I need the opinion of some of you who have used these lenses. I have a Nikon D500 and D800. My longest lens is a Nikon 18-300mm Dx which I use for my D500 as a walk around lens. There are occasions I need a longer lens, e.g. moonshot, birds on flight, sports. If I could, I’d like to use an FX lens for my D800. My main consideration is sharpness at near maximum focal length. My choices are: Nikon 200-500, Sigma 150-600 contemporary or sports, Tamron 150-600. Is there any other? What do you think is the best value for the money if it were you? Or buy the new Tamron 18-400 for half the price? It is a DX lens and would give me 600mm on both my D500 and D800? I could use it as my new walk around lens over my 18-300 which I could sell.

This purely an academic question. I rarely use editing programs and when I do I use PSE6 and I recently loaded PhotoshopCS2 as I read in UHH that it could be had without charge.
I have a D 5200 and once thought I would experiment with RAW, but nothing wanted to know RAW.
Picasa, CS2 or PSE 6. All did not recognise the RAW files. I am curious to know why. If I remember correctly, my D80 RAW pictures were shown without a problem. Obviously, I have set the camera to RAW or RAW+JPEG, but nothing.
Does any kind soul have an insight into this. Many thanks.

Yes russelray I agree with you. The Tamron G2 is a usable lens. The Sigma is so heavy. If you want a 400mm. lens the Canon 100/400 is fabulous. To get to 600mm. it needs a 1.4 extender and that puts you out to F8. The Tamron 150/600 gets to 600mm. and is F6.3. You really can't get that aperture at 600mm. with lenses as cheap as the Tamron or Sigma Sport. The problem with the Sigma is it is just so heavy.
I have just got back from a trip to Scotland during which I was taking pictures of an otter in very poor light. I was handheld at 600mm. at one fortieth second shutter speed. The shots are absolutely tack sharp. The otters whiskers are absolutely sharp and so are the water blobs on the whiskers. The image steady system on the Tamron 150/600 G2 is superb. The lens is staggeringly sharp, amazing at the price, and the resolving power of the lens is amazing. The detail in my shots is fabulous. There is simply no other way to get the aperture at the 600mm. setting unless you spend many thousands more. The Canon 100/400 is a fabulous lens but if you want the extra focal length without losing the wide aperture facility there simply is no other way. I have used all three of these lenses and without hesitation I would go for the Tamron G2. Not only is it lots lighter than the Sigma Sport it has other advantages. The image steady facility design for one.

Not ridiculous, it's s pretty common knowledge:

1. System resolution is a combination of the camera's and the lens's resolution.
2. Zoom lenses involve design compromises. They do not perform equally throughout their range.
3. A high resolution sensor will reveal the shortcomings of an inferior lens. You will just end up with bigger files.
4. When you look at any ranking of lenses, the best zoom lenses are way down the list behind the best primes. See DxOMark.

Nikon and other camera manufacturers would like you to believe that more resolution will make your pictures better. It's how they make money. Would you like some more Kool Aid?