View Full Version : D90 + Sigma 18-200 lens problem
HI all,
I have been using my D90 with Sigma 18-200 HSM lens with no problem.
But lately when i use it in Thailand, I found that the lens sometimes cannot do auto-focus, the lens just keeps moving front and back trying to lock in a point but just failed. SOmetimes it work back again if I turn it to manual, take a few shoot, and turn it back to Auto...it may work for a few shoot.
But it may fail again very soon.
It would work again if i detach the lens and reattach again...but it may fail again sooner or later and i still cannot fidn out the reason....
Is it likely to be a problem with my lens or body?
Thanks.
faisal
08-27-2009, 01:33 PM
The Sigma 18-200 for canon has terrible auto focus especially in low light and low contrast situations. What kind of subject/s were you shooting??
Make sure the the electrical contacts between the camera and lens are thoroughly clean.
think fais has nailed it. if you;re shooting in low light or low contrast subjects the lens isnt able to lock on.
i m quit sure the thing that i was shooting at were under enough lighting and enough contrast condition while this problem happens.
But i do agree with folks that i did encounter some situation like that...
easy way to test it out. go out in bright conditions and shoot some things. if it locks on under bright conditions then there is no problem. i suspect you will find that, as with most superzooms, the focus locking is a problem once the loighting is less than ideal.
I did Rooz....
the most frustrating thing is it works and does not work without particular pattern under the same condition....
The only catch is the problem only happens to me if i shoot outdoor...it has never happened indoor with air-conditioning..
can it be humidity?
and i hope it is the problem with the lens, not with body....otherwise i m scrxx
hmmm...thats wierd then. do you have any other lens' to try ?
can it be humidity?
Which is why I suggested a through clean of the contacts. There is not much else that an end user can do in those circumstances.
Is there in any fungus inside the lens?
no fungus at all....i am going really mad...the only observation I have is, those problematic incidents always happen at outdoor....
faisal
08-28-2009, 01:48 AM
To think about it, that has happened to me as well. The thing with Sigma lens (not the 70-200) that I own, once they fail to focus a few times, they refuse to focus again unless I put it in MF and then back in AF or give it a break. It happens a lot with my 18-200 but I just thought it was normal Sigma behaviour for the cheaper lens...
If its still under warranty, either contact the retailer or contact Sigma.
Dread Pirate Roberts
08-28-2009, 08:22 PM
High humidity is when you'd be more susceptible to poor lens body contacts.
Go outside in full sun find something with a hard edge like a bench or building against the sky. Put the focus area on that edge and see if you still have a problem.
If you do then it rules out the poor focus of the lens and says you've got some defect like the contacts.
i tried with another lens today, the same probleme exist, so i bet it is the body's problem...?
I took it to Nikon warrenty services, and they told me there is no problem with my body after checking with the computer as they see no error code...and ask me to go away.
Of course they will not check my lens as both of my lens are from Sigma...
but what is the chance that both of my sigma lens are defected?
what can i do now
what can i do now
For the third time thoroughly clean the electrical contacts between the camera and the lens.
To think about it, that has happened to me as well. The thing with Sigma lens (not the 70-200) that I own, once they fail to focus a few times, they refuse to focus again unless I put it in MF and then back in AF or give it a break. It happens a lot with my 18-200 but I just thought it was normal Sigma behaviour for the cheaper lens...
i think Sigma price is cheaper not because of its quality, just that its brand name is not as sexy as Nikon.
Indeed, I have been using Sigma lens from 50mm 1.4 to 18-200, all deliver good quality photos...
I do not believe this kind of focus problem is defacto...
i think Sigma price is cheaper not because of its quality, just that its brand name is not as sexy as Nikon..
not entirely no, but it is a reason, sigma and tamron are defiantely not as well built as canon/ nikon etc. and their quality control sometimes leaves alot to be desired.
i hope you can figure out what the problem is. if you bought it from a retailer just take iot back and demand they fix it.
For the third time thoroughly clean the electrical contacts between the camera and the lens.
Dont you hate when people ask for your help then just ignore it?;)
Dont you hate when people ask for your help then just ignore it?;)
I didn't ignore your advice :)
I did clean it...same effect...
Is there any special tricks or equippment to do it even better?
tim11
08-30-2009, 11:51 PM
I don't have problem with my Sigma lenses.
I don't know how much experience you have with cameras so just to clarify a few things:
What kine of subjects did you shoot when focus doesn't lock? Is there any contrasting EDGES for the camera to lock on too?
tim11
08-30-2009, 11:58 PM
i m quit sure the thing that i was shooting at were under enough lighting and enough contrast condition while this problem happens.
But i do agree with folks that i did encounter some situation like that...
Yes ... I'm aware the subject has been discussed before and your reply is there was enough contrast condition. I interpret that contrasting situation isn't the same as contrasting edge or outlines so I want to clarify that.
For example, I can't take focus on a page full of text on white paper unless I focus on the black text first and recompose the frame later. The same goes for taking a shot of something on a bright wall.
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