Aperature Vs. Shutter speed

poopingfish · Dec 13, 2007

Well, learning more each day..I recently learned using a higher fstop gives a generally crisper picture overall. This is good as I have not been happy with most of my pictures. Needless to say Ive been using an fstop of 3.5 to get the brightest picture possible with a decent shutter speed (atleast 1/30) and not a really high iso.
So..how do you use a higher aperature setting in general and a decent shutter speed without a very dark picture?

Josh66 · Dec 13, 2007

poopingfish said:
So..how do you use a higher aperature setting in general and a decent shutter speed without a very dark picture?

If you want a smaller aperture (bigger number...) and a fast shutter speed, you'll have to either increase the ISO or have more light.

If you don't want to (or can't) raise the ISO more (noise), you need more light (flash).

RacePhoto · Dec 13, 2007

Or a Tripod.

It's just a matter of light and physics. You can't make a camera do what's impossible.

In other words, you have to work within the limits and choose. You can't have high speed and small f stops. (well you can, but you pay the price of more grain and noise, because you have to use a higher ISO to do it)

That's why people pay big prices for fast lenses. More light = faster shutter speeds. Or in the case that you are asking about, people ask, why do I need a 2.8 lens, if I'm going to shoot at f/8?

Because the way lenses are made (and this is a very simple explanation) a 5.6 lens, shooting at f/8, is not going to give you as good of an image as a 1.4 lens, shooting at f/8.

If you have to go to 3.5 which is wide open on your lens, rather than having a 1.4 lens and stopping down to 3.5, the second lens will give you a sharper photo.

The 1/30th part is going to be the same. Once again without getting all complicated, if you are shooting hand held, with a standard lens, you probably don't want to go slower than 1/60th.

Alex_B · Dec 13, 2007

Simple answer if you want to avoid high ISO and still use a small aperture ("large f-stop-number"):

TRIPOD

.. only works if the subjct is not moving too fast of course.

Else you will have to choose the compromise which ist best for the effect you want to achieve.

BTW, a large aperture does not mean the image is less crisp, it just has a shallower depth of field (DOF), which means things closer to you or further away from you than the object you focussed on, appear blurred more pronounced.

Oh, by the way, the word is aperture.
(no offense, but on the www you read all those strange spellings from time to time, that people forget about the real word

)

BAB · Dec 13, 2007

Shutter speed and aperture represent a reciprocal relationship in terms of exposure. Understand that the smaller the aperture (higher number) the more depth of field. On the other hand the wider the aperture (smaller number) the poorer depth of field you will achieve. With shutter speed, the faster the setting the greater ability to stop motion and on the other hand the slower the shutter the less motion you will be able to freeze. There are technical and aesthetic reasons why one would choose a given aperture or shutter. To say that a smaller shutter yields a "crisper image" is not really correct. You may be confusing the greater depth of field of smaller apertures with crispness. As for exposure, here is where the reciprocal nature of the aperture and shutter speed come in to play. As an example if for argument sake, f11 @ 1/60 yields a properly exposed image, so too will f8 @1/125 and f16@ 1/30 and all the way through your range of aperture and shutter choices. This reciprocal relationship, frees the photographer to be creative and choose the aperture or shutter speed based on what his/her vision is.

poopingfish · Dec 13, 2007

Race-Thats interesting to here. Glad I have that 50 1.8 prime on the way..Budget lens all the way but hopefully will give more insight for me to how lenses function.

Im getting a tripod soon! Dont have one yet, but its definitely a priority!

BAB-Did you use any math to get there or are they general rule-of-thumbs to follow?
For now I will just have to settle with the flash, but I hate the reflection it gives.

I didnt exactly meant the lower aperture gave me a crisper picture, but when taking landscapes with a higher fstop things should be more in focus overall then.
-The reason I posted this, Is I was looking at the canon help pages. On a page they took pictures of flowers or a field showing aperture, and on each picture each was exposed very similarly and I wanted to know how they did this without getting a darker picturer! Perhaps they did lower the shutter speed, I just wish they stated it. Off to go download exif data and check now!

Hubertus Bigend · Dec 13, 2007

I gather many lenses are sharpest at f/5.6 - no need to go all the way to f/16 or higher.

Alex_B · Dec 13, 2007

Hubertus Bigend said:
I gather many lenses are sharpest at f/5.6 - no need to go all the way to f/16 or higher.

We should not confuse sharpness and depth of field though.

It is true that most lenses have their maximum sharpness of what is in focus around f/8 .. beyond that diffraction effects settle in and lower overall sharpness.

however, if you want a huge depth of field to have that grass in the foreground and those mountains in the background equally sharp, then (depending on the size of the medium, the distance to the foreground and the background, and the focal length) you will often need f/16 or beyond.