EVF or LCD Zoomed-In Focusing Implementations
See Optical and Electronic Viewfinders: EVF + Optical + LCD = Synergy for an important discussion on viewfinders.
This discussion applies to an EVF or rear LCD when used in zoomed-in mode, something extremely useful in nailing focus precisely, especially with manual focus or adapted lenses.
Let’s survey a few implementations out there.
Nikon D800E
Grade: A (but 'B' when image quality fully zoomed in is considered)
Rear LCD, no EVF. One button press for zoomed in to level of magnification of choice. Zoom in to various levels, scroll around right out to almost the very edge of the frame. Mangled image display (subsampled) when fully zoomed in, but usable in practice with high accuracy.
Canon 5D Mark III
Grade: A
Rear LCD, no EVF. Similar to the Nikon D800, a bit more restricted on how close to the edge one can get. Lower resolution, but arguably the Nikon is equivalent just by not zooming in fully.
Leica M Typ 240
Grade: C-
EVF and LCD. Center focus only, no zooming: this is as primitive and frustrating an implementation as one could imagine. It forced me to do all my comparisons only on subjects with something in the center—might this not affect composition in general?
Awkwardly-placed zoom button (could it have been worse?). No option to stay zoomed when pressing shutter, so context is lost. The auto-detect feature for focus movement often activates by accident with any camera motion.
Fuji X100S
Grade: B+
EVF or LCD (good!). One press to zoom in, but modal: to focus on a particular area, one must pre-select that area, then zoom in. A change requires choosing the AF area, confirming with button press, then zooming in again (3 button presses just to scroll a fraction of the frame in another direction).
It’s a frustrating experience: the 4-way controller could allow scrolling left/right/up/down. But it’s *way* better than center-only Leica M240.
Sigma DP Merrill
Grade: B-
LCD only, and a marginal quality one at that. Similar limitations to the Fuji X100S except that zooming in is limited to the central 1/2 or so of the sensor. No support for contrast detect autofocus when zoomed in.
Nikon Coolpix A
Grade: A-
LCD only (a real problem on a small camera). The plus/minus buttons are awkward in use, but one can scroll around freely at a variety of magnifications, and one button press zooms back out.
