Pancolar 50 f1.8 blades problem

alo91 · Joined: 20 Apr 2020 Posts: 18

Hi,
I bought a Carl Zeiss Jena Pancolar 50 f1.8 MC on eBay and when I have received it I noticed that the blades don't totally ”open” after they’ve been moved.
I need to unmount the lens to allow them to come back on the totally open position.
I’ve also noticed that if I put the switch on the lens on A the blames do the same.
Is there a way to fix it?

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

I haven't disassembled this particular lens, but this usually happens due to worn spring, or additional source of friction applied to aperture mech (oil on blades is the most common one), or some combination of both.
The good news are: I'm 99% sure this level of protrusion does not even begin cutting into the light path to the sensor.
While you can see the blades, the sensor is not yet affected.

You can raytrace this in the oldest way possible: by using Eyeball MkI and looking through the back, the same way you looked trough the front.
If the aperture does not cut into light before front or rear lens collar does, while you move your eyes in an area approximately covered by the sensor you intend to use it on, it simply can't have any influence.

In other words, this problem is not significant for adapted use on digital bodies at this time and does not require fixing.

alo91 · Joined: 20 Apr 2020 Posts: 18

Thanks for your answer.
I tried to watch from the back of the lens but I'm not totally sure that the blades not cover the sensor. I have a Sony a7 III and I would like to use this lens with it.
I tried yesterday night to do some photos to see if I could see the blades in the bokeh (I don't know if this have sense).

In addition, I also notice that the blades don't make a perfect hexagon until F4
Can I be happy for a cool bokeh or is this a problem?
Would be hard to fix? I know a repairman, but he charges just to see if he can fix the lens and I don't know if he could.

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

Zamo · Joined: 08 Feb 2019 Posts: 163

Totally agree with aidajo. It does not show on the bokeh circles, so not worth to do anything. I have the very same "problem" and mine does show very slightly. I have tried to fix it but couldn't without dismantling the whole lens, so I preferred to let it be.
As for the ninja star shape up to f4, that is how it is... if you do not like it there is no way to change that.
Enjoy the lens, one of my favorites... love the colors and the smoothness of th bokeh. Not the sharpest, but sharpness is overrated imho.

alo91 · Joined: 20 Apr 2020 Posts: 18

I'm looking forward for the end of this quarantine to go out and try this lens.
About the ninja star, I Love it, I just would to be sure that it wasn't a problem too. Happy it isn't.

Thank you for your answers.