Canon FDn 24mm f/2.8 on Sony A7

Canon FDn 24mm f/2.8 on Sony A7

These classic wide lenses performed poorly on APS-C cameras, do they fare worse on full frame?

The FDn lenses are good quality lenses built by Canon in the 80s, but were starting to show cost cutting. They forgo the breech mount per se since they no longer have a twisting ring to lock them down, and instead the entire lens turns like a classic bayonet mount.

The lens is fairly light at 240 g, and has standard 52mm filter threads. It has a minimum focus distance of 0.3 m, which is long for the class, providing only 0.11x magnification. The optical formula is 10 elements in 9 groups and has floating elements for better close up performance. The aperture has 6 slightly curved blades.

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Optical Performance

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Please click on the tab you want to view. Only 1 tab may be active at a time. MTF, Distortion, and Lat CA data acquired using Imatest
MTF20 Chart maxes at vertical resolution of the sensor (4000 LW/PH for A7). Anything above that is meaningless. The MTF50 chart is set based on a ratio of where f/22 appeared for several lenses and the vertical resolution.
Note: 4k video is 2160 LW/PH
Note: HD video is 1080 LW/PH
For video, you want your MTF20 values to be at or above those numbers. The green region and up is where a good photographic lens will lie, but decent is anything better than f/22 performance, so mid yellow and up. If you can’t see the colored borders, for MTF20 Red: ~1500 LW/PH, Yellow: 2700, Blue: 3500. MTF50 values are 900, 1620, and 2160 LW/PH.

Comments on the Results

The center is excellent throughout the range. Partway points are good at f/4, excellent by f/5.6 through f/11. The corners aren’t good until f/5.6, but the lens also has a fair amount of field curvature so watch focus point.

Distortion is wavy mustache distortion which is primarily about 1.2% barrel.

Lateral CA is noticeable.

Flare resistance: Haven’t checked.

Measured Focal length is 26mm at 1:35 magnification.

Pros and Cons

Effective Resolution

Aperture Weighted Center Partway Corner
f/2.8
14.8 MP
20 MP
10.6 MP
6.4 MP
f/8
19.7 MP
23.2 MP
17.4 MP
12.2 MP

Bottom Line

The 24mm or 20mm? They are both about the same. Get the focal length you need, the 20mm is much larger lens, so the 24mm is the better balanced choice. The 24mm, at least this sample, seems to have a slightly higher emphasis on central sharpness, with slightly worse edges, but overall I would call the characteristics similar.

The great thing with full frame is you actually get your wide/ultra wide lens out of the 24mm focal length instead of a very large standard wide lens. It is fine to use these on APS-C, but you don’t get a very good size/aperture ratio.

This is a good value lens, I will test this specific lens on a NEX 3 when I have a chance, but overall performance looks notably better than other 24mm SLR lenses I tested on the 3. This could be for a couple reasons, but one of which is that the larger pixels on the A7 are a bit easier on the lens. The lens is limited by the A7 so you shouldn’t see much improvement with an A7r except in the center.

As a reference, this lens is about the same in the corners as the kit 28-70mm lens, which isn’t bad at all, but not great. Compared to the Sony 16mm f/2.8 used on NEX 3 or in crop mode, this lens is much better.

So to answer my question in the blurb at the top, this lens is much better fit on FF then on APS-C. Even though the corners don’t look ideal, the larger sensor helps the overall resolution a lot. For APS-C the Sigma 19 or 30mm f/2.8 are two good choices.

Consider donating, it is about $50 a lens to rent.





6 Comments

  1. Loumin says:

    ” but were starting to show cost cutting. They forgo the breech mount per se since they no longer have a twisting ring to lock them down, and instead the entire lens turns like a classic bayonet mount.”

    Thanks for the useful test. The FD “new” (FDn) lenses were created not as a means of cost cutting but to use newer, lighter materials then available to lens makers. Many of the optical formulas were fine-tuned with more advanced computer-aided designs and coating technology was improved. The bayonet mount was a response to a need to have the lens lock onto the mount. The breech mount, besides being heavier, and more time consuming to mount, did not lock securely.

  2. Gabriel says:

    Hi!
    I am about to buy this very same lens for my NEX-6 but your comment got me worried
    “These classic wide lenses performed poorly on APS-C cameras”
    So I should stay away from it? Maybe just get a used Sigma 30mm or maybe a different 24mm to 28mm legacy?
    Thanks

  3. admin says:

    Plenty of people use them and are happy with them, but expect best performance in the center, and probably not that different than kit lens at 24mm near the edges. Honestly, the Sigma 19mm and 30mm are a step above in sharpness than the older lenses, but you do lose manual focus feel. So if you plan on manually focusing a lot or really need the 24mm focal length, get one. It really depends on your shooting style and if you need sharp corners near the edges. Hope that helps you make your decision. Eric

  4. Gabriel says:

    I am confused. You say “he Sigma 19mm and 30mm are a step above in sharpness than the older lenses” yet your tests show the Canon FD lenses beating both of them pretty much every where.

  5. admin says:

    Make sure you compare on the same bodies (I tag the body used in the post). The Canon FD lenses are fine as well, and very good on full frame, but say on APS-C the Sigma 19mm is better than the Canon FD 20mm also used on APS-C (plus it is smaller and lighter).

    The Sigma 30mm will do better than most legacy 28mm f/2.8 lenses on APS-C, the Canon 35mm f/2.8 is probably comparable though. So depends if you want manual focus or not.

    Full frame is a different matter. Most of those old lenses do great on full frame, and the Sigma’s are all APS-C lenses.

  6. Gabriel says:

    I should have added I am using a Lens Turbo 2 and after getting it I pretty much sold my all E lenses, like Sel35f18 because I found my FD lenses to be sharper with a rendering I prefer. So maybe the Lens Turbo 2 giving me a sort of FF setup is making that big a difference for me. THe only E lens I kept is the SEL16F28 because I got the UWA and Fisheye adapters but the resolution test you did look pretty sad for that lens which is what I see on my pictures so I am thinking on juts getting the FD 20mm which looks like it is better across the range plus it wont be that far from the SEL16f28 with the UWA in focal range..or maybe I will go with the 17mm F4 but I have not found any MTF test on that FD lens.
    I plan to make a small donation soon to you as this website is just an amazing source of information! 🙂