Sharpest F-STOP in 24-105mm L lens

Discussion in 'Canon EOS' started by tony_black|1, Jan 24, 2010.

  1. Which f-stop is the sharpest in 24-105mm L lens? And do other zoom lenses of Canon have that incredible distortion also?
     
  2. Most users and reviews agree the lens is quite sharp at f/4 and improves only slightly when stopped down. The main improvement from stopping down is a reduction in vignetting.
    The 24-105 has an exceptional amount of distortion at 24mm. Most lenses have less, though I concede I have not tried them all, so I can't say for sure.
     
  3. "Incredible distortion?"
    I don't see it. I guess my copy is good. Can you give us a sample and tell us what camera your using? I have used my for 4 years on 7 different bodies and it performed flawlessly. No it's not the sharpest or the fastest but it's the BEST walk around lens on my full frame. But to answer your question, I have shot it from F8 to F11 for best quality. You must be doing something wrong or you have a bad copy. What are you comparing it to 135 f2? v/r Buffdr
     
  4. Lens design involves trade-offs. If you want a wide zoom range at an affordable price, you end up with a slow optic with distortion. If you're willing to settle for a smaller zoom range, speed and distortion go down. The ultimate in speed and lack of distortion would be a prime like the EF 24 1.4L USM II or 24 TS. But you give up the convenience of zooming.
    My experience is the barrel distortion of the 24-105 is typical for this range. The EF-S 15-85 is actually worse whereas the 24-70 and 17-55 are better. I recall my old EF 24-85 3.5-4.5 USM was about the same as the 24-105 in terms of distortion at the wide end.
    With that said, I find the 24-105L to be a perfect compromise: high sharpness wide open in a nice range for travel and walkaround. If distortion matters for an image, I'd reach for a prime or smaller ratio zoom. Besides, the barrel distortion is gone with 2 clicks in DPP, so no biggie unless you shoot film.
     
  5. I, also, am surprised that you mention "incredible distortion". This is at odds with most reviews of this lens, for instance look at www.slrgear.com/reviews for their excellent and detailed review of this lens. They seem to find that the lens is good at most fstops, tailing off slightly from f11.
     
  6. General rule of thumb is to go three F stops under or over the smallest and widest apertures available for the lens. For my 24-105L, I go F8 for the sharpest but F4 is also sharp.
     
  7. I don't see it. I guess my copy is good.​
    Some aspects of lens performance can vary from copy to copy. Distortion doesn’t. The 24~105 has a high level of barrel distortion at 24mm, but it is easily correctable in DPP with very little downside in practice. Same applies to the heavy vignetting wide open. The 24~105 is my standard zoom on my 5DII and I'm pretty happy with it. I have actually owned four copies – the first, very early, version replaced by Canon for "heavenly rays", which I never managed to provoke; the second given to my wife; the third given to my son; and the fourth bought as the kit lens with my 5DII and on the camera as I write. I have noticed no copy-to-copy variation among them. Sharpest results are, as you would expect, in the f/5.6 to f/8 range.
     
  8. I use a 30d and i also see a good deal of barrel distortion at 24, kind of sad for a lens so expensive, but it is tack sharp, so i live with it. If someone had mentioned to me that there was distortion, i would have assumed it just showed up on full frame cameras, but alas, the crop sensors are not immune. it's nothing that can't be fixed in photoshop, but it's obnoxious. i don't notice it unless there are straight horizontal lines at the very top or very bottom of the frame.
     
