Loose focus ring - Cameras

Turn the grey ring around the lens (where the light comes from) until the image is sharp.

Hi.
There is a problem inside your lens. It can be a flexible PCB (printed circuit board) or screw out of possition, so the focus moving parts can´t complete the range.
If the infinity focus gets at 3ft, there are also some optical group loose. That is the reason infinity position is located closer than it must be.
Send it to a Sigma Service.

Measure out 100yards and focus scope to that then replace ring to the 100 mark and fix

The problem usually comes about when the focussing ring comes loose. Step 1 remove the 1.front round name ring 2. filter ring. this will expose three screws that hole the focus ring in place. reset the focussing to infinity on your viewfinder then set the ring to the infinity mark and retighten. If the helicoid has come apart then take the mount ring out, aperture ring out, and remove the two focus guides. turn the core out, set the fine thread back until it is almost against the ring directly behind it. make sure that it has at least one and one half turns. then engage the helicoid back. refit the focussing core into the lens and refit the two guides.reassemble the lens and revert to step one to reset the lens.

Needs service / repair

Hi, not sure if you still have this issue. I have just decided to look into it again, as I had a lot of focus problems with my Sigma 70-200mm HSM lens. Since there is no Sigma support here in Beijing, I took a look - and fixed it.

Here is what I did: On the front of the lens barrel is the rubberised focus ring. This can be removed (gently ply it away from the barrel by sticking a flat bit (or plastic letter opener) between the barrel and the rubber grip. It will come not entirely loose, so you need to work your way around the lens. Keep doing that until you moved it about half way forward. At this point two fixing screws become accessible on the barrel below.

In my case, one of the screws had come loose and that blocked the focus ring from turning, as the screw was blocking rotation in the access hole on the barrel.

Hope this helps others. Simple to fix, if you know how.

the same thing just happened to me like 3 days ago. The zoom ring was kinda sticky and then all of a sudden it just spins around and doesnt extend the barrel at all.

did you see any rubber gasket on the ring.. this could be the one turn out to be loosen,

did you dropped or any kind of incident happened on the lens.

This will need technical service eventually. Try temporary solution with Sellotape or similar

IF YOU TAKE A LOOK AROUND THE FRONT OF YOUR CAMERA THERE ARE SEVERAL SCREWS, ABOUT 4 I THINK,
1) 1 ON BASE
2) 1 ON THE LEFT LOOKING AT FROM THE FRONT
3) AND 2 INSIDE THE FLASH CASE
REMOVE THESE SCREWS AND THEN YOUR FOCUS RING AND SOME OF THE CASE SHOULD COME OFF
INSIDE THE FOCUS RING YOU SHOULD SEE 3 SREWS IF NOT CHECK THE CAMERA TO SEE IF THEY HAVE FALLEN INSIDE,
IF NO JOY YOU CAN REPLACE THE 3 MISSING SCREWS AND PUT IT ALL BACK TOGETHER

SWEET

DAVOS69

HOPE YOU DONT MIND BAD SPELLLLLING.........