camera will set the shutter speed for me.

If your goal is to manage the DoF then, whilst both methods can produce the result you want: generally the better Camera Mode to choose use would be “A” (Aperture Priority).

There are two main reasons applicable to mostly all “P” and “Av” Modes:
1. (already mentioned) once the Aperture is chosen in Aperture Priority Mode, the camera stays at that aperture until another aperture is selected.
2. The functionality of many cameras is that a manual override of exposure (Exposure Compensation) is easier to “ride” in Aperture Priority Mode.

The above is a general comment applying to most cameras – you should check your specific camera’s functionalities.

Another way to look to the question is that we can also manage the DoF by using the Shutter Priority Mode – but the functionality of doing so is more cumbersome and that cumbersomeness is more obvious.

WW

[Fit]

Francis- I have a D90. While it is true that using P allows you to fiddle with the aperture, the number of allowable combos is/can be very limited.
For example, while using the camera last night in a dark setting, I often had only two choices of A/S combinations the camera would allow me to choose.
In "A" I had the full range to select.

[Shadowman]

I definitely use "A" priority when it is important for me to keep the aperture (and thus the DOF) constant. This is especially important when shooting images that are intended for compositing such as in panoramas and HDR imagery. I will pretty well use "A" mode in most other shooting.

IMO, it is really six or one or a half-dozen of another when shooting individual shots whether you use "A" or "P" - as long as you are cognizent of the parameters of your exposure such as ISO, aperture and shutter speed. It is easy to switch the parameters in either of the above modes.

However, when changing the exposure parameters when you have selected the "P" mode, the camera will revert back, in subsequent shots, to what it considered correct parameters before you changed those parameters. When changing shooting parameters in the "A" mode the camera will retain the parameters selected by you in all subsequent shots of the same scene.

This is quite advantageous when shooting multiple shots in the same general venue. For most of my shooting, I like to shoot at the sweet spot of my various lenses (usually 2-stops below maximum aperture). However, when I either need extra DOF or if I want a narrow DOF for selective focus, I will adjust the aperture accordingly. This is also true when I am shooting in dim light and need the fastest shutter speed possible, when I am shooting action and want the fastest shutter speed possible or when I want the slowest shutter speed possible.

However, when I am driving back roads with the high possibility that I will see some wildlife; I keep my camera within grasping distance (my wife is very willing to hold the camera for me when she is a passenger), I have the longest focal length at my disposal mounted, I have the ISO set at 320 (which will give me excellent results but is a bit better in low light than my usual ISO 160) AND... I will have the mode set at "P" because it will give me the highest chance at a usuable image for a quick, off-the-cuff, shot.

A mode would be a necessity if you are setting up a bracketed shot. You wouldn't want your DOF changing during your shot would you?