CSS3: opacity vs filter opacity?
<p>I was playing with the CSS3 filter functions (blur, contrast, invert, etc.), and noticed there is an <code>opacity</code> function:</p>

<pre><code>filter: opacity(0.5);
-webkit-filter: opacity(0.5);
-moz-filter: opacity(0.5);
</code></pre>

<p>While we already have:</p>

<pre><code>opacity: 0.5;
</code></pre>

<p>If we apply both of them for a HTML element, it seems like it's getting double effect!</p>

<p>Now that makes me wonder, is there any difference?</p>

<p><strong>EDIT:</strong></p>

<p>I'm not asking about the old IE <code>filter: alpha(opacity=50)</code> as that is Microsoft's implementation. I'm asking about the CSS3 <code>filter</code> vs CSS3 <code>opacity</code>?</p>