Cdouthitt wrote:
For my test, I'll shoot from 2 vantage points, both at the minimum focus distances with 4 shots, each at various f stops (f2.5, f5.6, f11, f16). Would that be helpful...if not, it might just be an interesting study to see the affects of the helicoid on a lens.
This is the adaptor that I'm using.
http://www.amazon.com/Rainbowimaging-Adapter-Focusing-Helicoid-Panasonic/dp/B00E7HRGCC/ref=sr_1_1?ie=UTF8&qid=1395404459&sr=8-1&keywords=m42+to+m43+helicoid
Give it a try. I'm all for interesting studies. Is that extension tube strictly manual?