EF 100-400mm f/4.5-5.6 L IS USM Lens with Teleconverter

I have a 5D as well as the 100-400 lens. Trying to get wildlife photos, I find that I could use more reach. I was wondering if any of you had experience with teleconverters on the Canon 100-400 lens. I have been looking at the Canon EF 1.4xII and the EF 2xII. I realize that I would loose AF with the 2x and that both magnify the imperfections of the lens. I have a friend who has the 1.4x that she uses on her 20D. She doesn't like the loss of quality, but I wonder if that doesn't have something to do with the combination yielding an effective magnification of 2.24x (1.4 for the teleconverter and 1.6 for the smaller senser). I would presume that the effects would be comparable with film as with the 5D as they areas are the same. Any help would be greatly appreciated.

Hi Fred,
I recently tried the 100-400 with the 1.4x...the image quality is good, but not exceptional, and you really need to stop down 0.7 - 1 stop to gain some sharpness.

Regarding AF: it is impossible to AF at f/11 (100-400+2x)with any Canon camera. You can AF at f/8 (100-400+1.4x) with the 1 series cameras, and with other Canon if you tape the pins.

The trick of taped pins consists in placing a piece of tape on the first three pins of the converter (more info:http://www.fredmiranda.com/TipsPage/). It works only with some combinations: for example, it usually works well with 100-400 + 1.4x, but it doesn't work with my 600 f4 + 2x , nor with the 300 f/4 + 2x, as Ian reported.

I have the 100-400 and the 1.4 TC. I find that the sharpness is OK with this combo if stopped down as Juza indicates. However, it is not the best combination. On my 10D the AF doesn't work without taping the pins and with my 1DMK2 the AF is OK but no where near as fast as the 1.4 TC with my 500 f4. I find the versitility of the 100-400 is great. I like the images from it as a stand alone lens. However, I try not to use the 1.4 TC with it unless it is all I have available and need the larger image size. I believe the 1.4 TC with the 100-400 is better than achieving the image size by cropping. If you crop the image you have less pixles. The 1.4 TC, while not perfect, is still giving you more pixles to work with than a 50% crop.

So let me get this straight. According to Fred Miranda you can use either the 1.4x or 2x canon converter on say 100-400IS mounted on a 10D or 20D and achive full auto focus as long as the 3 pins are taped?

I wonder how sharp and responsive it will work if the camera is mounted on a tripod?

Martin

Martin, AF with the pins taped is only witht he center spot. It is also significantly slower. I actually used it on manual focus with the shutter 1/2 way down and confirming focus when the spot blinks and beeps. For me this was actually faster than depending on AF. Of course there are times when only AF will do, but as said it is slower.

Regarding AF: it is impossible to AF at f/11 (100-400+2x)with any Canon camera. You can AF at f/8 (100-400+1.4x) with the 1 series cameras, and with other Canon if you tape the pins.

Actually, the 1 series cameras will try to AF at f/11. If I stack the 1.4x and 2x on my 600mm f/4 the 1D MII will attempt to AF. As long as there is enough light and contrast in the subject it will lock focus.

Thank all of you for your answers. However, I think my main point has been missed. My camera has a senser induced multiplier of 1.0. What I was trying to find out was if there was additional loss of image quality as a result of this multiplier in addition to loss from the 1.4x or 2x teleconverters. Or should I just bite the bullit and buy the teleconverter and see what I can see?

I realize that the ability of the AF to function properly is a function of the amount of light getting through to the AF electronics. I often have found that I have to manually focus this lens in low light conditions with no teleconverters. I guess I ask for that when I try to make an image with teh sun below the horizon.

I loved the image quality of the 100-400L on my EOS 10D, very sharp and contrasty. On my Canon 1Ds, image quality is okay, moving up to "pretty good" if I stop the lens down to f/8, and back off slightly in focal length to 380mm or so. My understanding is that this is due both to the larger numbers of small sensors, and because more of the less perfect glass around the edge of the lens is used on the full-frame camera. I hope that answers your question.

I have never been happy with the image quality of my 100-400L with a Canon 1.4x tc. The tape trick did work for me on my EOS 10D, but autofocus was slow and uncertain unless you were in bright light with the central AF sensor on a high-contrast edge.

I have been using my 100/400L with taped pins and 1.4TC with great success. Just stop down one stop from wide open and the images are very sharp.

example: http://homepage.mac.com/meckstein/post/rbgull.jpg

Thanks for your responses. Taking into account the loss of sharpness and the fact that there will be pictures that I otherwise would not be able to get, I will go ahead and get the 1.4X. Somehow, I believe that this will result in less loss of sharpness than cropping. Thanks Michael for your example.

As far as taping the pins, I think that I will hold off on that. I spent too many years using manual focus lenses for that to be a big problem.