EF 24-70mm F2.8L focusing problem

[pacificus_.]

<p >I recently purchased a Canon EF 24-70mm F2.8L USM lens but found the pictures taken using it to be poorly focused. This is my first L series lens; my main lens has been an old Canon 50mm 1.8, which cost around one twentieth of the lens in question but seems to produce pictures of better focus, or at least within the standard expected of an inexpensive lens. The 24-70, however, produces highly unsatisfactory pictures, which leaves me wondering why.</p>

<p >If the exposure is correct, and in the absence of camera shake, and providing the aperture is selected properly and the point of focus is well chosen, then shouldn’t the picture be of good quality if the equipment is functioning as it should?</p>

<p >I sent the 24-70 lens back to the vendor but have just been informed that Canon technicians have determined that it does focus properly. So I am left wondering what the cause of the poorly focused pictures is. I expected pin-sharp images from this expensive L-series lens and was very disappointed with the results. The camera is an EOS 5D Mark II. The first picture below is a resized full-frame image taken using the 24-70mm lens; the second is a full size crop showing the lack of sharpness. This particular image was shot at ISO 1250, F22 with an exposure of 1/160:</p>

<p > <br>

<img src="http://img697.imageshack.us/img697/7569/2resized.jpg" alt="" /> <br /> <br /> <img src="http://img196.imageshack.us/img196/3540/2fullsizecrop.jpg" alt="" /> <br /> <br /> If anyone is able to advise me on this issue before I either accept the lens back or request a refund instead, then I should be most grateful.</p>

[pacificus_.]

<p>The second image, the full size crop, has actually been resized by the forum software. The actual full size cropped image can be seen be following the link below:</p>

<p>http://img196.imageshack.us/img196/3540/2fullsizecrop.jpg</p>

[scott_ferris]

<p>Several things are going to make it a damn sight sharper.</p>

<p>f22 is not the place to be, try f8 for a start, you are well into the diffraction zone at f22. Second do the micro AF adjustment, use <a href="http://www.northlight-images.co.uk/article_pages/cameras/1ds3_af_micoadjustment.html">this method</a> it is very easy and quick and accurate. Third, are you tripod mounting this? If not then you will get far better resolution if you do. Why 1/60 and such high iso? Get the iso down to 400 too.</p>

<p>Hope this helps, Scott.</p>

[jeremy jackson]

<p>Hi there, I would say that your 50 1.8 lens will give better results at almost every apeture than your 24-70 2.8l. Mine does. Sorry to do this to you.</p>

<p>You should check the focus on the back of your camera with Live View. If it looks clean and in focus on the back of the camera, then the image should be in focus. JJ</p>

[alan_bryant1]

<p>Definitely retest at f/8. Diffraction is a real problem at f/22.</p>

[jeff_higdon]

<p>Your comment re the 24-70 is pretty common to new owners of this lens - particularly when the user is coming from the 50mm f/1.8. I had the same problem with the 28-70 and 24-70. They are large, heavy lenses. It just takes some getting used to. Try a faster shutter speed or, as suggested above, use a tripod or monopod until you get comfortable with the lens. The 24-70 is an excellent lens. I suspect it is camera shake you are encountering. Ultimately, though I was delighted with the shots I got handheld outdoors in the bright sun and anywhere on tripod, I just found the lens to be too heavy for me handheld. I moved on to the 24-105 with IS and did not look back.</p>

[pacificus_.]

<p >Thanks for the replies. </p>

<p > </p>

<p >I was wondering about the small aperture (F22) but was remembering what I was told – that the smaller the aperture the greater the depth of field. Perhaps not enough emphasis was given to this diffraction issue. </p>

<p > </p>

<p >Scott, you misread; it was 160^th of a second, not 60^th . But either speed should have been fine handheld (the lens was set to wide-angle). </p>

