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Canon EF 50mm f/1.8 II vs STM – Key Differences

Over time Canon releases newer versions of its lenses and the ‘nifty-fifty’ Canon EF 50mm f/1.8 is no exception. 

The Canon EF 50mm f/1.8 II was first released in 1991 and was eventually replaced by the Canon EF 50mm f/1.8 STM in 2015. 

Since there were 24 years between these two lenses, there are quite a few differences between them.

This post covers the differences you need to know about between the Canon EF 50mm f/1.8 II and the EF 50mm f/1.8 STM.

If you want a quick summary then here you go:

💡The newer STM version of the Canon EF 50mm f/1.8 is better than the older Canon EF 50mm f/1.8 II. It has better image quality, autofocus, build quality, minimum focus distance and bokeh.

Image Quality

The image quality on the STM lens is slightly better as you can see when shooting wide open at f/1.8 that the STM version is sharper.

When looking at corner sharpness (sharpness in the corners of the frame) the STM version definitely wins. You can see when testing at various f-stops that it’s much better at f/1.8, f/2.8 and even at f/5.6. 

If you want to make sure you have the sharpest image quality on the STM version, read my post which tells you the sweet spot on the EF 50mm f/1.8 STM.

Autofocus

Both the EF 50mm f/1.8 II and the EF 50mm f/1.8 STM have autofocus, but the STM lens has a different type of autofocus motor. 

The STM version uses a stepper motor (this is what the STM stands for), but the II version uses a ‘Micro Motor’.

The stepper motor is a newer technology which is both quieter and faster than the older ‘Micro Motor’ autofocus technology.

You can see the video below which compares the two autofocus systems on these ‘nifty-fifties’.

Minimum Focusing Distance

The minimum focusing distance is also better on the STM lens as it can get 10cm closer to the subject compared to the older ‘II’ model.

There is a 45cm minimum focusing distance on the older model Canon EF 50mm f/1.8 II.

There is a 35cm minimum focusing distance on the newer Canon EF 50mm f/1.8 STM model.

This can make a difference for people who like photographing small subjects or for close-up shots.

Compatibility 

Both lenses are Canon EF lenses so they can be mounted onto any Canon DSLR with an EF mount or an EF-S mount.

This means the Canon EF 50mm f/1.8 II and the Canon EF 50mm f/1.8 STM can both be used on any APS-C Canon DSLR and any full-frame Canon DSLR. You can also use them on mirrorless Canon cameras if you use the right adapter.

Filter Size

The filter size is different on these two lenses so you would need different-sized filters or reverse rings for macro photography.

The Canon EF 50mm f/1.8 II has a 52mm thread and the Canon EF 50mm f/1.8 STM has a 49mm thread.

Build Quality

The mount for the older Canon EF 50mm f/1.8 II is made of plastic (this lens was called the plastic fantastic after all), whereas the Canon EF 50mm f/1.8 STM has a metal mount. 

This means that the STM is a lot sturdier and should take more of a beating. 

Build Weight

Since the STM has more metal parts, the weight of it is slightly more at 160g compared to 130g for the older model. Even though it is heavier, it is still a very portable and lightweight lens.

STM version: 160g

II version: 130g

Aperture and Bokeh

The Canon EF 50mm f/1.8 II and the Canon EF 50mm f/1.8 STM have an aperture range of f/1.8 to f/22.

However, the STM version does have 7 aperture blades whereas the older version only has 5 aperture blades. 

This means that the bokeh when using the STM version will appear rounder which some people prefer. 

By now you should know the differences between these 2 versions of the Canon ‘nifty fifty’. 

You can also watch the video below which goes over the differences too.

Just be aware that there is a mistake in the video where it states that the STM version has a 48mm thread size. The correct thread size for the STM version is 49mm.