If i buy a nikon slr (d3100) can i use lenses from a canon? Is that universal? - 1

If i buy a nikon slr (d3100) can i use lenses from a canon? Is that universal?

Each camera manufacturer uses a proprietary geometry for their lens mount. Thus, you Can't use one brand of lens on another brand's camera.

You can buy an adapter to mount and use them, but most of the functions of the lens will not work. It will be manual focus and you won't be able to set the aperture. Everything has to be set manually-no auto and the meter may or may not work thru the lens.So, as a novice with no camera knowledge they are useless.

You can. But you will need an adapter which will take 1-2 stops of light away, as well as take away any autofocus and possibly even metering

basically, its useless

Major dSLR manufacturers each have their own mount completely incompatible with the each other. That's why choosing your dSLR brand is very critical. You are buying into a system, not just a camera.

No, it is NOT universal. Camera mounts are proprietary and therefore unique to each brand. When you buy a DSLR, you are buying into a system of lenses and camera bodies. Most photographers stick with one lens system for decades. It's rare for people with multiple lenses to switch systems due largely to the cost of replacing those lenses with equivalent versions from another system.

For the record, I have never seen an adapter to allow the use of Canon EOS (EF/EF-s mount) lenses on a Nikon body. However, I've seen a great many adapters going the other way around, allowing the use of Nikon F-mount lenses on EOS bodies. Some of this is owed to the difference in the distance from the mounting flange to the sensor plane which would require corrective optics but, there's also a more significant issue in that Canon lenses have no mechanical linkage with which to actuate the aperture.

Canon EF and EF-s lenses are operated exclusively by electrical connections to the camera. And just like their respecitive mechanical mounts, the electrical connections that accompany them proprietary. The point lurking here is Nikon bodies can't "talk" to Canon lenses and this means the lenses have to be shot "wide open." This means you have 0 control of depth of field and it essentially makes the lens useless outside a small set of circumstances. If you want to swtich the Nikon, that's fine. Just plan plan on shooting only Nikon lenses or lenses designed for the Nikon mount. It is generally not worth the hassle to use lenses from a competing brand.

No you can't, one brand one mount of lenses.

Here's a DSLR Buying Guide - http://www.the-dslr-photographer.com/2009/11/which-dslr-to-buy/