Apeture? What do you use it for??

[Phazan]

I know that the apeture is the hole that lets light in the camera, but what do you use it for? There is a whole mode devoted to it on my camera, and all that I can think someone would use it for is to make a picture lighter or darker, but there must be another reason to use it besides letting more/less light in the picture. I looked through the manuel for my camera (Canon S3)and I don't really understand what it's talking about.

Can anyone help me??

-Thanks,

Brandon

 

[TBaraki]

In addition to the control over exposure it offers, the aperture allows you to change the depth of field of your image. A small aperture allows a greater DOF which will allow things further from your focus point to be in focus. Conversely, opening the aperture up wide open will result in a narrow plane of focus which is useful in isolating your subject from the background.

There are tons of tutorials and explanations around the net if you do a little bit of searching around.

 

[auer1816]

Smaller numbers (f/3.5) give a smaller depth of field (less in focus) but let more light in (need faster shutter speeds to compensate) -- the hole is bigger.

Bigger numbers (f/22) give a bigger depth of field (more in focus) but let less light in (need slower shutter speeds to compensate) -- the hole is smaller.

 

[shingfan]

i like to add a little more to auer's comment to help you understand when ppl say larger/small aperature....smaller number (f/3.5) refers to a larger aperature compare to a large number (f/22)....the smaller the "f" number....the larger the aperature...the larger the hole

 

[markc]

If you have trouble with the "reversed" f numbers, just remember that they are fractions. 1/22 is a lot smaller than 1/2. Same with f/22 and f/2.

 

[STINKY PICTURES]

So if you were taking a close up shot of a face for great detail, how would you have the aperature set. When the entire face is taking up the entire picture. I do tons of close up shots and I think this info may be very helpful to me. Thanks!!

 

[shingfan]

depends on what depth of field (DOF) you like...you want everything sharp...or you want a portion to be sharp while the remaining to be blur....is really a preference

 

[Phazan]

Cool, thanks everyone! That makes it a lot more understandable now!

 

[STINKY PICTURES]

Everything sharp, please.

 

[xfloggingkylex]

Everything sharp, please.

f/8 is a pretty safe choice

 

[GilTphoto]

HOW AND WHEN TO SELECT THE APERATURE

I shoot exclusively in Aperature Priority mode. The aperature I use depends on the circumstances of the image.

1. A larger aperature will allow faster shutter speeds. This comes in handy for shooting distant wildlife, or fast moving sports, or night scenes, when using a tripod is more difficult. The ability to get a shutter speed fast enough to handhold the camera and still get sharp pictures.
EXAMPLE: You're on the shuttle bus in Denali National Park in Alaska. The bus stops because there is a bear about 1/4 mile away. The weather is overcast. You aim your camera out the window with your 200mm f/2.8 lens with 100 ASA film set on f/2.8 Aperature priority. The meter gives you a shutter speed of 1/500th of a second, which is fast enough to still give a sharp picture handholding a 200mm lens. But wait, the bear is too small, so you change to a 400mm f/4 lens. Wide open at f/4, the shutter speed is now only 1/125th second, which is too slow to handhold a 400mm lens. If you could use a tripod and cable release, you could get the shot, but not handheld. What to do?? If using digital, just change the ISO speed to 400 and your shutter speed will be back to 1/500th second. If using film, either use 400 speed film and maybe even shoot at 800 and have the lab push process the roll.

2. A large aperature gives limited DOF which is good for isolating a subject from the background. A lens with a f/4 maximum aperature may not blur the background enough and make for a distracting or busy image.

3. Landscape images are usually more sucessful if they convey scale by having a close foreground object such as a rock or flower, leading up to the distant background view. This requires a small aperature such as f/22 to give maximum DOF for all parts to be sharply in focus. F/22 will almost always force you to use a tripod since the shutter speed may only be 1/4 second, even during a bright sunny day, (especially when using a polarizer too). Focus on the closer object, or 1/3 into the scene. What you see through the viewfinder will not be totally in focus as the view is at the maximum aperature. Use DOF preview if you have that feature to check your focus point and whether the DOF is sufficient.

4. If shooting a landscape on a tripod where nothing is close and your focus point is at infinity, nothing is moving, then shutter speed is not an issue, and DOF is not an issue. Then use the middle of the road aperature usually f/5.6-f/8 which is the sweet spot of the lens giving the sharpest focus.

5. Isolation of a subject from the background by using a large aperature such as f/2.8 is useful for flowers when distracting leaves or branches are close by. Also useful when forced to shoot through a fence. The fence can become totally invisible with very shallow DOF.

6. Macro subjects such as closeups of flowers or parts of the flower, or insects, require maximum DOF, so small aperatures are needed.

7. Portraits or people photography can usually be shot with middle of the road f/8 - f/11. Enough to get the entire person sharp, while slightly blurring the background. Another consideration here is how far the flash will cover. Using my Nikon SB-24 flash, the flash will reach 60 feet at f/1.4, but only 3-7 feet at f/16-f/22. In general, with Point & Shoot cameras the flash will only cover about 10 feet.

Hope that's enough info to get your feet wet and experiment!

 

[Phazan]

^Thank you sooo much!

Yesterday I went over a friends house and played around with the different apeture values.. It's pretty cool how that works. maybe I'll post a few in the general gallery later. Thanks for the help everyone! :thumbup: