Aperture Trouble

allsdown · Sep 15, 2009

I'm having difficulty adjusting my Depth of Field on a Nikon D70. When I play with the aperture the picture only gets really dark or really bright, the background doesn't change focus. Is there another setting on my camera I should adjust or what is going on?

Thank you!

Goontz · Sep 15, 2009

Are you also adjusting the shutter speed to compensate for the change in aperture? What's the light meter indicate?

Got any examples, preferably with exif data?

allsdown · Sep 15, 2009

I was only using the Aperture mode when doing this and that doesnt allow me to also adjust shutter speed. Should I go into Manual mode where I can adjust both? I'm really new to this camera

Overread · Sep 15, 2009

Distance is also a key component of depth of field - if you have a focused subject close to the camera -and then a far off background, even if you use a small aperture (big f number) like f16 then the background elements will still be out of focus since they are (reletivly speaking) so far away when compared to the foused subject.

That would be my guess of what you are experiencing - but as Goontz suggested if we could have a look at the shots you were trying to take and the exif (aperture, shutter speed, ISO) that you were using we might be able to better understand and advise.

allsdown · Sep 15, 2009

The shutter is on auto and the ISO is also on auto and set at 400

This is what I'm trying to get a picture of, this is taken in auto mode:

This is F 11 taken in aperture mode:

This is F 3.5 taken in aperture mode:

Goontz · Sep 15, 2009

Your exposure bias got bumped down to -5. That's what causing the underexposure. Put it back to 0 and you should be good to go.

Overread · Sep 15, 2009

Yep you have exposure comensation enabled - read up in your manual about using that feature and how to control it. Essentailly your camera is being told to meter the scene and then underexpose it by 5 stops of light - which is why your getting such a dark shot. There are times when you will need and use this feature - for when your shooting something that the meter can't get quite right (either over or under exposing) or when you want a select effect.

You might also find the following book - Understanding Exposure by Bryan Peterson - a very helpfull read and introduction into controling aperture, ISO and shutter speed as well as using them for "correct exposures" as well as starting to understand just what a correct exposure is

Lyncca · Sep 15, 2009

When I looked at the EXIF data it said, "Exposure Bias Value: -5EV"

This means the exposure is dialed in as 5 stops under, then it would indeed be dark at either aperture.

Lyncca · Sep 15, 2009

LOL, all 3 of us posted at the same time. At least I can figure out what is wrong now! This stuff used to drive me nuts.

Goontz · Sep 15, 2009

Overread said:
You might also find the following book - Understanding Exposure by Bryan Peterson - a very helpfull read and introduction into controling aperture, ISO and shutter speed as well as using them for "correct exposures" as well as starting to understand just what a correct exposure is

+1. An excellent book and very helpful.

allsdown · Sep 15, 2009

Thank you so much guys!! It was so frustrating not knowing what was wrong! Thanks a bunch!

Goontz · Sep 15, 2009

No problem, good luck!

Plato · Sep 15, 2009

allsdown said:
Thank you so much guys!! It was so frustrating not knowing what was wrong! Thanks a bunch!

I'm unable to see the pic that you posted from my work location so my comments may well be off base. However...

You're obviously using DoF Preview. I'm thinking that your original problem was nothing more than an inability to see the DoF as the lens closes down and, or course, the viewfinder gets darker. Take some test shots to confirm.

Aperture Priority is the correct mode. The camera will automatically change the shutter speed for you. Nothing wrong with full manual but then it's up to you to change both.

Lyncca · Sep 15, 2009

Sometimes its not so much understanding how to get correct exposure as knowing what buttons on your camera can affect it that you may not have ever changed deliberately.

I've gotten trigger happy before and changed settings without even know it and it took forever to figure out what was up.

allsdown · Sep 15, 2009

Ugh, well I'll go into my manual and read up on the metering but when I went in my menu to change the exposure compensation it was already switched off...