How to Tell If a Canon FD 35mm f/2 Lens Is Concave

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The quick answer

The easiest way to identify a concave Canon FD 35mm f/2 is to look at the actual front glass: it curves inward instead of bulging outward. If you're checking an online listing, the aperture ring is another useful clue. The early version stops down to f/16, while the later S.S.C. version goes to f/22.

In my video, I also use a serial number below 100,000 as a supporting clue for the S.S.C. version I'm demonstrating. I would check the glass and aperture markings together rather than let the number decide it on its own.

Watch the identification walkthrough

Watch the full video on YouTube.

Check the Canon FD 35mm f/2 front element first

“Concave” describes the shape of the front surface of the glass. It dishes inward toward the center. A convex front surface curves outward.

If you already have the lens, this is the most direct check. Look at the glass itself, rather than how far it sits inside the barrel. In the video I demonstrate the shape by touching it, but you can inspect it visually without putting your fingers on the glass.

Look for f/16 on the aperture ring

The concave S.S.C. example I show has this aperture scale: f/2, f/2.8, f/4, f/5.6, f/8, f/11 and f/16. There is no f/22 marking.

Canon's own specifications confirm a minimum aperture of f/16 for the early FD 35mm f/2 S.S.C. (I) and f/22 for the later S.S.C. (II). The New FD 35mm f/2 also stops down to f/22.

This makes a clear photo of the aperture ring useful when you're browsing listings. Make sure you're looking at the FD 35mm f/2, since this shortcut isn't a rule for every Canon FD lens.

Use the serial number as a supporting clue

I read the number on my example as 74,601. In the video, I call this a model or part number, but the number I'm using for this check is the serial number.

My shortcut in that walkthrough is to look for a number below 100,000 together with an aperture ring that ends at f/16. The number alone isn't enough. I also wouldn't use that cutoff as a universal guarantee across every version. If the markings don't agree, get a clear view of the front surface before deciding which lens it is.

A correction about the red S.S.C. lettering

In the video, I say a lens needs the red S.S.C. lettering to be concave. That statement is too broad: earlier chrome-nose FD 35mm f/2 lenses can also be concave without that lettering.

The S.S.C. checks in my demonstration focus on the version I have in hand. Red lettering by itself doesn't settle the question either, because both early and later S.S.C. versions exist. The front glass and aperture ring are the useful things to check.

What to ask for in an online listing

If the listing photos leave you guessing, I'd ask for these three views:

1. A clear angled view of the front glass so you can assess its curvature.
2. The complete aperture scale, including whether it ends at f/16 or f/22.
3. The serial number, alongside the lens name and mount.

That gives you more to work with than a listing title that simply says “S.S.C.” or “concave.”

For more vintage-lens options, see my four picks for a cinematic look in photo and video.

My final take

I think these are amazing lenses, and it's exciting to discover that you have the concave version. Start with the front glass, use the aperture ring to help identify the version, and treat the serial number as a supporting clue. Those checks are useful whether the lens is already yours or you're trying to identify one online.

For more vintage lenses and budget camera videos, visit my FoxTailWhipz YouTube channel.