Am i expecting too much from sigma 24-70

[Clint204]

Hi, I purchased me sigma 24-70 ex dg macro in May, but its been at sigma for most of that time. The focussing on the right side is out, noticable at f2.8. Just got it back today, but seems like the same problem. Attached is a test shot. Am i expecting too much from an EX lens?

[blonde]

a few questions for you:

what focusing point are you using? you shot this at 2.8 and the DOF is very narrow which might explain why the battery on the right is not sharp. also, why didn't you set them up at an angle instead of in a row? something like this might have worked better to show focusing issues:

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[tbrasington]

Try some shots of what you shoot normally / want the lens for and see if it is a problem there.

[Mr. Clean]

What camera are you using? Also, do them in a staggered formation as aforementioned and put them close together, also take the same pic multiple times, between each shot focus out to infinity and then refocus. Also, did you start doing test shots because your real world pics looked bad? If not, then don't worry about it :D

[Clint204]

a few questions for you:

what focusing point are you using? you shot this at 2.8 and the DOF is very narrow which might explain why the battery on the right is not sharp. also, why didn't you set them up at an angle instead of in a row? something like this might have worked better to show focusing issues:

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Focus was on the centre battery, on the eveready lettering, all the batteries were in a straight line, and therefore in my opinion all batteries should be sharp, or am i incorrect. I had taken pictures at a wedding which i was upset with due to the right hand side been OOF.

[blonde]

hmm, well, you focused on the center battery which means that it is possible that the lack of sharpness is due to the thin DOF @ f2.8

[Woolburr]

Are you positive that the line of batteries is absolutely parallel to the focal plane? With that shallow of a depth of field, it is entirely possible for one side or the other of the image to be soft. It seems to be the sharpest at the left side of the image and gets progressively softer as you move to the right. Looks more like a bad test.
Instead of wasting time shooting batteries...why not go take pictures? Or did you just buy this lens to shoot battery shots?

[Rhinotherunt]

Did you shoot on a tripod? I think I spy some camera shake. At 1/30 a second this could be possible.

[Clint204]

I used the lens at my cousins wedding with poor results, thus started doing test shots. Im using a 20D and sent all my equipment to Canon to check. Canon did some test shots and agreed that right side focus was out. Sent lens to Sigma, where its been for almost 3 months. Just got it back today and did some test shots. Attached are 2 more pics closer together and staggered. Even tho im using f2.8, shouldnt all items in that plane of focus be in focus?

[Rhinotherunt]

If you do not like the lense trade it in or sell it. ;) I tried one out and did not like it. The Tamron 28-75 2.8 is promising...

[Mr. Clean]

Man........I dunno, at f2.8 that's not bad at all from my POV.

[Benandbobbi]

I think you might be expecting "L" quality from a Sigma lens. JMHO since you asked.

[Clint204]

If you do not like the lense trade it in or sell it. ;) I tried one out and did not like it. The Tamron 28-75 2.8 is promising...

Well, i was thinking of both lenses, but decided on the sigma due to the 24mm wide end. Wanted something a lil wider than the 28mm.

[tbrasington]

Do you have an example of the wedding shots?

[Clint204]

Thanks for the feedback guys, will do some everyday shots later this week and see how it goes.

[Rhinotherunt]

Well, i was thinking of both lenses, but decided on the sigma due to the 24mm wide end. Wanted something a lil wider than the 28mm.

I understand that. That is why I got the Sigma 10-20mm... I also have a prime 30 1.4...

[Clint204]

I understand that. That is why I got the Sigma 10-20mm... I also have a prime 30 1.4...

Rhino, i got the EFS10-22, but its a pain to change the lens all the time. I have a Tamron 28-300 (cheap lens) and get irritated at 28 mm sometimes, always looking for that lil extra bit wider without having to change lenses. Ideally i'd like the Ef24-105, but out of my price range!!!

