Dude, you're not tempted by the sigma 150-600? Apart from the weight it's pretty sweet...cheaper than the mkii too.

I know it's heavy, blooming heavy! I've got one!

However, going from a crop sensor to full frame, I found 400mm just didn't cut the mustard any more. That left me with either the Tamron or Sigma 150-600 options.

I started out with the Tamron, it's actually quite a good lens, not too bad, did the job. Took it to Canada and took it on some hikes, got a few good shots:

Eastern Kingbird by Chris Moody, on Flickr

Least chipmunk by Chris Moody, on Flickr

North American beaver (Castor canadensis) by Chris Moody, on Flickr

So yeah, light is a bit of an issue. But one other benefit of going full frame, is you can get away with higher ISO. That beaver shot is at 3200, and was taken at dusk in very low light. I raised the exposure in post processing to bring it back to daylight levels. Yes if you look at it 100% there's noise, a stock agency likely won't take it, but it's still useable.

Yet for some reason I decided, that despite getting a good number of keepers, the Tamron wasn't for me. I traded it in and ended up with the Sigma 150-600mm Sport edition. Given that even the lens hood is metal, it's a good kilo heavier than the Tamron, and I seriously doubt I'd have been able to lug the Sigma around and up through the Rockies like I did the Tamron.

However, weight is the only real downside... autofocus is very reliable, the build quality also is nuts, so I know the lens will last me a good long while. To answer the question about needing the light for the motorsports, and if you're thinking the subjects in the above shots were stationary, the following weren't exactly slow movers, and were even photographed in this country in October last year, where the daylight isn't necessarily that great:

Curlew by Chris Moody, on Flickr

Kestrel with cricket by Chris Moody, on Flickr

And this one was stationary, but it shows the detail obtainable:
Ruff by Chris Moody, on Flickr



So all in all, on a full frame that does well in low light / high ISO, the smaller max aperture isn't too much of an issue. I'd be curious what Binary has to say about the noise on the 7DMkII compared to the 7D, which I found to be exceptionally bad.

Problem with the 400 +teleconverter is cost, when the 100-400 MkII is more than the sigma without the telecoverter on top, you'd also end up with an f-stop less light.  Depending on what you read as well there are some comparisons that suggest that there really isn't much in it in terms of image quality.

Last I checked Adam still did a bit of wildlife photography as well so yeah, it's all personal choice. The weight is an issue but for what I do its my best option.

When you look at this comparison between the 100-400 mk2 and the sigma 150-600 sport it looks pretty awful: http://www.the-digital-picture.com/Reviews/ISO-12233-Sample-Crops.aspx?Lens=972&Camera=963&Sample=0&FLI=4&API=0&LensComp=978&CameraComp=963&SampleComp=0&FLIComp=5&APIComp=0

So I ended up biting the bullet, as my wife and I still plan on doing a nature blog in the future, and our looming honeymoon is too good an opportunity to miss in terms of getting photographs of more exotic species. As a result the Sigma 150-600 is out and has been replaced with the 100-400mkII + a 1.4x II extender.

Initial thoughts:

• It's so much easier to carry around, I can actually fit it in my backpack without issue, and have it on a neck strap all day. In comparison, when I took my Sigma in to be part-ex'd, the only bag I had big enough for the box was a bin bag!
• Autofocus is very fast and accurate, more so than the sigma, which to be fair was perfectly adequate anyway.
• The 1.4x II extender brings the focal range almost in line with the 150-600...and it's fine for static, large, or slow moving subjects. Small fast moving subjects are a no go, could not achieve focus on some sand martins against a clear blue sky. without the extender the lens kept up easily. On the bonus side, my MP-E 65mm 1:1-5 macro can now be extended to 1:7 macro, which is pretty nuts.
• Unless pixel peeping, image quality isn't improved enough to warrant the upgrade. The main thing is size and weight.

So ultimately, I've given up some convenience of an all in one lens, for a lighter smaller package. The rest of the differences are minor enough to not factor in the decision making process really.

I am curious as to whether I'd have noticed any significant performance boosts if I'd bought the 1.4x III extender, but a second hand II model for £100 was too good an opportunity to miss.

Carrying a 70-300mm zoom is certainly more convenient than a 150-600mm - I can shove the smaller lens in my pocket.

Been considering a fishing waistcoat. BIG pockets to carry photographic stuff.

Well iv gone for it, ebayed some kit and ordered the 100-400mk2, looking forward to it