Strange problem with Telephoto lens

[thebeardedgroundsman]

I have an oldish 100 -400 GM lens, which does not communicate with my camera, however, it works perfectly well when I put my 1.4X teleconverter on.

I assume the contacts are worn, but I'm intrigued as to why it should work with the converter.

Any ideas?

[FunWithCameras]

Just a guess - does the teleconverter has spring loaded contacts that connect more firmly than the body?

 

[Phormula]

Occam razor mode ON.

The lens contacts work with the teleconverter ones but not with the camera ones.

FunWithCamera explanation is the most reasonable one.

[thebeardedgroundsman]

Yeah, I think the contacts on both the lens and the camera are both slightly worn, whereas those on the converter are nice and new, making a better contact on each of the elements. I don't have a problem with my shorter lenses.

Fortunately, I don't really need the focal lengths between 85mm (my Zeiss Prime) and 150mm (Tele zoom with converter.

 

Cheers

[XKAES]

Have you tried cleaning the contacts?

[thebeardedgroundsman]

I've tried cleaning them with a dry microfibre cloth - is there a better way?

[XKAES]

I'd use a little isopropyl alcohol on a Q-tip.

[Phormula]

On an old camera I used a cotton swab and contact cleaner for electronics. 

Since the contact cleaner was in a can, I sprayed it on a glass surface, then I picked it with the cotton swab and gently used it to clean the contacts. It worked.

[FunWithCameras]

8 hours ago, Phormula said:

On an old camera I used a cotton swab and contact cleaner for electronics. 

Since the contact cleaner was in a can, I sprayed it on a glass surface, then I picked it with the cotton swab and gently used it to clean the contacts. It worked.

Good advice - you don't want to spray things into the camera. Especially things like WD-40, because it is designed to leave a residue, and you don't want that on the sensor!

[thebeardedgroundsman]

Thanks everyone, I've done a more intense clean on the contacts, and it seems to have sorted the problem.