fourg1b2006 Loc: Long Island New York

These images came out very well.

Mac49

I have only limited use with extenders and ur hasn’t been that good. Not much technical to say except u should expect to rely on manual focus frequently for best results. Regarding shooting thru windows: several thoughts (since I have done same). 1. Take screen off outside if you have one on. 2. Darker the room ur shooting from, the better to avoid reflections, so turn off lites, pull shades on other windows, etc. 3. Don’t use flash. Assume u already know that but just saying. 4. Polarizing filter help also if u still have some reflection.
At the end of the day, ur still at a slight disadvantage cause ur window is not photo quality glass but I’ve found the ideas above help reduce/eliminate reflections.

danniel Loc: North Port, Florida

Fabulous shots :) the clarity of those jays, and I can almost feel that cold air down here in Florida

imagemeister Loc: mid east Florida

IMO, the best case scenario for extenders is on a Full frame body with a lower MP count.....in other words, where you absolutely NEED the focal length and have the better ISO performance to mitigate the light loss.

CanonTom Loc: Birmingham

If those shots are through a window, you are a fabulous photographer!

stenojj

All 3 shots are through a "clean" window. I'd have so much camera shake if I had to be outside in the cold so I really don't have a choice. What really helps is I use my tripod, back button focus, and then have my wired remote in my other hand. Seems to work for me. I just wasn't sure if an extender would be of benefit. Thanks!

CHG_CANON Loc: the Windy City

Since the question was about the 100-400L II and the 1.4x, here's a variety of images (close and far) that show the detailed captures this configuration can capture with a camera that supports AF at f/8. They're presented large so you can easily see the details ... If you're curious about the focal length and aperture, click the URL where the details for every image is available. If too large for your screen, they'll resize to your local display if you click the URL title for each image.

White-naped crane by Paul Sager, on Flickr
http://farm5.staticflickr.com/4523/38094289236_efac126e36_h.jpg

Black-tailed Prairie Dog by Paul Sager, on Flickr
http://farm5.staticflickr.com/4509/38149564831_6b7dcc4da6_h.jpg

Snowy Egret by Paul Sager, on Flickr
http://farm5.staticflickr.com/4506/26327681109_5627f55b5e_h.jpg

Lion by Paul Sager, on Flickr
http://farm5.staticflickr.com/4490/37440101804_5896549413_h.jpg

Black-tailed Prairie Dog by Paul Sager, on Flickr
http://farm5.staticflickr.com/4485/38050892456_6e22d07076_h.jpg

Nyala by Paul Sager, on Flickr
http://farm5.staticflickr.com/4473/38050879426_fa991b7eea_h.jpg

stenojj

All I can say is "WOW!"

Jim Bob

Exquisite!

CHG_CANON Loc: the Windy City

Larry - I didn't realize your recent exercise using KENKO was intended to disparage Canon's extenders!!! They're so unlike in the results, it's embarrassing to say the KENKO equipment can even be attached to Canon equipment...

Here's a small selection all with the Canon 2.0 III and a medium MP Canon EOS 5DIII (full-frame 22MP). They're presented large so you can easily see the details ... If you're curious about the focal length, apertures, and lenses used, click the URL where the details for every image is available. If too large for your screen, they'll resize to your local display if you click the URL title for each image.

Sahar by Paul Sager, on Flickr
http://farm2.staticflickr.com/1473/25945006332_8e5ed4b932_h.jpg

B-25 & P-51 by Paul Sager, on Flickr
http://farm6.staticflickr.com/5086/29540227614_707bf90946_h.jpg

P-51 Mustang - Baby Duck by Paul Sager, on Flickr
http://farm9.staticflickr.com/8548/29540229354_218f986971_h.jpg

Red-tail guenon by Paul Sager, on Flickr
http://farm8.staticflickr.com/7591/27129225855_8303dfd2d5_h.jpg

Susan Dacy in Big Red by Paul Sager, on Flickr
http://farm5.staticflickr.com/4400/36687403241_02f6929a1a_h.jpg

CanonTom Loc: Birmingham

Terrific photos Paul!

CHG_CANON Loc: the Windy City

stenojj - shooting through a window can be a challenge. The various "extended" examples I've posted this morning, both from the 100-400L II zoom and a few others from primes, they're all from mostly well-lit sunny situations and no windows, screens or cages. They're captured in RAW and processed to the best of my abilities & software to harvest the potential of the image as captured by the camera. Other words: they didn't come straight out the camera this way ...

You mention using a tripod and BBF in your configuration. Assuming you have AI Servo as your focus drive mode, I'd suggest too using a single focus point if you're not using this configuration already. Assure that AF point is set directly on the eye of the nearest animal in the composition, if possible. As much as I've tried to demonstrate the potential results from either of Canon's ver III extender models, the native lenses without the extenders will still perform better without the added glass and loss of light when using the extenders. Keep working and improving as practice and experience are the most effective ways to improve.

genocolo Loc: Vail and Gasparilla Island

genocolo Loc: Vail and Gasparilla Island

Terrific photos. I’m surprised they are so good considering the relatively high iso with many of them. What is your thought?

fetzler Loc: North West PA

If you really need a longer lens then get a longer lens. TC just magnify lens problems. Both Sigma and Tamron have 150 -600mm lens the Sigma lens comes with a matched TC (but do you really need it) One version of the Tamron (perhaps an older version) is on sale a Adorama for a about $750 the others are about $1300.
Sigma a Tamron lenses are often very good. I have a Tamron 10-24mm lens that I bought instead of the Nikon because it is better optically than the Nikon. I also have a Sigma and Nikon macro lenses (different focal length) both are excellent.