Tamron AF17-50mm F/2.8 Di-II LD Aspherical

[Kamal]

مقايسه MTF دو لنز تامرون 50-17 وكنون 55-17

[Hossein Nasiri]

با توجه به اينكه شرايط زيادي در تشكيل بوكه تاثير داره، آيا اين شرايط به صورت مقادير كمي در ريويو ها ارزيابي مي‌شن؟

اين لنز بوكه‌ي قشنگي داره. اما من نمي‌دونم كه لنزهاي مشابه در شرايط يكسان چه عملكردي از خودشون نشون مي‌دن؟

[arash1988]

با توجه به اينكه شرايط زيادي در تشكيل بوكه تاثير داره، آيا اين شرايط به صورت مقادير كمي در ريويو ها ارزيابي مي‌شن؟

اين لنز بوكه‌ي قشنگي داره. اما من نمي‌دونم كه لنزهاي مشابه در شرايط يكسان چه عملكردي از خودشون نشون مي‌دن؟

تا آنجا که من دیده ام معیار کمی برای سنجیدن کیفیت و زیبایی بوکه وجود ندارد و هر توضیحی هم هر جا دیده ام کیفی بوده است.

[MahBaz]

مقایسه tamron 17-50 f 2.8 و Tokina 16-50 f 2.8

http://www.kevinturcotte.net/?q=content/tamron-17-50-f28-vs-tokina-16-50-f28-test

البته قبلا در تاپیک توکینا 16-50 گذاشته بودم.

[Mashhadi Vahid]

سلام

رویوی نسخه لرزشگیردار در فتوزون:

http://www.photozone.de/canon-eos/482-tamron_1750_28vc_canon

دیستورشن در واید به طرز افتضاحی بالا است! حتی بیشتر از نسخه بدون لرزشگیر

Distortions
The AF 17-50mm f/2.8 SP XR VC produces a fairly strong degree of barrel distortion at 17mm (3.3%) - in fact this is a bit worse than the non-VC variant of the lens. At 24mm the problem is already very much reduced and no longer annoying. There're no relevant signs of distortion anymore at 35mm and 50mm.

Vignetting
The AF 17-50mm f/2.8 SP XR VC is a dedicated APS-C format lens and these lenses tend to produce comparatively high vignetting figures. The Tamron lens is no exception to the rule with a edge darkening of more than EV (f-stop) at f/2.8 at 17mm, 24mm and 50mm. Stopping down to f/4 resolves most of the problem although you may still spot a hint of vignetting at 17mm here.

MTF (resolution)
The lens showed a bit of a mixed resolution characteristic in the MTF lab. At 17mm the center performance is great straight from f/2.8 and the borders are also good at f/2.8 and very good beyond. However, the extreme corners remain rather unimpressive even stopped down. There's also a bit of a field curvature problem here. At longer focal lengths the center quality remains on a very high level but the borders are quite soft at f/2.8. Stopping down improves the performance at f/4 but it's better to go for f/5.6 here (unless you just need a sharp center of course). The generally very good maximum is reached at f/8 which is a bit "late" for such a large aperture lens.

Chromatic Aberrations (CAs)
Lateral Chromatic aberrations (color shadows at harsh contrast transitions) are very well controlled for such a lens. The "worst" figures were measured at 17mm (unsurprisingly) with a width of ~1.3px at the image borders at f/2.8 - this is already very acceptable and it's even less at smaller aperture settings here. The problem isn't overly field relevant at longer focal lengths.

Bokeh
We had a brief look at the quality of the bokeh (out-of-focus blur) at 50mm. The blur is generally very smooth both in the fore- and background. Bright out-of-focus highlights can produce an outlining effect at f/2.8 although the effect improves at f/4.

Verdict
The Tamron AF 17-50mm f/2.8 XR Di II LD Aspherical [IF] VC is a very promising lens based on its sheer specifications. However, it falls somewhat short of the high expectations especially when considering the excellent performance of its non-VC variant. The biggest weakness of the lens is the rather soft corner/border performance at large aperture settings. The quality increases when stopping down and it's certainly possible to achieve very high quality results from f/5.6 onwards (a bit of corner softness remains at 17mm). The level of distortions and vignetting is about average for a lens in this class. The good news is the unusually low degree of lateral CAs which increases the subjective quality perception at the image borders quite a bit. The quality of the bokeh is generally decent for a lens in this class.
The build quality of the lens is good although not professional grade (expectedly). The AF is very fast whereas the short focus path isn't exactly suitable for precise manual focusing. The primary new feature - the VC (vibration compensation) - works very well and its efficiency is easily comparable to Canon's native solution (IS). However, when considering all aspects here the Canon EF-S 17-55mm f/2.8 USM IS remains the lens to beat in this lens class.

پ.ن:
- ستاره های آخر رویو نیاز بسیار کم است, بخصوص در "کیفیت اپتیکی" که فقط 2 ستاره گرفته!
- نمونه عکسهای آخر رویو نیز با 7D است.
- فکر میکنم بهتر بود برای نسخه لرزشگیردار یک تاپیک مجزا باز میکردیم.

[Kamal]

مقايسه تامرون 17-50 با كنون 17-85
يك تست غير استاندارذ كه خودم انجام دادم نتيجه گيري با خودتون .

دوربين روي سه پايه خيلي محكم شده .قفل آينه فعال و لرزش گير دركنون خاموش

[Kamal]

سايت the-digital-pictureرويو نسخه جديد اين لنزو كامل كرده .
در مقايسه با نسخه قديمش يكم پس رفت كرده .

http://www.the-digital-picture.com/Reviews/ISO-12233-Sample-Crops.aspx?Lens=679&Camera=474&Sample=0&FLIComp=0&APIComp=0&LensComp=400&CameraComp=474&SampleComp=0&FLI=0&API=0

[Mashhadi Vahid]

سلام

بررسی نسخه لرزشگیر دار تامرون 50-17 در SLR Gear

http://www.slrgear.com/reviews/showproduct.php/product/1297/cat/23

Alternatives

Tamron 17-50mm ƒ/2.8 XR Di II LD Aspherical IF SP AF ~$400
The real question most people will be asking is how the new lens compares with the older version. In a nutshell, while the new lens provides vibration control functionality, the old lens provided better results for sharpness, resistance to chromatic aberration and corner shading; distortion is noticeably improved.

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Conclusion
Tamron seems to have had to make some sacrifices to add Vibration Control to its popular 17-50mm ƒ/2.8. It's not bad with regard to sharpness, just not as good as the non-VC version, leading potential buyers to decide how badly they need Vibration Control.

[khoddami]

من با خوندن پستهاي اين تاپيك به اين نتيجه رسيدم كه نسخي قديميش بهتر از نسخه جديدش هست ..چون قصد خريد دارم دوستاني كه تجربه كار با اين لنز رو دارن چه توصيه اي ميكنن..به نظر خودم با بودجه حدود 500 تومن براي دوربين من اين بهترين انتخاب هستش

[Herati]

من با خوندن پستهاي اين تاپيك به اين نتيجه رسيدم كه نسخي قديميش بهتر از نسخه جديدش هست ..چون قصد خريد دارم دوستاني كه تجربه كار با اين لنز رو دارن چه توصيه اي ميكنن..به نظر خودم با بودجه حدود 500 تومن براي دوربين من اين بهترين انتخاب هستش

اگر منظور تون canon 5D MKII است که این لنز برای سسنور های کراپ ساخته شده وبه درد کار شما نمی خوره