tthomsen's reviews

  • Sony 16-80mm f/3.5-4.5 DT Carl Zeiss Vario-Sonnar T* SAL-1680Z

    8 out of 10 points and recommended
    Very high center resolution, very good performance at 80mm and wide open, Very good color reproduction and contras
    Noticeable loss of corner resolution at some large aperture settings, Noticeable chromatic aberration in the corners at 16mm

    My copy has on the Sony DSLR-A300 a center resolution of well above 2000 LPH and corner resolution is typically between 1500 to 1700 LPH, measured in the range of biggest aperture down to f8. One special observation is the very good telephoto performance at 80mm at the wides aperture of f4.5: 2200 center, 1700 corner. The one negative exception is at 50mm and f4.5, where the LPH value falls to 1950 center and 1200 corner. Consequently, center resolution is exceptional, corner resolution is mostly tolerable, with 50mm/f4.5 unsatisfactorily. Here are the focal length/aperture settings that I typically use for my copy:
    16mm: f4.5 - f16
    24mm: f5.0 - f16
    35mm: f5.0 - f16
    50mm: f5.6 - f16
    80mm: f4.5 - f16

    Chromatic aberration is noticeable in the corners at 16mm, becomes less visible at higher focal lengths and disappears towards the center. I did not notice any distortion, vignetting or flare that is worth mentioning. Color and contrast are natural and quite attractive. Build-quality is acceptable for amateur-use. Focusing is fast and accurate, even at low-light conditions. The minimum focal length of 16mm saves an additional wide angle lens.

    One practical note: Use low-profile or slim-line filters with this lens, otherwise you will have vignetting at wide angles.

    Overall the lens is quite usable through its entire focal length, when you keep a few large aperture values in mind that you might want to avoid because of noticeable corner blur. I use the lens for about 90% of my photos and can currently not think of a better lens that has the same combination of versatility and image quality.

    reviewed December 24th, 2008 (purchased for $690)

  • Sigma 30mm f/1.4 EX DC HSM

    7 out of 10 points and recommended
    Very high center resolution, very good color reproduction and contrast
    Noticeable loss of corner resolution at f2.0 and larger, noticeable chromatic aberration in the corners at all apertures

    My copy has on the Sony DSLR-A300 a center resolution of more than 2100 LPH from f1.4 to f8.0. The corner resolution starts at around 1400 LPH at f1.4 and is going up to 1600 LPH at f8.0. When compared to the very good Sony Carl Zeiss Vario-Sonnar T* DT 16-80mm f/3.5-4.5, the Sigma is slightly better at 30mm/f4.5, but not really that much.

    Where the lens shows mediocre performance is in chromatic aberration. It is not noticeable in the center, but is noticeable in the corners throughout the complete aperture range. I did not notice any distortion, vignetting or flare that is worth mentioning. Color and contrast are natural and quite attractive. Out-of-focus blur is, for my taste, very nice. Build-quality is excellent. Focusing is fast and accurate, even at large apertures and low-light conditions.

    My first copy was actually defective, i.e. had unacceptable optical performance. Sigma acknowledged the technical defect. Since I bought the lens abroad, they required a proof that the lens was legally imported. Only then they exchanged the lens.

    One practical note: The Sony DSLR-A300 does not choose aperture values lower than f2.0 in "Program" or "Auto" modes. If you want to use them, you have to switch to "Aperture" or "Manual" modes and set those values manually.

    I bought this lens as a complement to my Sony Carl Zeiss Vario-Sonnar T* DT 16-80mm f/3.5-4.5 for low-light situations. The Sigma meets exactly this demand. The loss of corner resolution and the chromatic aberration in the corners are usually not that noticeable at wide-aperture shots, since those areas are usually out of focus anyways. As a result, the faults of this lens are acceptable for me. However, I would have expected a better performance in those areas from a prime lens with this price tag. Probably, Sigma put more effort into the excellent build quality than optical performance.

    reviewed December 24th, 2008 (purchased for $390)

  • Tamron 70-200mm f/2.8 Di LD IF Macro SP AF

    9 out of 10 points and recommended
    Very high center and corner resolution even at wide apertures, very good color reproduction and contrast, relative low price for the given optical performance
    Slow focusing speed

    My copy has on the Sony DSLR-A300 a center resolution of 2000 to 2300 LPH and corner resolution is typically between 1900 to 2200 LPH, measured for apertures from f2.8 up to f8. One exception from this is the 200mm focal length, where corner resolution is between 1800 to 1900 LPH. Those values are quite impressive, particularly the very high corner resolution. Such little fall-off of corner resolution as compared to the very high center resultion shows the optical excellence of this lens. I use the lens from its lowest aperture of f2.8 up to f11 at all focal lengths.

