Poss loose connection? DIY fix?

The Sigma 24-70mm has decided when in portrait composition to start saying F- on screen and then if it takes an image it's then overexposed. Flip the camera back into landscape orientation and it goes away! Seems to be when the camera is held upright.

Tried other lenses and no dramas so I think it's the lens and not the camera body itself. I've cleaned the contacts also to make sure it wasn't anything as simple as that but it didn't effect anything.

Wondering if it's a DIY fix or if it needs to go to Sigma?

Thanks

Will do. I have an electrical screwdriver set in work so I'll bring them home and check the screws. Will update tomorrow ....!

So tried the screws and all tight! Gave the contacts another good wipe over and when I tried portrait orientation shooting I had no issues!

Lets hope I'm not talking too soon but could this be problem solved!

Update
Was out last night with it and in portrait mode my issues reappeared. Got it home and checked the 3 screws and all were super tight. It does seem to have a millimeter of play on the body when when I looked this play with in the aperture ring so when the aperture is locked into A, I can wiggle the lens about a millimeter to bring up the F- on screen but wiggle it back the other way and we're back in the game,

looking at Sigma service tarrif it would be around £110 for repair Gareth. had my 17-70 done by them for £95, it is in a lower price band than your 24-70 f2.8. it had the image stabiliser replaced and came back looking like new. was away 3 wweeks .

Thanks Joe

Trying to convince the wife I should of done that upgrade and it's still not too late

good luck with that if you have one like me that just does not understand the needs of the photographer and LBA

So I called Sigma today and spoke with the service department. They think the A pin over time can get worn and this gives the F- error on screen. When I enquired about a price to repair he said they don't repair these lenses anymore and to go to an independent repairer and also they don't even have Pentax mounts there in the service department

Worrying if that means now then that if your lens develops a fault with the mount then you're screwed

Pass! I'll call an independent repairer later if anyone has anyone they could recommend?

That or its eBay time!

As far as I am aware your 24-70mm is about 3 generations behind their current version. I know that Canon don't service/carry parts for any of their lenses once they have been replaced by something more up to date and they are more than 5? years old so it's not just Sigma.

I think Alan Marlow my be winding down for retirement but worth contacting him. LINK

Thanks Mike will do. When I spoke with Sigma they didn't ask what model it was when he said they don't keep the Pentax mount in stock any more