Choosing a lens

Just yesterday, I was browsing for and reviewing the Nikkor 17-55mm f/2.8 lens.  It costs at least $800 used.  A few months ago, I was browsing for and reviewing the Nikkor 70-200mm f/.8 lens.  Again, this beast also costs at least $1300 used.  It begs the question:  do I really need any of these two lenses?  I like that they are really fast, but there is no VR.

ExposurePlot:  graphs of 234 photos.

Besides that question, my other question is, how often do I shoot in a certain range to justify such an expensive purchase?

I ran a quick search on Google and landed on one piece of free software called ExposurePlot.  I just had a quick look and I like it already.  I ran it against 234 photos I took at a niece's birthday party.  All the shots were made indoors with flash mostly.  I forgot now what ISO values or aperture settings I used.  This software answers this question in minutes.

I can see I left my camera on ISO 1600 the whole night, as shown by the big red bar.  Since I used Aperture Priority virtually all the time, with flash on, the shutter speed is maxed out at 1/60 seconds as shown by the big green bar.  I can see that a few times, I turned flash off, and they show up as those tiny green bars.

Now, for focal length--and this must be taken into context of an indoor party shoot--I spend most of the time shooting between 18-55mm (DX).  The graph converted my focal lengths into 35mm equivalents and I am not sure how to turn off that conversion yet.  I do shoot in the 70-200mm (DX) range but not as nearly often.  Overall, I can see that I do use the full 18-200mm range in a given night.

If I were to purchase a 17-55mm lens and a 70-200mm lens, I will likely use the 17-55mm much more often than the 70-200mm, but will I likely want to switch lenses during a party, or will I simply adapt (i.e., getting closer)?  I have brought just a 50mm lens to parties before and I was forced to adapt.  Hmmm...

I have to run now.  I will play with this software more a bit later.