Can the aperture be changed in P mode (for D90)?

[vino7272]

Is your aperture maxed out already? Or the flash is up and the highest shutter speed is maxed out at 1/200? Are you using a Nikkor lens?

I'm using nikon lens and use no flash.
This is what I encountered...
1. aperture was at 1.8 at night hence tried to rotate dial to step up but nothing changed.
2. aperture is at 4 right now and when I rotate the dial the numbers did change.

In both cases the P* sign appears.

Pls kindly advise.

 

[gorby]

Hi vino7272,

There are two possibilities.

1. You have either a speedlight connected or your inbuilt flash is on. When you turn the command dial in P mode with flash on, the exposure is compensated by the flash and that is why on turning the P mode to P*, the shutter/aperture remains the same, but flash compensates to provide the appropriate exposure (hoping that your are shooting within flash x-sync shutter speeds-1/200 sec for D90) . Once you disconnect the flash, and go to P*, you should see the aperture and shutter values change.

2. Your flash is not on, but in P mode, the camera shows Lo & F1.8. Also the exposure sign below the shutter/ aperture is blinking. This means that there is not enough light to take the picture at that exposure. Once you take the picture, it will display the shutter speed and exposure. Rotating the command dial to make it P* will keep the aperture fixed, since that is the maximum aperture of the lens. The shutter speed will be displayed as Lo. However after you take the picture, you will notice a difference in the shutter speed. If you have enabled auto iso in your menu, then instead of the shutter speed, the ISO will change.

Hope this helps.

I dont think there is anything wrong with your camera. I checked with my D700 and it behaves exactly the same.

Cheers,
Gorby

 

[daredevil123]

I'm using nikon lens and use no flash.
This is what I encountered...
1. aperture was at 1.8 at night hence tried to rotate dial to step up but nothing changed.
2. aperture is at 4 right now and when I rotate the dial the numbers did change.

In both cases the P* sign appears.

Pls kindly advise.

For

1. It was largest aperture and at night, probably the shutter speed is already too slow. If you try to increase it, shutter speed will be lower, so no better alternative.

2. I am not too sure. Is your room quite dark?

 

[ziploc]

Thanks all for the reply and Sorry if I've caused any confusion here.
Actually what I want to know is why my aperture number did not change on the top display when I rotate my main command dial???
The only change I see after rotating the dial is the P* sign but without seeing any change in the exposure value (aperture-shutter combination).
Is my D90 faulty??

Please check your D90's Auto-ISO setting (pp. 166 of your manual). The camera is unable to perform "flexible program" when the Auto-ISO is on, even though it will show "P*".

 

[vino7272]

Hi vino7272,

There are two possibilities.

1. You have either a speedlight connected or your inbuilt flash is on. When you turn the command dial in P mode with flash on, the exposure is compensated by the flash and that is why on turning the P mode to P*, the shutter/aperture remains the same, but flash compensates to provide the appropriate exposure (hoping that your are shooting within flash x-sync shutter speeds-1/200 sec for D90) . Once you disconnect the flash, and go to P*, you should see the aperture and shutter values change.

2. Your flash is not on, but in P mode, the camera shows Lo & F1.8. Also the exposure sign below the shutter/ aperture is blinking. This means that there is not enough light to take the picture at that exposure. Once you take the picture, it will display the shutter speed and exposure. Rotating the command dial to make it P* will keep the aperture fixed, since that is the maximum aperture of the lens. The shutter speed will be displayed as Lo. However after you take the picture, you will notice a difference in the shutter speed. If you have enabled auto iso in your menu, then instead of the shutter speed, the ISO will change.

Hope this helps.

I dont think there is anything wrong with your camera. I checked with my D700 and it behaves exactly the same.

Cheers,
Gorby

Hi Gorby, thanks for your reply. I don't think my flash is on...the pop up is down but I could have made some changes to the flash setting and have now changed it back to default.

I did notice a change in my iso but not sure if this is due to my auto iso setting or the P*.

After all the max aperture explanation, I think it just might be a case of too low light hence the shutter speed isn't able to compensate for any shift in aperture setting.

I'm trying it out at good light now and it works well.

THANKS ALL FOR YOUR HELP.

 

[vino7272]

Please check your D90's Auto-ISO setting (pp. 166 of your manual). The camera is unable to perform "flexible program" when the Auto-ISO is on, even though it will show "P*".

My ISO is set to auto but in good light the "flexible program" actually works...thanks again for your reply.


I think it could be a case of max aperture as pointed out by some CSers when it does not work.

 

[ziploc]

Ok just tested on my Fuji S5. Here are the results:

1. If the ISO is set to auto on and the light is bad, the "ISO-AUTO" will blink when I tried to "shift" in P mode, and the aperture will not change.
2. If the ISO is set to auto on and the light is good, the aperture will "shift".
3. If the ISO is set to auto off and the light is bad, the aperture will still "shift".

So there you go.

 

[vino7272]

Ok just tested on my Fuji S5. Here are the results:

1. If the ISO is set to auto on and the light is bad, the "ISO-AUTO" will blink when I tried to "shift" in P mode, and the aperture will not change.
2. If the ISO is set to auto on and the light is good, the aperture will "shift".
3. If the ISO is set to auto off and the light is bad, the aperture will still "shift".

