M42 adapter problem?

Hi, i have a nikon d5100 and helios 44m-4 lens. I ordered an adpater with correction glass but when i put it on the lens it seems like it's too short and i can't rotate the lens to infinity because when i try the lens hits the adapters glass.

Did a little research on the M42 adaptor. It may not be ideal for your Nikon. I found this in Wikipedia, "M42 adaptors work best on bodies with a flange depth less than or equal to the M42's flange depth, which includes the popular Canon EF-mount, the Pentax K-mount, the Minolta/Konica Minolta/Sony A-mount, the Sony E-mount, the Samsung NX mount and the Four Thirds System including the Micro Four Thirds system. This allows the lens to be physically mounted the correct distance from the film or sensor, retaining the original focus range of the lens without the use of correction optics."

You'll note that Nikon is not mentioned. Maybe the flange depth is your problem.

Most likely, your problem lies with the Helios. Although a good lens optically speaking, its design has altered quite a few times over the years, and even within one and the same generation of this lens the construction of the lens barrel and mount tolerances may vary considerably.

Unlike the (more modern) lens mounts of other camera brands, Nikon's F-mount that has been in use since the late fifties, requires an M42 adapter with an extra lens element to be able to focus to infinity using an M42 lens.
This should not be a problem with most M42 lenses which don't have rear optical elements that protrude too far into the camera's body, but the Helios' design was never intended to be compact or refined, so the designers didn't bother with rear optical lens element tolerances as long as the Helios could fit the Zenit camera bodies for which it was primarily intended.

I don't think this problem can be solved, at least not economicall, but you might consider using another M42 50mm lens, such as the (excellent btw) M42 pentax standard lenses, or the ubiquitous praktica optics.