Your DSLR’s autofocus · Part 4 of 4

The evidence: how much DSLRs need it

FoCal users have uploaded millions of results since FoCal launched. Here’s what they say about how much DSLRs and their lenses need calibrating.

Your DSLR’s autofocus: Part 4 of 4
  1. How DSLR autofocus works
  2. What goes wrong
  3. The fix
  4. The evidence

We process FoCal users’ results into typical figures for each camera and lens. They power the comparisons in FoCal Pro and the free performance site FoCal IQ. That’s where these figures come from.

Each result is one lens calibrated on one camera. The groups are the same as on our camera pages: an adjustment of 1 unit is minimal (it tips the odds slightly towards sharp shots, but you won’t see it), 2 or 3 is noticeable, and 4 or more is significant: clearly sharper pictures once it’s fixed.

Camera view: every lens on one camera

Nikon D850, all lenses: 16,645 calibrations
Nikon D850, all lenses: 16,645 calibrationsNikon D850: 67% significant, 19% noticeable, 9% minimal, 5% none.0%1%2%3%4%5%-20-15-10-50+5+10+15+20Adjustment needed (units): 0 = none
Significant: 4+Noticeable: 2–3Minimal or none: 0–1
NeedsSignificantNoticeableMinimalNone
Share of results67%19%9%5%

Source: FoCal IQ.

Only 5% of D850 calibrations needed no adjustment at all. Put another way, about 19 in 20 D850 and lens combinations would get something from calibration, and 67% would get clearly sharper pictures.

Canon EOS 5D Mark IV, all lenses: 28,397 calibrations
Canon EOS 5D Mark IV, all lenses: 28,397 calibrationsCanon EOS 5D Mark IV: 50% significant, 27% noticeable, 15% minimal, 8% none.0%2%4%6%8%10%-20-15-10-50+5+10+15+20Adjustment needed (units): 0 = none
Significant: 4+Noticeable: 2–3Minimal or none: 0–1
NeedsSignificantNoticeableMinimalNone
Share of results50%27%15%8%

Source: FoCal IQ.

Things are a little better in Canon-land, probably because the EF mount never had screwdriver-driven lenses, which are particularly poor at focusing. But it’s still 50% of 5D Mark IVs that would produce clearly sharper pictures after calibration.

And it isn’t just these two. Across all 24 Nikon DSLRs in FoCal IQ, on average 68% of results needed a significant adjustment; across 19 Canon DSLRs, 55%. Your camera’s own figures are on its camera page.

Lens view: one lens on every camera

Now the other way round: a single lens model, across all the cameras it was tested on. Zooms show the two ends separately, because many cameras can store a different value for each.

24-70mm f/2.8

Nikon AF-S 24-70mm f/2.8E ED VR
Nikon AF-S 24-70mm f/2.8E ED VR24mm: 69% significant, 17% noticeable, 10% minimal, 4% none. 70mm: 77% significant, 13% noticeable, 6% minimal, 4% none.0%1%2%3%4%5%-20-15-10-50+5+10+15+20Adjustment needed (units): 0 = none
24mm70mmSignificant: 4+Noticeable: 2–3Minimal or none: 0–1
SignificantNoticeableMinimalNone
24mm69%17%10%4%
70mm77%13%6%4%

FoCal IQ figures from May 2023, as published in the original blog post.

Canon EF 24-70mm f/2.8L II USM
Canon EF 24-70mm f/2.8L II USM24mm: 38% significant, 32% noticeable, 19% minimal, 11% none. 70mm: 43% significant, 30% noticeable, 18% minimal, 9% none.0%5%10%15%-20-15-10-50+5+10+15+20Adjustment needed (units): 0 = none
24mm70mmSignificant: 4+Noticeable: 2–3Minimal or none: 0–1
SignificantNoticeableMinimalNone
24mm38%32%19%11%
70mm43%30%18%9%

FoCal IQ figures from May 2023, as published in the original blog post.

Quite a difference: 69%–77% of the Nikon lenses needed a significant adjustment, against 38%–43% of the Canon. Before you decide your Canon doesn’t need it, remember that’s still almost 4 in 10 lenses clearly sharper after calibration, about 7 in 10 visibly better, and this is the newer Mark II. The original EF 24-70mm is much more likely to need it.

