For those who have and are learning how to use, or are in the market for, a 35 mm depth of field adapter... If you are not from a photography background, then you may need to take a bit of time to learn about precisely what lenses you will want to accompany your adapter (make sure you buy the proper lenses for your adapter mount of course).
Anyway, for those starting out, these are just a few links that will explain the differences between the various types of lens and what they will do for your perspective, depth of field and shot composition...
LENS SELECTION at PhotographyTips.com
LENS CHOICE TIPS at RomanZolin
The WIDE ANGLE LENS by RomanZolin
LENS USES at Luminous-Landscape
UNDERSTANDING DEPTH OF FIELD at Cambridge in Colour
APERTURE AND SHUTTER SETTINGS at PhotographyCourse.net
USING DIFFERENT LENSES at All-Things-Photography
A PODCAST by Redrock on Lens Selection for their Adapters
And as for Forum Threads...
NEWB QUESTION at PhotoTakers.com
STICKY at DVXuser.com about Lenses for your 35 mm Adapter
And here is ManualFocus, a good FORUM on Lenses...