Yes, the Sigma and Tamrons are completely compatible. They meter, AF, etc.
> A salesman told me some won't meter, but will AF, and vica versa.
I can't think of a single lens that will AF but not meter, other than perhaps one that is literally broken.
> there are some lenses that will break something off in the camera body, so you really have to be careful in choosing a Nikon lense.
Old lenses may fall into this category. They are generically called pre-AI or non-AI lenses. They're manual focus lenses that date from 1977 or earlier. And actually, the main issue with pre-AI is that, if not modified (to "AI" status), a lug on the lens breaks the physical aperture sensing mechanism on some later cameras. However, the D3200 doesn't have such a mechanism, so pre-AI's mostly are OK. Of course, they are manual focus, and precisely because there is no aperture sensing mechanism, there is no metering. But some of those grand old lenses make some great images...
The vast majority of pre-AI lenses are made by Nikon. However, pre-AI lenses were made by at least Tamron (I have one), and probably by Sigma too. However, anything that's got an AF mechanism obviously dates from the late 1980s or later, and there are *NO* AF lenses that are pre-AI.
You may read about incompatibility of third party lenses, usually with regard to Sigmas. There's a certain amount of truth to this, but it's not what I would call critical. Basically, lenses that have in-lens motors are occasionally made incompatible by cameras that appear long afterward. A great example of this is my old Sigma 12-24, bought in 2003. When the D200 came out in 2006 or so, this lens wouldn't AF on the D200 if you used the AF-ON button. (The usual shutter release mechanism was fine.) Sigma normally will upgrade firmware on such lenses, for free, although you have to pay shipping to them. In the event I never upgraded mine, because I didn't have a D200 and Nikon shortly fixed the problem with a D200 firmware upgrade.
Tamron and Tokina don't figure in this, mostly because they have only been shipping lenses with focus motors for a couple of years. Sigma started with in-lens motors in about 2001, so has **MANY** more lenses in the field spread over many more models. Likely they will have some trouble in the future too. Even Nikon has had some trouble with this!
_____ Brian... a bicoastal Nikonian and Team Member
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