Why should one should at a higher f-stop?

[FourAcesPhotography]

I just noticed something. Maybe it's because I do mainly portrait, and usually in situations where there is low light, but I always shoot at a low f-stop (below 5.6). It let's in more light so I can shoot with a faster shutter! It puts the object in focus and creates a greater DoF. Why would I choose to move up?

What's the trade off from shooting at f11 and f5.6?

What's a situation where you would use f11 vs f5.6?

I know, some rookie questions - but this IS the beginners forum right?

 

[KmH]

Portraiture is usually done with flash and the duration of the flash is usually much shorter than the shutter speed (as fast as 1/40,000 or more), thus more effective at stopping motion.

Shutter speed is more used to control the background exposure level, while aperture is used to control the subjects exposure.

DOF is controlled by the subject to background distance, the focal length of the lens used, and the camera to subject distance.

 

[PhotoXopher]

Greater depth of field... landscapes/cityscapes, etc. for one example. Slow exposure tripod shots, moon shots, for another example.

 

[Big Mike]

The lens aperture, besides controlling how much light gets into the camera, also controls the DOF. A smaller aperture (higher F number) gives you a deeper DOF.

You may want a deeper DOF when you have more than one subject that you want to have in focus. For example, a group of 10 people in three rows...you may need to 'stop down' to F8 or F11 so that the people in the front and the people in the back are all in focus.

Landscape photographers often shoot at smaller apertures. You might want the rock that is 10 feet from you, and the mountain that is 10 miles away, both to be in focus.

Also, most lenses are at their best when they are in the middle of their aperture range...or at least a couple stops down from wide open. With many lenses, you would probably get your sharpest shots at around F8.

 

[NateWagner]

well, actually it creates less of a DOF

People use smaller apertures for a number of reasons. One of these reasons is when you want a deeper DOF, an example of this is say you're doing group shots with a large family, you want the entire family to be in focus, so many times you'll need at least an f/8. Similarly, if you're shooting macro, the DOF is so shallow you often want to stop down so you can get the whole object in focus (this is also the case shooting dogs heads as if you're using a shallow DOF you'll frequently lose either the nose or the eyes out of focus.

Another reason is that many times lenses are sharper stopped down a bit, so, rather than shooting at 2.8 or 4, they may shoot at 5.6 or 8. Additionally, there are effects you can get by stopping down. if you're shooting into the sun, and you want the star pattern flare you generally need to stop down a fair amount.

 

[docphotog]

Also, most lenses are at their best when they are in the middle of their aperture range...or at least a couple stops down from wide open. With many lenses, you would probably get your sharpest shots at around F8.

Big Mike, that's a really cool fact, I never knew that thanks!

 

[benlonghair]

Mike's absolutely correct. My 70-300 is pretty meh at 5.6 but tack sharp at f/8-16 .

 

[Stormchase]

Hmm this thread might be explaining some of my .. well .. lack of sharpness ... lol thanks