Canon 50mm lens f/1.8 v/s 40mm f/2.8 STM lens

[sabcoolin]

I have an option here to keep either on of these lens, since i havent used any one of them, i am not sure which one to keep.

I am just a beginner as a photographer, so can you guys help me suggest which one i should be keeping?

Thanks

[ktuli]

Sachin,

What do you plan to use it for? The 40mm STM was designed specifically for video use - the stepping motor is designed to be quieter for focusing while shooting video. But the 50mm f/1.8 is a fun lens to shoot with - the razor thin DoF is always a nice option to have in your bag.

- Bill

[RustBeltRaw]

I think there's more to learn from working with the 50mm f1.8's narrow depth of field. The focal lengths are quite close, so the question is whether you need the 40mm f2.8 STM's small size or near-silent autofocus motor?

[rpcrowe]

I didn't think that I would like the 40mm pancake on my 1.6x gear because a 64mm equivalent focal length is kind of awkward.

However, I purchased a pancake (on a whim) when Canon had it on sale as a refurbished item. I really like the size of the pancake. Although the 50mm f/1.8 is not all that big, the pancake is really miniscule. The FL is not all that awkward and image quality is really quite good.

The pancake on a T4i would improve the focus capabilities in video mode. However, I really don't see any great advantage using the pancake with a non T4i DSLR in video mode. If I were shooting with a DSLR and a single prime lens, I would rather have that prime slightly wider than a normal focal length...

Since neither lens is really that expensive, I don't feel badly about keeping both for a while...

[inkista]

I think there are two main factors to consider:

Are you planning on using this lens for portraits? Or as a general-purpose walkaround lens? To me, the 50 is a better length for portraits on a crop (I favor using short teles for portraits) and a walkaround on full-frame, the 40 is better as a walkaround lens on both a crop and full-frame.

And what do you favor more: speed (max. aperture) or build quality/usability features?

The 50/1.8 II is a cheap plastic lens. Optically, the two lenses are mostly on a par--because the 50/1.8 II only really begins to get sharp around f/2.8, and has a sweet spot more in the f/4-5.6 aperture range. While you have access to 1.3 stops more aperture--those 1.3 stops are somewhat compromised by the softness of the lens used in that range. OTOH, 1.3 stops of aperture is still 1.3 stop more low-light capability. Also, the 50/1.8 II lacks a focus motor and has a plastic mount, no focus scale, and probably the worst manual focus ring of any Canon lens.

The EF 40mm f/2.8 STM has a metal build, is more compact, and has terrific optics--even wide open at f/2.8. It also has the STM focus motor in it so it's got silent autofocus, and will work better for video autofocus with any of the newer cameras that have hybrid contrast and phase detection AF (basically, a 2012 or later camera body). It also has full-time manual focusing (which the 50/1.8 II does not--you have to flip the AF/MF switch on the lens to MF to manually focus, or risk forcing the focusing motor and possibly breaking it).

I recently got the 40mm, and I'm probably going to sell my 50/1.8 II. But I shoot with a 5DMkII, which has great high iso performance up to 6400, and I plan on using the lens more as a walkaround prime for subjects like street shooting, cityscapes, and landscapes. For portraits, I have the Canon 85/1.8 and 135/2L (on crop, that would be similar to having the 24/2.8, 50/1.4, and 85/1.8).