How to Set the Correct Aperture?
By sdas86
@sdas86 (6076)
Malaysia
December 4, 2008 4:17am CST
I borrow a Sony Alpha 300 from my friend. I am trying to capture a good landscape photo which can have clear foreground and background image.
I am trying different setting of the aperture to get different effect photos. The problem is that I do not know which aperture is the best setting to use.
Anyone knows how to set the best aperture setting?
1 person likes this
4 responses
@Davidarich (985)
• Australia
5 Dec 08
There are two things to consider if you want both foreground and background sharp. The depth of field (sometimes erroneously referred to as depth of focus) and the closest object you ant to have in focus.
As has been pointed out, short focal lengths ("wide angle") and small apertures(typically f/16, f/22) maximize depth of field. To get the benefit of this, you need to understand where to focus. There is a concept called "hyperfocal distance" which allows you to calculate the maximum depth of field possible with any lens. Without going into the maths (which aren't that hard. but not needed for this post), if you set the smallest aperture (largest f/number) available in the light you have, and focus on a point about 1/3 of the way into the scene, you will have the greatest depth you are going to get.
This is because Depth of Field extends twice as far behind the point of focus (the only point truly in focus as it does in front of that point. That is why you need to know what the closest point you want to have in sharp focus: from there to the horizon is your focus zone.
if you had a Canon SLR instead of a Sony, you would have had a setting that automatically calculates the hyperfocal distance for you, but the 1/3-2/3 rule will work fine.
1 person likes this
@sdas86 (6076)
• Malaysia
5 Dec 08
Hi,
Great response. Do you mean that the smaller the number of apertures (f/6, f/22) will get the maximum depth-of-field?
I know that Sony DSLR do not have such function but Sony DSLR is more budget than Canon. 
I read about Canon 1000D. The Canon 1000D doesn't have depth-of-field preview function. It is quite sad.
I read about Canon 1000D. The Canon 1000D doesn't have depth-of-field preview function. It is quite sad.
@Davidarich (985)
• Australia
5 Dec 08
Well, you will not find f/6 on any lens (f/5.6 is the closest equivalent), but if you did, that would be a fairly wide opening with a relatively shallow DOF. f/22 is the smallest aperture found on standard lenses, and gives the greatest DOF. But remember, the focal length plays its part (wide angle, greater DOF ~ telephoto, shallow DOF) and so does the point of focus.
1 person likes this
@trickiwoo (2702)
• United States
6 Dec 08
If shooting a landscape where you want everything in focus, you want to use the smallest aperture possible. Which means you want to have a higher f number.
If you're shooting close up objects where you want the foreground to be in sharp focus against a blurred background, then you will want to use a larger aperture or smaller f number.
@Davidarich (985)
• Australia
6 Dec 08
Apertures are ratios: the ratio between the focal length and the lens opening. Think of them as fractions and you will see why bigger numbers mean smaller holes...1/2 is bigger than 1/6. With apertures it is Focal length/2 and focal length/5.6, or f/2 for short. Often it is written f2 and f/5.6, which hides the fact that it is a ratio and confuses things.
Every aperture lets in twice the light of the next larger one or half the light of the next smaller one. We call this a stop , because we used to used flat disks with holes of different sizes punched in them (like washers) to stop more or less light coming in...they still do with lens babies).
A lens with a larger maximum aperture lets you use a faster shutter speed, so it is referred to as a "fast" lens. The fastest I ever owned was a f/1.4. Most lenses are f/3.5 or "slower" while a lens of f/2.8 or larger is considered "fast".
A typical sequence of stops would start ot a large f1.4 and runs 1.4, 2, 2.8, 3.5, 4, 5.6,8,11,22,32. Remember, each stop is twice as fast as the one before, half as fast as the one after. Shutter speeds run the same way: each one lets through 1/2 the light of the one after, 2x as much as the one before. So if you increase the aperture by 1 stop, but reduce the shutter speed 1 stop, the exposure stays the same. This is called the Reciprocity Rule.
If all this has made you more confused, don't despiar! It will all fall into place and suddnely everything will seem so simple. Go and have a look at www.qassia.com/creative-aperture-control which I wrote to go along with similar articles for beginners on creative shutter control, focus etc.
1 person likes this
@ratyz5 (7808)
• Philippines
4 Dec 08
Wouldn't that be dependent on how far you are from the landscape wherein you want to take a photo of? I mean, if you have a particular set up, wouldn't that mean that you also have that particular distance from what you are trying to take a photo of, somehow similar to a studio set up? But here, your going for a landscape photo, so its really a hit or miss. Challenging as it is, trying a variety of aperture set ups and see which photos really get your attention and finding that shot you want if really rewarding..
Uhmmm, well, that's just what I think anyway.. (^_^") I could be wrong..
@simlock (28)
• United States
4 Dec 08
Basically for a landscape with everything in equal focus you want to set a smaller aperture. The higher the f-stop, the small the aperture, so f16 is a smaller aperture than f3.5 for example.
Lenses tend to have a "sweet spot" for aperture. Probably your best bet is to try f8-f11. Also don't forget that the wider you go with your lens (assuming you have a zoom) the greater the depth of field - zooming in will compress the depth of field and the range of focus from front to back will lessen.
@simlock (28)
• United States
4 Dec 08
Hi, yes a larger depth of field for landscapes is better - but selective focusing can be used creatively and that would be a function of your aperture and zoom range. (ie shooting a bed of flowers and you want the focus to drop off front to back - of courser ultimately it's "how good's the picture"!
1 person likes this
@sdas86 (6076)
• Malaysia
5 Dec 08
Hi,
Thanks for your explanation.
If I want to take photo of bed of flowers, I would make the front flowers to be clear and back flowers to be blur.
Would you check my photo of flowers at ViewBug:
http://www.viewbug.com/photo/128564/
The photo is taken using my Nokia N95.
Would you check my photo of flowers at ViewBug:
http://www.viewbug.com/photo/128564/
The photo is taken using my Nokia N95. 