Challenge I - Aperture and Depth of Field

**ricktas** · 24-01-2009, 12:08pm

Our first challenge to our members that want to learn to take control of their digital camera is based on the Learning Centre topic : Experimenting with Aperture

We would like you to set your camera to Aperture mode (sometimes called A or Av mode). Check your camera manual in need, on how to set your camera to Aperture mode.

We want you to go out and take two photos of the same subject. One at the largest aperture your lens will allow and one at the smallest. So take one photo at f4.5 and one at f22, of the same subject. Then post both photos in this thread, with comments about what differences you notice between the two photos.

**clm738** · 24-01-2009, 2:02pm

f4.5
only Noah in focus
shutter 1/160
file size 63.4kb

f22
more people in focus
shutter 1/6
file size 85.7kb

**clm738** · 24-01-2009, 2:04pm

Have now also noticed exposure difference

**Jcas** · 24-01-2009, 2:43pm

F4.5 Background not focused
F22 Background in focus.

**bigdazzler** · 24-01-2009, 4:37pm

with these, remember distance between subject and background has a great effect on DOF also ..

**ricktas** · 24-01-2009, 4:39pm

So if you wanted to take a nice portrait shot of a friend, given the above tests, what aperture would you use, and how would you place your subject in relation to the background?

**Nanny** · 26-01-2009, 2:14pm

I can see the difference in the background
in the first the background is blurred and the second is focused
and there is a difference in shutter speed.

**ricktas** · 26-01-2009, 3:45pm

When in Av mode (aperture mode) and you change the aperture, the shutter speed adjusts accordingly, by the camera. At f4.5 the aperture is wide open so a lot of light can come through the lens to hit the sensor. The camera knows this so will select a faster shutter speed to ensure a correct exposure. When you take your shot at f22, the aperture opening is tiny, and the camera compensates by slowing the shutter speed to allow enough light through the small aperture, to again get a correct exposure.

Nanny has commented on this, and it teaches you that shutter speed and aperture are inter-related. When you start using manual mode, you will have to select both the aperture and the shutter speed. So it is worth understanding the relationship between the two now, while we are still working in Aperture mode.

**Nic076** · 26-01-2009, 5:27pm

Great thread Rick. I have seen the difference quite a few times in many of my photos when I want a little more detail but suddenly need to be aware of the amount of light on the subject. Generally I have had to up the ISO to compensate.

I also took some photos for a friend a little while ago of her little girl. We were at a park and it was quite bright, and the lens I was using, although set to largest aperture was catching too much background detail. I then realised what you just mentioned about distance. By changing where she was sitting and how close the trees were behind her I managed to get them quite a bit OOF. It was really just trial and error at the time, but a good tip to remember.

**Jcas** · 26-01-2009, 6:31pm

Thanks for the example, it all helps, cute little girl too

**lourdes** · 26-01-2009, 6:51pm

Thank you for this, i can see it now.

**ricktas** · 26-01-2009, 7:31pm

Does anyone have any questions regarding Aperture and using Av mode? Please feel free to ask anything. Even if you think its a silly question. The only way to get the answer is to ask.

**J.davis** · 13-02-2009, 4:21pm

Two Macro shots I have taken today that realy show 'Depth of field' - Comments?
F5 @1/125 90mm

F57 @1.3 90mm

**ricktas** · 06-03-2009, 12:14pm

So John, what did you learn about aperture? and when would you use each in a real life situation?

**J.davis** · 07-03-2009, 12:53am

I cant hold still long enough to take a photo in macro longer than f22 allows.

**MrJorge** · 07-03-2009, 12:58am

Originally Posted by J.davis

I cant hold still long enough to take a photo in macro longer than f22 allows.

Lol!!

**Hamish McHaggis** · 01-05-2009, 9:04pm

What a great site Rick, I'm looking forward to learning heaps.
Here is my go at this challenge; first shot is at f/29, second is at f/4.5. Depth of field is obviously less at f/4.5.

cheers

**Kym** · 01-05-2009, 9:11pm

Good work Colin!
Keep this in mind next time you do a portrait / candid to kill the background (and for people focus on the eyes, not the nose)

**Hamish McHaggis** · 01-05-2009, 10:40pm

Thanks Kym, will keep that in mind!
My two pics seem to have disappeared....can still see them on Picassa though...odd...

**Kym** · 01-05-2009, 10:46pm

Originally Posted by Hamish McHaggis

Thanks Kym, will keep that in mind!
My two pics seem to have disappeared....can still see them on Picassa though...odd...

I can see them.

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Challenge I - Aperture and Depth of Field

Very good Thread

1st post from a newbie

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