Am I just stupid... - Aperture

[righteous_bucks]

So, I just ordered my Canon 20d so I've been reading over the specs for it and all, but I have a question about aperture. To change exposure manually, you can change shutter speed, ISO, and aperture, but do you not change the aperture on the actual camera like you do the other two? Or do you change aperture with the lens? When I look through the specs for this camera it doesn't mention aperture settings at all, so I'm confused

By the way, the 20d will be my first ever slr camera, so I've never messed with any of these manual exposure settings like this, so that's why this question is probably dumb to most people on here.

 

[chip]

you set the aperture on the camera. easiest is set the mode dial to Av and turn the wheel with your right index finger. Shutter speed will be automatically set in Av mode. If you set the mode dial to M you will need to choose aperture and shutter speed yourself.

 

[righteous_bucks]

Ok thanks for clearing that up for me. Does the 20d have a limit to the different apertures it can be set at? And also, if the aperture is set on the camera, what is the aperture number on the lens mean? Is that saying you can only set the aperture on the camera to that amount when using that lens?

 

[chip]

You can only set aperture on the camera. There is an LCD display on top of the camera to show you the aperture setting. You cannot set the aperture on the lens. You need EF-S or EF lenses. The aperture range you can set depends on the lens. I have a 24-105mm lens and it has a maximum aperture of f4. some nicer lenses have a maximum aperture of f2.8 or even bigger.

 

[righteous_bucks]

Ok awesome, that totally answers all of my questions thanks!

 

[righteous_bucks]

Sorry, one more question! I always read that to get a blurred background in a picture you need to open the aperture as much as possible, but how much do you need to open it in order to get the blur effect? Do you really need a lens that can open to 1.2? haha I'm just looking for the aperture number where blurring begins.

 

[benlonghair]

Sorry, one more question! I always read that to get a blurred background in a picture you need to open the aperture as much as possible, but how much do you need to open it in order to get the blur effect? Do you really need a lens that can open to 1.2? haha I'm just looking for the aperture number where blurring begins.

It's relative to the aperture, distance to the subject and length of the lens. A 18mm lens will have pretty much everything from 3' to infinity in focus even at a relatively low f/stop. A 300mm will be razor thin at it's minimum focus distance. As distance increases, so does DoF.

 

[righteous_bucks]

Ok, thanks!

 

[flyin-lowe]

My cheap telephoto is a 75-300 mm f 4-5.6. When I have that lens on the lowest number (larger aperture) I can go to when shooting at 75 mm is 4. If I am zoomed in and shooting at 300mm the lowest I can go to is 5.6. You can go to a lot smaller aperture, but this is the largest you can go to. Remember (you probably already know) the smaller the f number the bigger the aperture. It is backwards of what you would expect the first time you learn about it.

 

[syphlix]

Canon 20D Manual

 

[Samanax]

Sorry, one more question! I always read that to get a blurred background in a picture you need to open the aperture as much as possible, but how much do you need to open it in order to get the blur effect? Do you really need a lens that can open to 1.2? haha I'm just looking for the aperture number where blurring begins.

Getting the background out-of-focus is more than just using a wide open aperture.

Back to Basics - Depth Of Field

Depth Of Field

Tutorial: Depth Of Field

Depth Of Field Tutorial

Examples For Understanding Depth Of Field

Understanding Depth Of Field

Controlling Depth Of Field

Tutorials: Depth Of Field

Understanding Depth Of Field In Photography

 

[righteous_bucks]

Thanks Samanax, those links helped alot :thumbup: I think I got the idea of it all down pretty good now, I can't wait to try it out!

 

[chip]

How do you know how much depth of field you need - take a lot of pictures and look at them to get a feel for it.

depth of field of DOF is inversely proportional to:
focal length - the longer the focal length, the smaller the DOF
sensor size - the bigger the sensor, the smaller the DOF
aperture - the bigger the aperture opening, the smaller the DOF

depth of field of DOF is proportional to:
distance - the closer the distance, the smaller the DOF