sigma 10-20 softness

nickjohnwatson

nickjohnwatson

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Over the last week or so. I've noticed that my sigma 10-20 is soft at the left edge. I bought it on here probably 4/5 months ago and have had no issues up until now.

The rest of the picture is sharp and its less noticeable when used at 15mm+

I was shooting at f8 today and its very apparent.

Ill take a picture square on of a brick wall tomorrow and post it here to show the softness.

How much is a repair from sigma likely to cost? (I can't get on the sigma website for some reason)

Is there any point? I know its a fairly common issue with these lenses. Should I just put up with it?

Thanks guys
Nick
 
This lens is known to be soft at the edges. It would be best to compare a picture when there were no issues and one with issues (pref of the same subject) to see if it has developed over time or if it was always there.
 
nickjohnwatson said:
Over the last week or so. I've noticed that my sigma 10-20 is soft at the left edge. I bought it on here probably 4/5 months ago and have had no issues up until now.

The rest of the picture is sharp and its less noticeable when used at 15mm+

I was shooting at f8 today and its very apparent.

Ill take a picture square on of a brick wall tomorrow and post it here to show the softness.

How much is a repair from sigma likely to cost? (I can't get on the sigma website for some reason)

Is there any point? I know its a fairly common issue with these lenses. Should I just put up with it?

Thanks guys
Nick
Click to expand...

Where's the pic then? Suggest shoot at lowest f/number, and make sure you are exactly dead square to the wall. Sounds like a centering issue, not uncommon especially if the lens has taken a knock. Should be easy enough to fix, get a quote from Sigma.
 
Ok so here are some test shots.

I've looked at them at 100% and more, i dont get whats going on, sometimes the softness is on the left, at other times its in the bottom right and sometimes they are fine.

on these ones the softness is in the bottom right corner.

F4 10mm



F8 10mm



F16 10mm



F4 10mm



F8 10mm



F16 10mm

 
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I can't comment on your Sigma lens but I have a Canon 10-22 and have seen the type of thing you are experiencing.

My take is that the AF sometimes struggles with all the tiny detail seen in these wide angle shots, there is nothing meaty for the AF sensor to latch onto so it often makes a guess.

Well you might say I shoot at f8 what's the problem.

I have found that the lens is quite sensitive to being focused past infinity, and if the AF goes in this direction in error then all sorts of horrible things start to happen.

The wall shots you have taken seem to be closer than your group shot. I would suggest you try again at the group shot distance, see what happens.

If you have live view to focus try that as well.

I have resorted to using live view as a default to focus my 10-22 if the focus is really critical.

HTH

David
 
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nickjohnwatson said:
Ok so here are some test shots.

I've looked at them at 100% and more, i dont get whats going on, sometimes the softness is on the left, at other times its in the bottom right and sometimes they are fine
<snip>
Click to expand...

There's definitely a problem with the groups shot. From what you say, maybe there's a loose element wobbling about - that would be a very easy fix.
 
Willid1 said:
I can't comment on your Sigma lens but I have a Canon 10-22 and have seen the type of thing you are experiencing.

My take is that the AF sometimes struggles with all the tiny detail seen in these wide angle shots, there is nothing meaty for the AF sensor to latch onto so it often makes a guess.

Well you might say I shoot at f8 what's the problem.

I have found that the lens is quite sensitive to being focused past infinity, and if the AF goes in this direction in error then all sorts of horrible things start to happen.

The wall shots you have taken seem to be closer than your group shot. I would suggest you try again at the group shot distance, see what happens.

If you have live view to focus try that as well.

I have resorted to using live view as a default to focus my 10-22 if the focus is really critical.

HTH

David
Click to expand...

I usually use live view zoomed in on manual focus if im using the tripod, I need to get it sorted as its frustrating as hell lol

HoppyUK said:
There's definitely a problem with the groups shot. From what you say, maybe there's a loose element wobbling about - that would be a very easy fix.
Click to expand...

Would it need to go back to sigma for that? Their tariff states 98.00 for a 10-20 repair, do they service them when they do repairs do you know? Cheers
 
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nickjohnwatson said:
I usually use live view zoomed in on manual focus if im using the tripod, I need to get it sorted as its frustrating as hell lol



Would it need to go back to sigma for that? Their tariff states 98.00 for a 10-20 repair, do they service them when they do repairs do you know? Cheers
Click to expand...

Hard to say. Depends what it is, and where it is. I would.
 
I don't think that shooting bricks from a few cm will show anything too well. Shoot a normal distant detailed scene concentrating on one particular spot over different positions in the frame. That will tell you quickly where the problem is.

It is probably best to send it to repair, or just invest into a decent tokina.

P.S. group shots with ultra wide are pretty bad idea due to distortion of people near the edges
 
daugirdas said:
I don't think that shooting bricks from a few cm will show anything too well. Shoot a normal distant detailed scene concentrating on one particular spot over different positions in the frame. That will tell you quickly where the problem is.

It is probably best to send it to repair, or just invest into a decent tokina.

P.S. group shots with ultra wide are pretty bad idea due to distortion of people near the edges
Click to expand...

I think ill send it for a repair once I've been paid. Your right about the bricks I think. Didn't really show it too well. Its a lot more prominent on normal scenes. Hopefully it'll be sorted out when I send it off.

Cheers for the replies everyone :-)
 
When I was first looking for an UWA lens the 10-20 that I borrowed showed exactly the same problem. A quick search on the interwebs showed that this decentering problem is, while not common, not that unusual with this particular lens.

It's the reason I decided to scrap the Sigma from my list of possibles.
 
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