70-200mm f/2.8

Nikon AF-S VR 70-200mm f/2.8G IF-ED
Nikon AF-S VR 70-200mm f/2.8G IF-ED70mm: 82% significant, 10% noticeable, 5% minimal, 2% none. 200mm: 83% significant, 9% noticeable, 5% minimal, 2% none.0%1%2%3%4%5%-20-15-10-50+5+10+15+20Adjustment needed (units): 0 = none
70mm200mmSignificant: 4+Noticeable: 2–3Minimal or none: 0–1
SignificantNoticeableMinimalNone
70mm82%10%5%2%
200mm83%9%5%2%

FoCal IQ figures from May 2023, as published in the original blog post.

Canon EF 70-200mm f/2.8L USM
Canon EF 70-200mm f/2.8L USM70mm: 76% significant, 14% noticeable, 7% minimal, 3% none. 200mm: 64% significant, 21% noticeable, 10% minimal, 6% none.0%2%4%6%8%10%-20-15-10-50+5+10+15+20Adjustment needed (units): 0 = none
70mm200mmSignificant: 4+Noticeable: 2–3Minimal or none: 0–1
SignificantNoticeableMinimalNone
70mm76%14%7%3%
200mm64%21%10%6%

FoCal IQ figures from May 2023, as published in the original blog post.

Even more need here: over 8 in 10 of the Nikon and almost 8 in 10 of the Canon lenses would be clearly sharper with calibration. The charts show a couple of other things too:

  • The Nikon tends to back-focus at every focal length: the results lean towards negative values, which bring the focus nearer the camera.
  • The Canon back-focuses at 70mm but front-focuses at 200mm. One value can’t fix both, but most Canon cameras let you set the wide and telephoto ends separately, and FoCal calibrates each.

35mm f/1.4

Nikon AF-S 35mm f/1.4G
Nikon AF-S 35mm f/1.4G35mm: 66% significant, 18% noticeable, 10% minimal, 6% none.0%2%4%6%8%-20-15-10-50+5+10+15+20Adjustment needed (units): 0 = none
Significant: 4+Noticeable: 2–3Minimal or none: 0–1
NeedsSignificantNoticeableMinimalNone
Share of results66%18%10%6%

FoCal IQ figures from May 2023, as published in the original blog post.

Canon EF 35mm f/1.4L II USM
Canon EF 35mm f/1.4L II USM35mm: 42% significant, 30% noticeable, 19% minimal, 8% none.0%5%10%15%-20-15-10-50+5+10+15+20Adjustment needed (units): 0 = none
Significant: 4+Noticeable: 2–3Minimal or none: 0–1
NeedsSignificantNoticeableMinimalNone
Share of results42%30%19%8%

FoCal IQ figures from May 2023, as published in the original blog post.

A fast prime, where focus errors show most. 66% of the Nikon and 42% of the Canon lenses needed a significant adjustment, and over 7 in 10 at least a noticeable one.

An expensive way to buy a cheap lens

Canon EF 85mm f/1.2L II USM
Canon EF 85mm f/1.2L II USM85mm: 63% significant, 20% noticeable, 11% minimal, 5% none.0%2%4%6%8%-20-15-10-50+5+10+15+20Adjustment needed (units): 0 = none
Significant: 4+Noticeable: 2–3Minimal or none: 0–1
NeedsSignificantNoticeableMinimalNone
Share of results63%20%11%5%

FoCal IQ figures from May 2023, as published in the original blog post.

The Canon EF 85mm f/1.2L II is a superb, very expensive lens. 63% of them needed a significant adjustment. If yours is one of them, every shot at f/1.2, f/1.4 or f/1.6 is soft, and a well-tuned copy of the EF 85mm f/1.8, around a thousand pounds cheaper, could beat it from f/1.8 up.

If you’ve paid for fast glass, you owe it to yourself to check how it focuses on your camera. I’ve seen night-and-day differences from calibration on quite modest lenses, too. It’s like an upgrade for your camera and lenses.

In conclusion: check your DSLR autofocus

This guide started with a claim: you’re almost certainly not getting the sharpest shots from your DSLR, and it’s not your fault.

On a typical DSLR, it’s about the toss of a coin whether each camera and lens combination will be significantly sharper after calibration. For some lenses, nearly every copy needs it.

If you own a few lenses and more than one DSLR body, I’ll guarantee that calibration makes a significant difference to at least some of the combinations.

Start with a free check in FoCal Mobile, look up your camera, or go straight to FoCal Desktop. And if you use a mirrorless camera as well, read on: it doesn’t get off the hook.

Find out what your own kit needs

Check FoCal supports your camera, then calibrate every lens and see exactly how much difference it makes.