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Is my lens sharp? Help!
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Hi guys, wondering if you can help out and see if i’m being paranoid, making mistakes, or have a duff lens.
I have a Sigma 10-20 F4.-5.6 and i’ve been going through all my photos I’ve taken with it. I purchased it last year when I had much less of a clue about photography than I do now. I’m now getting paranoid and wondering what are acceptable levels of sharpness having scrutinised my photos. Everything I’m reading online indicates this lens is sharp as a tack. However many of the shots I’ve taken don’t appear to stand up to scrutiny at higher resolutions.
I’ve uploaded a few with 0 post processing besides the standard import to lightroom which does a small amount of sharpening. Please let me know what you think. (on sharpness, not the images themselves) – the lens did have a fall in September of last year but I’ve very few before and after photos – the before photos seem just as “bad” in terms of edge sharpness. The bump also damaged the camera – essentially a friend knocked the camera and tripod onto the front hood – the lense was fun but the mirror box fell apart inside the camera. It received a full service from Canon in Paris and has shot fine after – I have some ultra sharp shots taken on a sigma 70-200 F2.8 for example so I don’t think it’s the camera. Maybe it’s me? Do I need to start hitting F 16 or more before I see sharpness through the entire image? I thought it would be manageable with an F11.
I’m using this as a baseline for sharpness – it was linked by its owner on a photo.net forum and as you can see, it’s super sharp:
http://static.photo.net/attachments/bboard/00D/00DIPK-25284884.jpg
If any of you are willing to have a look through and just give feedback, is it me, is the lens, etc. I’ll link to the full resolution image. Thanks!
Shot 1 – Night time, 11mm, 25 seconds at F8, ISO 100 (before the bump)
Standard page: http://www.flickr.com/photos/neilwhelan/2854542094/
Full resolution – http://www.flickr.com/photos/neilwhelan/2854542094/sizes/o/Shot 2 – Night time, 13mm, 2.5 seconds at F8, ISO 100 (before the bump)
Standard Page: http://www.flickr.com/photos/neilwhelan/3782974544/
Full resolution -http://www.flickr.com/photos/neilwhelan/3782974544/sizes/o/Shot 3 – Day time, 10mm, 1.6 seconds at F8, ISO 100 (before the bump, I don’t have the original unprocessed image, sorry)
Standard page: http://www.flickr.com/photos/neilwhelan/2683434969/
Full resolution – http://www.flickr.com/photos/neilwhelan/2683434969/sizes/o/Shot 4 – Day time, 10mm, 1/400 second at F8, ISO 100 (after the bump)
Standard page: http://www.flickr.com/photos/neilwhelan/3275242802/
Full resolution – http://www.flickr.com/photos/neilwhelan/3275242802/sizes/o/Shot 5 – Day time, 13mm, 1/100 second at F10, ISO 100 (after the bump)
Standard page: http://www.flickr.com/photos/neilwhelan/3782166877/
Full resolution – http://www.flickr.com/photos/neilwhelan/3782166877/sizes/o/Shot 6 – Day time, 10mm, 1/80 second at F11 ISO 100 (after the bump)
Standard page: http://www.flickr.com/photos/neilwhelan/3782980830/
Full resolution – http://www.flickr.com/photos/neilwhelan/3782980830/sizes/o/Shot 7 – Day time, 10mm, 1/640 second at F7.1 ISO 400 (after the bump)
Standard page: http://www.flickr.com/photos/neilwhelan/3782984054/
Full resolution – http://www.flickr.com/photos/neilwhelan/3782984054/sizes/o/Shot 8 – Day time, 10mm, 1/160 second at F9 ISO 400 (after the bump)
Standard page: http://www.flickr.com/photos/neilwhelan/3782988012/
Full resolution – http://www.flickr.com/photos/neilwhelan/3782988012/sizes/o/Thanks a lot guys, cookies for anyone in the Cork area for helping :)
From my experience it is not possible to have an unsharp image from a 10-20mm lens and from these images I stand by that. they’re fine.
Have fun.
Alan.
Well it could be a dud lens . . .
It happens even with top of the range L lenses.
It could also be a focusing thing with the camera.
I use a lot of manual focus lenses with focus confirm
adapters on the 5D and I was having problems with
front focusing.The camera was beeping when the lens was focused
but whe I checked the image on the pc the main subject
was out of focus.Below is a sample taken with an Olympus Zuiko 135mm
focused on the model but the front of the wall is in focus
and not the model. the pic has not been processed ion anyway
and is a crop of the original.
The next picture was taken after a slight modification
the the camera body . . . with am Olympus Zuiko 200mm lens.
I forget the f#
again no processing on this and is a crop of the original.What I did to the camera was remove the shims behind the focusing
screen in the camera. this corrects front or back focusing.this could be worth a try!!
Oh yea and did you try and change your picture style settings in your
camera to increase the sharpness a tad from the factory default?that could be worth a try too
They look normal to me. Corner sharpness has never been the strong side of that lens, and you need a very stable tripod and head to get the most out of it. And as Alan said, some sharpening can be beneficial, too.
I have the Nikon mount version of the same lens, at first glance I suspect mine is a little bit sharper than yours but it’s hard to be sure. PM me with your email address if you would like me to send you a Raw file taken with it.
(And I’m in Cork so I could claim the cookies too!!)
Aedan
I think there is nothing wrong with your lens as has been said a tripod is a good idea to get the most but if you look at the so called tack sharp image you will see its actually over shapend and has what i would call ringing artifacts (thats my past life as a TV engineer coming through).
That said the 10-20 i think quite rugged and I actually slipped and fell down on the lens and bent the cokin filter adapter such that i cant get it off now but the lens works fine as does the camera still (nearly became a very serious fall that).
I got your PM and have sent a Raw file for you to compare. It’s a pretty big attachment and I’m on a very slow link so it might take quite a while to work it’s way through to you.
Aedan
isityourself wrote:
Maybe it’s me? Do I need to start hitting F 16 or more before
I see sharpness through the entire image? I thought it would be manageable with an F11.Those shots look pretty ok to me.
I know your question relates to whether your lens is sharp or not but there is more
to achieving perceived front to back sharpness than simply what F number is set.You probably know all this already and millions of words have been written on
how to achieve you’re desired zone of acceptable sharpness in an image.The zone of acceptable sharpness or depth-of-field extends in front of and behind
the point that you actually focused on.
The size of the zone is determined by three key factors – the aperture of the lens,
the focal length of the lens used, and the distance you are from the subject.This dosen’t answer your question and maybe even muddies the water a bit. :)
I’ll go now before I confuse myself again. :?
Hope your lens is ok.
John.
Thanks for all the help guys. Yeah I understand the zone sharpness and so on, been reading a lot on it the last few days, but just wanted to double check. Reassuring to see that everything is hunky dory :)
Thanks a lot to everyone!
i like…….
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