If I attached non Canon lens to my Canon 18-55 lens...

[JABrazer]

If I attached non Canon lens to my Canon 18-55 lens...For example a wide angle non canon lens...
Would that mess up my calibration of my 18-55 lens?

[Waddizzle]

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@JABrazer wrote:
If I attached non Canon lens to my Canon 18-55 lens...For example a wide angle non canon lens...
Would that mess up my calibration of my 18-55 lens?

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Do you mean adding a screw on filter/adapter of some sort?  Yes, it will likely affect the way the lens focuses.  As far as "messing it up", and causing damage, that is uncertain.

Your 18mm is already fairly wide for an EF-S mount.

[JABrazer]

Ok. That's what I am curious about. It is a screw on adaptor. Canon told me they don't make that and it could damage it.

[Waddizzle]

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@JABrazer wrote:
Ok. That's what I am curious about. It is a screw on adaptor. Canon told me they don't make that and it could damage it.

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That's the answer that they should give you.  They know that attachments like wide angle, or close-up, filters and adapters will change the focusing behavior of the lens, and most likely not for the better.  The lens will only work harder to focus when it is operating outside of its' design parameters. 

My suggestion is to manually focus the lens anytime you are using a focusing adapter like that.  BTW, such devices offfer an inexpensive opportunity to dabble into different types of lenses.  Because they contain internal lenses themselves, the adapters will only take away from the image quality of the original lens.  But, they are a good means to test the waters, but are not a very good permanent solution, or substitute for an actual wide angle or macro lens.  Not even close actually.

[ebiggs1]

"Canon told me they don't make that and it could damage it."

The reason is that lens does not have the strength integrity to support heavy attachments to its front element.  You can seriously damage the lens.  It is always best to stick with true Canon equipment and accessories.  Most third party accessories is junk.  Some can even be dangerous to use, like third party batteries or chargers.

If this was from a package deal purchased from places like Amazon, I would return it today and buy the camera from a known high quality retailer.