01-07-2017 09:13 AM - edited 01-07-2017 12:16 PM
"The EF 100-400 L IS II with the 1.4X III extender still bests the image quality of the Sigma or Tamron 150-600s."
Of course this is wrong. Even if you take published data on the three lenses mentioned, they are nearly identical in IQ. Actually owning and using all three confirms it. Adding a teleconverter to any one of them vs one without one, will degrade its IQ.
Your statement that they all have nearly identical image quality is false. The Tamron lags the other lenses in the group. That has been shown by a number of testing and comparison sites. And the used market for those lenses is the biggest indicator of that. The Tamron 150-600 now sells on the used market for well under a thousand dollars, and only about a $100 more than the Sigma 150-500 OS that you've often maligned here.
All of the testing and comprison sites confirm that the EF 100-400 L IS II with the 1.4X III extender still bests the image quality of the Sigma or Tamron 150-600s.
The easiest way to see for yourself is at the-digital-picture.com That's at 600mm stopped down to f/8 on the Tamron, and roll over to see the Canon at 560mm f/8 at the center there isn't much difference, but, by the time you get to the corners it is clear that the Canon has superior image quality..
01-07-2017 12:07 PM
Nice Shot, TTMartin. 8^) Mine was taken in the Rio Grande Bosque with my Tamron 150-600.
Watching and hearing a Sand Hill Crane in flight is an experience straight out of Jurassic Park.
01-07-2017 12:30 PM - edited 01-07-2017 12:31 PM
I've shot the Sigma 150-600 C all of last season & it has benched my 100-400 L IS Ver 1 which is quite sharp. I finally got a shot I've been after for the last 2 seasons because for once I decided to use the right shutter speed because I really wasn't after prop blur. I have come very close at getting this result at 1/500 a few times but I think this confirms that the Sigma is sharp enough for most hand holders. Wing span is 88 inches & it's flying right to left doing rolls, I've turned it for the crop. (note slight prop blur even at this setting so likely at full power). First the full frame then a crop to the autographs of the Snowbird pilots 3 years ago & ISS Commander Chris Hadfield. Shot hand held with a 1D mark 4, Sigma 150-600 C @468 mm, f 6.3, 1/2000. At the end of the season I started shooting that lens on my 7D2 with excellent results & I plan on using it together next year along with the Canon 28-300 L IS on the 1D4.
01-07-2017 04:22 PM - last edited on 01-07-2017 04:29 PM by SamanthaW
Look and decide for yourself.
[Removed link per Forum Guidelines]
Compared to the 100-400 II with 1.4X III teleconverter, it's fairly obvious ...
- Tamron 150-600mm G2 is pretty equal at the center, but slightly softer away from the center at 500mm, and more-so at 600mm.
- Original 150-600mm is softer away from the center at both 500mm and expecially at 600mm.
All the comparisons I did were on full frame (1DSIII) and "wide open" in all cases (that means effective f/8 on the 100-400 + 1.4X and 1/3 stop faster f/6.3 on the Tamron lenses). The selectable focal lengths are slightly different, too... 560mm for the 100-400 + 1.4X versus 500mm and 600mm with the Tamrons.
I'll leave it to you to compare other settings or the comparable Sigma lenses, if you wish. If you do so, just be sure to select the same camera body for the comparisons. It doesn't really matter which camera, so long as the same one is being used for both the lenses in the comparison.
Compared to the Tamrons, while the center on all of them seem pretty similar, it looks to me as if the 100-400mm II with 1.4X is slightly superior in the corners and at the edges... on a full frame camera. Using any of these lenses on crop sensor cameras, the difference would probably be pretty hard to see.
I've got the 100-400mm II... but haven't had chance to try it with 1.4X yet. Using it on APS-C cameras (7DII), I just haven't needed any more than 400mm yet. Not sure if it will work as well with the 1.4X II that I have, as it appears to with the 1.4X III.
01-08-2017 12:57 PM
"I've shot the Sigma 150-600 C all of last season & it has benched my 100-400 L IS Ver 1 ..."
It does show that real world shooting and data from testing sites can be very different and misleading. I own, or rented, and use all of the lenses mentioned in this thread. For most people I still maintain there isn't a nickels worth of difference between them.
However, in the hands of certain people there can be quite a difference. Also it depends on how much cropping is done or required. For most people, they will see a degrading of the IQ with a teleconverter with any of them. It is my belief and experience that a lens without a converter is better than one with it.
01-08-2017 06:22 PM
Thanks much for your comments and for an illustrative image with the lens and extender. You've told me everything I wanted to hear as I do have the second, more recent version of the Canon telephoto zoom lens. I also know a few guys who have the Sigma 150 - 600 mm lens and so I was also interested in your comments about the Canon versus Sigma/Tamron lens and their image quality. Again, thanks.
I chose the Sigma 150-600mm "C" over the comparable Tamron for one reason. Sigma dock. If you take the time to carefully calibrate your lens, you will be rewarded with really great photos.
And, I do mean take the time when doing focus adjustments. I spent about three weeks testing and re-testing until I came up with a consistent set of average results. Much of that is due to the number of calibration points  in the Sigma. I finally found the best way to test it was outdoors, in bright sunlight, aiming at the lines of empty parking spaces in a large parking lot. The lines of the parking spaces offered a quick and dirty way to measure distances accurately enough for the calibration testing.