Gordon at CameraLabs.com has posted a nice video overview of the Pentax 40mm and 70mm Limiteds, which, among other things, gives you the best idea short of seeing them in person just how small these lenses actually are. It's part of a more complete suite of Pentax reviews.
Posted by: MIKE JOHNSTON, thanks to Eolake
Featured Comment by Jeff Kott: "I recently acquired the K10D and the six Pentax limited lenses. After about a month of use I will probably be selling the DA 40 and DA 70 because I find I am using the 43mm ƒ/1.8 and 77mm ƒ/1.8 instead.
The 43/1.8 is not that much bigger than the DA 40, but you gain over a full stop and the 43mm is sharper than the 40mm at ƒ/2.8. I have started using the lens hood from the DA 40mm on the 43mm. The DA 40mm lens hood makes the 43mm very compact and it works great with the APS-C sensor. My never leave home without it camera is the K10D plus 43mm with the DA 40mm lens hood attached in a Lowepro Sliplock 50 pouch. BTW, the DA 40mm lens hood is available separaely from B&H.
"Similarly, the 77/1.8 Limited isn't that much bigger than the DA 70mm, but you get an extra stop.
"The 40mm and 70mm focus a little quicker than the 43mm and 77mm and have the quick shift focus option. But, for a minimal increase in size, I'll find myself going for the wider aperture of the 43mm and 77mm."