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http___fotozine.org__knjiga_vijesti_poglavlje_2008_list_9_element_808_4.xml
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Canon EF-S 55-250/4-5.6 IS Lens Review by Bob Atkins, July 2008 The EF-S 55-250IS is a relatively new lens designed to supplement the EF-S 18-55IS "Kit Lens" for the Digital Rebel line of DSLRs. the 55-250/4-5.6 IS uses Canon's new low cost IS system. Nevertheless, Canon claims up to 4 stops of additional stability, which is as good as (or even better than) lenses with Canon's traditional IS control. Canon suggests that sharp images can be obtained at shutter speeds as low as 1/15s. Like the image stabilized EF-S 18-55IS, the EF-S 55-250IS seems to be Canon's answer to low-cost DSLR bodies with stabilization built in, which are currently being offered by Sony, Pentax and Olympus. With those DSLR bodies a stabilized lens is not needed to make a stabilized system, thus potentially lowering lens cost. The EF-S 55-250IS has been designed to meet a low price by the extensive use of plastics - even the lens mount is plastic. However, the optics of the lens haven't been compromised too much, and in fact the 55-250IS uses a special element of ultra-low dispersion (UD) glass in order to minimize aberrations. The front of the lens rotates during focusing, which can be inconvenient when using a polarizer. The EF-S 55-250IS is designed for use only with small (APS-C) sensor Canon cameras introduced after the Digital Rebel. It will not physically mount on cameras with larger sensors (EOS 5D, EOS 1D(s) series) and it will not mount on early APS-C DSLRs such as the EOS It cannot be used with any Canon or 3rd party TC, nor can it be used with the original Canon extension tubes. Lens Performance Despite the relatively low cost and plastic construction, the EF-S 55-250/4-5.6IS is optically pretty good. Sharpness holds up all the way At maximum aperture there is quite noticeable vignetting and this shows up quite clearly if, for example, you're photographing flying birds against a blue sky. Stopping the lens down a stop or two minimizes the vignetting, but that's probably not something you really want to do if you're capturing action and want to keep the shutter speed up. Vignetting can be corrected using Canon's DPP RAW conversion software, in fact DPP can do it automatically during the conversion process. It can also be corrected in JPEGs by many image editors including Photoshop. The 55-250mm range covers a variety of applications from portraiture at the short end of the range to sports and wildlife work at the long end. In terms of angle of view, the 55-250IS is the equivalent of an 88-400mm lens on a full frame 35mm camera. When paired with the Canon EF-S 18-55mm f/3.5-5.6 IS, (compare prices) (review), you get two lenses, which cover the whole range from 18mm to 250mm (29mm to 400mm in full frame equivalent terms). In addition, both these lenses are small and light and when paired with a camera, such as the Canon Digital Rebel XSi (review), they make a very portable outfit. Overall, I can certainly recommend this lens if you're looking for a small, light, inexpensive telephoto lens for an APS-C DSLR. It doesn't have quite the reach of the 70/75-300 zooms, but it matches better with the EF-S 18-55IS kit lens, it's optically as good as or better then the non IS 75-300 zooms - plus it has IS! Alternatives There are several alternative lenses which cover a similar focal length range, but all are either significantly more expensive or lack The Canon EF 70-300mm f/4-5.6 IS USM, (compare prices) (review), is a better-built lens, has more telephoto reach, and can also be used on full frame cameras. It doesn't show the vignetting that the 55-250IS does, but it's about double the price. The Canon EF 75-300mm f/4-5.6 III USM, (compare prices), is cheaper and has a longer reach, but it lacks IS and I don't think it's as sharp since it lacks a UD element. The Sigma 70-300/4-5.6 APO Macro is interesting, it has 1:2 macro capability and has two SLD (super low dispersion) elements. However, it lacks stabilization, which can be very useful indeed for a handheld telephoto lens. Where to Buy The Canon EF-S 55-250mm f/4.0-5.6 IS, (compare prices), is available from amazon.com. It's normally in stock and overnight shipping is available. More Newcomers to the Canon line of DSLRs and lenses might like to take a look at an overview of the Canon EOS DSLR system. Technical Specifications Canon 55-250IS Example Images
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Canon EF-S 18-200mm f/3.5-5.6 IS [napisao Gand. 6 Rujna 2008.][vijest pročitana 494 puta] Canon je obogatio svoju seriju objektiva EF-S svestranim novim modelom: objektivom EF-S 18-200mm f/3.5-5.6 IS. Taj objektiv nudi ekvivalentnu žarišnu duljinu od 29 do 320 mm i zum od 11x, što znači da je sada moguće koristiti samo taj snažan i lagan objektiv, bez potrebe za nošenjem više objektiva na snimanje. Objektiv EF-S 18-200mm f/3.5-5.6 IS namijenjen je korištenju isključivo s fotoaparatima EOS s postoljem za objektiv EF-S, što obuhvaća nove fotoaparate EOS 50D, EOS 1000D i EOS 450D te starije modele. Visokokvalitetna optika EF-S 18-200mm f/3.5-5.6 IS odlikuje se konstrukcijom koja se sastoji od šesnaest elemenata i dvanaest grupa. Njima su obuhvaćene i UD i asferične leće koje minimiziraju kromatske aberacije te jamče oštre detalje na čitavoj slici i pri svakom stupnju uvećanja. Podrška za žarišnu udaljenost od svega 45 cm fotografima pruža neograničenu fleksibilnost pri kadriranju. Optički stabilizator slike s četiri položaja brzine zatvarač Canonov optički stabilizator slike s četiri položaja brzine zatvarača, osmišljen posebno za specifični raspon žarišnih udaljenosti ovog objektiva, pridonosi smanjenju zamućenja slike koje se ponekad pojavljuje kada se snima bez stalka ili pri manjim brzinama zatvarača. Automatsko prepoznavanje panoramskih snimki jamči učinkovite performanse pri praćenju objekata u pokretu. Osim toga, budući da se IS sustav nalazi u objektivu, rezultati su vidljivi u tražilu tijekom kadriranja. Bez popratnih slika i odbljesaka Zbog odbijanja svjetlosti sa senzora za sliku na digitalnim fotoaparatima mogu se pojaviti popratne slike i odbljesci. Da bi se to spriječilo, na objektivu EF-S 18-200mm f/3.5-5.6 IS koriste se optički elementi premazani Canonovim patentiranim premazima Super Spectra te se tako dobivaju oštre, nedeformirane slike s prirodnom ravnotežom boja.