are you sure it’s not the set? ttartisan only sell their titanium lenses (17, 35 and 50mm) as a set. that would explain the big price difference. Aside from that, if you’re buying ttartisan you’re looking for a cheap lens. why do you even consider a $150 more expensive option?

It’s a ti finish… Pure aesthetics. Actual ti would cost a fortune. It’s pretty. I’d spring. If you didn’t, I’d think you’re smart.

Its negligible in day to day use, unless your work requires heavy duty activity.

Like, I have a Nikon FM2/T. Its only 25g lighter than the regular FM2 and I don’t technically need it to be ultra durable. But it looks cool, so I got it.

Titanium seems to have a low coefficient of linear thermal expansion.

I suppose this could have advantages on keeping a lens focused in situation where the temperature change a lot and the focus need to remain the same.