2026-09-07 Canon FDn 28-50mm f/3.5 Zoom Lens

    The Canon FDn 28-50 mm f/3.5 Zoom was Canon’s second zoom in this focal range. The first was introduced in 1976 labelled as a Canon FD 28-50mm f/3.5 SSC.  The SSC refers to Super Spectra Coating, which was Canon’s designation for using more than one coating on the elements. Previously they had marked their optics as SC—Spectra Coating—to indicate single lens coating. Later Canon stopped using both the SC and SSC designations as almost everyone was using coatings to improve their lens performance
    In 1979 the 28-50mm zoom’s designation was changed to FDn—sometimes described as the “New” FD mount—because the mount had changed from a breech mount to a bayonet mount. It didn’t matter to the camera, both mounts work. The breech mount is placed against the camera mount’s lugs and then a (breech) ring is twisted to tighten the lens and camera together. The New FD mount simply bayonets on and off—no ring.
    The FDn lens is 20 g lighter than the SSC version. It weighs 470 g (16.5 oz). Both lenses have 10 elements in 9 groups. Both change the angle of view from 75º to 46º. Both have a 1.79 zoom ratio.
    The zoom’s design is considered a two-stage zoom. The front end creates the image, while the distance to the back set of optics changes the focal length. Later zoom lenses quite often had many more moving groups of optics, but things started simply. This zoom has a constant f/3.5 aperture.  
    The SSC lens didn’t have an official Canon hood. The FDn lens uses the W-69B hood—a push-on hood with thumbscrew tightening. The lens itself takes 58 mm screw-in filters. Both SSC and FDn zooms have small projections on the front that some wonder about. The front rotates as you focus, so they can’t be any form of flare control. I suspect they help protect the front element from scrapes.
    The FDn lens has an unusual exposed lens guide system. Focus moves the front lens elements just a little, while zooming moves the front elements a lot. As the front zooms towards the camera, the side guides for the front section become visible. You would think dirt and moisture would gum up the zoom’s action, but this lens’s zoom action is still very smooth.
    Mention is made of the 28-50 mm f/3.5 zooms extremely fine performance, its relative scarcity, and its high original cost. The price ran in the $300 range, close to $1200 in today’s currency. That would explain why there aren’t many around. As for the performance, mention is made of no vignetting and high resolution. 
    One drawback of the 28-50mm zoom is the close focusing in normal operation is just slightly under a meter (3 feet). This isn’t particularly close for a 28 mm lens. There is a Macro range—at the 28 mm end of the range, reached by sliding a switch—that can get you much closer. In Macro mode the lens will focus down to 0.25 m (<10 inches) and give 0.23X magnification. 
    There was a 1983 FDn 28-55mm f/3.5-4.5 zoom that uses three groups of lenses to drop the weight in half and reduce its size. It too uses ten elements. This 28-55 mm zoom changed its aperture when zoomed. It was introduced in 1985 with the Canon T70.

    The case the Canon zoom came in was made by Vivitar in the US. It fits the zoom very well.

    The zoom doesn’t change length much when zoomed. This is at the 28mm—Macro position.

    While this is at the other end of the zoom range—zoomed to 50mm with the lens focused at infinity.

    

    The FDn bayonet uses the red dot (at the 6 o'clock position in the image to the right) to align the bayonet with the red dot at the twelve o’clock position on the camera. A slight twist locks the lens to the camera. A release catch—at the 4:30 position, image right—is used to release the lens so it can be twisted off.

    

    Note the small projecting ridge in the lip of the lens. As mentioned in the text it isn’t a wide-angle lens hood. The lens hood for this camera slides on the outside of the lens barrel and attaches with a tightening strip. I suspect the ridge helps position the lens hood correctly. Also note no mention of SSC or that it is the “New” FD mount (although it is both).

 
    

    Most of the interior surfaces have a ridged black finish to control flare to the lens elements. The zoom takes 58 mm filters screwed into the lip of the front element. So the zoom has to be focussed to its closest distance at 28 mm to get the front element far enough out to be able to screw in a filter. The clearance for the installed filter to allow the zoom action is pretty tight. Using a Polarizer filter—that requires rotating to operate—would also be difficult most of the time.

    The front cap is 69 mm inside diameter and unusually deep (1.75 cm / 11/16 inch) to cover both the projections in the rim and the rim itself. The rear cap has an arrow—at the twelve o’clock position—that is aligned with the red dots mention earlier before being tightened on.

    

    This is the zoom focused to infinity. There is a small relief between the outside of the zoom and the moving front lens element. This relief disappears when focused as close as it will go.

    

    When the lens is zoomed to the 50 mm end of the range the front group gets much closer to the camera. Now the troughs the group’s rollers are constrained in are revealed (at the 2 and 10 o’clock positions in this image).

    

    The “Macro” slider allows the zoom to move below its minimum focus distance at the 28 mm end of the zoom.