https://community.usa.canon.com/t5/EF-RF-Lenses/Filter-holder/m-p/261144#M11770 <P>Recently purchased a used ef 400l f/2.8 IS USM. Just got it yesterday, haven't used it yet. When I was inspecting it I noticed there was a slight booger of some sort on the drop in filter holder, towards the top off to the left side. Did the obvious, tried to clean it with 0 luck. Just wondering if the filter holder from a second generation lens will work?&nbsp;</P> Sat, 08 Dec 2018 16:38:59 GMT inkjunkie 2018-12-08T16:38:59Z https://community.usa.canon.com/t5/EF-RF-Lenses/Filter-holder/m-p/261144#M11770 <P>Recently purchased a used ef 400l f/2.8 IS USM. Just got it yesterday, haven't used it yet. When I was inspecting it I noticed there was a slight booger of some sort on the drop in filter holder, towards the top off to the left side. Did the obvious, tried to clean it with 0 luck. Just wondering if the filter holder from a second generation lens will work?&nbsp;</P> Sat, 08 Dec 2018 16:38:59 GMT https://community.usa.canon.com/t5/EF-RF-Lenses/Filter-holder/m-p/261144#M11770 inkjunkie 2018-12-08T16:38:59Z