So there you go.

Really appreciate your time and help.:angel:

 

[gorby]

Hi vino7272,

I did some more reading. It is quite interesting and I have enlightened myself in the process. Have pasted some text from Thom Hogans Guide to the D90.

"the Program exposure mode uses a predetermined combination of aperture and shutter speed based upon how much light is in the scene and the maximum aperture of the lens. I call this the “program.” You can override the program by rotating the Rear Command dial when the meter is active. Note, however, that the overall exposure remains the same; in other words, if your override increases the shutter speed, the aperture is decreased, and vice versa. A small icon (]*) appears in the top LCD when you’ve overridden the camera’s program settings. Note also that once you override the program, it remains overridden by that same amount until you change the exposure mode, turn the power switch to OFF, use the Rear Command dial until ]* no longer appears, or perform a camera reset.

There are bunch of things to note in the above chart (it really is an important thing to study):

• The <55mm column is basically the same “program” that is used in the professional cameras (D200, D300, D700, D2 series, and D3).

• If you’re using consumer lenses on the D90 (e.g. the 18105mm kit lens) many of the table values can’t be reached! For example, at 105mm the kit lens is f/3.5 at maximum, so until you get to EV 9 or 14 you’re a bit stuck with the main program (the “program” will always pick f/3.5 or 5.6 and have to compensate with setting a slower than usual shutter speed). I’ve highlighted the reachable exposures with the kit lens in bold gray text.

• The matrix metering system only extends out to 17.3 EV at ISO 200, so some of the upper limits of the table won’t be used with that metering method and may result in overexposure.

• While Nikon doesn’t specifically say so, this table is also the underlying exposure assumption for all the Scene exposure modes, as well. Program exposure mode has some hidden liabilities when using flash, but also because most users don’t take the time to understand exactly how the camera is making its exposure decisions or even that once they’ve overridden the “program” it tends to stay overridden.

Automatic ISO
The ISO sensitivity auto control option (part of the ISO sensitivity settings item of the SHOOTING menu) tends to be misunderstood by virtually all users; it does not operate quite as you’d expect and has definite limitations. What happens when this Automatic ISO function is active (ISO sensitivity auto control set to On) depends upon what exposure mode you’re using:

• In Manual exposure mode, the ISO is changed if the shutter speed and aperture combination you pick won’t achieve a proper exposure (manual exposure bar centered at 0: ó). For example, if you were at ISO 200 and set f/8 at 1/125 but the meter thought the exposure should be f/5.6 at 1/125, the camera will boost the ISO one stop to 400 (f/8 is one stop underexposed compared to f/5.6 in this example).

• In Shutter-priority exposure mode, the ISO is changed when the camera runs out of aperture range to use. For instance, assume that the initial ISO value is 200 and the aperture set by the camera to the lens’ maximum of f/2.8. If the lighting changes such that f/2 is required, the ISO will be boosted one stop to 400 (f/2.8 is one stop underexposed compared to f/2 in this example).

• In Program (including the Scene exposure modes) and Aperture-priority exposure modes, ISO isn’t changed until the exposure reaches the extreme at either end of the shutter speed range (1/30 second at the bottom end unless you set a different value for the Minimum shutter speed option); the upper limit is always 1/4000). As long as the camera will set a shutter speed between those two extremes, the ISO value won’t change.

• In all exposure modes the ISO sensitivity will never be set higher than the value you set for the Maximum sensitivity option. One nice touch is that last item: you can set the maximum ISO value (between 400 and Hi 1) for the camera to use when Automatic ISO is active. Plus the camera sets the ISO value in sixth stop increments when this feature is active. The Top LCD and viewfinder show the ISO-AUTO indicator If the ISO-AUTO indicator is not flashing, the ISO has not been changed from your setting. If the indicator is flashing, then the camera has changed the ISO value (to find what it changed to, take a shot and examine the Data pages for that image, the altered ISO will be listed in red:

Note: If you use flash and Automatic ISO your previously set ISO may be used! ISO won’t be boosted unless the camera thinks the flash range will be exceeded. So normally with flash, the ISO AUTO indicators in the viewfinder and top panel stay lit (does not blink). This is Nikon’s subtle reminder that “more light” is better than “higher ISO.”

Hope this helps.

Cheers,
Gorby

 

[tunge]

Thanks all for the reply and Sorry if I've caused any confusion here.
Actually what I want to know is why my aperture number did not change on the top display when I rotate my main command dial???
The only change I see after rotating the dial is the P* sign but without seeing any change in the exposure value (aperture-shutter combination).
Is my D90 faulty??

No it is not faulty.

It simply means there is no alternative better exposure permutations, (either it is too bright, too dark or you are using flash causing the shutter speed to be fixed, thus fixing aperture too). Remember P calculations do not take auto ISO into consideration.

+1

yeah it'll work only if there are possible other combinations of shutter n apperture for select. personally i don't think the P* mode is useful, u really want control just use A, S or M mode.