Focal Length Difference

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Don’t we all love wide angle lenses for landscape photography? After all, they are amazing in gathering in as much of the scene as possible. However, what happens when there are many things in a scene that we do not wish to include, but at the same time we want to keep that stunning foreground object as large as possible? Pictures and simple words are the best way to explain the focal length difference.

I will refer to the foreground as FG and the background as BG. Let’s pretend that the 24mm lens is our FG and the tilt/shift lens is our BG. In all 3 pictures I tried to keep the FG the same size. All pictures have been taken at f/16 aperture and focused on the FG. However, there are some differences.

Free-Advice-Focal-Length-Difference-28mmPicture 1: I kept the camera as close to the FG as possible. The zoom lens on my camera indicated 28mm. Notice how far the BG appears to be, although the distance was only 25cm. Also notice that my lens could not focus perfectly on the FG at such close distance.

Free-Advice-Focal-Length-Difference-70mmPicture 2: This time I moved the tripod further back and zoomed in at 70mm. I adjusted my distance from the FG in order to make it look the same size as in picture 1. However, although the FG in both pictures looks the same size, the BG now appears to be larger and closer, and the angle of view narrower. If there were certain elements in the scene that I didn’t want to include in the frame, 70mm would be the perfect choice. Notice that now f/16 was not enough to keep the BG in focus. However, with more precise focus adjustments, I could have the BG in better focus.

Free-Advice-Focal-Length-Difference-145mmPicture 3: I repeated the previous step and this time I took the picture at 145mm. The FG is kept the same size but the BG looks even larger. Now, imagine the BG lens being a mountain. Do we always need to use the widest lenses in landscape photography? Food for thought.

Read this article, and many more, in High Definition, inside Issue 28 of Landscape Photography Magazine.

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  1. Thank you very much sir Dimitri for your quick response. now i know that i even the most expensive lens on the planet will not be able to achieve what i wanted. however, i am considering about doing the other way you mentioned. taking 2 different shots of the moon and the light post and stitching them together will eventually solve the problem. Again, thank you very much for the quick reply. cheers!

  2. Hi Dylon

    This article is about the difference in focal lengths and not focusing techniques, your question would require an entire article to answer it. For the above example I focused on the fg lens because the focusing technique was not the main subject of this short article. In a real life situation and if this was a landscape, I wouldn’t have focused on the immediate fg but slightly further, I would have taken a test shot and readjust my focusing.

    However, here is my very short answer. In landscape we have foreground and background, the latter often being referred to as infinity, although real infinity is the extreme far distance. What you are referring to in this question is the moon, which in theory is beyond infinity as it is far away from our planet. No matter what aperture you will use, you will never be able to have the fg and the moon in focus at the same time. There are two ways to achieve this. One is to take two different pictures and blend them together. The other is to purchase a tilt/shift lens and learn how to use it properly. Remember though, even with a tilt/shift lens you will have problems. The two subjects (fg & moon) will be in focus but other things along the way might not be. You can find more on this subject by reading about the Scheimpflug principle. Here is a video to watch. http://www.youtube.com/watch?v=gR4m70xr9mE

  3. “Notice that now f/16 was not enough to keep the BG in focus. However, with more precise focus adjustments, I could have the BG in better focus.” – Sir, i am really banging my head to make the BG in focus. (in my case: the full moon) i used the moon as a BG and my idea is to keep it in focus and enlarged with respect to my FG (in my case: a Street Light). you mentioned about more precise focus adjustment to achieve it.. do you mind sharing us how?

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