Like many people I'm contemplating upgrading to full-frame with the introduction of the 6D and Nikon's D600.
Given I won't be able to use my EF-S lenses on the 6D the Nikon is a possibility.
Given cost and weight considerations I want two lenses to cover the 24 to 300mm range.
For Nikon this means 24-85 and 70-300. But when looking at test results on slrgear.com the results for these lenses do not seem as good as Canon's 24-105 and 70-300.
However, I was still somewhat disappointed by the 24-105's results from 70 to 105 at full aperture on a full-frame camera. (see link below), yet the lens is widely praised on this forum.
http://slrgear.com/reviews/showproduct.php/product/145/cat/11
How useable is the 24-105 from 70mm upwards?
The results for the 70-300 seem very good (given it's price) at full aperture on full-frame. The review site suggests they are better then the 70-300L for sharpness. Yet the non-L lens seems to get criticised on this forum. (see link below)
http://slrgear.com/reviews/showproduct.php/product/253/cat/11
As I'm primarily concerned about sharpness, given most other things seem treatable in software, I'm wondering whether Slrgear got atypical copies of these lenses, or are their results not consistent with peoples' experiences of using these lenses? I'm confused!
I would appreciate the comments of people who own, or have used these lenses.
Thanks
The Canon 70-300L is absolutely sharper and, above 200mm, more contrasty than the 70-300 non-L from Canon. SLRGear was doing silly things there. I've had both and so have many others. The non-L used to be the best one around (other than the 100-300L in some ways) but the new L is definitely the best 70-300mm anyone makes. The Tamron 70-300 VC is also one to look at if the 70-300L costs too much.
24-105 is loved by many but I didn't like it that much, it seemed kinda soft at the edges wide end FF and it just seemed to be priced too high for the IQ IMO, I hated it, but many love it, it's a weird lens I see it more often on favorite Canon lens lists than any other lens and yet I also see it more often on least favorite/most hated Canon lens lists more than any other

. Probably due to a mix of expectations and how people use it and some getting blinded by buying it as their first L and then over-rating it and copy variation (

). It is very convenient, great range, IS, fast AF, pretty contrasty. Lots of distortion at the wide end, and, IMO, a bit softer than some others. My vastly less expensive Tamron 28-75 2.8 was sharper at 28mm. But many do swear by it.
The 24-70 II from Canon is really good but $$$$$ the new Nikon 24-70 is pretty solid too also $$$$.