I have a Canon 60D. About two years ago, I purchased a Tamron 18-270 lens for a" walk around" lens. I've always used only Canon lenses (e.g.., 17-40 f4 l, 70-200 f4 l, etc. ) But I found that when traveling with others, that it was a bit frustrating to always be changing lenses. So the Tamron seemed to be a good compromise. It's also easier to walk around with one lens in a camera bag than several lenses.
At this point, though, I'm rather disappointed with the overall sharpness of the Tamron lens as well as with chromatic aberration issues. I had more than a few images from the Badlands this summer that were unusable for those reasons.
So I've been able to acquire the Canon 24-105 f4 L lens at a good price. (That bridges the range I have with the 17-40 L lens and the 70-200 lens). But I'm not sure about recouping the long lens capability of the Tamron. The Canon 100-300 f4-5.6 L IS lens is quite appealing but it's also relatively expensive. It would duplicate much of the range that I have with the 70-200 lens.
OTOH, I could upgrade my 1.4 teleconverter to the series iii version to extend the range of the 70-200 lens (I have an old teleconverter the first version) and put the money towards the full-frame Canon EOS 6D. The full frame plus the newer version of the converter is somewhat, but not excessively more, than getting the 100-300 l lens.
So three possible options:
1) Keep the 60D and the 1.4 teleconverter I have and acquire the 100-300L lens (I doubt that I'd get too much for a trade in on the 70-200 f 4 l lens). Possibly add the 1.4 iii teleconverter if it's really superior to the original version.
2) Acquire the EOS 6D and add the 1.4 iii teleconverter to the 70-200 f4 L lens. It would be really nice to have the full-frame camera for wide angle shots. (Or just keep the teleconverter that I have as well as the 60D unless I got a good trade in for it).
There are some other variations. But if anyone has any suggestions for selecting between the alternative, I'd be grateful.
Is the 100-300 L lens that superior to the 70-200 with the 1.4 teleconverter?
Is the series iii 1.4 teleconverter really superior to the original version of the teleconverter. (I can't find any online comparisons.)
Is it worth the upgrade to a full-frame digital from the 60D. I'm not a professional by any means. But I do try to take my work as seriously as I can and as time allows.
Thanks for any feedback and for taking the time to read a long post.
Firstly I think you may mean the 70-300 L IS vs a 100-300 whatever and that 70-300 gets excellent reviews re AF speed & IQ so it's well worth considering. I also suspect it to be a better value than adding the 1.4 TC ver 3 to your non IS 70-200 L. The real question is what do you want the extra range for & which is more important, more range at the price of bigger & heavier, or a bit less by stopping at 300 mm. The 100-400 L IS is worth looking at if you don't think 300 will meet your future needs.