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Saturday, March 26, 2011

Distance to Subject and it's visual impact on the photo


When you pick up your camera do you twist the zoom ring until you have the framing you want?  Maybe you shoot with primes and you do the foot zoom to get the framing you want rather than change the lens.  If one of these scenarios sounds familiar to you then you should learn to ask yourself why you do that.  

Let me explain what I'm getting at.  DISTANCE TO SUBJECT.

I think this is a very underrated tool.  How many times have you been told that if you want to create compression in the photo to use 85mm FL (focal length) or if you want a lot of compression use a 200mm FL?  Maybe you have heard over and over that if you want the photo to have more depth even exaggerated depth then use a wide angle lens.  

What if I told you that focal length plays absolutely no part in this characteristic of the photo!  Don't get me wrong focal length can have a lot of influence over the look of a photo it's just that it has nothing to do with compression or lack of.  

You have likely heard that you should use between 85mm and 135mm for portraits so that peoples faces look natural.  The advice is sound enough because using an 85mm lens forces you to stand further back creating a pleasant compression on the face but it leads you to believe that there is some magic in these focal lengths but in reality the magic lies in the distance to subject.  There is nothing wrong with using a 24mm lens for people as long as you are aware of the effect of distance to subject.  If you try to use a 24mm lens to create a tight head and shoulders shot by getting close you will see an unnatural representation of the facial features, but if you stand back for a more environmental portrait with the 24mm you will get the same compression as with the 85mm.

A lens on a camera is not all that different than the one in your head (I'm talking about your eye in case you haven't had your coffee yet).  So you can test this theory without a camera.  Sitting at your table put your eye down low to your cup of coffee and look at the sugar bowl sitting just 30cm away.  If your eye is low and close you'll notice that the coffee cup is large an ominous compared to the sugar bowl which makes the sugar bowl appear far away.  Now step back as far across the room as you can and line up your site on the same two objects.  You'll notice they appear to be closer together than when you had your nose in the steam of your coffee and they will also appear to have a more natural size between them. 

This is the very simple principle used in photography to give a photo it's depth or it's compression.  Let me explain further.  When you select a 28mm FL and get very close to an object such as I did with the stone below with the church in the background,  you'll notice that in the image the stone appears very large and is clearly the main subject and it somehow is more ominous than the church.  Select a FL of 85mm and move back  to get the same image framing and you'll notice that the church now overpowers the stone and the church seems to be right there on your lap.  This is simply a function of distance to subject not 28mm vs 85mm as many believe.  



In the next two photos you can see that his is very true.

The photo on the left was taken with a FL of 85mm and the photo on the right is taken with a FL of 28mm at the same distance and cropped to match the framing of the 85mm lens.  As you can clearly see the effect of compression is identical with the 28mm as it is with the 85mm.  The un-cropped photo from the 28mm is shown below.







There is good reason to select a wide angle for adding depth to a photo but it's not magic as many would have you believe but rather that it simply has a wider field of view that allows you to get very close to the subject while still fitting in a lot of background.  By all means choose a telephoto when you want compression but just remember that it is your distance from the subject that is giving you that compression and using a wide angle from the same distance would give the same compression but would require a lot of cropping!

So now you are asking why is this important to understand?  Do you remember my first questions at the start of the article?  Next time you see an object you want to photograph don't just pick up your favourite zoom lens and start twisting the ring until you get the framing you want but rather look at it with your eyes for a moment, then move closer then further and think about how your distance will impact the relative size of objects in front of and behind the subject.  Once you have given that some thought then choose your focal length based on how far away you want to stand (or sit).  This thought will prevent you from being disappointed by the photo of a person with the mountain in the background and everyone says "that mountains looked so much bigger in person"!  This is a good example of where simply changing the distance to subject could have had a huge impact.  By moving way back and just selecting whatever focal length gives you the framing you want the mountain would be as big as everyone remembered.   Try this very scenario by taking a full length portrait with a mountain in the distant background from 2m away and then take another full length portrait from 10 or 15m away, and just choose a focal length that gives you the framing you want.  You will never forget this lesson once you have experienced it.

Don't fret over small changes in distance but rather just pay attention to what is changing and ask yourself if these changes are what you want.  I use prime lenses for most of my work so I use the foot zoom a lot so I just pay attention to what is changing in the photo when changing my distance.  If changing my distance changes my vision of the photo then I probably need to change my focal length rather than moving.

Once you have done this for a while you will no longer need to think about it you will immediately know what FL you need for any given shot and you will be a better photographer for it.

4 comments:

  1. we need to hear more from you bro. this article just cleared so much of my doubt.

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    1. I'm so glad it helped you out!

      Any suggestions for topics you would like to see me cover?

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  2. Hey Trevor! I have a question about distance from subject and the depth of field.
    Suppose that you have two objects in a photo. You want both of them to be in focus, but can’t stop the aperture down (it’s already dark). You are in position where 35mm focal length makes you a good composition. Could you expand DOF by going a few steps back and zooming in (at, e.g. 50mm)?

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    Replies
    1. No that would give you roughly the same DOF and less background.

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