Curve_in Loc: Virginia

Has anyone used two sets on Kenko automatic extension tubes on a handheld field rig?
I think the 36 + 36 + 20 + 20 would be the combo I'd use. My thoughts were that I'm cropping about 30-50% on most of my images so I'm already shooting at about 3:1. The additional magnification would give me more pixels in my final images so they could be a bit better (sharper).

tradio Loc: Oxford, Ohio

Interesting concept! Have you considered a bellows?

Curve_in Loc: Virginia

I need the "automatic" setup for in the field otherwise, the image is too dark to see for focusing.

naturepics43 Loc: Hocking Co. Ohio - USA

I tried it a couple of times. Camera & tube sets ( 136mm total ) were mounted on a long lens tripod mount system using a modified tripod lens ring to hold everything in alignment. Very, very awkward to handle, lighting was difficult and I felt the images were very soft. Not OOF but soft. I think BobR is experimenting with a combo of tubes & 2X TC. TC's have always kinda been taboo but BobR is getting very good results. So good that I tried it yesterday and was very impressed with the results. I think it may have a lot to do with a specific lens/ TC combo or lens/ tube set-up.
Try it, you might get better results. Good luck.

LoneRangeFinder Loc: Left field

I just find it difficult to hold steady with the added length and the decreased DOF. Perhaps it's an eyesight thing. I've lessened my use of even one set of tubes. The more you shorten your working distance, the more shallow the DOF. In some cases, I find it beneficial to shoot at 3:1 and crop the final image. I know you lose pixels….

Curve_in Loc: Virginia

I did try a bellows for a bit. The setup was way too heavy to be mobile so I sold it. I never used it outside. http://www.uglyhedgehog.com/t-253989-1.html

I've been getting in better shape and I think that has helped with my steadiness. If I had more resolution, I could just crop more. Mostly, I'm looking for a way to stay happy with my current D7000 until the D7200 get to the half price mark.

Nikonian72 Loc: Chico CA

This device allows your CANON DSLR camera to communicate with lens, through manual extension tubes or standard bellows.
Auto-Aperture and Auto-Focus are functional. No Nikon F-mount equivalent, yet.
http://www.amazon.com/Neewer%C2%AE-Multifunctional-Electronic-Automatic-Extension/dp/B00LJRD8PW
http://www.amazon.com/MK-C-UP-Electronic-Extension-Reverse-Adapter/dp/B00LJJDMV0
http://www.aidisan.com/neewer-multifunctional-electronic-automatic-af-auto-focus-macro-reverse-mount-on-lens-extension-tube-with-58mm-67mm-72mm-77mm-adapter-rings-for-canon-efef-s-mount-lenses-fits-canon-eos-5d

Neewer Multifunctional Electronic Auto Focus Macro and Reverse Mount

imagemeister Loc: mid east Florida

There are some AUTO bellows out there.
Long tubes have the ability to reduce contrast from internal reflections off the side walls.

Not sure if your NEX has the clear image zoom feature - but if it does, I would certainly give that a try for what you want !
Traditional TC would give you more magnification but also light loss.

mawyatt Loc: Clearwater, Florida

Very true. I have been constructing my own macro lens for greater than 2X. I found, as others, that modern microscope objectives with proper "tube" lens can take you up to 20X with good contrast and sharpness. These combined lenses (objective and tube) require long spacing (~200mm) which can be achieved with fixed aluminum extension sections screwed together to make a long (12 inches) high macro lens. The inside of these extensions are painted flat black to help reduce reflections, but this isn't totally effective I found (look thru long extension at bright source and you cans see internal reflections). There is a special telescope "flocking" material called Photostar designed to eliminate reflections in high end telescopes. This material is absolutely black from any angle, it's the blackest material I have even seen (or not seen :>). Kind of a super black velvet look.

For folks with internal reflection problems with bellows and/or extension tubes, Photostar is a good solution. Just Google to find more details. Mike