bobgreen Loc: Maryland

I must confess that my recent GAS attacks have left me short of funds even though I'd love to purchase a macro lens. My current thinking is to purchase some extension tubes. One problem is that it's been 20 years since I used them and my memory isn't what it used to be.
I could really use some insight, advice, and opinions on their use. I looked at Adorama and B&H and also see a wide variation in prices as well.
I have a Nikon d7100 and plan on using them outside in natural light to photograph flowers and insects. I have Nikon 50 and 85mm 1.8 lenses.

rwilson1942 Loc: Houston, TX

LoneRangeFinder Loc: Left field

Make sure you get the auto-extension tubes, if that is the route you choose. Kenko makes them, so check at B&H.
If you use flash to supplement your lighting (many macro shooters do), the loss of light is negligible.
Other options, a Nikon 6T, which is a diopter which threads onto the front of the lens.
Other options are bellows (unwieldy for hand-held), reverse adapters (a PITA).
Check out the Users group here. Lots of set up ideas....

Mark Sturtevant Loc: Grand Blanc, MI

This is right in my wheelhouse since I used this method exclusively to do a LOT of macrophotography for 2 years. Like all approaches, there are pros and cons.
Pro: Inexpensive. Use the lenses you have (the 50mm will be best). No added glass so loss of image quality is minimal.
Con: Like imagemeister points out, you will need to remove the lens to put on. To get different magnifications you will do it repeatedly. There is a risk there, but I always had a set protocol for doing it as quickly and safely as possible. Still, it got to be tiresome and I am glad to have a real macro lens now.

For extension tubes, the Kenkos are of high quality, but that 'quality' is really in the well made spring loaded mechanism that makes electrical contacts to the camera. I used considerably cheaper Neewer tubes. About 10% of the time they would fail to make contact, but I simply released the mount and clicked it firmly back into place. It was no biggy and I never regretted my choice to prioritize $ in other things.

Another option: Attach a Raynox lens to the front of the lenses you have. These are also not expensive, and the image quality is quite good since they include a set of corrective elements. Pros use them. Here are pictures taken with the help of a Raynox 150 lens: https://www.flickr.com/groups/2011238@N25/pool/ There is also the Raynox 250 lens (higher mag is more challenging, though).
What is convenient is you use the lenses you have (try any lens. They can be adapted to any lens that has a lens filter thread in front). You can take landscapes, portraits, etc. See a butterfly? Pop on the Raynox and get it. Then take it off when you want. Obviously you are not removing the main lens, unlike extension tubes. I carry my Raynox 150 in a little zippered pouch that is lined with microfiber cloth. It is easy to reach and put away.

LoneRangeFinder Loc: Left field

The Raynox is a nice addition to any macro tool chest. I have the 250 version. One size fits all lenses. Easy to put on and remove.

Screamin Scott Loc: Marshfield Wi, Baltimore Md, now Dallas Ga

I have the Raynox DCR 150, but rarely use it. I have both mechanical & electrical extension tubes & rarely use them either, Ditto for my bellows. The "True" macro lenses are so much more convenient.

Mark Sturtevant Loc: Grand Blanc, MI

True. It was late last summer that I got my macro, and could not believe how much easier it made things. But the they cost a lot more. OTOH one could get an off-brand macro like a Tamron for significantly less than the Can-Nikon brand names. Also older model macros that are still electronic focusing are still darn good.

LoneRangeFinder Loc: Left field

There's a Lester Dine in the classified. I think Screaming Scott needs another one.

Nikonian72 Loc: Chico CA

This thread was written specifically for YOU:
FAQ: Extension Tubes vs Bellows vs Tele-Extenders vs Add-on "Close-Up" Diopter Lenses at http://www.uglyhedgehog.com/t-26496-1.html