Lens Not Reading F Stops

Hi all,

Lens - Sigma 18-250 OS HSM

The lens isn’t showing the F Stop information on the camera display, the display just shows F---- and the images come out very, very white.

If I press the lens release button and twist the lens a quarter of a turn then turn it back to lock it back onto the mount again the F stops work as they should and the images are as they should be, this lasts for a good number of shots before the fault shows up again.

I have cleaned the contacts on the lens but it's not helped any.

The fault seems to be intermittent but I have tried the lens on my Samsung GX10, K20d and my K5II and the results are all as above.

The lens is still covered ( just ) by Sigmas 3 year extended warranty.

Any ideas as to what the problem could be before I send it off to Sigma.

Below are 2 photos to show what they are coming out like ( these were taken using shutter priority @ 1/125 )

Regards,

Chris.

the lens is shooting wide open and overexposing, have you knocked it at all? It's as though it can't or won't stop down.

As the lens is the same on all cameras it looks as though it's the item at fault. It may well not be stopping down, so other than clean the contacts, which you've done, there's not a lot else.

Quote for repair?

If it's still under warranty send it back- no messing. An intermittent fault like that is unlikely to self heal. I was going to suggest unmounting the lens and giving it a fairly gentle shake in case there was dirt or debris lodged where it can't be seen

I have phoned sigma just to confirm that the lens is still covered by the 3 year extended warranty and it is, until September.

They told me to package it up and return it to them for repair.

Thanks for the replies.

Regards,

Chris.

My 105 did exactly the same thing. All I did to get it back was loosen off the screws on the mount, not taking them out, and giving the mounts a jiggle then re-tighten them, the screws look like a Philips cross head screw but they aint, its a JIS screw.

BUT if its still under warranty send it back. that's what the warranty is for after all

Sounds like a problem with contacts somewhere and because it's the same on several bodies it must be the lens. Possibly just needs some internal contacts cleaning. Send it back.

--

My 70 - 300 does this - I just move the aperture ring from 'a' wiggle it between apetures and put it back to 'a' and hey presto it works again

The 18-250 doesn't have an aperture ring.

It has now been posted back to Sigma.

Regards,

Chris.

** UPDATE **

I have now received the lens back from Sigma.

The enclosed paperwork said that after initial testing no connection issue was found.

The work carried out was - repair zoom, check mount, reset, check & test.

I gave the lens a good testing today ( over 1000 shots taken ) and it worked without a problem all day.

Not sure what Sigma have actually done but it seems to have worked, for the time being at least.

Regards,

Chris.

Perhaps just resetting it did the trick, but let's hope it stays fixed and they've solved the problem for you.