I'm worried about some "greasy marks" I found on my Canon 50mm STM Lens.

[mannualv]

Today while I was cleaning my Canon 50mm 1.8 STM lens, I noticed by using the DOF preview button that when it was on f22, there were some visible streaks or oily marks on the aperture blades. I don't know if this is normal, or if this is the way this lens was designed, or if I did something wrong or took improper care of my lens for these marks to appear. Any help would be appreciated, and if someone had this lens, could you also take it to f22, to see if this appears? Thanks.

 

[beagle100]

Today while I was cleaning my Canon 50mm 1.8 STM lens, I noticed by using the DOF preview button that when it was on f22, there were some visible streaks or oily marks on the aperture blades. I don't know if this is normal, or if this is the way this lens was designed, or if I did something wrong or took improper care of my lens for these marks to appear. Any help would be appreciated, and if someone had this lens, could you also take it to f22, to see if this appears? Thanks.

I don't think those are "oily marks" but if I get a chance I'll look more closely at my 50mm STM lens at f22

 

[tirediron]

I can't see anything that looks like oily aperture blades to me, however the images are very small. Regardless, it's extremely unlikely that even if it is the case, you had anything to do with it.

 

[mannualv]

Today while I was cleaning my Canon 50mm 1.8 STM lens, I noticed by using the DOF preview button that when it was on f22, there were some visible streaks or oily marks on the aperture blades. I don't know if this is normal, or if this is the way this lens was designed, or if I did something wrong or took improper care of my lens for these marks to appear. Any help would be appreciated, and if someone had this lens, could you also take it to f22, to see if this appears? Thanks.

I don't think those are "oily marks" but if I get a chance I'll look more closely at my 50mm STM lens at f22

Thanks. I'll appreciate if you can share if you see this marks on your lens as well. I'm worried