Soft Focus Issues / Lens Test

Discussion in 'Digital SLR' started by Robert R Kircher, Jr., Jun 20, 2005.

  1. So I was out the other day shooting and when I got home that afternoon I
    wasn't very unhappy with the results from my EF 28-135mm f/3.5-5.6 IS USM.
    Everything seemed too soft. This prompted me to go out the next day and do
    an unscientific test of all my lenses. The results can be seen here.
    http://www.pbase.com/rkircher/lens_test

    I shot this test using 3 of my lens in an effort to compare their
    performance.

    Lenses used:
    Canon EF-S 18-55mm f/3.5-5.6
    Canon EF 28-135mm f/3.5-5.6 IS USM
    Canon EF 100-400mm f/4.5-5.6L IS USM

    These images are shot at the minimum focal length of the lens used. Other
    then shutter speed I kept all other camera settings the same. The lenses
    were auto focused using the center focus point only. I took a series of
    pics with each lens all of which looked just about the same. The images
    were processed using Capture One where I applied the same amount of
    sharpening and adjusted exposure and contrast.

    The processed images look pretty good, however, you can see that the
    original images are all very soft. I'm concerned that the originals should
    be sharper and wondering if my camera needs adjusting. I keep reading post
    saying that the 18-55 is a fairly sharp lens but I wouldn't call my results
    sharp at all.

    Does this look like an issue with the camera? Is it something I'm doing? Or
    is this what I should expect from these lenses?

    I have to say that I've had little to no problems with the EF 100-400mm
    f/4.5-5.6L IS USM lens. But the 18-55 and the 28-135 seem way too soft.

    Any thoughts or comments would be appreciated.

    Thanks,
    Rob
     
    Robert R Kircher, Jr., Jun 20, 2005
    #1
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  2. Robert R Kircher, Jr.

    Craig Flory Guest

    What was your aperature ? If wide open, that could be your problem. For
    maxiumum sharpness, you do know to stop down to the optimum f-stop. For most
    lenses you should be stopping down to at least f8.0. For scenics like you
    have shown make sure you are using a tripod. Try stopping down to f11 or
    smaller aperature. The images you posted are not bad but could be even
    better on a tripod at f16. Experiment to see how the aperature effects your
    images.

    Craig Flory
     
    Craig Flory, Jun 20, 2005
    #2
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  3. They were all shot at F8.
     
    Robert R Kircher, Jr., Jun 20, 2005
    #3
  4. According to Canon (EOS Magazine March 2005), "Digital cameras do not take
    sharp images. This is nothing to do with focusing - it is caused by the
    interpolation of colour data". It follows that all digital images need some
    sharpening and this is more true of the EOS SLRs than digital compacts.
    In-camera sharpening is performed in the compacts. There are many, many
    articles on this subject and many different views about the best methods and
    optimum results. The end result required will depend on personal taste and
    the eventual output wanted (web, print, screen). For me, for example, your
    sharpened 18mm shot is a touch over-sharpened.

    Also, you can get the 300D to perform some of this if you take in JPEG
    format. In that format, you can set elements of in-camera sharpening as well
    as colour saturation.

    Mike Bernstein
     
    Mike Bernstein, Jun 20, 2005
    #4
  5. Now you got me puzzled...
    I downloaded one of your images at "original" size, and Photoshop reports it
    at 1014 x 676 pixels.
    My EOS10D images from the same CCD are ~3000 x 2000 pixels, and boy!, are
    they sharp when I use my EF 50 f1.4.

    Anyway, using my standard Unsharp Mask (200, 0.6,4), your image sharpens up
    nicely. In matters like this, I'd suggest getting a copy of the EF 50
    f1.8 - despite its poor build quality, it's very sharp, and easily acts as
    an affordable bench mark.
     
    Malcolm Stewart, Jun 20, 2005
    #5

  6. Malcolm,

    I appreciate the thoughts. I've down sized the image to conserve space on
    the website, however, the full size image is just as soft.

    As far as sharpening the images, I've been able to get all my images
    sharpened in post processing, my concern is if I'm getting the best possible
    image out of the camera to begin with. Maybe I am, I just don't know for
    sure.

    Rob
     
    Robert R Kircher, Jr., Jun 20, 2005
    #6
  7. I'm not an expert on this but, AFAIK if you save as RAW there is no
    sharpening done in camera, and you have to do all the work, but the results
    can be excellent.
    Alternatively, if you crank up the sharpness in camera prior to saving as a
    jpeg, your results will initially look better, but you may be stuffed if you
    want to do further work on the image, as it will already have the beginnings
    of sharpening halos.
    Personally, I mostly save as jpeg (neutral EOS10D parameters) but tend to
    use prime lenses all the time, and good prints to A3+ are easily made. I
    have a range of zooms, and used them much more with my EOS3 and Provia 100F.
    Affordable scanning seemed to make all my lenses look alike, and grain
    aliasing was the real problem!
     
    Malcolm Stewart, Jun 20, 2005
    #7
  8. Robert R Kircher, Jr.

    Roxy d'Urban Guest

    I think you may find this has something to do with the sensor being a CMOS
    and not a CCD. I read an article recently that explained the major
    differences between the two types of sensor and the gist of it suggests
    that CMOS sensors require a lot of in-camera processing to reduce the
    amount of noise they generate. Ironically a CCD is not as noisy in its raw
    state, but costs a lot more to manufacture than a CMOS sensor, which is
    why manufacturers have gone from CCD to CMOS.

    This probably explains why CMOS appears to be less noisy at higher ISO
    levels than a CCD, but it's a false reality, since most of the noise is
    removed by software, which will obviously have some kind of effect on
    optimum image sharpness.

    Don't shoot the messenger.
     
    Roxy d'Urban, Jun 21, 2005
    #8
  9. Robert R Kircher, Jr.

    Don Stauffer Guest

    I think it is easy to underestimate what even slight movement can make
    to sharpness, hence Robert's good suggestion to use tripod whenever
    possible. The higher resolution of digicams get, the more necessary
    tripods are.

    Also, it doesn't take much crud on lens front surface to affect
    sharpness of high contrast scenes.
     
    Don Stauffer, Jun 21, 2005
    #9
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