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Question: More Rebel XT Questions on Aperture!.!.!.!?
Ok, so I've learned quite a bit already (Thank you Pooky) but I need some more help!. What's this great thing about Aperture I always hear about!? I know it allows the amount of light in and out of the camera (I think) as well as plays with the depth of field but here are my questions!. How the hell do I use it!? I know that Av is Aperture Priority Mode!. The numbers it shows me is 4!.5/5!.0/5!.6/6!.3/7!.1/8!.0/9!.0 All the way up to 22!. Is this Aperture Priority!? Let's say for instance I'd like to focus on one person, one thing!. We'll say a Hawk sitting on a tree for instance!.!.!. All I want the camera to focus on is the bird itself!.!. Kinda for example like this!.!.!.
http://www!.flickr!.com/photos/richlegg/24!.!.!.It's an easy 10 points!.!.!. Please provide as much detail as possible, I appreciate your help in advance!
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:-)
The aperture, also referred to as 'f stop'-can be confusing!. Think of it this way!. For example, a 50 mm lens f 2, the "f 2" means the aperture diameter is 25 mm!. Basically the f number is the focal length divided by the aperture diameter!.
So when Leitz (a German camera maker now called Leica) came out with a 50 mm with the aperture of f 1, the aperture diameter is 50 mm, which is kinda big!. Here is a photo (this is not my camera) http://www!.flickr!.com/photos/22701595@N0!.!.!.
So the larger the "hole", the lower the number!. My latest buy was Canon 50 mm f 1!.4, but just a week before that, it was the legendary Canon 135 mm f 2!. When used at f 2, I think it can see in the dark, and focusing was quick, because it lets a lot of light in, like this: http://www!.flickr!.com/photos/little_pook!.!.!.
If you want to see what it can do at f 2, here is a sample!. Taken from Griffith Observatory in Los Angeles!. Click on all sizes to see larger one!. http://www!.flickr!.com/photos/little_pook!.!.!.
You may ask, why does the photo of the play - the background is not blurry like the 2nd one!. Keep in mind that the 2nd photo, the background is miles away!. The foreground object (the telescope) is just a few feet away!. The first photo, the boys and the stage background were not that far apart!.
For the same subject, I did a test shot!. This one at f 2!.8 (Canon 100 mm f 2!.8 Macro)
http://www!.flickr!.com/photos/little_pook!.!.!.
Then, at the same spot, at f 9!.6!.
http://www!.flickr!.com/photos/little_pook!.!.!.
See!? It was still focused on the big flower (manual focus, by the way), and yet, at smaller aperture, background is not so blurry!.
Another one (no comparison photo),
http://www!.flickr!.com/photos/little_pook!.!.!.
Click on ALL SIZES to see the largest one!. Behind the boy with the blue sweater--see the "creamy" background!? This was at f 2!.8 (135 mm f 2)--but yet the tree is not that close to him, so it's out of focus already!.
I shoot most of my photos in P mode!. The little dial thingie next to the shutter release button allows me to change the aperture / speed shutter at the same time!. This means the photo above (with the two boys)--it was f 2!.8 at (I'm coming up with this number randomly), say, 1 /250!. So if I open the lens to f 2!., the speed shutter will have to be at 1/500 (bigger hole, so it requires less light--so the shutter speed doesn't have to stay open as long as before)!. But if I close it down to f 11, the shutter speed may have to be as long as 1/60 (I'm not entering precise number here)!.
If this doesn't make sense, think of it as a garden hose!. If it's a large one, more water comes out, and it doesn't need that much time to fill a cup!. But if the hose is kink, so the "hole" is smaller, it takes more time to fill a cup!.
(This is how I explain blood pressure to a patient--as I am a nurse!)
Photography is fun--and thank goodness, we can reuse the memory card over!.!. and over!.!.Www@QuestionHome@Com
Yes, Av is aperture priority mode, it actually stands for aperture value!.
The lower number is wider and will show a narrower depth of field!. That hawk probably had an aperture somewhere between F/2!.8 to F/5!.6!.Www@QuestionHome@Com
The lower the number, the smaller area of focus it will have!.
So basically, you want a lens that can take pictures at f/1!.8 and you will have a very blurred background!.
Please see http://digital-photography-school!.com/bl!.!.!.Www@QuestionHome@Com
I just saw this on Photo!.net yesterday!. It explains it in a visual way!. http://www!.photonhead!.com/simcam/shutter!.!.!.
EDIT:
Oh jeez princess, that hawk had an aperture of f/4 with a shutter speed of 1/500th!. ISO 100 and the focal length was 140mm!. http://www!.flickr!.com/photos/richlegg/24!.!.!.
The closer the focus, the more pronounced the Bokeh (background blur) will be!. The more of a telephoto lens you use, the more it will be also!. With 140mm you could be 10 feet away and have an aperture of f/8 and get that effect!. Everything is relavent!.
Look at this chart http://www!.fredparker!.com/ultexp1!.htm#EX!.!.!. Choose an EV number!. Now choose an ISO and find that on the chart!. To the right you will see a bunch of shutter speeds that correspond to aperture values at the top!. These are all properly exposed for that EV, but the thing that changes is the depth of field and how well it can stop action!. f/1!.4 will have a very shallow depth of field, where as f/32 will have everything sharp and clear!. Most people dont need f/32 to achieve this, f/16 or f/22 can usually get everything for quite a ways in focus!.
Now, to the original questioner, you said 10 points!. Pick a best answer and dont let it go to a vote!.Www@QuestionHome@Com
To isolate your subject you will need to use a bigger aperture, which is a smaller number!. I can tell you're really getting a handle on the aperture deal!.
Just remember: The smaller the aperture, the bigger the number, the bigger the number, the less light comes through and the less light comes through more will be in focus!.
Think of the small aperture(large number, like 22) like a lazer!.!. and everything in it's path will be in focus!.
Think of the big aperture(small number, like 3!.5) like a big fan blowing everything away from the subject!
Hope this helps you understand!Www@QuestionHome@Com