New Lens? For Wildlife Photography

I've been vascillating between getting the Sigma 50-500mm f/4.5-6.3 or the Tamron 200-500mm f/5-6.3. I've looked at comparisons online and found that the Tamron is slightly sharper on the 500 end and with the application of judicious retouching...I can get rid of the chromatic aberration that seems to be prevalent in lower end superzooms.

Some examples

Sample Photos from the Tamron 200-500mm taken by other photographers.

Sample Photos from the Sigma 50-500 (the Bigma) by other photographers.

Keep in mind though that the examples shown here were posted up by these other photographers after some retouching (even more so on the Sigma).

To me though, with wildlife and aviation photography as my stock photography forte, I need something with solid, tack sharp imaging at the 500 end...and all the unretouched photos seemed to give the edge at 500mm to the Tamron. So that's the 300-500 range lens that I'm going to go after.

The Bigma (Sigma 50-500)



And the Tammy Long (Tamron 200-500)



At least this will give me the edge and the focal length to go after the birds and the other fauna that I can't usually get close to enough to use my 70-200mm f/2.8 or my 70-300mm f/4-5.6 G

Since wildlife and aviation photography are strees-relaxer genres for me I like have the opportunity to shoot with a long lens and make the day out at the wildlife sanctuary or zoo worthwhile.

This lens will be the stop-gap lens (the interim lens) between the saveup and acquisition of the AF-S NIKKOR 600mm f/4G ED VR and AF-S NIKKOR 400mm f/2.8G ED VR.


AF-S NIKKOR 600mm f/4G ED VR


AF-S NIKKOR 400mm f/2.8G ED VR

I've come to the realization that anything closer than 400...I can manage handheld with either a 1.4X, 1.7X or a 2X teleconverter on my 70-200mm f/2.8