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The "Super 35" format size

Doug Kerr

Well-known member
It appears that the newly-announced Canon EOS C300 cinema camera has a "Super 35" sensor size.

The Super 35 frame size format family was introduced for modern cinematography on 35-mm film. For the basic form (the "4-perf" form), the frame size is 24.89 mm × 18.66 mm. (4-perf means that one frame occupies a "four perforation" length of film.)

I do not know if this is the exact sensor size of the C300.

Interestingly enough, this frame size is essentially that which was first standardized for 35-mm cinematography prior to the emergence of sound movies. When sound movies were introduced, the actual frame size was reduced from its prior size to accommodate the sound track alongside the picture frame. [Although there was not usually a sound track on the camera film, the frame size had to be the same as on the release prints (which of course had sound tracks), which were produced by contact printing (at 1:1), a several-generation chain being involved in most cases.]

When used for various "wide screen" formats, the frame height is reduced to suit the larger aspect ratio. Then, sometimes, each frame is allocated a three-perforation length of film, avoiding the wasting of film area. This is called a 3-perf Super 35 format.​

As a side issue, evidently the new line of EF mount Canon cinema lenses have image circles large enough that they can be used on full-frame 35-mm size EOS cameras.

A lot of neat stuff happening!

Out: "Watch the birdie".

In: "This is picture". (That's what I always say anyway when shooting.)

Best regards,


Doug Kerr

Well-known member
In my earlier note, I said:
As a side issue, evidently the new line of EF mount Canon cinema lenses have image circles large enough that they can be used on full-frame 35-mm size EOS cameras.

In fact, that is apparently true only of some of the lenses in this new family. For others, the largest still camera sensor size they will support is the "1.6X" size; some will also do "1.3X" machines (remember 1.3X?).

The entire new lens family seems to be identified with the prefix "CN-E". The CN may mean "Canon" or "cinema", and the "E" apparently reflects the cousinhood between these lenses and the EF series. (The ones with an actual EF mount are apparently generally workable on EOS cameras at large, subject of course to image circle considerations, as I mentioned just above.)

The maximum apertures of these lenses are rated in terms of "T-stops" (e.g., "T1.5"). The T notation, long used in cinematography, takes into account the transmission of the lens. A T1.5 aperture will have the same effect on exposure as an f/1.5 aperture on a lens with 100% transmission.

There are many nice design wrinkles on these lenses to suite them for the cinematographic world. For example, the focal length is marked in bold characters on the left side of the barrel near the front. Focus distance and aperture scales are designed so that (to the degree practical) they can be read from behind the camera.

The mount ends of all the lenses are in a "metallic red" color, apparently the hallmark of the Canon cinema stuff (along with a new logo, a lower case "C" in a metallic red circle).

Yes, our boys have really "gone Hollywood". Good for them!

Best regards,


Ben Rubinstein

pro member
Did you notice the focus rings on the new lenses? Those detents are designed for a focus pullers wheel, not sure how comfortable they would be to move by hand for any length of time but they weren't designed for that.