IS question...

[cosiecki]

I was planning my dream lens list the other day (dont't laugh, you all do it too :) ) and I thought I had an epiphany that would save me over $1000. In my list I had both the 70-200 f2.8L IS and the 100-400L IS. Then it hit me that I could just get a 2x TC and that would cover my 400mm range and I would be set. A few hundred dollars instead of $1500 or so. Then I got to thinking.... hmm, "is the IS system "tuned" for a certain focal length?" If you put a 2x TC on a 70-200 IS, do you cut the effectiveness of the IS in half? If so, does it then perform worse than the "native" IS on the 100-400? Does anyone have any experience with this situation. I am years from affording either, so I am not even in the market yet, but I thought it might be an interesting question to ponder.

-Chris

[robertwgross]

A 2x teleconverter is going to do a couple of things:
(A) cause a loss of two stops of light
(B) cause a small amount of fuzziness of the resulting image

If that is the only way to get there, then so be it. For some purposes, the loss of two stops is significant.

It has been said before that if you start with a really sharp lens and put a really sharp 1.4x teleconverter on it, you won't see much image degradation. If you put the sharp 2x teleconverter on it instead, you'll see more degradation. Instead, if you start with a non-sharp lens, things turn to mush a lot quicker. Still, that might possibly be better than nothing, but don't expect a lot.

If I.S. works inside a given lens, then it is going to work similarly when working with a teleconverter in tandem.

---Bob Gross---

[DocFrankenstein]

This is what I'm wondering about too...

When it's f/2.8 with 2x converter, it's only 4.6 at the long end...

And 100-400 is 6.3, right?

So if you're not a pixel peeper, then it may save him some $$

[robertwgross]

This is what I'm wondering about too...

When it's f/2.8 with 2x converter, it's only 4.6 at the long end...

And 100-400 is 6.3, right?

So if you're not a pixel peeper, then it may save him some $$

Let's get a fact on the table. A constant f/2.8 lens, coupled with a 2x teleconverter, gives you a constant f/5.6.

The long end of the 100-400 is f/6.3 (which is very little beyond f/5.6).

In my opinion, the 100-400 image at 400mm will be sharper than the long end of the 70-200 with a 2x teleconverter.

---Bob Gross---

[cosiecki]

Actually, the 100-400L IS is f5.6 on the long end. With the 2x TC the 70-200 would be f5.6 constant for the equivalent of 140-400. So, it would be a little darker on the short end, but that wasn't really the initial point. I was wondering if the IS in the 70-200 is "tuned" for 200mm and the IS in the 100-400 is "tuned" to 400mm. Do the gyros move the IS element more in the 100-400? Does the IS in the 70-200 not stabilize as well with the TC, since you are multiplying the magnification, but not the amount the IS element moves. With the combination of 2 stops darker and a less effective IS, are you really benefiting? Just thinking.

-Chris

[blackviolet]

you may also find that it hunts a lot more with the TC - potentially causing you to miss shots.

but i suppose it depends on your usage requirements. if i remember correctly, kennyg posted a very nice, and relatively sharp shot awhile back with the 2x TC

[robertwgross]

And 100-400 is 6.3, right?

Cosieki has a good point. Where did f/6.3 come from?

Mine is f/4 at the short end and f/5.6 at the long end. Maybe Doc's is different.

---Bob Gross---

[perfectpixel]

also I've heard that you lose quite a bit of sharpness with the 2XTC. Not so much with the 1.4XTC.

[Tapeman]

Most of the posts I have read here favor the 100-400 if most of your shooting is near the 400 end.

I have the 70-200 2.8L and use it with both the 1.4 & 2X Canon converters.(MKII)

Since I would not be without a 70-200mm and I have had excellent results with the extenders this is the combination I prefer.

A bonus is that carrying the extender(s) does not add much to your bag.

If you can afford it buy every lens Canon makes... Problem solved. :)

[darkdrakon]

I will also recomend the 70-200 with 1.4x you will have almost no dedrigation of the image with this combo.

[PacAce]

I was planning my dream lens list the other day (dont't laugh, you all do it too :) ) and I thought I had an epiphany that would save me over $1000. In my list I had both the 70-200 f2.8L IS and the 100-400L IS. Then it hit me that I could just get a 2x TC and that would cover my 400mm range and I would be set. A few hundred dollars instead of $1500 or so. Then I got to thinking.... hmm, "is the IS system "tuned" for a certain focal length?" If you put a 2x TC on a 70-200 IS, do you cut the effectiveness of the IS in half? If so, does it then perform worse than the "native" IS on the 100-400? Does anyone have any experience with this situation. I am years from affording either, so I am not even in the market yet, but I thought it might be an interesting question to ponder.

-Chris
The IS should work fine weather you use a TC or not. The IS works by the amount of motion detected by the lens and not the focal length it's working at.

Since this is just a dream list, why not just leave the 100-400L in the list. Who knows, you may become independently wealthy some day. :D

[cosiecki]

Actually, since I will be moving close to a zoo, I think the next lens I will buy, after my 17-85 next month, will be the 100-400L IS. Lots of reach to get to the animals. Then of course I will need a fast wide angle (Sigma 20 f1.8) for my night photos. Then a super-wide, maybe the 10-22. By that time, my poor DRebel may need upgrading... Gosh, it never ends does it ;)

[CyberDyneSystems]

The 2X won't hurt the effect of the IS.

The 2X WILL hurt your image quality signifocantly.