Dear colleagues: I am planning the purchase of one or two Canon lenses and would greatly appreciate your feedback and opinions. 1. First I wish to purchase an all around lens and have heard good things in general about the new EF 24-105mm f/4L IS USM lens. This is the type of lens that is versatile and a good one to have if I can only bring one lens along with me. However, I have seen a few reports on the Internet about recalls and complaints about image flaws. 1.1 - What are your feelings about this new lens ? 2. I planned on having a longer telephoto zoom lens to carry with me and was impressed when I saw the EF 70-300mm F/4.5-5.6 DO IS USM lens for its very small size and weight. This is the type of lens that is easy to carry around because of its extremely compact size. It also has IS which is certainly a benefit. Despite the size advantage, I have heard from several different sources that image quality is lacking and some users have even returned this lens to Canon and exchanged for another model. According to some photographers I have spoken to the new EF 70-300mm f/4.5-5.6 IS USM is a better lens that offers much higher image quality despite the fact that it is a bit longer and heavier (but still much lighter than the L series lenses). The price is also nearly half of the DO lens. 2.1 - What are your opinions about these two lenses ? 2.2 - In case you had to choose a telephoto zoom and wanted one that was relatively small and lightweight, which one of these two lenses would you choose ? 3. For higher quality and improved telephoto range I have considered the L series lenses. The options include the EF 100-400mm f/4.5-5.6L IS USM zoom, the EF 70-200mm f/2.8L USM and the EF 70-200mm f/2.8L IS USM. 3.1 - Since one of the 70-200mm lens offers IS while the other doesn't, is there any reason that would make one choose the one without image stabilization ? 3.2 - The 100-400mm lens offers the obvious benefit of improved telephoto zoom range. However, the 70-200mm lenses could be fitted with the Extender EF 2x II to transform them into 140-400mm lenses. I've been told that in doing so the maximum aperture is reduced and I should be careful since the minimum aperture compatible with autofocus is f/5.6. 3.2.1 - Is this correct for this extender ? 3.2.2 - In this case what would be the resulting aperture from adding the 2x extender to the 70-200mm f/2.8 lenses ? 3.3 - The benefits of using the EF 100-400mm f/4.5-5.6L IS USM lens include the simplicity of working with just one lens (no extender) and the greater zoom range of 4x (100 to 400 mm). The major benefit of working with one of the 70-200mm f/2.8L lenses is the larger maximum aperture, even across the entire zoom range. The disadvantages include the need to work with one more piece (the extender) besides the lens and the reduced zoom range of 3x (140 to 400 mm). 3.3.1 - What are your feelings about the choices here ? Which is the best choice in your opinion ? 3.3.2 - In using the Extender EF 2x II, is the camera operation still automatic in terms of metering and autofocus (I am almost sure that autofocus is maintained but don't know if the camera compensates for the two f-stops that are claimed to be required when working with it. How does it work ? Please forgive me for the longer post but these are issues I felt were worth discussing not just to help me with my buying decisions but also to help others who may be experiencing the same problems and may have the same or similar questions. Thank you in advance for your help. Joseph --- Dr. Joseph Chamberlain Oral and Maxillofacial Surgery
