In this post I am going to talk about lenses again. I know I did this before in an earlier blog post, but I think I should get back at that again. The reason is quite simple: last week a friend asked about lenses he would need. Now, I am a noob, but I do happen to have DSLR with three different lenses. And I have actually read a bunch of articles. He was not at that stage yet. So we spoke about what he wanted to do and then I told him what I would buy.
The funny part is: it is the exact same advice as I gave in that earlier post. During that talk however, we also came to a topic that is not mentioned in the previous post. But it is an important one, so I will talk about that part in this post.
In case you think every guy loves the Formula 1 and this is about pit stops in the Formula 1, you're mistaken. We're still talking photography, and it's about a thing you can see on your lens.
|Nikon 18-300mm F3.5-5.6|
In the image you can see the mention about the F-stop. Of course, they do not make it very clear, as the letter F is not mentioned there. But it is the part with 3.5-5.6 in it. There are also lenses with only one number there. Every prime lens, which has a fixed focal length, always has only one number. But a zoom lens can have either one number, or a range. The F-stop means your widest aperture. If you have a lens with one number, it has that widest aperture on every focal length (zoom level). If you have a range, the lowest number is the widest aperture when not zoomed in at all. The higher number is the widest aperture at full zoom. In general you can say that the lower the number, the better. And that means also more expensive. Just as lenses with a fixed aperture on all focal lengths are more expensive.
I can see that the question would then be: why would you want these lower numbers? What does this F-stop thing do?
Light and focus
And this heading here is the answer to the question in the previous paragraph. An F-stop can be seen as a number telling the wideness of aperture. A low number means a wide aperture. A wide aperture allows more light into the camera. And that means you can shoot in darker situations, or raise the shutter speed to freeze motion. Being able to do so, is of course nice. And that is why you should like a lens with the lowest possible F-stop value you want to pay for. However aperture has another effect, namely the Depth of Field (DoF).
The photo here demonstrates this effect. Now, I do not have lenses with really wide aperture like F1.4 or F2.8, but I suppose this example suffices. The photo shows the bird sharp. It's focused on it. You can see the branch it's sitting on is also quite sharp. The branches further away are... well... I guess we know they should be branches, but it's definitely not very sharp. In photography this is often a desirable effect. In this case I want you to look at the bird, not the branches in the back. If you want to show a landscape, it is often not what you want. A wide aperture gives a small depth of field, so with a wide aperture (so: low F-stop), we have a shallow depth of field and get blur sooner. With an F-stop of 1.4 and taking a close-up of a person, you might notice that when you focus on the tip of the nose, the eyes are already not sharp anymore.
That last remark brings us to the second ingredient that makes up the Depth of Field: distance. The closer the object is that you focus on, the shallower your DoF will be. So if the previously mentioned person would be not close by, but say 30 meter away, then with the F1.4 he would still be fully in focus. So, there are two things to consider, the F-stop and the distance to the object to focus on.
The images here represent you: the photographer on the left. Your subject, the princess model in the middle and some background: a forest. The first image uses a wide aperture and makes sure your princess is in focus. The green around her shows what's in focus and what is not. And as you can see behind her is clearly more. Everything in the white area would be blurred.
The second image shows a much smaller aperture. And while the forest is getting into focus, the area right in front of you is still mostly out of focus. Rule of thumb is: 1/3 in front of the subject and 2/3 behind the subject is the focus area. With changing aperture, you can set the depth, but always in these proportions.The other way to set the depth would be walking closer or further from the subject.
What F-stop do you need?
So, you want those nice blurry backgrounds? Then you need an F1.4 lens, obviously. Or... no. You don't. The previous examples already showed you can get that also with higher F-stops (so, a narrow aperture). If you are close to your subject, you already make the DoF shallower. And a shallow DoF means your background gets blurry sooner. The other trick would be to move your subject further away from the background. And this is also demonstrated with removing parts in front of the subject.
|A bear looking at a snack?|
I took this photo in the zoo, and I can assure they do not let you go near the bears. Nor do they allow the bears to go to you, it might mistake you for a snack, after all.
So, there are fences, like you can see in the background. Such a fence is also in front of the bear, yet you don't see it on the photo. This is also an effect of Depth of Field. The distance between me and the bear was quite some meters and with an F5.6 it has a reasonably small DoF. The distance between me and the fence was pretty small, so all it gave was a tiny blurry line. Which I mostly removed in post processing. So, do you really need that F1.4? I cannot decide that for you, but I would at least say: unless you want to go the path of a professional photographer - in which case you should not read this blog, but write it - you probably don't. Simply start playing with your aperture, look at the effects and don't forget to try out small apertures and wide apertures, both close by and at a distance. And then, after having seen what your current camera and lens can do, you can decide whether you need that. And in case you happen to have a spare one fitting my Nikon D3200: I would be a happy receiver, even if I think I do not need it, nor feel willing to pay the price for it.
Now, please go make great pictures with blurry backgrounds and perhaps we will next time talk about bokeh.