Sigma 10-20 - Is mine a duffer?

morleymackam · 13-10-2008, 8:01 PM

Bought a 10-20mm Sigma from Jessops and having taken my first few shots i'm concerned that it's not the ultra sharp beast it's touted to be.

I see there are problems with quality so took a photo of a brick wall at 10mm to try and figure it out. The 1:1 crop is the centre of the frame and it just doesn't seem sharp enough to me. Should I return it?

Pics are clickable

johnaalex · 13-10-2008, 8:08 PM

I do not think this is a good test to see the sharpness of the lens, I would try some other subjects, something with fine detail and at various apertures and focal lenghts - lenses do have sweet spots! Having said that, if you are unhappy with the purchase for whatever reason then the sooner you take it back the better.

morleymackam · 13-10-2008, 8:10 PM

Quote:

Originally Posted by johnaalex

I do not think this is a good test to see the sharpness of the lens, I would try some other subjects, something with fine detail and at various apertures. Having said that, if you are unhappy with the purchase for whatever reason then the sooner you take it back the better.

I presumed the brickwork would be goof for fine detail? I took the same shots with a friend's 30mm prime and it's soooooooo much better. I would expect a bit but not the full amount.

As for taking it back. I really want a wide angle and the £300 for the sigma is as far as I can stretch. If I can get a better copy though I want it!

RobDickinson · 13-10-2008, 8:14 PM

What aperture was that? , focused properly? Tripod/shutter speed?

johnaalex · 13-10-2008, 8:17 PM

Quote:

Originally Posted by morleymackam

I presumed the brickwork would be goof for fine detail? I took the same shots with a friend's 30mm prime and it's soooooooo much better. I would expect a bit but not the full amount.

And how much did the 30mm prime cost? Also I just looked at this review Sigma 10-20mm f/4-5.6 EX DC Interchangeable Lens Review and they say one of the weaknesses of the lens is "Softish edges in middle of range", but they say it is better wide open.

Quote:

Originally Posted by morleymackam

As for taking it back. I really want a wide angle and the £300 for the sigma is as far as I can stretch. If I can get a better copy though I want it!

So take it back and try another copy of the lens while at the store.

Peakoverload · 13-10-2008, 8:21 PM

At 1/160th you can obviously rule out camera shake. However you've used an aperture of f/4 and that could possibly be where the problem lies. The Sigma at large apertures isn't particulary sharp with small fine detail (although I'd have to say that I would expect it to me sharper than these images appear). I'm not saying that what you've got is acceptable but it might be worth trying again using f/8 or f/11 just to see if that improves things.

morleymackam · 13-10-2008, 8:21 PM

This is another centre crop - this time at f9. Still at 10mm though.

I did realise it was going to be a little soft at the edges but like you say it's supposed to be good wide open. I know the 30mm will have been expensive and it is a prime but I would expect the 10-20 to get a little closer. Most of the landscape shots I've seen seem pin sharp.

RobDickinson · 13-10-2008, 8:26 PM

I dont have any 100% crops online from mine but the center at f8 is dead sharp, it does have softer edges.

Peakoverload · 13-10-2008, 8:32 PM

Quote:

Originally Posted by morleymackam

This is another centre crop - this time at f9. Still at 10mm though.

I did realise it was going to be a little soft at the edges but like you say it's supposed to be good wide open. I know the 30mm will have been expensive and it is a prime but I would expect the 10-20 to get a little closer. Most of the landscape shots I've seen seem pin sharp.

Okay, that is just plain out of focus!

Assuming you didn't move and that you did autofocus and that the lenses AF switch was on, then based on all of that the lens is either front or back focusing. Either way, send it back.

RobDickinson · 13-10-2008, 9:07 PM

Out of focus at f9 / 10mm ?

1st find and print a focus test chart,
2nd use it, tripod , 45degrees af on the center, see its focusing.

3rd tripod a scene with selftimer at f8 and see how it comes out.

richard plumb · 13-10-2008, 9:26 PM

first shot looks ok if its straight out of camera. A little soft, but its a 100% crop.

take another lens you're happy with and do a comparison.

morleymackam · 14-10-2008, 8:20 AM

I am erring towards taking it back to be honest. I'll try a test card and a tripod if I can find one online. I can find plenty of references to it - just no card!

dazza74 · 14-10-2008, 8:36 AM

I've taken my best pics with this lens from around 12-14mm. I've recently sold mine to a relative I just prefer the sharpness of my tamron 17-50. I'll probably look at the Nikon 12-24 later down the line if I really need the width.