Nokton 50mm 1.5 Focus shift?!?!?!

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AncientCityPhoto

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I was wondering if anyone has experienced focus shift on this lens.

I decided to order one brand new. I have ended up comparing 4 lenses. All new in box.

All 4 demonstrate focus shift. 2 were pretty extreme to the point that by f4 my original focus point was very out of focus and blurred with focus being sharp well behind it.

1 copy shifted back all the way through the range until f/8 or so.

1 copy was perfect until F/2.8. It then shifted back a little bit, but stayed there for the rest of the range. This was the best of the 4 copies.

I am going to keep that copy and have the focus adjusted forward overall a little so even when it shifts I should still be in my range of focus based on where I designate. I can live with that.

I hear so much good about this lens. Yes, it looks great, and I am loving the images from it, but has anyone else dealt with focus shift? I am used to hearing that this is not a shifting lens.

I was testing carefully on a lensalign system. Obviously I can't adjust my own lenses, but it has so far been accurate in revealing if I have a lens or body out of spec and for what problem.
 
I am fairly certain that the Nokton 50mm f1.5 and the c-sonnar 1.5 exhibit the exact same focus shift, and are similar designs by the same manufacturer. There was a thread up yesterday about the focus shifting in the c-sonnar that you should check out.
 
Nope. I had one, it never focus shifted. The f1.1 version does have it but the f1.5 doesn't. The use of aspheric elements in the f1.5 version is supposed to eliminate shift. I think it works based on the one I had.
 
I put one on magnified live view on a GF-1, and focus shifted about the same as a 50mm pre-aspherical. Pretty obvious at close focus.
 
On the copy I am keeping this issue is worst at minimum focus distance. Of course I do a lot of my shooting at minimum focus distance. From 2 meters on back, the focus shift in this copy was not as bad in real world shots. It is definitely noticeable closer than 2 meters though.

The other copies I tried were ridiculous. Seriously unusable from F/2.5 on back.

Otherwise, the lenses were great. Where the focus was on were incredibly sharp, nice contrast, and wonderful colors. I'de love a copy that didn't shift period...but I can live with minimal shift that can be adjusted to stay within range and never have my true focus point out side the depth of field.
 
The ltm mount is nice since one can lap or shim an adapter (if needed) so that it has a slight front focus at f1.4 close up, and objects will be in the acceptably sharp zone at smaller apertures. This was how mine was with my adapter, and I never noticed focus problems.
 
I have to say that I've seen this sort of discussion about several CV lenses and have never seen it myself.

I have LTM 15mm, M 40mm f/1.4, ltm 35mm f/2.5 pancake, and a new M Nokton f/1.1. My experience with the latter is it's dead on, but down the road I'll see. But I've never had this problem with the CV lenses.

One of my CV lenses is from a place I trust, but not Steve Gandy, who I think is seriously good. He takes CV issues more seriously, the price is about the same, generally at least as good, so why not.

The other people I deal with also will take back things I find to be defective. I have a track record with most and don't invoke it short of a problem.

If you're havig a problem, You should immediately contact the seller and say you have a problem and give them a chance to address it. I will say I work to be sure I'm not imagining the problem, but if you're not sure, send it back. There's a process.

The deal rhas to deal with the maker (marketer) but honestly, they'd rather have more business from you than sell your crap. Which in my view, agrees with CV policy.
 
Chriscrawfordphoto said:
I know krosya did it with a 35mm Ultron, but I cant remember who did it to the 50 Nokton. Search here, it was on RFF
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I did both Ultron 35/1.7 and Nokton 50/1.5 - in both cases worked great. Here is Nokton thread :
http://www.rangefinderforum.com/forums/showthread.php?t=95660&highlight=nokton

And Ultron is here:
http://www.rangefinderforum.com/forums/showthread.php?t=97167&highlight=nokton

BTW, never noticed any focus shift with either, but that just may be me ;)
 
jsrockit said:
I did not see shift in this lens... and I used it extensively wide open. Perhaps user error?
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None of the lenses I tested shifted wide open. They were all fine. Most were fine at f2 as well. The major shift only started after that. What was in focus would move backwards of the focus position with each stop after f2. If I shot only wide open, I never old have noticed anything.

I be Ed my lenses to be accurate wide open...but I do shoot at whatever aperture is necessary for what is am trying to achieve. If I cant focus on my subject at a certain aperture because focus no longer lies where the rangefinder tells me, the lens is unusable. It becomes a toy, versus a tool. My clients won't take an out of focus shot because some lenses just focus shift.

This has been the one issue that has forced me to be a lot more critical with rangefinder lenses and which ones I choose to own.
 
AncientCityPhoto said:
None of the lenses I tested shifted wide open. They were all fine. Most were fine at f2 as well. The major shift only started after that. What was in focus would move backwards of the focus position with each stop after f2. If I shot only wide open, I never old have noticed anything.
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I guess I shouldn't have said specifcally wide open, but I meant from 1.5 to 2.8 or so. It's weird since its a planar design and this is the first documented sign of it having shift. Perhaps you have a lemon.
 
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