Sigma 2.8 18-50mm Focusing in Dark.

ant1

ant1

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Hello,

Just like a little help on my new Sigma lens.
It focus' perfect when in the light, and even if i'm in the lighter room of the venue. (Talking nightclub photography here).

But when it comes to the main room, with the band. Bit darker, strobe lights. I have my flash on, with AF Assist light. It doesn't want to AF, it makes me look a right nob when taking a photo of a couple, and have to switch to M focus, can be risky when its dark haha.

I have a jessops flash, bought it to get me by. Worked perfect last week in the dark, with the 18-55mm kit lens. So wouldn't have thought it was the AF Assist light being naff. The batteries were fully charged.

Any ideas here? Does it have a slow focusing motor on it. Making it difficult for it to focus?

Tried different things, f2.8. up to f8/f10. Also ranging from 1/20 to 1/80. Nothing seemed to help.


Any ideas or help really appreciated.


EDIT: Photos last week with the 18-55mm kit lens were better.. way sharper. WTF?
 
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Any ideas people?
actually thinking of sending it back aha and getting a kit lens now after the kit lens photos were better. What was i doing wrong.
 
I was using a Canon 400D last night. Wouldn't have thought it be down to this as like I said, worked fine in the dark etc last week when using the kit lens?

Cheers,
Ant
 
Just a poor performer in low light, have a google and see what others say
 
Also had problems today in day light. Think the auto focus is temperamental. It is second hand mind. So sending it back going to get my money back as it wasn't sold / described as being faulty. (When it is). And for what I need it, I need it to AF really.

Sigma do seem to have problems with AF on some lenses, google searches show.
 
I have this lens and I have never had a problem with it, used in weddings indoors and on night road rallies
 
Apparently some didn't work with the Canon 20D, later models were rechipped, something to consider
 
Seems like I have just purchased a faulty one then really. Or obviously my camera doesn't interact well with it.

Cheers both. Waiting until Monday for them to get my email, send it back and refund me hopefully. Will then borrow my mates kit lens for the time being for the bar.
 
Yes sure, I found that the auto focus is actually faulty. Working or not working, being very temperamental. So will be going back.

The images, really are prob down to my settings, As I was messing with them to try and get it to focus haha. Here is one with the sigma.
http://www.flickr.com/photos/antparkes/8104153459/in/photostream

F/7.1 (i think).
1/20
1600.
The main part of the image is because, obviously its noisy, from 1600 ISO. I used 1/20 most the time last week and was fine. But was using f/5.6 last week not 7.1.

My flash, it set to 45degrees, diffused. TTL.

Here is one from last week, seeming much sharper etc. (With the kit lens).
http://www.flickr.com/photos/antparkes/8091841386/in/set-72157631755801741/
http://www.flickr.com/photos/antparkes/8091847806/in/set-72157631755801741
http://www.flickr.com/photos/antparkes/8091843084/in/set-72157631755801741

These are f/5.6
1/20
ISO 1600.

FLash the same as above.

So the settings aren't all that different, yet image quality is greater with kit lens.
 
I get the same problems.. I think its more to do with getting the flash right.

I've the Nissin Di622 MkII (£99) you get better shots if you bounce flash upwards and use the little white card that pull out the flash.. that then directs the flash to what your photoing.

have you tried that instead of defusing it?

I had my flash direct to this girl, with the defuser cap on. think its a bit too much flash, wish I had pointed it up with the defuser taken off and use the bounch card on the flash instead

MFN portraits Oct 2012-6 by salsa-king, on Flickr
canon 50mm f:1.8 lens used this time
 
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Don't forget in dark/dim situations that the ad can struggle. I usually find it works ok if I find a contrast edge, something with a dark to lighter edge.
 
Salsa-king. Thanks you for your input. Yet also tried the flash up, well, slightly off right up with the bounce card. Was exactly the same really.

Byker28i. I realise that any lens really can struggle in the dark. Sometimes the kit lens did last week when I used that. But like you say, I found a light piece of clothing or something to focus on and then recomposed. My main problem was that it wouldn't even focus in daylight. Natural light that is, outside. Now that then gave me the impression of the AF being faulty. Almost as if the camera isn't communicating with the lens, the lens doesn't turn and not focus. It just doesn't do anything haha.
 
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