Question - DPChallenge Forums

Canon EF 70-300mm f/4.5-5.6 DO IS USM

01/30/2006 11:01:31 PM · #1

These pictures were shot at f9. Shouldnt the background be in focus at that aperature?

It also seems to me that I'm having to shoot at much slower shutter speeds than seems right. Both of those pictures were shot at 100 ISO and about 250 shutter speed. Anything faster than that, and the picture is much too dark.

cpanaioti

Canon EOS-40D

01/30/2006 11:05:28 PM · #2

1: What focal length?
2: How far away is the background?
3: What is the background?

As the focal length increases, the depth of field will decrease.

Message edited by author 2006-01-30 23:05:51.

Canon RF 24-70mm f/2.8 L IS

01/30/2006 11:08:50 PM · #3

I was using my 14-45mm lens with close up lenses attached. The background was additional branches on the tree.

kirbic

Canon EOS R5

01/30/2006 11:11:32 PM · #4

1/250 @ f/9 is about right in sunny conditions, give or take a stop. You're much closer to the subject than you are to the background, so no, the BG won't be in focus.
The larger sensor of the DSLR means shorter DoF, which can be both a blessing and a curse. It's very different from a P&S, that's for sure!

SDW

Canon EOS-60D

Tamron AF 28-300mm f/3.5-6.3 XR Di LD Aspherical IF for Canon

01/30/2006 11:14:46 PM · #5

The DOF is a result of a few factors.
1) What lens you are using
2) What f/# used
3) How far from the object was the lens

Lets say you have a 50mm lens taking a macro shot from 4 feet away @ f/9. You would have a near focus of 3.55 feet from the lens and your far focus would be 4.57 feet. That would only give you a DOF (in optimal focus) of only 1.02 feet.

paddles

Pentax K10D

Pentax FA 50mm f/1.4 AF

01/31/2006 03:34:53 AM · #6

Originally posted by ragamuffingirl:

I was using my 14-45mm lens with close up lenses attached. The background was additional branches on the tree.

Well yes, you'd normally get a fairly wide DOF with a 14-45 mm lens at f-9. But as soon as you put close-up filters on the front of your lens (or extension tubes on the back, or go into macro mode on a proper macro lens), your depth of field will shrink to a pretty narrow range - measured in centimetres or even millimetres - or fractions of an inch, for our American brethren and sistren :)

Canon EF 24-70mm f/2.8L USM

01/31/2006 07:03:31 AM · #7

Okay, I feel better. I was starting to worry that something was wrong with my camera.

TroyMosley

Canon EOS-5D

01/31/2006 10:14:32 AM · #8

nope your camera works just fine,
what you are doing is a great learning tool. it is helping you learn about Aperature, shutter speedn and ISO, and how they each work together to creat an image.