Is it me or the camera???

[Westgippywoman]

I have a Nikon D90, and I often use a Tamron 70-200mm F2.8 lens. I was using it in the apperture priority mode, and I noticed that one photo would come out at 1/2000 at 2.8, then the very next photo would be 1/200 at F10.0. I assume it is me, does anyone know what I am doing wrong?

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[rachard1583]

If you are using an older lens with an aperture ring, make sure to set the aperture on the lens to the largest number. There should be a lock on the lens to keep it at that number. If you are getting an error on the back LCD of the camera when you press the “Info” button, you should go back and make sure that the aperture ring is set correctly. This is not an issue on most new lenses and the latest generation of the Nikon lenses labeled with a “G” do not have this ring at all.


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[Forkie]

If in aperture priority mode, when you stop the aperture size down the camera will adjust the shutter to speed compensate for the decrease of light entering the lens. It needs to have a slower shutter speed to let in the same amount of light as it did when you had it at f/2.8.

As an experiment, in manual mode try taking the same two photos again; the first at f/2.8 and 1/2000 and another at f/10 and 1/2000 - you'll notice that the second picture is much darker (even black if the lighting conditions are poor), this is because not enough light is getting to the sensor. Therefore, in aperture mode the camera will automatically choose the appropriate shutter speed for the aperture that you have chosen to get a correct exposure.

[KmH]

I have a Nikon D90, and I often use a Tamron 70-200mm F2.8 lens. I was using it in the apperture priority mode, and I noticed that one photo would come out at 1/2000 at 2.8, then the very next photo would be 1/200 at F10.0. I assume it is me, does anyone know what I am doing wrong?

You need to read your D90 users manual again. You don't yet have a good understanding of how your camera works, so you can't tell if you are dealing with a camera that is working correctly or a broken camera. In this case I think the camera is doing it's job as it was designed to do it.


3 things you need to check:

1. the metering mode the camera is set to
2. that aperture priority is actually set
3. and if ISO is set to Auto.

In aperture priority the camera automatically selects the shutter speed, and will also automatically select the ISO setting if ISO is in auto mode.
The metering will effect how much of the scene is metered, from just 2% in spot metering to averaging the entire scene in Matrix metering mode.

Psoting examples with intact EXIF info would help us help you.

[Westgippywoman]

How do I post EXIF info - sorry, new to this...

[480sparky]

How do I post EXIF info - sorry, new to this...

If you post a photo straight from the camera (no post-processing, etc), the EXIF data should be attached to it automatically. Otherwise, use an EXIF reader program and copy & paste it.

[MissCream]

I don't know if I'm reading this right. So you were shooting in aperture priority mode at f2.8 and without manually switching it, it jumped to f10?

[Westgippywoman]

Yes, MissCream, that's what it did....and I want it at 2.8, that's why I bought the lens....

[KmH]

Ya, I wondered about that too. In aperture priority the shutter speed, or ISO, or both changes automatically.

If the lens used is a variable aperture lens the aperture will change automatically between the widest at each end of the zoom range but that would not include f/10.

I suspect the OP is not yet knowledgeable enough to properly describe their issue.

Was the ISO set to auto?

1/2000 at f/2.8 is not the same exposure as 1/200 at f/10. 1/2000 to 1/200 on the shutter speed is 3 stops, while f/2.8 to f/10 is 5 stops so something doesn't compute.

[Davor]

Yeah the OP's problem seems very confusing to me and doesn't make much sense, im wondering if maybe the OP accidentally turned the front dial to f/10 without noticing.

[Overread]

The way I see it the OP set the lens to f2.8 and got 1/2000 sec shutter speed.
They then set it to f10 and got the 1/200sec shutter speed and the confusion is to why changing the aperture has resulted in the dramatic difference in shutter speed.

My advice is that you've got to learn the exposure triangle - that is how ISO, aperture and shutter speed each contribute to the whole of the exposure. The book Understanding Exposure by Bryan Peterson goes into this subject in a good level of depth for the beginner and includes a series of trials and case studies as well as creative ideas that you can put to your own use and practice.