Hi Guys,

Just some quick questions - and if these have been asked to death can you point to the right kind of search terms as photography lingo definitely isn't my usual forte!

Okay:
  1. f/stop and filters - when a ND or Polarizer states it will reduce the light by X amount of f/stops am I to assume this will not affect DOF?
  2. For longish night shots with a f/4-5.6 300mm cheapo lens what would be the ideal aperture for DOF especially when zoomed? I like the time lapse effect caused but want to reduce noise while increasing DOF
  3. And lastly equipment:


Okay I have the D90 with the generic 18-55mm and the cheap AF 70-300mm f/4-5.6 non ED lens and I have a Tokina Macro lens on the way since I love the world up close.

What should I look at buying next? My two areas of interest are Nature and Macro photography - landscape, birds, animals, insects etc.. Should I invest in a flash setup such as the R1C1 or some SB600s etc or should I invest in a more quality zoom lens with ED to avoid chromatic aberration etc which I have already experienced once?

Thanks very much in advanced all.

-Ant