Hidden number in Zeiss Lens

[needfx]

So, there I was taking a photo of a Zeiss 35mm f2.4 flektogon I am selling, and I see this number appearing only on photo...

Has anyone seen anything like this before? Does anyone know what it might signify?

 

[cebseb]

Odd. Did you inspect the lens after? Or maybe the lens is magnifying something behind it.

 

[AlexH]

Hmm, that is odd. As cebseb noted, it could be magnifying something behind it, or reflecting something. I'd try to reproduce the shot with a different background. May sound obvious, but have you looked through the glass? See anything odd?

 

[needfx]

Odd. Did you inspect the lens after? Or maybe the lens is magnifying something behind it.

Hmm, that is odd. As cebseb noted, it could be magnifying something behind it, or reflecting something. I'd try to reproduce the shot with a different background. May sound obvious, but have you looked through the glass? See anything odd?

I did look through it, and there was nothing behind it other than the cardboard, which when I saw it the 3, I removed the lens to inspect it, then put it pack there.

I'll try it again and revert later

 

[acearchie]

I wonder if it is a QC purpose imprinted on the glass in some sort of way.

Only when light hits it from the side (which wouldn't happen when attached to the body) is it visible so if they have an issue with a large amount of lenses they can help sort out the problem?

 

[drambuie]

You can't see the number with the naked eye, but the camera can see it. That makes me think that it may be some kind of production mark only visible at infra-red wavelengths which camera sensors can also detect, the same way they can detect the IR LED beams from TV remotes.

 

[cebseb]

You can't see the number with the naked eye, but the camera can see it. That makes me think that it may be some kind of production mark only visible at infra-red wavelengths which camera sensors can also detect, the same way they can detect the IR LED beams from TV remotes.

Wow. That is crazy. Feasible, but I'm sure there would have been some other instance of this occurring and someone mentioning it.

 

[Berlepsch]

My first idea was that you just built yourself a telescope by accident. In that case, the "3" might be some distance away from the lens on the table.

On second look, it seems more likely that your flash illumination caused some back reflection in the objective, similar to lens flare. The number could be engraved on the rim of a lens or some other part of the mechanism.

I seriously doubt that this number is an IR only marking on the working surface of the lenses, because this would also influence image quality in the visible range, and of course in IR photography.

 

[kenoh]

I was caught out by that once, took a picture of a lens for the bay and saw 49mm in the lens... was momentarily confused until I saw that 49mm was engraved on the inside of the rear lens cap...

I am sure you are more switched on than me but.... just checking...

 

[needfx]

thanks @all for your responses

I am having trouble finding the number today. I tried emulating the shot, but with no luck until now. Lens & camera angle, shot exposure particulars, etc etc

By studying the original image, there is nothing behind the lens that could actually refract that number into it other than the rear-cap it is steadied on. I checked all my rear-caps, there is no mention of the number 3 anywhere, and the cap is not visible in the photo anyway. Cardboard in the shot is the same, and it's plain cardboard.

Will try again tomorrow, kinda tired now