i think that is not the filter. its the coating of the lens.

D50's kit lens is good, but the D70's kit lens is better. in terms of range the 18-70 wins. but when it comes to using built in flash, the 18-70 will have some problems since when you pull it to wide and take pictures with built in flash, you will notice a shadow at the bottom . easily solved by getting an external flash. in terms of picture quality, both lenses perform GOOD. as long as you dont go pixel peeping and try REALLY HARD TO FIND their flaws. anyway, get any camera and start shooting. build the photographer in you and not the equipment collecter in you.

hehe... 18-70mm is a very good range as a walk around lens. if you really want to get into macros. u can always purchase some close up filters( 2 +4 close up filters should do the job ). but dont buy nikon's since they are really really really expensive. or another good alternative is get the sigma 70-300mm f/4-5.6 APO DG MACRO. the one with the red ring. its a good telephoto lense and also a good macro lense.... its really soft at around 300mm but until around 250mm its really usable... if you step down the aperture to around f8 it should be acceptable for all focal lenghts.... the sigma would cost around RM750 for a new one. comes with a soft pouch + lens hood summore.

dont think many 20d users will switch to 30d since the changes from 20d is not much. just add some megapixels.... spot metering ( not that i use it, but some people need this feature for fine composing ) .... ISO step from 1 step to 1/3 step ( not many will use it anyway, i like it better with 1 steps ).... but if your upgrading from 300d @ 350d it might be worthwhile. .

that should depend on how deep your willing to dig into your pocket . tighter focal lengths usually is better but depends once again on how you are going to use it... i suggested the Sigma since sumone wants to use a macro and a telephoto. since the lens has fairly good aspects in both the macro and telephoto ( and also it has a very good price tag ).

but if it comes down to getting a good macro and telephoto on one lense, you could always result to the Zoom Micro Nikkor 70-180mm f/4.5-5.6 ( which has a price tag of nearly RM4k ).