After market lens for Nikon cameras
Sigma lens are more widely known as an after market lens for Nikon. Although there are other name brands on the market Sigma some how became the undisputed king of after market equipment. The best thing about Sigma is that they do deliver a good package deal for a great price. They do however lack a few of the amenities afforded by the original brand but that's the whole point. Give the customer something great at and even better price.
Must have lens
A little on the high end of the lens scale the Sigma 24-70mm and the Sigma 70-200mm f2.8 lens for Nikon are great runners-up to the real deal. It seems since the destruction of the Nikon factory in Japan the prices for Nikon lens have skyrocketed faster than the space shuttle Atlantis into orbit. This makes it really hard to own a these great lens in the Nikon brand. The problem is that a Nikon 24-70mm f2.8 lens cost about $1700.00, while a Nikon 70-200mm f2.8 can run up to $2,200.00 that's a lot of aspherical lens right there. The good news is there is hope if you want a good lens but for roughly half the price but just as good quality.
The main difference I have found between the Nikon and the Sigma are subtle and not a big deal for many photographers including myself. Firstly the Sigma does not have weather sealing, so just be careful when it rains or if you have a lot of sunset at the beach shoots watch out for that salt spray. Secondly the focus is not as fast as the Nikon but still fast enough to capture moving objects like sporting games or racing. The biggest problem most people may have is the sharpness. Sigma just isn't as sharp as the Nikon and this is to be expected, you just can't beat the real thing.
So here are some of the pros and cons of having a Sigma lens vs the Nikon lens.
Nikon 24-70mm f2.8 vs Sigma 24-70mm f2.8 on a budget
Sigma Pros and cons
If your a hard core Nikonian using a Sigma will feel kinda awkward and take some getting used to mainly because the focus ring turns in the opposite direction from the Nikon. I still have to intentionally think and remember that its reversed. Even within the lens the barrel the elements move in opposite directions than the Nikon so that takes some getting used to. Sharpness. the Sigma is not as sharp as the Nikon especially when wide open and f2.8 and it has more chromatic aberrations than you will have to be aware of and of course its not weather proofed. The good thing about the Sigma brand...ITS AFFORDABLE. It still produces great images and its durable. What more can you ask for? Price was an issue for me which is why i opted for the Sigma brand and I have no regrets at all. As a photographer we know that good tools only help to make your work easier but makes no sense having great tools if you don't know how to use it correctly. Its not the arrow that counts but the Indian shooting the arrow.
Nikon 70-200mm f2.8 vs Sigma 70-200mm f2.8 on a budget
The build and fell of the sigma lens is strong and durable and it just about as heavy as the Nikon. It has internal focusing which is a great upgrade from the Sigma 24-70mm f2.8. Focusing is fast and its actually pretty sharp. If you never shot with the Nikon 70-200mm and went directly to the Sigma 70-200mm you would be amazed. Its not that far in sharpness from the Nikon actually. I haven't had much problems with chromatic aberrations with the Sigma 70-200mm f2.8 in fact I use it as much as I can. I really love this lens. Its quiet, feels good in my hand, the zoom and focus is not reversed like the Sigma 24-70mm so it reminds me more of the Nikkor brand.
All in all for the price this lens is my major workhorse for weddings, head shots, and in many instances individual portraits.
NIkon 18-200mm vs After market 18-200mm on a budget
The Nikon 18-200mm is noted as one of the best lens to have when you travel, this its known as a Travel Lens. The reason its called the travel lens is that it covers a wide spectrum when it comes to zoom. At one end you have a large wide angle view at 18mm and at the other end a tight zoom at 200mm. You can cover the pyramids (at the right distance that is ) as well as the finer details of the Sistine chapel. This lens is not considered a fast lens with a maximum aperture of f3.5 but it gets the job done quite well. As great as this lens is for an all around everyday use were looking for a good lens on a budget, while you may want to upgrade to this lens later you may want to consider an after market lens.
Two manufactures that come to mind for this lens are Sigma and Tamron. It's a known fact that they can never compare side by side with the original NIkon but they do get the job done. The Nikon is equipped with VR stabilization for that long zoom at 200mm while incorporating 2 ED glass elements and three aspherical lens. To make a long story short, it cuts down on lots of problems plagued by such super zooms. The Sigma has tried its best to match the Nikon with Optical Stabilization (OS) and Special Low Dispersion Glass (SLD) built into their 18-200mm lens. Its not as great as the Nikon but comes close while costing half the price.
The Tamron 18-200mm like the Sigma did their best to match the special features of the NIkon while keeping cost low. Ive heard fellow photographers mention that its not as good as the Sigma and as usual no compassion to the Nikon. Good thing were shopping for a lens on a Budget and this is at the lower end of the list. Although less expensive it does help capture great images just don't expect sharp detail and you will experience more aberrations under certain circumstances.
18-200mm Super Zoom Travel Lens
In a nutshell if you travel a lot and love to take your camera along, this lens will cut down on your camera bag weight so yo u can focus more on getting the shot rather than trying to figure out which lens should I use. Ive also heard that the 18-200mm makes a great video lens.
Now you can own you personal Super Zoom travel lens on a budget thanks to after market manufactures.