  9. Which f-stop is the sharpest in 24-105mm L lens? And do other zoom lenses of Canon have that incredible distortion also?
    The answer to the "sharpest aperture" question depends on whether you shoot crop or full frame and on how you define sharpest - do you mean the aperture at which somewhere in the frame (probably the center) the greatest measured sharpness can occur, or do you mean the aperture at which the image is on average sharpest across the frame.
    www.slrgear.com provides a useful way to visualize sharpness at various apertures and focal lengths via 3-D blur charts. Follow these links to versions for this lens of cropped sensor and full frame cameras. Every so often I run informal tests on my lenses so that I can better understand their performance characteristics. One set of tests I did on this lens showed that it produced very sharp results at f/8-f16, and fine results at other apertures. My shooting experience is that it is competitively sharp even at f/4
    The short answer is that the 24-105 is a fine performer for a zoom in terms of sharpness. It is as sharp as any other zoom that you might choose to cover the same focal length ranges. It is plenty sharp enough to produce photographs that can be printed at quite large sizes.
    All lenses have compromises of one sort or another. A prime may give you slightly better IQ and larger apertures, but it sacrifices versatility. A large aperture zoom may provide better low light performance and smaller DOF but it costs a lot more and is much bulkier and heavier. The pluses for the 24-105 include: excellent sharpness, relatively large focal length range, image stabilization, reasonably small size/weight. The minuses include: barrel distortion at the very wide end, vignetting wide open and especially at 24mm, and some limits to photographing active subjects in low light.
    The lens does vignette - like all lenses - but it is more noticeable at f/4 than on competing lenses. Vignetting can be a problem, neutral, or even regarded as a good thing - it depends on the shot and your intended outcome. If you need to shoot at f/4 at the wide and and don't want vignetting, fortunately it is very easy and quick to fix it in post.
    The lens - again, like virtually all lenses - exhibits barrel/pincushion distortion. It exhibits noticeable barrel distortion at 24mm, especially when the subject includes straight lines near the edges of the frame. In most shots this isn't really visible or noticeable, but when it is and you don't want the effect you'll have to fix in post. Fortunately, this is quick, easy, and effective.
    (I posted a couple of examples of this in a thread at a different forum earlier today. They include an unprocessed version of a shot at 24mm with this lens that includes an architectural subject, along with a corrected version of the same shot.)
    Dan
     
  10. I find my copy of the 24-105 to be very sharp at f/4. This lens never seems to disappoint me under any conditions.
     
  11. I would love to see some samples of this lens at f4. Mine seems pretty soft compared to my 70-200 2.8 and primes. I keep considering either sending it in to Canon or just selling it.
     
  12. I shoot with the lens on a 5D. In my experience it has only two failings, both at 24mm, and those are the vignetting and the distortion. I have not found sharpness to be a problem at any focal length or aperture - my copy is very sharp.
    I don't generally shoot subjects where the distortion matters much, so that is usually not a problem for me. But no doubt on full frame it is pretty serious (photozone.de measured it at 4.3% - that's a lot). If distortion matters to you and you're unwilling/unable to fix it in post, this lens may not be a good choice.
    The vignetting is the only problem with the lens that bothers me, and I do avoid shooting at 24mm f/4. f/5.6 is significantly improved, but I use f/8 when I can. I realize "you can fix it in post" but that means severely underexposing the corners, which can make the noise go out of control, even shooting at low ISO.
    On the whole I'm very pleased with it. No lens does everything - this lens does a lot.
     
  13. The 24-105 lens is sharpest at f8 at all focals. In the 24-35 range, there isn't much of a difference between f4 and f8, while in the 70-105 range, that difference is significant. See my Canon lens test results . FYI, I have recently repeated those tests on 1D2 mark III with a more recent version of Imatest, and the results were very consistent, for the better samples of that lens.
     
  14. As for distortion, no other 24mm lens that I have (including 24-70/2.8, 17-40/4, 24 TS-E, 24 TS-E II) is that bad. There are some numbers in my <a href = "http://terragalleria.com/blog/2009/11/11/canon-ef-24-1054-l-is-vs-24-702-8-l/">24-70/2.8 versus 24-105/4 comparison</a>.
     
  15. I get minimal distortion at 24mm on my 25-105mm. It's sharpest at f8.
     
  16. thank you all. But this lens is not have distortion at 24mm but also almost every focal lenght. I just switched to canon 5dmk ii from my mamiya rz67 so may be thats why i see this incredible distortion compared to mamiya lenses.
     
  17. you would not realize the distortion if you are shooting clouds or landscapes. but if you are shooting architecture or something which has vertical or horizantol lines you even realize the distortion on the viewfinder right away.
     
  18. david_henderson

    david_henderson www.photography001.com

    I really cannot understand Buffdr's post. The distortion at the wide end is obvious and significant. Sometimes correcting for costs you part of your frame. It is a considerable weakness. Try shooting at the ocean with supposedly level horizons.
     

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