Advice on standard zooms

The Zeiss 24-70 is not at it's best for small aperture landscape. It doesn't gain as much in sharpness stopped down and lags a bit in the corners. It's virtue is at f/2.8 and with it's acceptable bokeh.

The usual advice is to go for a tamron 28-75/2.8 which pulls ahead of the Zeiss above f/4 and has truly great corners stopped down. It's bokeh is not something to write home about. Sony make an optically more or less identical lens at a rather higher price which has a motor rather than tamron's screw drive. It isn't faster on an a900 but on an a99 I don't know.

You could think about the minolta 28-135 which has great sharpness but perhaps not the greatest contrast. It is also rather heavy which can count more than you might expect.

My favorite is the Sony/Minolta 24-105mm which has decent bokeh and a very useful range. A little more CA. It is small, light and cheap. It does as well as my tamron 28-75/2.8 stopped down to f/8 but I wouldn't want to use it in low light. No matter how much you stop it down it is always going to vignette a bit. The good thing is that the size and price means you should still have room for another faster lens.

I had the minolta 24-85mm and found it unconvincing but it has its fans. Perhaps I had a bad copy.

I doubt that a 70-200/2.8 will give you much that you want. The sony 70-300mm was never the most exciting of lenses at the long end but between 70-200mm and well stopped down it should do the job as well as any.   

Lens selection is a very personal matter. My views are different from Blame's.

The Tam 24135 is a "slow" lens (although that won't matter with an A99 and the ability to push the ISO.) It has a zoom lock, a most useful range, a hood: it is relatively light, and short in the wide mode, and my copy is free from the tammy yellows.   it is most inexpensive for a quality lens.   it's a great and under-appreciated fullframe lens.

I prefer the Tam 241235 to my Min 28135 (no lens shade and strong flare) or my Tam 2875/2.8 (a little too short at the long end, and yellow) or my 24105 (very bad chromatic aberration at the edges.)

It is difficult to find a better telezoom than the 70300G. I prefer my 100300APOD, but that is just orneriness on my part. The 70300G is a bazooka with its lens shade, but the image quality is very high indeed, the colors are Minolta, and again, while it is "slow", it can be pushed on your A99.

People will tell you about the 70200G and the 70400, and they are phenomenal lenses, but the first is heavy and the second is gynormous. The 70300G is too big for my taste, but if you've got it, use it to the fullest!

Constant f4 would be the beercan - apart from CA it isn't that far behind canon or nikon.

I've been enjoying my minolta 20/2.8 and samyang 14/2.8 on my99

Oh, almost forgot, the Canon 24-105 has lousy corners, not at all a landscape lens..... The new 24-70/4L might be better in this regard.

JamesD wrote: Thanks all for the comments. As I suspected, for my usage there is a diminishing return on the Sony 24-70/2.8. I guess I'll do some testing to compare the 28-75 and the 24-85. I think too, I'll wait and see how the new Tamron 24-70/2.8 and 70-200/2.8 pan out. I surely do wish Sony would come out with a constant F4 like the Nikon 24-120 or the Canon 24-105L. It seems there would be a big demand for it among Sony FF users. Maybe there's just not enough of us to justify the cost to produce it.

Hey. It's a bit difficult to give advice if you keep changing the requirements. We have been assuming that you are after sharp landscape lenses to use stopped down without spending more than you need. Those new Tamrons are high priced fast glass. Great lenses but not exactly a good fit to the original specification. They lack the focal range, modest weight and price while they will probably have no better IQ well stopped down.