Can i get some opinions on these lenses?
Here are two lenses i'm considering adding to my collection, both from Amazon…
this is the main one, i really need an ultra wide angle as i do a lot of landscape shots…
http://www.amazon.com/...0026FCKC8/
and this one, looks like a prefect combo for me as it is a telephoto and macro rolled into one, it also is listed under sports lenses, BUT it is pretty cheap which is a warning sign for me…
http://www.amazon.com/...0012X43P2/
what do you think?
The Nikkor lens is excellent as you would expect. It's ideal for dramatic wide angle landscapes.
The Sigma lens is worth what you pay for it - and that's not much at all. It's not a proper macro lens, despite the claims. The magnification ratio is only 1:2 - a true macro is 1:1
I own one of those lenses, I didn't pay for it, it came with the deal when I bough a camera. I wouldn't have purchased it otherwise. It is also has the noisiest, slowest autofocus I have ever encountered on any lens. Best avoid it if you don't want to be disappointed. Although since it's not a lot of money, I suppose it is what it is. It will of course take photos, it's just not very sharp at the telephoto end of the zoom. If do you use it at 300mm, you'll need to adjust the sharpness/contrast in image editing software.
I'm not saying all Sigma lenses are bad, but that is certainly not one of the good ones. Sigma currently makes two versions of the 70-300, the APO one is said to be better than the really cheap one. Although I have my doubts. Really the price should tell you all you need to know about those lenses.
I have bought other Sigma lenses which are excellent, but they were not that cheap, so don't let the ultra budget lenses put you off.
As a Canon user, I can't give any actual use reports on Nikon lenses. I can only speak in terms of opinion, and it is this. I avoid third party lenses. Some people say they are fine, but experiences with both Sigma and Tokina have never been the best for me. They work in the sense that they will put an image on your sensor, but, as said it the other answer, there have typically been other problems with things like contrast and sharpness or slow focus or noise or the lens barrel creeping down. To be fair to the third party lenses, I have never used one that was expensive. It could be that I simply got what I paid for. If I'm going to spend a lot of money on a lens, however, it is going to be a brand that matches the camera, i.e. Nikon for Nikon or Canon for Canon.
Your Nikon lens selection will likely please you just fine, but I would have to think long and hard about that Sigma.
If you're leaning towards the Sigma lens, get this one instead:
http://www.amazon.com/...0012X61U2/
It's about $10 more, and considerably better in quality -- though it won't match faster, more expensive lenses from Nikon or even others from Sigma. This is a budget lens, and it's also not actual "macro" (though it can do decent magnification decently close).
I always try to buy the camera manufacture lenses. I have rarely used third party ones.
If your interest is in landscape photography then the Sigma 70-300mm is NOT the lens you want. Landscape photography calls for a wide-angle like the Nikon 10-24mm. Buy that lens and a good tripod (if you don't already have one) and you're good to go.
NOTE: Zoom lenses with the word "macro" in their description are, in my opinion, bordering on what I consider false advertising. A true macro lens is always a fixed focal length prime lens such as 40mm or 60mm or 90mm, etc. And capable of giving you a full 1:1 life-size reproduction ration. Manufacturers would be more honest if they labeled their zoom lenses as "close focusing".