RF 24-105 f/4 L - Dust inside rear element?

[gnartS]

Will canon actually clean dust/"things" inside the rear lens element that is absolutely affective image quality.

Looking inside my lens i can see a white blob (almost like fibre) towards the outside and a further smear of maybe dust towards the centre.

It shows clearly on blue skies as a large instinct dark circle at f/10 on my R6 and a very very obvious blob(s) at f/16 and narrower.

Im certain its not sensor dust:-

- The blob changes size as the lens is zoomed

- The blobs still exist but in a slightly different position when used on my crop R7.  Its gone on my R6 zoomed in past about 40mm (its on the top middle edge).

- My 100-400 is clean taking the same test shots.

Lens is about 5 years old, bought new.  Its been there at least a year.

My RF 16/2.8 has  similar but nowhere near as bad issue.

What are the options here ? The lens is far too expensive to dump but its also only about half usable now unless i zoom in or make sure theres no sky in a shot.  Yes i could edit every image but video its even harder.

R6, 24mm f/22. Right hand, top and centre blobR7, 24mm (so 40ish). Centre visible, right visible. Top cropped off with APS-C

[shadowsports]

Greeting,

Yes, Canon will clean your lens.  Start by registering the lens in your MyCanon account. Then initiate the cleaning/maintenance service in the portal. It includes a multi-point inspection for your product.

You may want to take a look at your sensor too, to make sure that it's not dirty before sending in your lens.  

https://myprofile.americas.canon.com/us/signin

[gnartS]

Lens is registered (and repaired by them previously about 3 years ago with a front element scratch that was visible).

Sensor is fine-  i check and wet clean it myself when needed.  Lens is showing the blobs on 2 bodies (one of which is 3 days old only) and is causing issues.

[ebiggs1]

"Will canon actually clean dust/"things" inside the rear lens element that is absolutely affective image quality."

You need to ask for a C&C. But be warned if that "blob" is fungus Canon will most likely not clean it or even touch it.

Good lord you have a lot of mess inside your lens. I would strongly suggest you change your shooting habits or storage habits completely. 😲

[gnartS]

Not a lot i can change when its used for shooting in temperature and tropical climates on a daily basis.  First lens ive ever seen with this issue in 25 or so years of using Canon lenses.

Expected L to be more resistant (my 100-400 is fine though, as are various non Ls)

[Stephen]

A clean and check does *not* include taking apart the lens to clean the individual elements. You can find everything that is included in the different types of maintenance service options at https://canon.us/CMS 

When you request the cleaning, be sure to document in the repair request that you have dust *inside* the lens so that they understand the request completely. Once they receive your gear, they will evaluate it, and if it falls outside of a normal maintenance repair, they'll email you to let you know what they found, and they'll include an estimate to see if you want to move forward with the repair. You can get started at https://canon.us/repair 

[jrhoffman75]

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@gnartS wrote:

Will canon actually clean dust/"things" inside the rear lens element that is absolutely affective image quality.

Looking inside my lens i can see a white blob (almost like fibre) towards the outside and a further smear of maybe dust towards the centre.

It shows clearly on blue skies as a large instinct dark circle at f/10 on my R6 and a very very obvious blob(s) at f/16 and narrower.

Im certain its not sensor dust:-

- The blob changes size as the lens is zoomed

- The blobs still exist but in a slightly different position when used on my crop R7.  Its gone on my R6 zoomed in past about 40mm (its on the top middle edge).

- My 100-400 is clean taking the same test shots.

Lens is about 5 years old, bought new.  Its been there at least a year.

My RF 16/2.8 has  similar but nowhere near as bad issue.

What are the options here ? The lens is far too expensive to dump but its also only about half usable now unless i zoom in or make sure theres no sky in a shot.  Yes i could edit every image but video its even harder.

R6, 24mm f/22. Right hand, top and centre blobR7, 24mm (so 40ish). Centre visible, right visible. Top cropped off with APS-C

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That looks like fungus. Isolate it from your other camera gear because it can spread. Besides being on the elements it could also attack the coating. 

[JeffXB]

I moved to the Philippines last year and one of the first things I did was invest in a dry cabinet (90 liter). If you don’t have one, you might consider getting one. Will help again fungi and other issues relegated to living in tropical and sub tropical environments. 

 

[gnartS]

Have seen those but not really travel portable when spending 2-3 months in a place typically.  Nor would be that useful when i lived in the Philippines with the power cuts but thats very regional.

Thinking about it the lens has been in the UK for 95% of the time since i had it (post covid) which really shouldnt get growth.  Canon did open it and replace the front element 2-3 years ago for a crack.

Im going to have to find a 3rd party to clean or replace that element if Canon wont touch it.

[ebiggs1]

"Im going to have to find a 3rd party to clean or replace that element if Canon wont touch it."

No shop is going to touch it, if it is fungus and I agree with JRH it looks like it. Two reasons, one "because it can spread", so they can't take the risk.  And two, if it damaged the lens coating it not repairable period. Replace is the only option, either the element assembly or the entire lens.