If you’ve read the last four or five posts, it’s probably occurred to you that, in the new high resolution digital image, focusing is a challenge. Indeed; if you want to take full advantage of all the pixels that modern technology can give you, I think focusing is the most problematical operation in photography.
It wasn’t always so. When we had manual focusing, we had better focusing aids. In the 35mm and medium format SLR world, we had microprism collars and split image centers on the focusing screen. With view cameras, we could plunk a 10X loupe over the ground glass.
With medium and small format cameras, the resolution of the film we used wasn’t that great. That gave us two advantages in focusing: we could use smaller (numerically larger) f/ stops without worrying about diffraction, and if we were off a little bit, the film had a hard time resolving it.
Autofocus came along, and we gained in focusing speed, but sometimes lost in consistency and accuracy. The optical focusing aids in the finder disappeared as the manufacturers figured that people didn’t need them anymore. The autofocus lenses didn’t have the nice feel of the old ones when manually focusing, and the amount of rotation for a given focus shift got smaller.
At first, the digital cameras worked about like the film cameras that they largely supplanted. But the sensors grew larger and denser. This was great for quality, but now many of the sensors are unmerciful in revealing focusing errors, and even higher resolution sensors are on the horizon.
What to do?
First, make sure your autofocus is doing the job. Check every body/lens combination; it’s quick and easy, and you can often dial in corrections that the camera will remember. If there are body/lens combinations for which autofocus is not reliable, use an eyepiece magnifier or live view in situations where you know that depth of field is not going to paper over misfocusing.
More to come on each of these.
Jim,
I couldn’t agree more. Focusing has become the key technical issue in my photography, eclipsing exposure/development from my film days.
Fairly early on in my experience with digital cameras I realized that there had been a tectonic plate shift in photography. Where I used to lose images due to flaws in exposure and/or development, now more often than not images are lost due to flaws in focusing. Using RAW files, I rarely lose images now due to exposure problems. Where I used to expend extraordinary amounts of care to stabilize the camera and expose with an eye on the Zone System procedures, now with high ISOs, RAW processing, and optically stabilized lenses, it is focus that is my primary technical concern.
In fact, during my recent trip to China I created about 1,800 exposures and only one is exposed so poorly that it is unrecoverable: a case where I inadvertently moved the mode dial to manual by mistake. However, I’ve found a couple dozen images where the auto focus simply zeroed in on the wrong part of the image and my “subject” is out of the plane of sharpest focus, or the auto focus simply didn’t lock in on anything and my too-fast trigger finger pressed the shutter release without a focus lock.
Unfortunately, my current camera does not offer “focus bracketing” and doesn’t re-focus during burst mode. So, I’ve become more and more sensitive to this as the key technical issue that can ruin an otherwise good composition.
Brooks
I consider myself from the old school where I practiced zone system in my college days, I am one of the early adaptors of digital photography. The only thing I haven’t change is the use of manual focus lenses on my DSLRs, this combination give me exactly what I wanted as I do a lot of street photography.
My most recent purchase was Olympus EPL1 with VF2 finder and Panasonic GH2, the reason being is I fall for these cameras is the digital viewfinder offers zoom in focus for manual lenses which no prism optics can do, and both camera can take all my older Leica M lenses. I believe electronic viewfinder will be the next big push for DSLR’s as the resolution and quality screens begin to improve because of demand.
Brooks,
The primary reason I use single point (select one rather than multiple points) auto focus and then recompose is to avoid (control) “…auto focus simply zeroed in on the wrong part of the image…”