Many a time, I have been asked a question on what exactly isolates the subject in your photograph.
The answer lies in Exposure.
Exposure - the combination of the right iso, shutter speed and f stop.
The types could be broadly classified into a story telling exposure and an isolated subject exposure.
This article will not talk about the histogram, as it will be discussed in a later post
Most point and shoot cameras do not give the user, control of ISO, Shutter speed, and f-stop as a DSLR does. However these days point and shoot cameras and even mobile phone cameras give you some control, but I doubt it if they give you so much control as a DSLR does.
But, what would be the perfect exposure?
Let us look at a standard ISO of 100, which ensures that the picture is not grainy. I set my Canon DSLR 1200D in manual mode, used a Tokina macro f2.8/100mm and all pictures have the same distance to the subject (the flower) , and the focal length in all these pictures is 100mm. This leaves us with the f stop I decided to use - f32 - the narrowest aperture. The exposure meter on my DSLR was at the center for a shutter speed of 1/2 a second.
and this is what I got
The above image is slightly blurry in the background, giving you a clue that this flower was shot in some garden, or park. That's a story telling exposure. The petals are clear and sharp and no blurriness here.
Now, widen the aperture by changing the f-stop to f13, the exposure meter balanced at the center at 1/10th of a second, with same ISO of 100, and the below image is what I got.
The above image clearly isolates the flower all the petals are clear and sharp, the leaf is blur to a certain extent, and the background is blurrier than before.
Let us now look at the isolated exposure below, where in I just want the flower and a complete blur background. I simply went to the lowest f-stop of f2.8 on my macro lens giving me the widest aperture available (this is always not good, as we shall see in the below image). The background is as blurry as it can get, and it would be difficult to tell a story , the leaf has blurred out too, but alas the petals at the back are not very sharp, they have blurred to an extent too.
The answer is, we need to keep trying and taking photos for an isolated exposure I believe an f3.5 or f4 could have made the back petals sharper while keeping the background completely blur. As a general rule of thumb, if the histogram is anywhere closer to a bell curve, that would be enough.
Additional reading:
For a more in depth article on Macro Photography do visit Macro Photography - A Complete Guide
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