Hi Tim.. I have been on the MM boards for awhile.. I am sure you may recognize my name from over there, or from sending things into MDP. I finally decided to register over here as well, and join the discussion as best I can. I teach digital photography classes as part of my job out here in Oregon. Yesterday I was teaching a class and had a question I just didn't have enough experience to answer. I am hoping you may have an opinion or anyone may have some resources so that I can steer this guy in the right direction. Here is his e-mail to me this morning: "Hi, We talked at the end of your photo presentation at the Homecoming Rally. I was wondering if you had any information you could share on a reliable independent source of lens testers. I am trying to determine if I should purchase a 1.4 or 2.0 tele-converter to extend the focal length of my lens, or should I purchase the lens at the required focal length without considering the tele-converters. Of course Canon's position is the lens and tele-converters are perfectly matched and there is no difference between image quality of a single lens or a matched lens and tele-converter. I have been looking for an independent study on the subject but have found nothing yet." So there you go.... any insight? When he came up to me after the class and asked the question, I immediately thought about you and wondered if you would have more experience in this arena than I do. Thanks for the help!
Calvin, I know that you meant this for Tim, but I would like to answer. Even Photozone hasn't compared the two officially as far as I can tell. But Bob Atkins did an basically non-scientific test here: http://photo.net/learn/optics/tc2/ In general, the consensus online that I have seen indicate that a single lens is superior than a shorter lens + TC. A strong reasoning for that includes the # of elements - a longer lens w/o a teleconverter usually has less elements. But I think that the majority of the time if you are shooting stopped down it won't be as apparent, unless you are using a full frame camera and pixel peeping. Plus the quality of the teleconverter is extremely important. I use Canon's 1.4TC almost all the time on my 70-200/2.8. Mostly because I want the reach, and I don't mind shooting at f/4. Granted, my next purchase is going to be: a) 100-400 L IS, b) 400/5.6L, c)300/4L IS The 300 would become an IS 420/5.6L, but if I got the 400, I would have the ability to go to 560/8. But no IS. But if you need a long lens at 2.8, you are just going to have to fork out the big bucks.
Thanks for the note rlongenbach. I really appreciate the input! Yes, I addressed this to Tim, since I really don't know any of the rest of the board... but by all means, I welcome feedback and posts from everyone on this!!!! So If you have an opinion, feel free to chime in! Thanks!
if I were to make this purchase, I would buy the lens at the length needed and forego the TC. I like to take as many variables out of the equation and keep it simple. Although canon claims no loss in quality with a lens + TC, you will lose one stop of light with a 1.4 and two stops with a 2.0. So in my opinion, you are adding stuff and losing light which is a bad combo. Stick with the lens itself..... IF you can afford it.