<p > </p>

<p >Am I really to expect better results with a £50 50mm lens than with a £1000 24-70mm L-series lens? If that is the case then what is the point in paying so much more for the L? Do the zoom lenses really sacrifice quality for the convenience of having a choice of focal lengths within a single lens? This is depressing, and I am left wondering whether or not I want them to send me this lens back. What should I buy to guarantee good quality? I wonder what the difference is between a non-L zoom and an L zoom of the same aperture and focal ranges. If the quality is no better then I may as well save a few hundred pounds. I can live without the red stripe! </p>

<p > <br>

When I started taking pictures I used an EOS 5 and almost exclusively used ISO 6400 film, so I was never really into pin sharp or highly resolved photography. But now, after spending thousands on equipment on my return to image taking, I at least want the tools to be capable of high quality.</p>

[sheldonnalos]

<p>The 24-70L is a great lens, but it's not going to beat out primes for sheer resolution. The reason it's expensive is because it combines the flexibility of a zoom, a constant aperture f/2.8 and excellent image quality.</p>

<p>Of course if you are looking at resolution per dollar spent the 50mm prime or any other prime represents a better "value". But when it comes to having a flexible tool that will work in most any photographic scenario, the 24-70 really shows why it's worth the money.</p>

<p>PS. There's no other lens like the 50mm f/1.8 in Canon's lineup so it's not really fair to use it as the benchmark. All the other primes are $300-400 or more, and you need 3-4 of them to cover the same range as the 24-70. And yes, the 24-70 is a much better lens than any of the non-L zooms that Canon makes, both a faster aperture and much better IQ.</p>

[paddler4]

<p>yes, all other things being equal primes are better, but this is a distraction here. That is a VERY good lens. I bought the Tamron 28-75 as a cheaper, good but less good, alternative, and I very sharp images. If Canon says the lens is functioning properly, then the problem is probably technique. Shoot a bunch of images of things with clear edges, at various distances. Things like gables work well for this. Use a tripod just for the sake of the test--or a very fast shutter speed--and an aperture in the range of f/8-11. If those are sharp, you have your answer.</p>

[zhesun]

<p>As far as i know, the advantage of 24-70 is the color and exquisite workmanship, not the sharpness.<br>

you can adjuest the sharpness of camera to make up for that</p>

[ken schwarz]

<p>Since you've already had Canon look it over, the lens is almost surely fine.</p>

<p>Try doing your testing at f/2.8 and set the zoom to 50mm focal length. Turn off AF and use Liveview to judge focus at 10x and then compare results of your 50/1.8 and your zoom. The results should be VERY close but I would expect the 50/1.8 to win. This is not because your zoom is bad, it is because the 50/1.8 is brilliant and is so simple that it doesn't have to cost a fortune. Sorry.</p>

<p>If your AF system and your manual focusing disagree, then you need to make some "micro-focus" adjustment for the lens. Check your 5D2 manual for details. It makes a big difference to have this correct!</p>

<p>Remember that when you view at 100% you are getting a lot of magnification. Even a smidgen of subject or camera movement will wreck sharpness when you view the picture this close up. The 1/focal length rule is not enough for such rigorous testing. If you are shooting at f/2.8 and have good light, try to use 1/500 sec and the lowest ISO setting that gives you reasonable exposure. Note, too, that ISO lower ISO settings will also help you get more sharpness, but if you keep it the same when comparing your zoom with the 50/1.8 it doesn't matter for your test.</p>

 

[lad_lueck]

<p>The other concern is appropriate sharpening (and other processing parameters). Check the following link for -completely- unsharpened RAW files, and how they look after sharpening for print. The difference is huge.<br>

<a href="http://home.earthlink.net/~ladlueck2/sharp2470.htm">http://home.earthlink.net/~ladlueck2/sharp2470.htm</a></p>

 

[craig_meddaugh]

<p>Did you do any research before buying this lens? You pay extra for the zoom range and the build, not the image quality. As others have mentioned, this is a typical issue.</p>

<p>Also, don't mindlessly shoot at f/22 and make sure you properly expose your images as the noise-reduction in the newer Canons makes for muddy images when you underexpose. You're example looks about 1.5 stops under... you can't trust your meter with white objects but as the proud owner of 4K in equipment you already knew that... right? </p>

<p> </p>