DeepDiscovery 0 Posted January 10, 2005 I have found a non USM 100mm macro lens that I am considering buying but wanted to hear opinions on this lens before making my final decision. How much slower is the focusing vs. the USM? Does this lens have full time manual focusing as many other Canon lenses? Any other thoughts? Thx for your help. Share this post Link to post Share on other sites
Giles 1 Posted January 10, 2005 It must be a lot cheaper if you are asking the question !!! I'd be interested in the answers too .. such as has anyone upgraded to USM because it is that much better ? Share this post Link to post Share on other sites
segal3 0 Posted January 10, 2005 Only USM lenses allow FTMF... ~Matt Segal Share this post Link to post Share on other sites
yahsemtough 0 Posted January 10, 2005 Because I am unable to switch the 100mm lens from MF to AF while housed the USM is a great feature allowing FTMF. I can't comment on the difference between it and the non-USM version but the USM version is a very fast lens. Share this post Link to post Share on other sites
bvanant 174 Posted January 11, 2005 Bill: The non-USM version is considerably slower than the USM version. It does not allow for FTMF. That being said, my non-USM version is (I think) slightly sharper than my USM version and also has "nicer" tonal gradation when shooting B&W above water. Underwater, I don't notice any perceptible optical differences but the focusing speed is indeed noticeable as is the noise, which can scare some of the more sheepish critters. Bill Share this post Link to post Share on other sites
DeepDiscovery 0 Posted January 12, 2005 Thanks for the responses. I noticed that Canon has two new extension tubes, 12mm and a 25mm. Anybody know anything about using these? What effect would they have on my 50mm macro in terms of working distance? Are they better than the dedicated life size converter? They are certainly less expensive and since there is no glass I'm assuming no degradation of picture quality? Or would I be better off just buying the 100mm macro? Share this post Link to post Share on other sites
bvanant 174 Posted January 14, 2005 The problem with extension tubes is that you can no longer focus at infinity so fish shots are out. A diopter might be a better choice, but if you know that you will only shoot tiny stuff get the extension tubes. I have a Kenko set that I use topside all the time for super macro stuff. Bill Share this post Link to post Share on other sites
