Lens sharpness

Discussion in 'Canon EOS' started by duncan_twentytwo, Oct 17, 2009.

  1. I use a Canon 50D but shortage of funds means the current lens I use is a Canon 18-55mm IS.
    Nothing wrong with the lens but I am considering replacing it with the 17-55mm 2.8 IS USM.
    I Know all the advantages such a replacement would give me like shooting in low light,fast focus etc but my main question is about the sharpness. If I was to compare a print from each of these lens taken under the same conditions would it be obvious which lens had taken which photograph.
    The inexpensive canon 18-55mm gives me fairly sharp pictures at close range but I find it poor for Landscape photography and this is what I would mainly use it for.
  2. I don't think you would see much difference, my opinion. The extra money for the 17-55 goes into maintaining similar image quality while offering a much more difficult to design f2.8 aperture lens.
    Wow, I just found out what they retail this lens for. Save a bit more and get the 16-35/2.8 L. You could even get a used one for the same price as the 17-55. My first inclination was for you to consider the 17-40/4 L which would save you a lot of money and provide far superior image quality, to the 17-55, especially for landscape photography. Another option in the used department is the 17-35/2.8 L. Check out keh.com for all the possibilities.
    If you are going to take landscape photography seriously enough to spend $1000 invest in a tripod instead of IS.
    My only other concern is that as you develop your photography is that a 17mm lens on a crop body may not be wide enough, since it only provides a moderately wide view equal to a 28mm lens on full frame. You could consider a third party lens like the Sigma 12-24 which will work on both crop and full frame bodies, unlike the Canon EF-S 10-22mm.
  3. I've not used the 18-55IS, but I can tell you my 17-55 2.8 IS is as sharp as any of my L zooms, maybe even sharper, including the 16-35L II for anything other than landscapes. For landscapes, my fav is still the 16-35L II.
  4. Duncan,
    i had 17-55 a while ago for my 30D and i tell you one thing - i only sold it because i went full frame and 1.3 and it didn't work on either of them cameras... this lens is really sharp; some people even say that it should be considered L series... comparing to 24-70 (the one that i had) it was sharper at any focal length up to f4 - 5.6; after that point they were equally sharp; i heard some good things about 18-55 IS too; people at photozone.de were surprised when testing this lens at how sharp actually it was...
    i'd second what was said before - the biggest difference is apperture, i'd say build quallity and of course price; there were some issues with distortions and vignetting on 18-55 comparing to 17-55...
    regarding 16-35 (which i also had) - it's different lens. even though i liked it (i got it mostly for 16mm- wide end, not for apperture) i wouldn't give it edge over 17-55. most of the time that i used it, it was stopped to f5.6 - so can't say anything about sharpness at higher appertures...
    if you use low appertures i wouldn't buy anything expensive for aps-c... you might want to go FF one day and such a lens is useless then...
    and the last thing just to answer your question - i don't think that if you shoot raw with f8 and tripod, convert to tiff, process in PS for colours, contrast, etc. you will see huge difference between the 2... so really if you need faster, constant apperture go for it - if you don't - save some money for some primes like the new 24mm f3.5L (tilt and shift one - it's amazing how sharp it is - some test and comparison on www.the-digital-picture.com) or 35mm L and then you'll see some difference...
  5. I'll second the comments about how your usage will affect relative sharpness. I've been very plesantly surprised about how good my 18-55mm IS lens performs.
    According to the Imatest numbers at Photozone.de, at f/8 the two lenses are very close in sharpness:
    18-55mm: http://www.photozone.de/canon-eos/181-canon-ef-s-18-55mm-f35-56-is-test-report--review?start=1
    17-55mm: http://www.photozone.de/canon-eos/178-canon-ef-s-17-55mm-f28-usm-is-test-report--review?start=1
    The cheaper lens does have more distortion at the short end of the scale (which I've personally noticed - but it hasn't bothered me), and the build quality is quite "plastic'ey" (but decently solid).
    Personally, unless you need to shoot wide-open alot, or if the distortion bothers your, I would stick with the kit lens for awhile.
  6. 17-55 is possibly the best general range zoom canon makes. i've never seen images from other canon zooms in this range that match those produced by 17-55. sharp wide open, barely sharper at optimum f stop(s). more vibrant image than many primes can manage.

