EF 100-400L with a 2x teleconverter?

Does anyone use a 2x teleconverter at 400mm on this? What are the downsides and how do you overcome them?

tvphotog wrote in post #16486855
Does anyone use a 2x teleconverter at 400mm on this? What are the downsides and how do you overcome them?

Downsides are no autofocus and degraded image quality, plus being wide open at f/11 means you need quite a lot of light if you need high shutter speeds or you have to use high ISO.

This lens does not like teleconverters, or filters come to that, and even a 1.4x TC will show noticeable degradation in the image. I have the 100-400L and also 1.4x and 2x TCs, I only ever tried them on the lens once and wasn't happy with the results.

How to overcome them? There isn't much you can do about the IQ issue, taping the pins might get you some sort of AF, but even if it "works" it will be slow, inaccurate and prone to hunting. F/11 makes the viewfinder quite dark, so manual focusing isn't always easy.

sandpiper wrote in post #16486871
Downsides are no autofocus and degraded image quality, plus being wide open at f/11 means you need quite a lot of light if you need high shutter speeds or you have to use high ISO.

This lens does not like teleconverters, or filters come to that, and even a 1.4x TC will show noticeable degradation in the image. I have the 100-400L and also 1.4x and 2x TCs, I only ever tried them on the lens once and wasn't happy with the results.

How to overcome them? There isn't much you can do about the IQ issue, taping the pins might get you some sort of AF, but even if it "works" it will be slow, inaccurate and prone to hunting. F/11 makes the viewfinder quite dark, so manual focusing isn't always easy.

Thanks.

I wouldn't spend money on a 2xTC for an F5.6 lens. If you already have one, it's worth a try, I guess.

jefzor wrote in post #16487629
I wouldn't spend money on a 2xTC for an F5.6 lens. If you already have one, it's worth a try, I guess.

I bought a 2xIII for my 100-400 to use at 800mm, f/11, and have no regrets. Of course, I am very experienced and very good at manual focus. If you can't manually focus, you won't like the results except for the rare time when you're accidentally in focus.

The dark viewfinder relative to ambient light is a little challenging, but not a major obstacle most of the time. If it's too dark to see, just take it off and accept the pixelation from cropping. Same if you need AF for BIFs. For any situation in which manual focusing is practical, you'll get better potential results with a quality TC like the 2xIII than with cropping.

Whenever this topic comes up, people talk about degradation of IQ. That's true, but irrelevant, if your usage of the TC is mainly for the very realistic goal of spreading your subject over more pixels in focal-length-limited situations. Some people seem to think that a TC only achieves its purpose if you can get an image just as sharp by shooting 1.4x or 2x as far away, and they deem the TC a failure because of their unrealistic expectations. I don't use TCs for simulating longer lenses of the same quality; I use them to tap every bit of detail my lens can deliver, when I would otherwise be cropping without it. I usually use the same shutter speed, and same physical aperture as I would without it, or something close, and I still think that there is a benefit in using it. You don't have to increase the shutter speed, but if you can, that's great. Increasing the ISO because of the so-called "light loss" (it is not really any loss of total subject light, but just a loss of light per unit of sensor area) does not increase noise of the subject; only of the full frame. Noise has just as much to do with cropping as it does with ISO.

Sometimes using Kenko 2X and 100-400L...gives me AF(one focuspoint). Downgraded IQ but still useable pics with 800mm!

I sometimes use a 1.4X TC with my 100-400, rarely use a 2X, and very rarely stacked TCs. I have Sigma TCs rather than Canon's so that may make a little difference. Here are a couple of images, first one without a TC and the other with a 2X, both taken with a 7D and 100-400 on a tripod with remote shutter release.

bob_r wrote in post #16488657
I sometimes use a 1.4X TC with my 100-400, rarely use a 2X, and very rarely stacked TCs. I have Sigma TCs rather than Canon's so that may make a little difference. Here are a couple of images, first one without a TC and the other with a 2X, both taken with a 7D and 100-400 on a tripod with remote shutter release.

If that's a 100% crop, looks very good to me.

tvphotog wrote in post #16488901
If that's a 100% crop, looks very good to me.

It's SOOC and was not cropped. Here's a shot of a hummingbird feeder shot with the same setup as listed above and taken from 41 feet. It was not cropped or processed other than to reduce the file size. The second image is a 100% crop of the previous image.

tvphotog wrote in post #16488901
If that's a 100% crop, looks very good to me.

Nothing to complain about with those images.
What was the focussing like?
Exactly which model TC did you use?

Thanks Mark

tvphotog wrote in post #16486855
Does anyone use a 2x teleconverter at 400mm on this? What are the downsides and how do you overcome them?

crap AF and IQ. don't use 2x TC or 1.4 TC.

unistudent1962 wrote in post #16489190
Nothing to complain about with those images.
What was the focussing like?
Exactly which model TC did you use?

Thanks Mark

Mark, my Sigma TCs read APO TELE CONVERTER 2X (OR 1.4x) EX DG. I didn''t have a problem using manual focus with the TCs, but that's what I used for my first 45 years in photography, so I was used to it.

If anyone is interested in seeing a shot taken with the 100-400 and the 1.4X, this shot of a hummer was taken with a 30D, 100-400+1.4X, 580EX flash and a Better Beamer flash extender.
The shot of the egret was taken with a 30D, 100-400, Sigma 1.4X and 2X stacked TCs. The egret was way out in the middle of Reelfoot lake when I took this.

I never take the 1.4 TC off My 100-400.

The 2x, like any TC, has advantages and disadvantages. You won't get as many "keepers" but you may get nice shots because of the extra reach. Good technique can improve your results, but a bare lens of the same focal length will almost always have much better IQ.

For me the two best reasons to use TCs are; Cost and size.

I am never without my TCs and very often have the 1.4x mounted to my 500. (one of the lenses it pairs extremely well with)

Tapeman wrote in post #16489959
The 2x, like any TC, has advantages and disadvantages.

IMO, the only real disadvantages of a quality TC are:

• Darker viewfinder - harder to find subject and/or manually focus.
  
  
• Loss of AF or speed or accuracy.
  
  
• Possible power loss to IS from extra connections (my 50D could not handle my 100-400 with two Kenko Pro 300 DG 1.4xes stacked, and made a straight angular blur in about half the shots).
  

Of course a bare lens with the same focal length and f-stop would likely be better, but why would that be the standard for TC use? That is very unrealistic, and not what a TC is really for. The TC puts the subject over more film grains, and now, over more pixels. The more you magnify a lens, the softer it gets at the absolute level at the focal plane, but that does not mean that there is any loss of detail or information in the narrower FOV captured. What you are losing is aliasing artifacts, and the influence of the AA filter relative to subject size.

By that I assume that you mean that it behaves much as you would expect a standalone 700mm f/5.6 lens to behave on your camera, which is a desirable thing, but I certainly would not let that be the only standard by which I would decide whether or not to use a TC.