lenses?
i bring a 17-50 f/2.8, 28-75 f/2.8, 70-200 f/2.8, 35mm f/1.8, 50mm f/1.4, 85mm f/1.8, 180mm f/2.8
nothing wrong with going with tamron or sigma. I would say go with OEM equipment if you have the budget for it, but i have seen plenty of Pro's with top end gear that don't produce any better results than amateurs with cheaper third party gear. dont get hung up on the equipment brands, get hung up on using the gear to its best potential. My 70-200 f/2.8 is tamron and is a great lens. AF is fast, and optics are great. never had an issue with it. my primes are all Nikkor.
you can also look at used or refurb lenses to save some money.
Ye I know that.. thats why I want to know everything and rethink it a lot of times..
Don't you want to upgrade it to the nikkor, or the sigma/tamron is doing very well?
Are you contented with the image quality of your tamron 70-200? by the way does it have IS, right?
Ye I wanna but don't know if it's worth it, because I want to use the lens for a long time.. dunno if it's worth that to buy second hand lenses
our 70-200 does not have IS.
haven't really needed it. I have been able to shoot plenty slow enough not to need it. eventually i will probably replace it with something with IS and keep this one as a backup. the image quality from our tamrons have been great. I think sometimes its a matter of getting a "good" copy, but i have heard people getting bad copies of Nikon and canon lenses too. If you buy new, you can always test and return it. if your buying used, its buyer beware no matter what brand you get.
some stores like
adorama,
keh, and
B&H offer a return policy on used gear. (14 days i think) long enough to give it a good test run.
I believe for the most part, you could not pick out an OEM -vs- third party lens by looking at the photos they took.
what you get from OEM stuff is typically a better build quality, sometimes better optics (if your pixel peeping on a computer), and better future compatibility.