Before you crown the 85mm, measure the room

The Canon RF 85mm f/1.2L USM has the sort of reputation that can make a portrait photographer forget to measure the room. In Fstoppers, Alex Cooke examines its claim to the portrait crown, drawing on photographer John Gress’s preference for a Canon RF 70-200mm f/4L IS USM.

For those of us loading film, the useful question is how we choose a portrait lens in the first place. What framing do you need? Where can you stand? How much of the person should be sharp? Those decisions deserve a turn before maximum aperture gets the casting vote.

Start with where you can stand

On a 35mm film camera, an 85mm is a short telephoto: it gives a narrower view than a normal lens, letting you frame a face from farther away. That working distance is part of its appeal. You can give someone breathing room while keeping the photograph close.

But the flattering perspective often credited to the lens comes from camera position. Move close to a face and the nose becomes proportionally larger than the ears. Step back and that difference diminishes. Changing focal length from the same position changes the framing; it does not rearrange those proportions.

This matters when your portrait moves from a head and shoulders to a person standing in their kitchen. To include more of them with the same lens, you must retreat. Eventually there is a wall behind you.

Before loading a roll for an indoor sitting, put the camera to your eye in the actual room. Try the tight portrait, then the widest composition you expect to make. Leave space around the subject rather than treating the viewfinder edges as a packing problem. If the room defeats your intended frame, choose a shorter lens or another position.

Keep format in mind, too. The same focal length gives a wider view on a larger negative. Advice about an 85mm on 35mm cannot simply be carried across to a medium-format camera.

Give the aperture a job

Cooke reports that Gress found little sharpness difference between his RF zoom and the 85mm prime at f/5.6 or f/8, with the zoom potentially edging ahead at f/8. As Cooke tells it, Gress traces the prime-beats-zoom rule to the DSLR years, when it held, and argues that much of today’s advice was formed then. Both lenses are for Canon’s mirrorless RF mount and were tested on digital bodies, so no film camera will take them. What carries over is the method: test the apertures you actually use with your own equipment.

A maximum aperture of f/1.2 admits light when you need it and permits very shallow depth of field—the limited range of distances that appears acceptably sharp. Both can be useful. Neither tells you how much of a particular portrait ought to be in focus.

Consider a face turned slightly away from you. Focus on the nearer eye at a wide aperture and the farther eye may fall outside that sharp range. That can make a lovely photograph. It can also leave you wishing you had stopped down when the print arrives.

For a portrait with hands, clothing or a meaningful room around the sitter, try giving those things enough depth of field to register. Check the exposure as you close the aperture: less light reaches the film, so you may need a slower shutter speed. A tripod steadies the camera; it cannot keep your subject from moving.

The useful habit is to choose the aperture after deciding what the picture needs to describe.

Judge the portrait on paper

Give your existing lens a small assignment before shopping. Photograph the same sitter with consistent framing at a wide aperture and a smaller one, adjusting exposure accordingly. Note the settings against the frame numbers. Compare prints at the same size and ask where your eye goes first.

Look beyond the eyelashes. Does a recognisable background strengthen the portrait? Do the hands matter? Does blur remove a distraction, or remove the reason you made the photograph there?

There is another practical check in Tom May’s school-portrait essay for Digital Camera World. He discusses a 1927 Mountain School photograph from Wilbraham, Massachusetts, and argues that careful captioning helps make school portraits precious later.

I would add that to any portrait lens test. Record your sitter’s name and the circumstances alongside the exposure notes. Sharp eyes deserve a name attached.

Take the lens you already own into the room, find the frame, and make a portrait worth labelling.