cons and pros of  a 50mm, 70mm, 110mm macro lens
I am thinking of a Sigma 70mm for the D90-what's the 
cons and pros of  a 50mm, 70mm, 110mm macro lens for coral closeups?  So the application will alway have a glass in between, there is some distance we have to compensate, and the most importantly, I will shoot  them in actincis and coral fluorescent.  Is there a need to use a filter?
 
I will also use this camera for taking pics of my psychedelic artworks(which are also fluorecent in general).  Any advise will be greatly appreciated.
 
I already see the big difference using an expensive great camera vs a small point and shoot camera even though  I am using the big camera in point and shoot fashion too:shhh:.  The sensor, the lens and such makes the picture so much sharper and more faithful to the original color.