f stop

I am not the best at technical terms...f stop is a term I learned in high school, but never really figured out until a year or so ago when I really concentrated on shooting in manual mode. F stop or aperture, this is very key to getting great "depth of field" shots. That blur, bokeh, hazy look. A lot of this has to do with the lens you have. I mentioned the 50mm lens because the fstop on that lens goes down to 1.8 on the inexpensive lens. Most "kit" lenses only go down to f/5.6 which doesn't give much in the way of blur. I'll explain it how I know, then try to find a few links that will explain it in the "professional way." The numbers indicate the size of the whole and how much light is let into the camera. The smaller the number, the bigger the hole, and thus the most light is let in. So with an fstop/aperture at 1.8 you are shooting "wide open" a common term in the photography world. It's all about the light, doncha know? The more open your aperture is, the greater depth of field possibility or blur factor surrounding the subject. If you are photographing people, you can really only shoot that "wide" with 1 person up close. If you have 2 people up close, then its likely that 1 will be in focus and the other more blurred. If you are further away, you can have to peoples faces in focus and the rest will be thrown out of focus.

So when I do a family shot, I cannot go below f/4 because I want everyone to be in focus. When I did the large extended family in the previous post, I couldn't go above f/8 so the larger group would stay in focus. For single or double subjects, I usually stay around f/2.8 or for a more dramatic effect, go to 1.4 on my lens.

Make sense? It takes a lot of patience to really figure this out...just like anything, practice practice practice. If you have a wide open aperture, depending on the light around you, you usually have to have a high shutter speed to compensate or you will get a nearly all white image. You have to have 3 components working for you, which is a future tutorial...shutter speed and ISO. I'll do those soon so you can work on it.

For more reading: I love wikipedia, here is an explanation of bokeh and samples and here is fstop with a sample of the 1.4 size compared to the 5.6 size...great stuff! Scroll down on this aperture page to see a great sample of a flower one with a wide aperture, and one not so much. It gets into fractions and how the human eye see's...

They give good samples, but I just stepped in my backyard and grabbed a few shots of my tree. Nothing fancy, just to show you the different fstops.... For each aperture change, you also have to change your shutter speed. The shutter speed often revolves around the aperture selected, so it is important to understand this. Data below each image. Click on each image to see it larger.




f/1.4
ss 1/5000
ISO 200
nice bokeh/blur/depth of field
very low aperture, pretty much only that one leaf is in focus while everything else is blurred...focus on the leaf...very high ss (shutter speed) to darken the image so it isn't blown out...brightly lit



f/5.6
ss 1/320
ISO 200
*with the 5.6 more brances in focus



f/8
ss 1/100
ISO 200
*you can see more twigs/branches are in focus than before



f/16
ss 1/60
ISO 200
*darker image b/c the fstop is high and the ss is kinda low, but i didn't want out of focus...needed to move my ISO to 400



f/22
ss 1/30
ISO 800
*In this one, the opening was so small with f/22 that I had to bump my ISO up to 800 and the shutter speed to a really sloooow 1/30 and got blur...if the shutter speed is slow, more oportunity for shake and you get the blur/out of focus that you don't want. Click on image to see it larger and you can tell it is out of focus


Thinking of somthing sporty to capture for my weekly blog post...not my area of expertise....