    it's ridiculous to say L lenses produce (far) better images than the 17-55
  7. There is a whole range of factors that affect the quality of your photographs, and sharpness is one of them. There is a whole range of factors affecting the apparent sharpness of your photographs...
    ... and choice of lens is but one of them.
    If you are maximizing all of those other factors (camera stability, careful AF/manual focus, shutter speed, smart choices about aperture, careful post-processing regarding curves, sharpening methods) AND you make fairly large prints on a regular basis (let's say 12 x 18 or larger) and your photographs are still not sharp then switching lenses might make a difference.
    On the other hand, let's imagine that you are hand holding the camera and shooting somewhat quickly, that you don't do any particular post-processing work, you rely on in-camera sharpening, and that your final product is generally a jpg shared in email or online or perhaps you print small, no larger than letter size.
    If the latter, you are very unlikely to see any difference in sharpness by moving from the EFS 18-55mm IS lens to the (6x the cost?) 17-55mm f/2.8 IS. The latter really is a very fine lens, but in your context of "sharpness," there is much more to the issue than getting this lens.
  8. Aside from other issues, the EF-S 17-55 f/2.8 seems to be an "L" lens in all but name, certainly in price it is. For some reason Canon has decided not to term any EF-S lenses as being Ls, but it looks more and more like they are building some lenses to a higher build and optical standard. Perhaps they should call them D lenses for "De luxe" ;)
  9. If you plan on sticking with the 50D the 17-55 is the lens to have. I used to own it but like an earlier poster I sold it off when I went full frame. Prior to that I owned the first version of the 16-35 f/2.8 and other than build quality and a little red paint I saw no mearsurable difference in the quality of the images produced. In fact I'd give the nod to the 17-55 given that it has IS and the 16-35 doesn't. My keeper rate definetly went up when it came to handheld shots in low light. The 17-55 is a very sharp lens. It holds it value well too. From the time I purchased it new to the time I sold it I only saw a loss of $70. It is the only f/2.8 general purpose zoom that Canon makes with IS and it is a gem.
  10. There are many advantages to the 17-55 but the difference in sharpness would not be a huge one. The 18-55 IS is very sharp for a lens of this price.
    I suspect your unsatisfactory results on your landscape shots are due to another reason. Can you tell us how you typically shoot landscapes? Are you using a tripod? What settings are you typically using? Can you post some samples? It could be diffraction, too slow a shutter speed (leaves move in the slightest wind), camera movement, a host of possible issues.
  11. Why bother with digital. If sharpness is what you crave and landscapes are your primary pursuit, medium or large format photography beckons.
    That being said, you should probably grab the 17-40 and pocket the difference. The 17-55 is a great lens, but a bit over priced and the bigger aperture doesn't do much for you.
  12. If you are buying it mainly for landscapes then I may well prefer the 17-40 because it is very resistanct to flare which is much more noticable with the 17-55. I bought the 17-55 because I found the 17-40 too short at the top end for a walkabout lens.
    But with landscapes at f8 to f16 I don't think the difference between the 17-55 and the 18-55 will be huge. I would think very carefully about any shortfalls you have found with the 18-55 then try to should rent/borrow one (or at the every least use one in the shop) before you spend a whole lot of money on this.
  13. Many thanks for all your answers. Certainly given me something to think about.
    I do use a tripod but a very light one (Slik pro) simply because I do a lot of fell walking and lugging a heavy tripod about is out of the question.
    Unfortunately due to cost I am unlikely to ever move up to a full frame camera but from what has been said about the cost of the 17-55mm holding it's value so well I guess that if I sold it, I would lose little money and looking at old photo magazines the cost of this particular lens new has gone up !
    At one time you could get it for £675 but the cheapest I have found is Amazon at £735 !
  14. All this talk about sharpness and no one has yet to mention a prime lens. If you want sharpness for landscapes, get a 24mm prime. No this isn't super wide on an APS-C, but you can stitch 2 or more photos to get a wide shot. I prefer stitching to using a super wide lens anyways because IQ and sharpness is better for large prints.
    Bottom line: If you want a sharper lens get a prime, and yes you will be able to tell the difference.

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