Bokeh separates a real camera from an iPhone
Apple’s billboards seem to suggest that any iPhone or the new iPad cameras are just as good as traditional DSLR or mirrorless cameras. After all, they cost the same. That, however, is literally smoke and mirrors.
Bokeh is where the rubber meets the road, specifically, this is when out of focus high lights appear as soft soap bubbles of light and color. Bokeh is a property of lenses and lens design. Actually, it is an optical aberration specific to a particular lens. The Meyer-Optik Gorlitz Trioplan 50 mm f2.8 is sometimes called the king of bokeh. It was designed in the 1930s and has 3 lens elements. In addition to soap bubble bokeh, this old lens design is also prone to characteristic swirly aberrations. This lens also is never really sharp. Anyone who looks at the photo above knows which lens it was taken with. Some people think it is a gimmick.
Bokeh does not just happen. It happens only at wide-open aperture shot against blinding highlights with a normal (50 mm) or telephoto (100 mm) lens. This is when autofocus fails. This is when exposure meters fail. In fact, the three lenses use here are all used with manual focusing and manual exposure settings.
Most iPhones pictures are taken with a wide-angle setting (26 mm) and high aperture f2.0 at 12 MP. The new iPhone cameras have 7 lens elements to correct any aberrations, i.e. bokeh. To get to 100 mm requires an optical zoom, which brings down resolution.
Bokeh is more than out of focus softness, but bokeh requires an extremely shallow depth of field. One the Leica summilux 50 mm, f1.4 only 1 inch of the image is in focus. For shooting portraits, you typically can get the eyes in focus, but never the entire nose.
The Leica Summilux-M 50mm f1.4 is corrected for barrel distortion, so very little swirls, and almost perfect circular bokeh. It has eight elements in five groups, so it is a much more modern lens, listed at $4,495 new.
Bokeh happens at the edge of lense capabilities: shallow depth of field, large focal length, low ISO. Shooting a 50 mm lens at f1.4 means low noise as very little sensitivity is needed to collect the light. That light is captured by a sensor that is roughly 10 times larger than the iPhone sensor.
When the Trioplan was designed in the 1930 people did not know better and did not have precision optics, such as aspherical lens grading equipment. When the Summilux was designed in 1961, the craft of lens making was at its peak because cameras still used 35 mm film, not sensors. So there was no option to electronically correct, or introduce, lens characteristics. This lens was designed for this look.
Not every 50 mm lens is optimized for bokeh. The Zeiss Planar 50 mm f2.0 was designed to have no optical aberrations whatsoever and to be the sharpest lens at the time. It is almost impossible to get bokeh; observe how tack-sharp the electric bulbs are in this shot. Of course, the last image is focussed at a distance of 8 feet (on the bass player), so nowhere near as close as the images above. Because of its design philospohy this lens is too sharp for portraits: every pore becomes visible. An iPhone camera is much more forgiving. Again, a person skilled in photography will instantly recognize this lens look, which emphasizes micro-contrast.
In sum, each lens is optimized for one function. It is technically impossible to make a lens that does everything. This is why DLSRs have exchangeable objectives and why Apple keeps adding more lenses to their iPhones. Still, 90% of iPhone pictures are selfies (3 feet) or landscape shots, where everything is supposed to be in focus and where the image is shared on social media. That is what iPhone lenses are designed for. If you are interested in different shooting scenarios, you need a different lens. For me the fun begins, when you push the envelope and create photos that stand out from the crowd. Bubble Bokeh will do that for you.
