So I finally reached my camera kit target, that I set a long time ago, of one full frame SLR, and two lenses: a constant f/2.8 short zoom and a constant f/2.8 long zoom. In the meantime, while I was waiting for this day, I amassed several other interim lenses that have now been added to either my film camera bag, or my crop-sensor camera bag, but may still be called upon for use with the full frame camera, especially the f/1.8 and f/2 lenses.
The transition to a constant f/2.8 short zoom on a crop sensor camera was my first upgrade. The learning curve was small, the zoom being wide enough to never feel the ‘squeeze’ of too narrow depth of field (DOF). The extra several f/stops of the f/2.8 over the f/5.6 kit lens that came with my crop sensor camera was a breath of fresh air, and the sharpness upgrade was impressive.
My next upgrade was to Full Frame. Wow, the image improved several hundred percent (unscientific observation), and the learning curve was still fairly easy. The major differences were that my wide angle zoom was even wider and the max ISO jumped from 1600 to over 4 ISO stops more.
But the upgrade to a constant aperture f/2.8 long zoom does have a learning curve. And the lessons it will teach you can be painful. Of course the immediate impulse when I got the lens was to shoot everything at f/2.8. The subject isolation and bokeh is beautiful, and low light hand held shots are amazingly clean and bright. However this lens requires constant attention to produce the best results, for the following reasons:
1. Depth of field changes with subject distance. I might get a fantastic portrait of my dog at f/2.8 with the dog 30 feet away, but as he runs closer, the DOF shrinks – to the point where when he is at minimum focusing distance of 3 or 4 feet, only the texture of his nose is in focus. Unless I’m adjusting the aperture dial as he runs closer, most of my pictures will be unusable.
2. I now have to choose between subject isolated shots, or group shots. I was shooting a group event, which included a bike race. As the groups of bikers passed, I was shooting with aperture wide open, and I got good shots of individual bikers. However when reviewing the pictures, I saw that bikers before or after the biker I was shooting were often waving or smiling or doing other interesting things that I didn’t get in focus, because I was focused on one person. I took a number of pictures at a wedding reception – not as the official photographer, just as the camera crazy uncle – and I got a lot of portraits where just one eye or just the nose was in focus…
At that point I decided that what I needed was to make up a set of guidelines to use when shooting with this lens. I can’t say that I have anything yet. I have a feeling that it would look something like this:
1. Photowalks: keep a large aperture for narrow DOF. Open up if the situation demands it.
2. Events with lots of people: adopt the photojournalists rule of thumb – f/8 and be there.
3. If a single object or person stands out: dial all the way down to f/2.8 and take the shot.
4. In close quarters: Keep the aperture at f/4 f/5.6. No point shooting at f/2.8 if I can’t get farther than 20 feet from the subject anyways.
5. Landscapes: f/4 for sharpness, not necessarily DOF. If foreground objects are in the picture and there’s lots of light, f/8
It’s easy to get enamored with f/2.8 on a long lens, but it’s all too easy to abuse it.