Help me select a lens, please!

[Richard Lane]

As kingb has pointed out, the f/4 lens with 2X extender wont AF on your camera. You would need the f/2.8 lens to be able to add the 2X and still keep the maximum aperture at f/5.6 to AF on your camera.

Initially you mentioned that you wanted to fill the gap between 50-105mm. For that the 85mm f/1.8 is great, but you also own the 100mm f/2.8 and they are pretty close in focal length, unless you need f/1.8. Now, it appears that you're looking at longer focal length's which is totally fine by the way. If you really need 300 or 400mm, then the 100-400mm is a good choice too which is more expensive, however you would save some money by not needing to purchase the extenders.

Another option is the "135mm f/2L" ($1000) that was mentioned earlier in this thread. It's a great lens with fast AF, that produces beautiful images. There's no IS, but I find that it's such a fast and lightweight lens that you generally have room to raise the shutter-speed, therefore IS becomes less important. The 135mm can handle the extenders, however it does take a a fairly big hit in IQ with the 2X extender. Generally speaking, it's a good rule to stop down 1/3 to 1 f-stop with the extenders if possible, to reduce the hit in IQ. Of course, the 2X on this lens only gets you to 270mm.

Acceptable with the 1.4X, if you stop down a bit:

http://www.the-digital-picture.com/R...mp=3&APIComp=3


Not that great with the 2X, also stopped down a bit:

http://www.the-digital-picture.com/Reviews/ISO-12233-Sample-Crops.aspx?Lens=108&Camera=453&Sample=0&FLI=4&API= 4&LensComp=687&CameraComp=453&SampleComp=0&FLIComp =6&APIComp=3


Another option is the "200mm f/2.8L II" ($800) which can also take the 1.4x or 2x extender. It seems to handle the extenders better than the 135mm. Since the 70-200mm f/4 can't accept the 2X on your camera, I will compare the 200mm f/2.8L II to the more expensive 70-200mm f/2.8L IS II with 1.4X and 2X.

Comparing 1.4X:

http://www.the-digital-picture.com/R...mp=6&APIComp=1


Comparing 2X:

http://www.the-digital-picture.com/R...mp=7&APIComp=1


Also, keep in mind that the extenders are not cheap, especially if you need two of them, so it's also important to think of what your most frequent focal length will be, and look at the extenders as a bonus.

It's going to be hard to find one lens that covers all of your criteria at that price. So, lets try and figure out what your primary use will be.

Rich