topic Re: What is this single white dot inside my lens? in EF & RF Lenses

What is this single white dot inside my lens?

starboltbnu — Fri, 01 Jul 2022 15:51:03 GMT

Hello

I recently purchased a used Canon Rebel T7i camera and apparently everything is OK with it, except the lens. On closer inspection I noticed that there is a white dot on the inside of the lens glass.

I've seen a few threads here talking about problems like this, but many were different from mine (which only has one dot).

My main concern is that this could be a fungus. From the photos, can you tell if this is something I should be concerned about or could it just be dust?

The strange thing is that as I change the angle of the lens, it seems that this spot gets brighter. I thought it was a scratch on the lens, but that dot is below the glass.

The lens is an 18-55mm that comes with the camera kit.

Thanks

Re: What is this single white dot inside my lens?

normadel — Fri, 01 Jul 2022 16:21:41 GMT

Looks like a piece of debris of some kind, not fungus. Lenses "develop" dust and other stuff internally over time.

The important thing to remember is that internal dust etc. (also surface stuff on the front lens element) do not affect images. If you don't see it in the viewfinder, it doesn't get seen by the sensor either.

Surprisingly, it takes a LOT of inside contamination or surface defects to affect things. A lot of haze/fungus does affect light transmission, but you still don't see it in the viewfinder or at the sensor.

Re: What is this single white dot inside my lens?

Tronhard — Fri, 01 Jul 2022 17:13:38 GMT

There is a famous case where Lens Rentals found a dismembered fly inside a Canon EF 70-200L lens! Even that did not obviously impact on the picture quality until the lens was seriously stopped down - although they did disassemble the lens and remove the offending insect. HERE is the article.

Re: What is this single white dot inside my lens?

Tintype_18 — Fri, 01 Jul 2022 19:52:14 GMT

I have the same thing in my 18-55 lens plus what looks like water spots; almost like tape that isn't stuck good. In getting info from the group, since it doesn't affect the photos, ignore it.

Re: What is this single white dot inside my lens?

normadel — Fri, 01 Jul 2022 21:42:48 GMT

Some time ago I came across an article on the Web (can't tell you where) where the author took an unneeded lens and did all kinds of things to it to see how much it takes for contamination to show up in his viewfinder....sticking pieces of paper to it, drawing with a Sharpie, lumps of grease,scratching it, even badly cracking the front element. NONE of it showed in the viewfinder. He had take some really extreme measures to affect the transmitted image.

Re: What is this single white dot inside my lens?

ebiggs1 — Sat, 02 Jul 2022 14:35:28 GMT

One reason being is all that stuff is OOF so it doesn't impact the image until really bad and affecting light transmission.

Re: What is this single white dot inside my lens?

shadowsports — Sat, 02 Jul 2022 16:23:03 GMT

Rocket blower to the rescue. Won't do the inside though.

Rocket Blower