Almost every photographer out there craves the beautiful bokeh and shallow depth of field of the F2.8 aperture – regardless of the focal length. The effects of a shallow depth of field are simply breathtaking in terms of making your subject “pop” from the background and foreground.
Not all photographers can afford, or justify the expense of these lenses though. If you understand how aperture and depth of field works then you will know that you can achieve similar results without a maximum aperture of F2.8.
Lets assume you are shooting of the ever popular Canon 100-400mm or the 80-400 Nikon. Both have a maximum aperture of 5.6 when shooting at 400mm. All of the images used below were shot at a focal length of 400mm at F5.6 on a Canon 100-400mm lens (various bodies).
Tip 1: Zoom In
Your focal length has an impact on your resultant depth of field at a given aperture. At 100mm your depth of field will be far greater at F5.6 than it will when you are fully zoomed in at 400mm. The zoom factor brings your subject closer and makes the resultant depth of field shallower.
Tip 2: Get Closer
Just as focal length impacts depth of field, so too does the distance to your subject. The resultant depth of field at a given aperture decreases the closer you are to your subject. Assuming you are shooting at f5.6 and are fully zoomed in (at 400mm), the closer you get to your subject, the shallower your resultant depth of field will become.
Don’t forget that every lens has a minimum focussing distance so don’t get too close that you can’t achieve focus. As most readers of this blog are wildlife photographers I probably should state the obvious and remind you not to get too close to wild animals and dangerous game (insert generic disclaimer here).
Tip3: Open Wide
Small F numbers (large apertures) create a shallower depth of field than larger numbers (smaller apertures). In our example of the 100-400 & 80-400mm lenses, you’ll want to open up as wide as possible to F5.6.
It may not be F2.8 but I tell you what, the resultant shallow depth of field in all of these images still makes the subject pop does it not?