I have owned a Nikkor 500-mm f/8 Reflex (mirror) lens since the early 1970s. I still use it, tripod-mounted, on my Nikon D5000 for waterbird photography at distance. I have seen several listings of the same lens on eBay for affordable prices.

Snowy Egret via Nikkor 500-mm Reflex lens

I like this image. A 6-second exposure is quite a long time for such little white water blur. I supect that there was not much water actually falling. You have done a good job of capturing this waterfall. Is this your longest exposure of this scene?

After saving, my next two step are culling, then tweaking, then cropping.

I dump my memory card into a new file, named to indicate the day taken. Today, September 04, 2011 = 11-0904.

Once saved, I open folder 11-0904, and immediately create a new folder called 110904 Prime, into which I copy all acceptable images.

Then I open Prime, and create a new folder 110904 Best, into which I copy the best of similar photos, and keeper unique images. Be judicious!

Then I open Best, create folder 110904 Tweaked. I use Picasa Picnik to tweak each photo, and save tweaked image under new name (-1), and place in Tweaked folder. You can do the same with PhotoShop, etc.

Then I open Tweaked, and create folder 110904 Cropped. I again use Picasa, crop each image, save under another new name (-2), and transfer to Cropped folder. I shoot macro, so I crop quite tight to subject.

Images posted to the internet come out of Cropped folder. Images to be printed come out of Tweaked folder, because 4x6 or 8x10 prints are different formats, requiring the use of un-cropped image frame.

If you do not critically organize your images, chaos will soon overwhelm your ability to easily & accurately retrieve from storage.

My main suggestion (for internet display) is to crop as tight as possible, keeping all limbs complete. For printing to standard formats (4x6 or 8x10), crop tightly to those formats at time of printing.

I have also added more discussion via e-mail.