Hi, In digital photography, when setting your apeture there are numbers like 5.6 or 1.8 what do these numbers represent? For example with zoom you have numbers like 50mm which represents the focal length. Can someone pls explain? Many thanks.
The lower the apeture, the more the light you let into the lens. The results are a lower depth of field and a higher shutter speed. Low apetures are great for getting the blurred bokeh effect as well as getting a higher shutter speed should the lighting be poor or it's dark. On the other hand, the higher the apeture number, the less light you let into the lens thus a lower shutter speed. You will get more in focus. f2.8, for example is great to use for taking shots in dim light or if you want a good bokeh effect. f5.6 would be a good all rounder, generally the best quality you'll get from your lens. f8 to f11 are good for macro. Landscape pictures are generally taken at f11 or f16. You'll get everything in focus but you'll have to have good light to get pin sharp pictures. A tripod should be used if very dark unless you can hold the camera extremely still.
As kanej2007 said, it's about how much light is being allowed into the lens although it also has the effect of determining how blurry your background is. This link does a really good job of explaining it. https://photographylife.com/what-is-aperture-in-photography To understand it properly, it's relationship to ISO and Shutter speed also need to be understood too.
^ Good guide uberdruid. And yes, it certainly has a relationship between iso and the desired shutter speed... with regards to iso, quite simply use the lowest possible number in good light. You will get little to no noise and a clean image. When lighting is poor, iso will need to be increased to get a usable shutter speed otherwise you'll get blur. Otherwise, using a tripod means there isn't a need for such a high iso and you'll get no shake/camera movement... However, with very high end cameras such as Nikon D4/D5, you could easily shoot using extreme high iso of 12,800 or even 51,000 with almost no noise! For other smaller cameras/compacts, you'll get a $hitload of noise at even iso 800 or more due to the $hitty pea sized sensors.
so just to add on what's already been said, aperture is effectively the "opening" of the lens, the bigger it is the more light it lets in now smaller the f stop number (1.4, 2, 2.8, 4 etc) the bigger the actual aperture, as it is expressed as 1/x, therefore a f stop of 1.4 is actually bigger aperture than that of say 4 now bigger the aperture (or smaller the f stop number) the more light it lets in, which in terms allows you to use faster shutter speed or lower ISO, it also reduces depth of field (that is the "depth" or "plane" that is in focus), different to what people like to say "bokeh" which is more in reference to the quality of the blur itself as others have mentioned it's important to understand the relationship between shutter speed and ISO (effectively your exposure triangle) and know what situation and what settings to use to get the shot you want
First photo is a wide aperture, F1.8 if I remember correctly, it was shot on film with an old Pentax Spotmatic, the next is at F8. As you can see, the photo shot at F1.8 has a very narrow depth of field, it is also shot at close range which magnifies that effect. The other shot is basically sharp all the way through. R1-04185-011A by Steve, on Flickr IMGP0691 by Steve, on Flickr
I understand aperture a lot better after reading this article but when i practice it, i still get a blurry picture. I have a Nikon D40 with both Nikkor lenses 18-55mm and 55-200mm and when i try to take a picture on A mode, it takes a long time to process it and it comes out blurry. Do I have to have the camera on a tripod when i am taking the picutre on A mode? or is there something else that i have to do or put the camera on different features? I have always taken pictures on automatic mode and now, I am trying to learn the features of the camera.
Also, the depth of field you get at f/1.8 and let's say 50mm will be different than that of a 100mm zoom. If your pics are blurry, you're focus is off or your shutter speed is too low, your hand shakes when you press the shutter and you end up with blurry pics. The relationship between ISO, aperture and shutter speed is the key to understand when you're taking pics. Would be good if you uploaded some pics (with exif) and we could have a look. Like I said above, the depth of field also depends on your focal length. Example, shooting macro, you'll have a very narrow depth of field even at f/13 at 90mm. If you're shooting a landscape in the distance at say 200m, even a f/3.5 will produce pretty much the whole pic in focus.
If I can carefully hijack the thread: does your lens actually limit your usable aperture? I'm using a entry level Nikon D3300 with Nikkor 18-55 f1/3.5 kit lens. Can I use an aperture of say f1/1.8 with this lens? I am experimenting and it doesn't seem so, but that might very well be my mistake
Based on your 8 posts so far you're either a spam bot or the worlds most banal poster (no offence intended).