No the pentax adaptor sits flush with the body/lens mount. It lets the lens sit flush against the mount.
I just did a test with the helios and vivitar 135 and they are both off at infinity... (the fence in the backyard is blurry, and can not be focused.
With the 58mm helios I have about 18ft of usable focus range. Anything past that is blurry.
It would be great if you could get the mods to let you change the title of the thread as it might confuse some with the "best" in the title.
It is usable, but not the best for all situations. Unfortunately, IMHO the best is still the pricey original Pentax version.
I am one of the cheapest guys with a camera... I cant wrap my mind around 700 dollars for a DA 55 when I have a 20 dollar Helios. But when it comes to this adaptor... there is no question the original is worth the extra money...
PentaxWebstore Mount Adapter B (35mm Screwmount to Bayonet)