[Arvid]

It also looks underexposed to me. Helios lenses are most vulnerable to a loss of contrast when shot fully open. Judging from the depth of field in that first picture, the aperture must have been rather small. Depending on what version of that lens you were using, it can get a little fiddly, especially when you set an aperture, adjust the shutter speed on a manual camera and then shift the aperture ring by accident after that while not realizing it, as you are concentrating on the composition of the photo you are about to take.

I own a 44-2 and a 44k lens and I use them both on a digital and analog bodies. No hood. No filter, except for when I am shooting black and white film and use colored filters (crucify me, if you want to). Never did any of my images affected by stray light look anything like this. As someone mentioned above, for some reason it must have been underexposed and if this is a lab scan, their computer algorithms probably gave you this. If you scanned the negative yourself, better do it again instead of trying to get something out of that jpeg as was demonstrated above. In my honest opinion these two attempts don't really offer an improvement above the original picture that you posted.

[farhaddad]

I can't help you with the what went wrong part (Which doesn't matter since everyone else here did) but I just wanted to say that I actually like the shot. It has a vintage look to it. I know you didn't want that to happen but sometimes you can take advantage of errors. Yes, the offset needs more contrast but you can easily fix that. Here is a quick fix.