Large Lens Aperture – Avoiding the Trap – Rudi Hulshof

For many photographers, be they enthusiasts, hobbyists, or amateurs, the inevitable dream, especially with regards to Wildlife Photography is to own a long focal length lens with a large aperture. A trap many end up falling into, is not adjusting their chosen aperture when taking photographs, falsely believing that the larger the aperture, the better the image. To make this totally understandable, in plain simple English, I will keep this post not only short, but use layman’s terms, and speak from personal experience. For years I could only wish for a lens of at least 300mm focal length with the magical maximum aperture value of f2.8, or a 400mm, 500mm, or even a 600mm lens at f4.

Just imagining the pin sharp details of an animal’s face, with a smooth creamy background, made available only by using the largest available aperture ( Smallest Number eg f2.8 or f4 in the case of Longer lenses ), was enough to make me drool. Over time though, I realised through my own faults that to get a great image, the Largest aperture was not the holy grail of photography. Other than the wished for Shallow Depth of Field (Blurry Backgrounds) made possible using this large aperture, of what we refer to as a fast lens, the aperture is also critical in controlling the shutter speed. When a large aperture is selected, more light is allowed through the lens to the camera sensor, this serves to increase the shutter speed, and hence hopefully freeze a split second in time, making for pin sharp, super focused images. There is less chance of lens or camera blur when using a large aperture than when using smaller apertures. ( Large Number eg. f11 ) because the shutter opens and closes much faster.

Let me get back to the initial aim of this Blog though, else I may go off on a full photographic tutorial. The trap I specifically refer to in this instance is by choosing a large aperture when the subject is too close for the desired image. When a close up portrait is taken, and the subject is not far away, be sure to take the distance into consideration. With a shallow Depth of Field, less of the subject will be in focus. At close proximity to the subject, this would mean that the point of focus will be sharp, but the detail will soon be lost, leading to an image that seems out of focus.

To illustrate, I have included a few Images all taken with the Sigma Global Vision 120-300mm DG OS HSM f2.8 Sport lens with a Sigma 1.4x converter, attached to a Nikon D3. Effectively this allows me to photograph Wildlife at 420mm Focal length with a maximum aperture of f4. This combination is my favorite go to setup when conducting my Wildlife Photographic Safari’s.

Please compare Images:
1 and 2
3 and 4
then 5 and 6

Be sure to take careful note of the detailed information provided with each image to help understand.

Take note of the detail loss surrounding the point of focus, when the Depth of Field is too shallow ( Aperture too Large ) Also included are a few cropped images, to better illustrate the loss of detail, resulting in un-attractive images, made much more visually appealing when decreasing the aperture size, resulting in the increase of detail. ( Larger f number = Smaller Aperture)

NB: Click on the image to enlarge it to see as much detail as possible.

Image1

– ISO 1000
– f4
– 1/2000s
– 420mm

Image2

– ISO 1000
– f5.6
– 1/1000s
– 420mm

Image3

– ISO 800
– f4
– 1/4000s
– 380mm

Image3a

– ISO 800
– f4
– 1/4000s
– 380mm

Image4

– ISO 800
– f6.3
– 1/2000s
– 420mm

Image4a

– ISO 800
– f6.3
– 1/2000s
– 420mm

Image5

– ISO 500
– f4
– 1/1000s
– 420mm

Image5a

– ISO 500
– f4
– 1/1000s
– 420mm

Image6

– ISO 500
– f5
– 1/640s
– 420mm

Image6a

– ISO 500
– f5
– 1/640s
– 420mm

I hope this helps you in your photographic development, and more importantly that you do not set yourself up for dissapointment when downloading images after a shoot, expecting a magical image that just does not materialize on your screen after downloading.