Every vintage lens collection needs a true wide-angle prime, but every lens system has its pros and cons.
Today, we’re diving deep into lens characteristics and performance of the Canon “New” FD 24mm F2.8, backed by quantitative analysis using the Lens Analysis Suite (LAS), a open-source tool for measuring lens sharpness across different apertures.
The Canon FD 24mm F2.8 is an affordable option, with rough copies going for approximately $125 up to around $250 for a nicer copy. I got mine for $85, which you can do if you’re willing to wait and stalk on eBay.
This lens was tested in conjunction with 24mm Pentax, Nikon A.I.S., Contax Zeiss, and Olympus lenses. Posts for those are coming soon. Also, this software is in beta, so expect significant changes.
The Numbers Behind the Glass
This lens ended up being really interesting. Not only did the data from LAS confirm everything I’ve read and heard about Canon FD lenses (that they’re sharp, essentially), but it also revealed some very desirable lens characteristics.
Wide-Open Performance (f/2.8)
The Canon NFD 24mm f/2.8 is sharp wide open, with several noteworthy stats:
- Highest mean variance (1313.12) among all tested 24mm lenses at f/2.8
- Maximum sharpness of 2340.15, showing strong center performance
- Notably uniform field of focus, with a standard deviation of 450.37
In the heatmaps below you can see how much larger the in-focus area is on the Canon. While not as sharp as the Contax 25mm in absolute terms, it’s still very sharp compared to other 24mm vintage lenses.
I should note that in previous version of the software, including in the video above, these scores were normalized to 1-100. This does make the data more readable, but I’m leaning toward using raw scores until I have time to really thing through a scoring system.
Sweet Spot Analysis
The lens reaches its optimal performance at f/5.6, where we see:
- Peak mean variance of 2125.56
- Excellent maximum sharpness of 2838.63
- Improved uniformity with a standard deviation of 441.28
Diffraction Impact
One interesting characteristic of this lens is its more pronounced diffraction effects at smaller apertures:
- At f/16: Sharp decline to mean variance of 909.78
- At f/22: Further drops to 600.52
This suggests that for optimal sharpness, you’ll want to avoid stopping down beyond f/11 unless depth of field requirements demand it. It should be noted that the other lenses aren’t like this, but we’ll have to get to that in another post. I would love to see whether this behavior is shown in other Canon lenses from the same generation.
Update: Someone in the YouTube comments mentioned that this diffraction effect might be due to focus-shifting while changing apertures.
Yes, mechanically, as in simply bumping the focus ring, but if you shoot vintage lenses enough you know that sometimes there is something about the optical formula that necessitates re-focusing at different apertures even without touching the focus ring at all. If you’re an optical engineer and you know what this effect is, please reach out!
Anyway, TLDR, I will re-focus at all F-stops when I do my next round of tests and see if that has an positive impact for the Canon FD 24mm.
Practical Implications
When you consider the price, the weight, and the sharpness, I think the Canon 24mm F2.8 is no-brainer for a walk-around lens. And that has been my experience shooting with it in real life, too; if you’re planning your exposure triangle and using your f-stops to your advantage, you should have no problem getting critical focus with a lens like this.
Comparative Context
When placed against its contemporaries, some interesting patterns emerge:
- The Canon has the largest in-focus field and is a very sharp lens IRL
- While the Contax Zeiss lenses show higher peak sharpness values, they do so in a more concentrated center area
- The Olympus shows interesting behavior, performing modestly at wider apertures but maintaining its sharpness better at smaller apertures (notably at f/16)
Conclusion
The Canon New FD 24mm f/2.8 proves to be a remarkably well-balanced lens. Its strength lies not in achieving the absolute highest sharpness numbers, but in delivering consistent, reliable performance across the frame.
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Canon NFD 24mm F2.8 Performance Analysis
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Understanding the Measurements:
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Mean Variance: Average sharpness across the entire frame
Higher numbers indicate better overall sharpness
Median Variance: Middle value of all measurements
When close to mean, suggests even performance
Minimum Variance: Lowest sharpness measurement in the frame
Typically found in corners or edges
Maximum Variance: Highest sharpness measurement in the frame
Usually found in center
Standard Dev: Measures sharpness variation across frame
Lower numbers indicate more consistent performance
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Performance Across Apertures:
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f/2.8 (Wide Open)
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Mean Variance: 1313.12
Median Variance: 1315.74
Minimum Variance: 442.05
Maximum Variance: 2340.15
Standard Dev: 450.37
Notes: Nearly identical mean and median suggest very balanced performance wide open.
Standard deviation indicates moderate variation from center to edges, excellent
for a wide-angle lens at maximum aperture.
f/4
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Mean Variance: 1993.34
Median Variance: 2090.26
Minimum Variance: 702.90
Maximum Variance: 3006.47
Standard Dev: 524.39
Notes: Significant jump in overall sharpness. Minimum variance improves by nearly
60%. Higher standard deviation suggests more pronounced center sharpness.
f/5.6 (Peak Performance)
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Mean Variance: 2125.56
Median Variance: 2235.59
Minimum Variance: 897.68
Maximum Variance: 2838.63
Standard Dev: 441.28
Notes: Lens sweet spot. Highest mean variance combined with lower standard
deviation than f/4 indicates peak performance with excellent consistency.
f/8
---
Mean Variance: 1903.95
Median Variance: 1962.10
Minimum Variance: 965.58
Maximum Variance: 2510.44
Standard Dev: 329.21
Notes: Overall sharpness begins to decrease, but shows most even performance
across frame, as shown by lowest standard deviation yet.
f/11
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Mean Variance: 1461.61
Median Variance: 1489.03
Minimum Variance: 733.18
Maximum Variance: 1867.14
Standard Dev: 217.59
Notes: Diffraction begins to affect sharpness, but uniformity continues to
improve. Low standard deviation indicates very even performance.
f/16
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Mean Variance: 909.78
Median Variance: 924.09
Minimum Variance: 491.91
Maximum Variance: 1189.26
Standard Dev: 116.23
Notes: Significant diffraction impact evident, though extremely low standard
deviation shows remarkably even performance across frame.
f/22
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Mean Variance: 600.52
Median Variance: 609.86
Minimum Variance: 376.44
Maximum Variance: 723.84
Standard Dev: 48.37
Notes: Heavy diffraction effects present, but lens maintains incredibly uniform
performance across frame, as shown by minimal standard deviation.
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