Focus Problem with 24-70L, I'm About to Return It! - Please HELP

[tdigi]

<p>I tried mine out and at 24mm its probably not its sharpest ( especially wide open ) but mine copy is sharper then the sample you provided. Stopped down it seems very sharp at 24. Note, My test was basically just taking some photos and seeing how they look so not a real scientific test.<br>

I have heard from a few people that this is not a really sharp lens on the wide end.</p>

[picturesque]

<p>Try Bob Atkins' article.</p>

<p><a href="http://www.photo.net/learn/focustest/">http://www.photo.net/learn/focustest/</a></p>

[tom_collins3]

<p>Thanks Nadine. Well here are the results of my test. It looks to me that the focus is dead on. What does everyone else think? The focus point on the chef guy (with red hair and mustache) was his right eye.</p><div></div>

[tom_collins3]

<p>24mm 100% crop</p><div></div>

[tom_collins3]

<p>70mm 33% crop (so you can still see the other lines)</p><div></div>

[tom_collins3]

<p>Chef guy 100% crop (focus on his right eye)</p><div></div>

[picturesque]

<p>I agree. Does not look like calibration is the issue. On to other things.</p>

[tom_collins3]

<p>I was REALLY hoping that was the issue, but I guess not :) I am really in a pickle here because tomorrow is the last day of the return policy to return the lens. I just need to make sure that this lens is right for me (whether or not it has been "right" for others), and I need to decide tonight! I have started using the "AF-ON" focus button that Robert Body recommended and I think I really like that technique (along with disabling the half-press shutter for focus). Maybe that will solve the problem! What would YOU do if you were in my shoes?</p>

[picturesque]

<p>The decision to make, given the timing, is whether to take the risk of keeping the lens with the idea that you can make things work with it vs. returning it period, with the possibility of wrestling with the issue again after more research and experimentation, perhaps with a rented 24-70mm, or deciding upon a different lens altogether.</p>

<p>The lens holds its value well, but of course, new is new. You will take a small hit if you sell it later, even if pristine.</p>

<p>Re the AF button--I agree, it can help, but I find it slower than the half press on the shutter button. Sometimes, it makes a difference, and it may not be the same for you.</p>

[tom_collins3]

<p>The fact that it holds it's value well is good to know. The only other lens I've even considered is the 17-55 2.8 especially due to the fact that I'm on a crop sensor body right now. Only downside with that is when I upgrade to the MK II. I just took a bunch more test shots, about to check them out. </p>

[picturesque]

<p>My opinion, Tom, is that unless you will be upgrading to the MkII within the next 2-4 months, I'd get the 17-55mm f2.8. The 24-70mm on a cropped sensor body is not ideal. With the 17-55mm f2.8, you enjoy that nice range NOW, and the resale on it is probably almost as good as the 24-70mm. Again--just my opinion.</p>

[tom_collins3]

<p>I probably won't be upgrading to the MkII in the next 2-4 months, but I suspect it won't be much after that either. I have 3 weddings this year that I'll be shooting on the 40D, but shortly after that I'll be upgrading to the MkII. Would you buy the 17-55 for 3 weddings knowing that after that, knowing that you'd be on the MkII? </p>

[picturesque]

<p>Perhaps not, but I might return the 24-70mm, rent the 17-55mm for the 3 weddings, and in the meantime, think about and experiment with the 24-70mm separately, or wait until I could experiment with it when I had the MkII in my hands.</p>

<p>What general purpose lens do you have now?</p>

[picturesque]

<p>I would also throw this out... Since the 24-70mm in hand seems to be a 'good' one, you might consider just keeping it til you have the MkII. This might seem riskier than just returning it and getting another one, but you have a known quantity now, and ordering another one later might bring you a lemon. Yet another thing to consider. I have to say that an associate of mine has a MkII and uses a 24-70mm with no apparent focus problems (other than the usual), and it is a nice range on a 1.3x crop body. For all you know, it might work better on the MkII.</p>

<p>I know--doesn't help... :^)</p>

[tom_collins3]

<p>My only general purpose lens (besides the in question 24-70) is the 18-55 3.5/5.6. So that's my problem, I really need either the 24-70 or 17-55 ASAP. I'm going to look for some 17-55 vs 24-70 posts because I'm sure there are some. </p>

[picturesque]

<p>I might also consider buying a used Tamron 17-50mm f2.8. It also holds its resale value well. As far as I know, the 17-55mm is almost as good as the 24-70mm as far as image quality is concerned. About the only negative I have heard is that the IS tends to go out.</p>

[ryan_s]

<p>Before you get rid of the lens, focusing/recomposing at wide focal lengths, especially if you put your subject far to the side of your frame will throw off the plane of focus. There's a nice graphic here: http://blog.duncandavidson.com/2008/09/focus-and-recompose-exposed.html. Have you tried composing your image and then using the nearest AF point to your subject to focus rather than the center AF point?</p>

[tom_collins3]

<p>Well I'm really leaning towards the 17-55 now. Thank you so much for all of your help and I'll let you know what I decide!</p>

[tom_collins3]

<p>Ryan, thanks for that article, that's very interesting and I suspect that may have been part of my problem. I did however return the 24-70 today (not because there was anything wrong with the lens) and opted to go for the 17-55 since I'm on a crop sensor 40D. I'll definitely keep this principle in mind, and try to get used to moving the AF point when I want to set the subject off-center. <br>

Nadine (and everyone else), thank you for all your help working through this issue and I'm glad I learned some new techniques because of it!</p>

[jim_krupnik]

<p>You will really like the 17-55 lens. It is a fantastic performer by any measure, and it's IS function is pretty close to magic. As others have mentioned, it's resale value is very good. Mine is five years old now, and it's used value is almost the same as what I paid for it new.</p>

<p>The only suggestion I would add is that you buy the factory hood, and use it all of the time. It not only keeps IQ at it's peak, but the hood is nearly bulletproof. It has saved my lens and two cameras from destruction twice already during face first falls on fully extended tripods (both times, a camera mounted 580EX broke in two or more chunks). They also protect the front element from dust, fingers, spray, bangs, and bumps better than any other option short of leaving the lens home on a shelf.</p>

<p>Here is an example of how well the IS performs on this lens on a 40D in very low light. The shot below was taken inside a TGIFridays in NJ on Dec 20, 2007 at 10:07 pm. Needless to say, it was coal dark outside, and extremely dim inside the bar. The shot was made hand held (elbows on the table top) with a 40D set to ISO 3200. The 17-55 lens was zoomed to 55 mm, and the camera set the exposure at 1/4 sec @ f/2.8. You can see that the woman I photographed was tapping her knuckles on the table, as her fist is blurred, but for a 1/4 second exposure at ISO 3200, there is an amazing amount of sharp detail in the image. The shot was converted to jpg in DPP a day later. The lighting was awful, as it was a mix of various artificial sources from neon signs, and dimmed tungsten bar lamps inside, and a variety of parking lot poles outside, but DPP made reasonable sense of it with a click on her white blouse. Anyway, the 17-55 is a great lens. I think you will be glad that you had trouble with your 24-70...<br>

<img src="http://farm3.static.flickr.com/2053/2142588250_5b2ba81727.jpg" alt="" width="500" height="333" /></p>

<p>Good luck with your new lens!</p>