Sigma 10-20mm optimum settings...now with samples!

willbaroo

willbaroo

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William
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Good afternoon all.

I recently purchased a Sigma from Kerso on the forum and I am struggling to get tack sharp images from it (I might be pixel peeping)

I don't have any examples at the moment but will try and upload some 100% crops when I get home from work.:(

What are your Sigma 10-20mm settings that you find best work for you?:thinking:

I have heard of re-chipping for the Camera but that seems a little extreme for an 'out of the box lens'.:thumbsdown:
 
Not unknown to get a soft sample of this lens, bought mine s/hand from here after seeing sample pics.

With mine I usually use it at f/11 and above, but on occasion I have found f/8 to be pretty good, a good 90% of my shots are tripod mounted too

Don't think its especially great wide open though or not from my experience anyway.
 
You should be able to use a lens that wide open at f/5.6 with no problem for most things. as said above though, if it's a soft version you'll need to have it replaced.
 
Ok thanks guys, I am going to go home and run some tests at f8 and above and see what happens. I think that may have been my problem this weekend.
 
as you have the 50D have you check if it is foucing correct. you can make micro adjustsments for the lens. I have been doing my lens
My 10-20m is very good here is one shot

click for Large size.
Exposure: 1/320
Aperture: f/9.0
Focal Length: 10 mm
ISO Speed: 400
 
Right here we go folks, this is one taken from the weekend with the 10-20mm.

Shot information: (no tripod)

Model = Canon EOS 50D
Orientation = top/left
Software = Adobe Photoshop CS4 Windows

[Camera]
Exposure Time = 1/640"
F Number = F6.3
Exposure Program = Aperture priority
ISO Speed Ratings = 200
Metering Mode = Pattern
Focal Length = 10mm
Exif Image Width = 3168
Exif Image Height = 4752


Full JPG Image (from RAW): http://will-belcher.co.uk/photos/sigma/IMG_0226full.jpg

What i've cropped:

cropexample.jpg


The crop its self (no PP whats so ever):

crop100.jpg


Is it a soft example or am I expecting to much OR am I doing something wrong?
 
Can I ask you if you have a filter fitted to the lens? :)
I bought my sigma used via ebay and it came with a Hoya uv filter.
I wasn’t impressed with it the first time and thought the focus was very soft.
I then removed the filter and found it far better and whilst I’m still getting to know the lens I’m more than happy with it.:thumbs:
 
ive used that lens a few times and i think i had a fairly decent copy, but they are generally prone to quality control issues and a lot of soft copies are floating around. Personally I wouldnt be pleased with the samples you posted. as suggested earlier, micro adjusting the camera for the lens may be a solution, but ive never done it myself.
 
On the image you posted, where was the focus point? If you crop or zoom in to that point, is it sharp there?
 
There appears to be 3 active focus points? (Not a Canon user, so I'm not sure on the details) but presuming that the centre focus point was used - then yes, it seems to be more acceptable.

Have you tried sharpening it a little more in PP?

Also, it's been mentioned on TP a lot that the Sig10-20 seems to have a sweet spot for sharpness at about f8 - maybe try the shot again, at f8? (or a similar shot)
 
That confirms my observation with a 'test' copy of the lens. From f/8 it was acceptable right in the centre, towards the corners, but completely dreadful in between. I don't know if they are all like that or just most, but I really didn't want to bet my money and got Tokina instead.
 
It's frankly impossible to say whether that lens is up to scratch or not on the basis of one sample image.

The only way to make any meaningful judgement is to compare two identical images, one taken with your new Sigma and another with a lens of known quality. Identical everything.

Do you have another lens that overlaps on focal length? If you have a poor copy it will show up at all focal lengths (and there are better tests you can do to check that).

BTW it's virtually impossible to have a focusing problem at that distance, at that focal length and at that f/number.
 
From the photo you've uploaded and the focus points shown, I'd say it looks pretty sharp, the spire to the left of the enhancement wasn't on a focus point so at this stage, seems ok.

Have you tried enlarging the window near the centre of the building, where the focus point has been acheived to see how sharp this is ?
 
hsuffyan said:
ive used that lens a few times and i think i had a fairly decent copy, but they are generally prone to quality control issues and a lot of soft copies are floating around. Personally I wouldnt be pleased with the samples you posted. as suggested earlier, micro adjusting the camera for the lens may be a solution, but ive never done it myself.
Click to expand...

I find that very off puting. That lens was on my "maybe" list, but not now.
Something not right with the engineering when it gets noticed that soft copies are on the go.
 
This is what I found when trying to decide between the Sigma 10-20 and Canon 10-22... The Sigma simply wasnt as sharp, particually in the corners (which is why I didnt buy the Sigma). Going by what you have posted though, this does look like a particually soft copy? I wouldnt be happy with this one.

As has already been posted, try micro adjusting it with the camera, and then trying it against a lens you know to be sharp, or at least fairly decent (your kit lens would be an interesting comparison!) at the same focal range and settings, and on a tripod so user error can be discounted from the equation! Failing that I would try and swap it for another.
 
Best bet is buying a secondhand one on here and then you can at least see some examples.
Also most likely that the original owner would have returned a soft sample, worked for me and very happy with my "preloved" Sigma 10-20
 
If you want to see if the lens is any good or not, the only way to tell is by comparing it side by side with another lens of known quality. As mentioned above. Bear in mind that image processing can made a huge difference.

If you want to know if you've got a good copy or not, 90% of the quality control problems are because the elements are not properly centred and this shows up with one or more corners of the image being softer than the others. Just shoot a target a little distance away (to minimise any focusing errors) at lowest f/number (to minimise depth of field that may conceal a problem) and a high shutter speed (to reduce camera shake). Lock the exposure on manual and take four shots with the target in all four corners of the frame.

Then enlarge the target sections and compare - they should all be the same. Don't expect them to be really sharp because they will not be - this is a tough test. They just need to be equally sharp (or equally unsharp). You won't have to look hard, if there's a problem it will be obvious. You can even do it on the LCD if you have a decent 3in screen.

FWIW I think that QC problems with Sigma are not as common as pixel peepers make out. It is just unrealistic to expect a lens that costs half the price of the similar Canon to be as good. Also, it cannot be a focusing problem - there is so much depth of field with that lens. If you're concerned about it, compare the AF with a manual shot focused in live view.
 
O.k guys so I carried out some more tests last night...

Pretty much what you stated in your last post Hoppy.

When shooting @ around f/8-10 @ 10mm focal length there is a noticable improvement in sharpness in the corners. I am going to try it again properly when my red snapper arrives.

Thanks for your input so far guys!
 
All this really confirms is that my 10-22mm was a bloody bargain at £320. :)
 
HoppyUK said:
BTW it's virtually impossible to have a focusing problem at that distance, at that focal length and at that f/number.
Click to expand...

I don't know if it's the same with this lens but my Canon 10-22 will focus past infinity (little L shaped on the focus scale goes past infinity).

I discovered that at wide apertures this did affect the image quality, not so noticeable at small apertures.

Usually I focus maually at infinity with this lens to ensure it at infinity (often use live view 10X to check).

HTH

David
 
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