Nikon 50 f1,2 not so sharp

Phalbert · Joined: 17 May 2009 Posts: 359 Location: Namibia

Hi. I got this lens in exchange of others and I compared it immediately to my 55mm f 1,2 AI only to realise that @ 1,2 the 55mm is sharper AND has more contrast than the 50. I understand it is supposed to be the opposite. Now I see that the 50 has been knocked because a small dent on the filter ring has been fixed. It has also been opened because the fastening things (slots ?) on the front ring show some work on them. There is no other external sign of work or damage, but the aperture ring doesn't turn as it should either. It feel a bit hard and "sticky" . I realise the lens has been worked upon, but now my question is, is it possible to misalign something while fixing a dent, in such a way that the lens doesn't perform anymore the way it should ? And should I send it out again to be checked ? Thanks a lot for reading.

cooltouch · Joined: 15 Jan 2009 Posts: 9097 Location: Houston, Texas

I've never worked on this lens, but with other lenses I've worked on, I've found that there is usually only one way for an element to rest in its receptacle, such that collimation shouldn't be a problem. But there's always the chance that this isn't always the case. Besides, if it's been opened up to the point that elements have been removed, it's at least remotely possible that one or more may have been flipped around.

If it were mine, I'd take it to a good repair tech and have him take a look at it.

Phalbert · Joined: 17 May 2009 Posts: 359 Location: Namibia

Thank you Michael. I think you're right about the check thing. This is always frustrating here since the workshops are far and beyond our borders. I'm gonna wait a bit.

aidaho · Joined: 29 Apr 2018 Posts: 456 Location: Ukraine

Phalbert · Joined: 17 May 2009 Posts: 359 Location: Namibia

Hi Aidaho. If it is so, then it's bad news indeed... Before sending it somewhere I think I'll talk to the technician first. Maybe that is the reason why the previous owner let it go easily... Thanks for your thought.

cooltouch · Joined: 15 Jan 2009 Posts: 9097 Location: Houston, Texas

Ah, yes, that's something that hadn't occurred to me, but which I now think is a good possibility. It might be that when that lens was bumped, if it were bumped hard enough and at the right angle, the lens barrel itself might have gotten tweaked. You mentioned a rough spot in the focusing. This might be symptomatic. If the barrel was distorted, no amount of collimation will correct the problem. If this is indeed the case, the only way to salvage the situation that I can see would be to swap the glass from yours into another lens that might have bad glass but be otherwise OK.