[Mr. Clean]

I think you might be expecting "L" quality from a Sigma lens. JMHO since you asked.
I dunno - maybe it's just expecting a lot at f2.8? There's a few threads in here for each manufacturer that mention softness at f2.8.

[nitekatt2006]

Although I haven't used Sigma 24-70mm, a shooter I know has one on his 20D and it is sharp as a tack. I have a Tokina 80-200 f2.8 pro series that was so out of focus, it looked like everything I shot was underwater. It went into the service center not once, but twice before it came back primo. That lens has been great for low light dance clubs and the ballet I shot. Tack sharp and fast, not a Canon L. but still pro quality. katt

[ksgeag]

Does the focusing ring feel a little tight? I have a 24 -70 ex for my sd that I sent back twice because I felt it was soft at 2.8. Then some one suggested the sigma needed some time to "break in" After some use i found that the focus seemed faster and my pictures looked sharper. I am very happy with the results I get now.
Also your test shots look close, dof is VERY shallow at close distance.

Good Luck
K.S.Greene

[Benandbobbi]

I dunno - maybe it's just expecting a lot at f2.8? There's a few threads in here for each manufacturer that mention softness at f2.8.
My 24-70 is tac sharp at 2.8...unless you blow it up to see each pixel that is.

[Big Hands]

Provided you didn't goof up the shot, it sure looks soft to me.

If that's the best it can do wide open, I would get rid of it.

[Rhinotherunt]

Rhino, i got the EFS10-22, but its a pain to change the lens all the time. I have a Tamron 28-300 (cheap lens) and get irritated at 28 mm sometimes, always looking for that lil extra bit wider without having to change lenses. Ideally i'd like the Ef24-105, but out of my price range!!!

True it can be a pain to change the lens, but I force myself to use a lens as much as possible without changing. I also have my 7-200 mounted on another 300D. One wedding I almost shot the 30mm exclusively. The Bride and her family LOVE the results. That was before I got the 10-20mm. My next wedding I am going to push myself to try to use it exclusively.

[DavidEB]

I agree you have a problem but I don't think you've isolated which of the many possible causes are at play. Above all else you need to eliminate camera shake, and you need to remove closer items that the AF might try to focus on (remember that the AF sensor is bigger than the red rectangle).

AF innacuracy: take a shot of a flat piece of paper, with fine print, taped flat to the wall. A dollar bill works well. make sure your camera is set up directly in line with the target, and is exactly perpendicular to the wall. Use a tripod. Use center point AF. set mirror lockup and self timer (to reduce camera shake). Try manual focusing several times, alternating with AF. take a half dozen shots each way (AF/MF), select the best of each, and compare.

Right side out, versus target not exactly aligned with focal plane -- similar technique to test 1 above, but use a larger target. second test for this: Piece of graph paper taped to wall, camera at same vertical level but moved so that view is from 45 degrees to wall. mark center of the graph paper with a bold, crisp tick mark (to focus on). Take a half dozen images. See if the top and bottom extensions of the vertical lines are in focus at the same distance to the camera. Turn the camera to portrait mode, and repeat. You should get the same results in both landscape and portrait. If not, then the "right side is out" or some similar conclusion. Mal-alignment of the lens axis with the image plane is uncommon unless somebody's dropped the lens.

good luck,

[pfogle]

I've seen this problem (one side soft) on several lenses - the worst being a Sigma 15-30, which I sent back; the replacement was much better, and a s/h EF 17-35L (the lens before the newer 16-35L came out) which was just horrible, so I didn't get it.

I gather it's not at all uncommon for Sigma zooms to be out of alignment - if I was buying one, I'd try 3 and pick the best. If one side is soft in a wedding situation, you should send it back. I really don't think you'll get much from the battery shots, unless you do some really careful setting up first, with tripod. The real-world situation is much more useful as that's the bottom line.

From tests online (check out fstopjojo's page) the Sigma is certainly capable of producing results up there with the Canon 24-70L. Chances are you've got a bad one.