The Sigma 50 is wider than Canon's 50mm lenses

Some people have stated in the past that the Sigma 50mm f/1.4 was more like a 46 or 47mm lens than a 50mm lens, so I did a quick comparison between the Sigma and the Nifty 50. Camera was tripod mounted and not moved for both shots. Both were at f/2, focused at 1 meter on a 5D. Uncropped images posted below.

Nifty:

...or are the Canon ones longer...

Thanks for the images! I don't know which lens is closer to 50mm, but prefer the slightly wider version since I can just mount an 85 or longer when I need something tighter.

From a few days ago. https://photography-on-the.net/forum/showthre​ad.php?t=954866

NinetyEight wrote in post #11241100
...or are the Canon ones longer...

1.4/1.2 maybe, but most definitely not the 1.8

This is not an unusual thing...

Yup, the Sigma is closer to a real normal lens on FF.

Thank you for the samples, I'm sure this will be helpful to some users. But this is fairly typical that lenses that claim to be the same focal length are slightly different. The same is true @ 24mm with the 24-70 vs 24-105.

Nothing to lose sleep over.

Looks like the Canon is really 50.8mm and the Sigma is 48.3mm....give or take.

Same goes for the Canon and Sigma 85mm lenses.....the Sigma is slightly wider.

According to TDP, the Sigma is actually ~46.5mm:

http://www.the-digital-picture.com …X-DG-HSM-Lens-Review.aspx

RaZe42 wrote in post #11241376
Yup, the Sigma is closer to a real normal lens on FF.

twoshadows wrote in post #11249420
According to TDP, the Sigma is actually ~46.5mm:

http://www.the-digital-picture.com …X-DG-HSM-Lens-Review.aspx

Guess that makes Sigma not as close to the "real normal lens on FF."

jwcdds wrote in post #11250205
Guess that makes Sigma not as close to the "real normal lens on FF."

Just the opposite, actually. The Sigma is closer to being a real "normal" lens than the Canon version.

A true "normal" lens should have a focal length equal to the length of the sensor diagonal. For a 35mm sensor, that would be a 43mm lens. In previous eras, 43mm primes weren't uncommon. But for some reason they have been replaced by 50mm primes over the years.

@stargazer Booyah!

Orly? Hm.. if that's a good thing, I wonder why Sigma doesn't just call it the Sigma 46mm.

Did you (or any other website) test this under various focus distances? I can imagine the focal length being determined at infinity, but many lenses become "shorter" once you move focus towards MFD. For example, the 100mm macro is only like 70-75mm near it's MFD.

The above examples look closer to MFD than to infinity, and still show only a very minor difference... almost negligible.