F/ Stops and depth afield: Please help a woman who is so forgetful. I am so trying to learn this F stops and depth a field. I am taking a course on line (it is free) and it has very...

bonniekr Loc: Upper Peninsula of Michigan

Please help a woman who is so forgetful. I am so trying to learn this F stops and depth a field. I am taking a course on line (it is free) and it has very good information but when i try to take a picture or two I look in the view finder and get lost as to how to set my F/stops. I have a Canon Rebel xsi 450 D. I was told as long as you get the aperture and the shutter speed down it will fall in to place. Well this lady is struggling.
Could someone please explain this to me in a very simple way. I would appreciate it.
I am trying to take pictures of my new granddaughter without all the stuff in the background.

snowbear

The larger apertures (small numbers) give you shallow depth of field while smaller apertures (larger numbers) give you deeper depth of field from the same distance.

The closer you are (more magnified) to the subject, the shallower the depth of field while the farther you are away, the deeper the DoF for the same aperture.

In other words: f/4 will be shallower than f/8 at 25' from the subject. 15 feet at f/8 will be shallower than 50 feet at f/8.

bonniekr Loc: Upper Peninsula of Michigan

I do understand how the F/stops are measured...when I try to set an F/stop to say 2.8 it does not show that stop in my viewfinder...

MadMike Loc: SALT LAKE

I found the best way for me to remember is that small numbers (f2.8) give me a small spot of focus. A large number (f22) gives me a greater focus area. Just remember that speed changes the same. Small f stops high speed. Big f stops Slow speeds. The further away a flower is from it's background, the better with low f stops. Hope this helps.

bonniekr wrote:

Please help a woman who is so forgetful. I am so ... (show quote)

MadMike Loc: SALT LAKE

Look at your lens, it should tell you what your lowest f stop is. This also depends if you are using a telephoto lens, it changes with zoom. Confusing, but you will get used to it.

bonniekr wrote:

I do understand how the F/stops are measured...when I try to set an F/stop to say 2.8 it does not show that stop in my viewfinder...

travlnman46 Loc: Yakima WA

bonniekr wrote:

Please help a woman who is so forgetful. I am so ... (show quote)

Hi bonnieker: This may help, it's a web site that does a great job of explaining not only f stops but DOF and ISO as well and just how they work together. There are some great illustrations as well as photographs that make it easier to understand all three.
http://www.cameraporn.net/2007/12/24/aperture-iso-and-shutter-speed-the-good-kind-of-threesome/ Hope this helps. THe best way to learn is just practice looking at the results... Here is another website that is a camera simulator. You can change the various setting and immediately see how the changes affect the picture. http://camerasim.com/camera-simulator/

sarge69 Loc: Ft Myers, FL

Gotta love that simulator in manual mode.

Thanks for the practice field. It is in my favorites.

Sarge

djmarti Loc: cape cod,

I also have and xsi and when you shoot and looking through the viewfinder when you hold the shutter halfway to focus the F number will show in the viewfinder. You just put the camera in av mode and the wheel on the top you turn it to the left and the fstop number will go down. Also never set your f stop higher than a 14. What happens is you get deffraction and your image sharpness comes down and by f22 it really goes away. Eventually you can just look at what your shooting and know what f stop to set. It takes a lot of practice and patience because every shooting situations different. The fun and frustrating part is when you think you know everything, your so far from knowing everything about your camera.

ziggykor Loc: East Texas

The problem could be that the lens you are using will not open to f/2.8. Each lens will have the maximum aperture marked on it. The way it's marked may look something like this: "24 - 135mm 1:3.5 - 5.6". The numbers after the focal length indicate the max apertures available.

In the case above it indicates that at 24mm this lens has a maximum aperture of f/3.5, as the lens is zoomed the max aperture becomes f/5.6.

Looking through the viewfinder the set aperture should be to the right of the set shutter speed, so you should see something 100 8.0. Shutter speed being 1/100 sec and aperture being f/8.

Hope this helps,

Ziggy

ljmeis76 Loc: Bedford, MA(Delray, FL)

the problem you are having is due to the fact that in every camera i have used, what you see in the viewfinder is with the lens wide open regardless of what aperture is set. this is to facilitate focusing. the only way to see what the picture will look like at the aperture you set is to use dof preview. not all cameras have this function. check you manual. on my km 7d and sony slt55 it is a button on the lower body near the lens base which stops the lens down to the taking aperture while pressed.

ljmeis76 Loc: Bedford, MA(Delray, FL)

the problem you are having is due to the fact that in every camera i have used, what you see in the viewfinder is with the lens wide open regardless of what aperture is set. this is to facilitate focusing. the only way to see what the picture will look like at the aperture you set is to use dof preview. not all cameras have this function. check you manual. on my km 7d and sony slt55 it is a button on the lower body near the lens base which stops the lens down to the taking aperture while pressed.

Vick I Loc: Texas

Line up a bunch of coins on a long table or counter. Put them in a line with a couple of inches between each one. Then set up your camera and take a series of pictures from the same point with the same focus, but just changing the aperture from lowest number to highest. Then look at your pictures on your computer and pay attention to what is in focus and what is not. I found that a very helpful exercise to cement the knowledge in my brain.

travlnman46 Loc: Yakima WA

sarge69 wrote:

Gotta love that simulator in manual mode.

Thanks for the practice field. It is in my favorites.

Sarge

Hi Sarge: Yeah it makes a pretty good practice dummy, great way to experiment with different settings. Even though the same thing could be with a real camera, the ability to control, the apeture, ISO and shutter speed along with lighting and distance, help a new photographer easily understand how these combinations work or fail to work together.

melphoto60

bonniekr wrote:

I do understand how the F/stops are measured...when I try to set an F/stop to say 2.8 it does not show that stop in my viewfinder...

what lens r u using if its a f3.5-5.6, f2.8 is not available...

Dun1 Loc: Atlanta, GA

The rule of thumb I use is if you have a row of six swings, you wish to have only the first swing in focus, set the f stop on the smallest setting F/2.8 etc, if you wish swings one thru three to be in focus try setting you lens on F/8, is you wish the entire row of swings to be in focus set you lens on the largest number on your lens F16 etc. More than likely if you shoot your grandaughter using spot focus on the smallest lens setting she should be in focus, and the background should be out of focus, so to speak.