So F/8.0 lets in 16 times less light, so using that setting, the exposure must be 15 times longer. If you change your camera from F/4.0 to F/5.6, your exposure will be twice as long.
If you need a specific shutter speed, you can adjust the aperture to get the proper exposure.
The other thing that aperture affects is depth of field - which is how much is "in focus". The higher the F-stop number, the larger the depth of field, so more will be in focus.
So, let's say you take a picture of something, using F/2.0, and the depth of field ends up being 1 foot. That means that everything from 6" in front to 6" behind whatever you focused on will be considered "in focus" (it's not really split 50/50 like that, but we'll skip that for simplicity).
So increase the F number to 8.0. Now your depth of field may be 5 feet (depends on the lens and lots of other factors). So everything from 2.5 feet in front of, to 2.5 feet behind what you focused on will be considered "in focus".
Finally, there is usually a "sweet spot" for sharpness, that's generally around halfway between the ranges of F-stops the lens will do. On my camera, the range is F/2.0 - F/8.0. The sweet spot is at F/5.6. Things are a touch more blurry and you get some color artifacts at F/2.0, and a touch blurry at F/8.0. At F/5.6, my camera lens is providing optimal image sharpness.
If you're trying to achieve some specific effects with your picture, you can use aperture to do that. If you want a lot of the picture in focus, use a high F-number (like F/8.0). If you want just your subject in focus, but the background blurred, use a low F-number (like F/2.0).
Hey, Ragz, check this out.
Kinda cool simulation.
For the aperature part, go to here.
It's called the simcam. Gives you and idea of what to expect under various conditions.
Or just play with your camera. Tak alot of shots. Write down the settings for each shot. Then view them on your PC's monitor and see how each change affects the picture. Sounds tedious, but think how it was/is for doing the same with film SLR's. U don't have to wait for developing [if you don't have your own lab.]
Enjoy! [Another expensive hobby, eh Ragz?!?!?]
[ QUOTE ] raggie33 said:
i kinda doubt it baker i can try tomorow.i wish i had a teloscope that can hook to it
[/ QUOTE ]
Here's my weak attempt at photographing the moon through my telescope:
I'm not a wizard at this by any means. This was taken with my digital camera, afocally mounted on a little Meade ETX 105mm telescope. I used a 26mm eyepiece in front of the camera lens. This was my first attempt, and pretty much beginners luck - it's hard to focus.
Best of luck on your attempt raggie! A tripod helps a lot. I'd think you could get at least some detail at 12x.
ok im still confused i read many websites and still confussed..ok a smaller number lets in more light?now whcih one has the bigest area that will be in focus.man this is confuseing as hecti like this hobby but man there is much to learn. i still have my old pentax k1000 to
I suppose you could say to use the slowest shutter speed you can without blurring your pic in order to get the greatest depth of focus. This won't work if you are trying to stop motion, but it might be a good rule of thumb.
[ QUOTE ] raggie33 said:
cool picit came vout great does the moon ever get closer to earth.i see on tv sometimes where it looks huge
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Thanks! Yeah, the moon does get closer to the earth by a little bit - but it's not terribly easy to notice the difference. The main thing that makes the moon look larger is how close it is to the horizon or the zenith. When the moon is low in the sky, it looks huge, and when it's high overhead it tends to look smaller. It is, in fact, the same size - it just looks bigger when it's low. This is an optical illusion.
Also, they can cheat on TV... [img]/ubbthreads/images/graemlins/tongue.gif[/img]