Lens problems...

[Xarra]

My 105mm 2.8 Sigma and 30mm 1.4 Sigma are both having horrible focus problems. The 105mm is not finding it easy to focus and the 30mm I think that there's a bit of the focusing in the middle not working properly...

I'm not sure how I can get these looked at (one's a refurb...) and how much it'd cost... Or if I can look at it myself...

 

[Flash In The Pan]

Do you have any example images you can post - that'll help diagnose the problem(s)

 

[Xarra]

Once it's focused, it's fine. But the 105mm takes AGES to lock on unless there's very high contrast and the 30mm I have to manually focus to one extreme or the other and it will then focus as long as it doesn't go through the middle or something...

 

[stan the man]

if your sigma 105 is the macro lens,then yes,it will hunt a lot unless you switch it from full to limit....it will then not go through the full range of trying to focus.

 

[Xarra]

Even on limit it hunts a lot!

 

[stan the man]

mmmmm....to be honest,i generally only use mine in MF for macro work,but if i do use it in AF it's pretty good at finding focus.

 

[Graham004]

Don't know if there is any connection but I had focusing problems with canon 24-70 in that it would not focus on the wide angleside. It was only when I took the lens off and found that a screw was missing from the rear end of the lens. This had a dramatic effect on focusing.Its been sent to canon today via calumet who charge £25 to send. Jessops doing the same job charge £35 before its even looked at.

 

[sdb123]

Contact Sigma's service department through the Sigma website, they are very helpful and would be best placed to answer your questions.

 

[OutLore]

Quick question - do you have any other lenses to use? If they are the only 2 you have then it may be a camera issue, not a lens issue?

 

[HoppyUK]

Quick question - do you have any other lenses to use? If they are the only 2 you have then it may be a camera issue, not a lens issue?

Yeah, possible body problem. That's what I was thinking. It's the body that decides the focus point, and tells the lens to move there. The lens just follows instructions in that sense.

Either way, you should check the lenses on another body, and other lenses on your camera. Should be able to isolate the problem that way, without sending stuff off.

 

[Xarra]

Body is fine with my other lenses - and the 30mm definately feels 'odd' on the manual focusing... Like something isn't connecting...

 

[OutLore]

Body is fine with my other lenses - and the 30mm definately feels 'odd' on the manual focusing... Like something isn't connecting...

Sounds like it may need to be checked then... Would still be worth (in my humble opinion) checking it on another camera body though.