sfdgs Posted February 26, 2007 Share Posted February 26, 2007 I recently purchased a Sigma 24-70 f/2.8. About half the shots are blurry and the sharpest ones still aren't that sharp. Did I get a bad copy or am I expecting too much from this lens? I did sharpen these in photoshop at 150% and .5 pixels and this is the best I could come up with BTW these are just quick shots in the back yard of my daughter so don't worry about the aesthetics and lighting. Thanks for any help!<div></div> Link to comment Share on other sites More sharing options...
sfdgs Posted February 26, 2007 Author Share Posted February 26, 2007 f 5.6<div></div> Link to comment Share on other sites More sharing options...
awindsor Posted February 26, 2007 Share Posted February 26, 2007 I can't see much wrong with these but it would have to be pretty terrible for the softness to show up in web sized full shots. Try posting some crops. The bokeh is pretty terrible. Seem to be a lot of doubling. There is also low contrast which could be a lens defect or flare from a filter or not using the lens hood. The contrast loss can be fixed in PS. Link to comment Share on other sites More sharing options...
sfdgs Posted February 26, 2007 Author Share Posted February 26, 2007 sorry about that- this should be a better example Link to comment Share on other sites More sharing options...
mawz Posted February 26, 2007 Share Posted February 26, 2007 The Sigma gets softer the wider the aperture. At f4 its soft, at f2.8 it's damned near blurry. It's all right at f8 or so. Return it, get the Tamron 28-75, which is a lot sharper at wide apertures. Link to comment Share on other sites More sharing options...
awindsor Posted February 26, 2007 Share Posted February 26, 2007 There is considerable sample variation in both. I know a guy who had both, compared them, and sold the Tamron. Nothing to separate his on IQ but the extra 4mm pushed him to the Sigma. I have tried a good sample of the Tamron and would be quite happy recommending that. The follow up shot does appear slightly soft. There are a two obvious possibilities: bad optics or bad focus. A number of people have complained about AF with this lens. Link to comment Share on other sites More sharing options...
shambrick007 Posted February 26, 2007 Share Posted February 26, 2007 You missed focused. The stiching on her sleves is in focus. Link to comment Share on other sites More sharing options...
sfdgs Posted February 26, 2007 Author Share Posted February 26, 2007 Thanks for your responses. I had the camera on a sturdy tripod and took 3 shots at each aperture from f2.8 through f11 and the ones posted here are the sharpest. I've taken approxiamtely 200 shots testing this lens and about 75-100 of them are marginally acceptable. I used the lens hood with no filter so I think it's in the lens I am going now to return this lens to the dealer and see what they can do for me. Thanks again- Jason Link to comment Share on other sites More sharing options...
sfdgs Posted February 26, 2007 Author Share Posted February 26, 2007 Sheldon- thats the another part of the problem. The focus point was set on her right eye which is why her face is on the top center of the frame. I checked the focus point in the zoombrowser program and it verified for me that it was on her eye. I read that this lens also has a problem with front and rear focusing. Maybe that's what this is? Link to comment Share on other sites More sharing options...
acurlee Posted February 26, 2007 Share Posted February 26, 2007 I am going through the same debate. The reviews I have read say both the Tamron and the Sigma were very soft at 2.8. I wanted to avoid spending $1200 on the Canon L lens, but I need a usable 2.8. I haven't purchased anything yet, so I can't speak from experience. But all the reviews have said you get what you pay for, and your test shots are in line with the samples in the reviews. here is one link: www.the-digital-picture.com Link to comment Share on other sites More sharing options...
sfdgs Posted February 26, 2007 Author Share Posted February 26, 2007 I returned the sigma 24-70 and got the canon 24-70. I didn't want to spend the extra money, but I can say that after taking 20 shots with it, it definitely appears to be worth it. I briefly thought about the tamron but I still use my eos 3 quite a bit so I didn't want to by a digital only lens. I appreciate your input. Maybe the sigma I got my hands on was just a bad copy, but its hard to spend that money if the pics look like i just drank a couple pots of coffee. Link to comment Share on other sites More sharing options...
sfdgs Posted February 26, 2007 Author Share Posted February 26, 2007 P.S.--- I did buy another sigma too. the 105 2.8 macro. i won't have much time to use it til the weekend, but i've read that it is good for a sigma Link to comment Share on other sites More sharing options...
steve_dunn2 Posted February 26, 2007 Share Posted February 26, 2007 <cite>The focus point was set on her right eye which is why her face is on the top center of the frame. I checked the focus point in the zoombrowser program and it verified for me that it was on her eye.</cite> <p>I don't know for sure about your Rebel XT, but for at least many EOS bodies (including my 20D), the AF points are significantly larger than the indications in the viewfinder - up to about 3x the size. So you may <em>think</em> you focused on her eye, but you might actually have focused on anything nearby. Or it may be an issue of focus calibration. Or perhaps she didn't stand absolutely perfectly still; if she rocked back and forth slightly, whether intentionally or not, she could move outside of the relatively shallow DOF.</p> <p>If you want to do a solid test of the lens, make sure both the lens <em>and the subject</em> are stationary, which rules out a lot of potential subject such as humans, other animals, or anything that might be moved around by wind.</p> Link to comment Share on other sites More sharing options...
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