I’m continuing this “one chapter a day” walk through Ansel Adams’ three-book fundamentals set—The Camera, The Negative, The Print—and translating it into how we actually work now.
Today is Chapter 3: Medium-Format Cameras.
And right away, Adams frames medium format the only honest way to frame it: Medium format isn’t “better.” It’s a compromise you choose because it fits the way you want to work.
Medium format sits in the middle for a reason
Adams defines medium format loosely as anything bigger than 35mm but smaller than 4×5. In practice, it’s a bridge between two tempos:
- the fast, reactive feel of small cameras
- the slow, deliberate control of large cameras
Medium format gives you more negative area—several times more than 35mm—which buys you cleaner enlargements: more sharpness, less grain, more ease when you push the final image size.
In 2026 language, it’s the same idea as moving up a sensor size or a resolution class: you’re buying image quality headroom. Not so you can pixel-peep—so you can print bigger, crop harder, and still land the plane.
Roll film is the default—and it shapes the whole experience
Adams notes that medium format is mostly built around 120 roll film. That matters because roll film brings a very specific set of tradeoffs:
- You get a larger image area than 35mm.
- You still get multiple frames per load (unlike sheet film).
- But you don’t have the same per-frame flexibility that sheet film gives you later (especially in development).
That limitation becomes important later in the chapter, when he starts talking about interchangeable backs and why they’re such a big deal.
The twin-lens reflex: the old workhorse with real quirks
Adams gives the twin-lens reflex (TLR) its flowers. For years, it was a serious professional tool—especially in the era when 35mm wasn’t considered “pro enough” for many applications.
The TLR design is simple and brilliant:
- one lens for viewing
- one lens for the exposure
- both the same focal length
- mechanically linked, so focus matches
But Adams is equally clear about what comes with that design:
- The image you view on the ground glass is reversed left-to-right, which is disorienting until it becomes muscle memory.
- Because the viewing lens doesn’t stop down, the depth of field you see doesn’t match what the taking lens will record.
- And the big one: parallax is unavoidable because you’re not viewing through the taking lens.
That’s Adams’ recurring theme across formats: every design solves one problem and creates another. Your job is to know which problems you can live with.
The medium-format SLR: where “system thinking” really begins
Then Adams moves to what most people think of when they think “medium format”: the modular SLR—Hasselblad-style “box” cameras, plus a few that look like oversized 35mm bodies.
He describes why the modular approach matters: the camera becomes a system.
You’re not just buying a body. You’re buying a platform where you can swap:
- film magazines
- viewfinders
- lenses
- accessories built around specific kinds of work
And then he gets practical in the way only Adams can: he talks shutters.
Many medium-format SLR lenses use leaf shutters because focal-plane shutters are harder to engineer efficiently for the larger image area. Leaf shutters bring a huge upside:
- flash sync at all shutter speeds
That’s not nostalgia—that’s a capability. Even now, that’s the reason some people love leaf-shutter systems: control over flash timing and ambient light in ways other setups fight you on.
Adams also points out the less romantic, very real considerations:
- If each lens has its own shutter, each lens may need its own calibration to be truly accurate.
- If the camera uses a single shared shutter (like a focal-plane shutter), you calibrate once, and every lens behaves consistently.
This is Adams in his element: fundamentals aren’t just exposure theory—they’re reliability, predictability, and control.
The “ideal format” question: square vs rectangle
Adams touches on the idea of “ideal format” cameras—medium-format rectangles that enlarge directly to 8×10 proportions (like 6×7 and similar variants), versus the classic square format.
And then he drops a personal preference that I appreciate because it’s not a spec-sheet argument. It’s a working-photographer argument:
He likes the square because it lets him compose either horizontally or vertically without rotating the camera, and because he can visualize and crop to whatever proportions he wants afterward.
That’s a useful reminder in 2026: format choice isn’t only about resolution or aspect ratio. It’s about how you see, how you move, and what keeps you fluent when things are happening.
Interchangeable backs: changing film is changing intent
This is one of the most “medium format” advantages Adams points to: interchangeable film magazines.
With a darkslide in place, you can remove a back mid-roll and swap:
- fast film vs slow film
- colour vs black-and-white
But there’s a deeper point: roll film normally forces you into one development treatment for the whole roll. Adams notes that multiple backs can be marked and used to manage contrast and intended development (he points ahead to The Negative for that part of the workflow).
Even his mention of Polaroid backs is really about the same underlying principle:
feedback and control.
Check, confirm, refine.
Medium format becomes a way to build flexibility back into a roll-film workflow.
My takeaway: medium format is for photographers who want headroom without giving up mobility
Adams closes the chapter with the most grounded statement of all:
No camera does everything.
Medium format exists because some photographers want:
- better image quality than 35mm can deliver
- more mobility and speed than 4×5 allows
It’s not a status symbol. It’s a working choice. A set of compromises that—if they match your needs—work for you instead of against you.
One chapter a day
That’s the project: one chapter a day, working through all three books over the coming weeks.
Next up: Chapter 4 — Large-Format Cameras.