    Slight chromatic aberration is noticeable in the corners at the two focal length extremes of 70mm and 200mm, but is almost unnoticeable at other focal lengths and disappears towards the center. I did not notice any distortion, vignetting or flare that is worth mentioning. Color and contrast are natural and quite attractive. Out-of-focus blur is, for my taste, very nice. Build-quality is acceptable for amateur-use. Focusing can be very slow, if the lens has to travel a long distance to find the focus, but has typically been very accurate. If you do sports photography, you need to pre-focus the lens to be ready in time.

    To increase the maximum focal length to 280mm, I use the Kenko 1.4x Teleplus Pro 300 teleconverter. Center resolution drops by about 200 to 300 LPH in the center and 300 to 400 LPH at the corners. Given the already high resolution of the lens without teleconverter, you still get photos of quite acceptable quality when using this teleconverter. Chromatic aberration appears to me very slightly increased in the corners, when directly comparing images. I do not notice deterioration of color, contrast, distortion or vignetting. Please note, that the actual aperture values are reduced by 1.4x, but the camera does not show this reduction on the display. For instance, if the camera shows an aperture of f2.8, you actually have an aperture of f4.0 when using the teleconverter. Exposure times are increased correspondingly.

    Overall the lens is absolutelly usable through its entire focal length, even at its highest aperture. The optical performance is just outstanding. Combined with the Kenko 1.4x Teleplus Pro 300 teleconverter, you can see a slight drop in image quality, which is expected, but the images are still very good and clearly outperform such lenses than the Tamron AF70-300mm F/4-5.6 Di LD Macro 1:2 or the Minolta AF 100-300 F4.5-5.6 APO, who cover this range without teleconverter.

    reviewed December 24th, 2008 (purchased for $699)

  • Tamron 70-300mm f/4-5.6 Di LD Macro 1:2 AF

    7 out of 10 points and recommended
    Very good value for it's price, Light and compact, good for traveling
    Strong purple fringing at high contrast edges

    My copy has on the Sony DSLR-A300 a center resolution of 1500 to 1800 LPH and corner resolution is typically between 1300 to 1600 LPH, measured in the range of biggest aperture down to F8. One special observation is the good telephoto performance at 300mm and the widest aperture of f5.6: 1650 center, 1550 corner. The worst wide-aperture image quality is at 180mm and f4.5, where the LPH values fall to 1450 center and 1300 corner. Consequently, center resolution is acceptable for a 10MP camera, and corner resolution is just tolerable, with 180mm/f4.5 unsatisfactorily. Here are the focal length/aperture settings that I typically use for my copy:
    70mm: f4.0 - f16
    100mm: f5.5 - f16
    135mm: f5.6 - f16
    180mm: f8.0 (only)
    300mm: f5.6 (only)

    Chromatic aberration is noticeable at the longer focal lengths and in the corners, but is no issue at shorter focal lengths and in the center. The big problem of my copy is strong purple fringing at high contrast edges. Just one other reviewer noted this in this forum, so I assume that this could be a specific problem of my copy. I did not notice any distortion, vignetting or flare that is worth mentioning. Build-quality is acceptable for amateur-use. Focusing is slow at times but always accurate and I noticed occasional hunting at low-light.

    Overall the lens is usable through its entire focal length, when you keep a few large aperture values in mind that you might want to avoid because of noticeable corner blur. The purple fringing can be quite disturbing in high-contrast photos and it cost quite an effort to alleviate the effect in Photoshop. However, what makes this lens still very attractive is its low weight and relatively small dimensions, making it a good choice for travellers. Given the very low price of this lens, the image quality is actually quite acceptable.

    reviewed December 24th, 2008 (purchased for $160)