yashinon 5cm lens on nex question

venkys52 · Joined: 05 Apr 2011 Posts: 8

I got a yashinon 5cm f2 lens recently.

I have 2 questions,

1.
I see the aperture blades don't move even if it is rotated to f16 - it is always wide open.
I tried getting the "silver" knob to close and open while rotating the aperture ring still it remains open.
Am I doing some thing wrong?

2.
If I mount this on the nex with the m42 adapter, I see that the focusing ring doesn't move beyond 3m.
Is anyone else having this issue? It appears that this element protrudes back when ring is turned beyond 3m and the adapter is blocking it?
I use the adapter got from rainbow imaging.

Thanks for the help

Smoli4 · Expire: 2013-06-07

if there an outo/manual switch on the lens, it should be on manual or M for the aperture blade to move accordingly, if there isnt such a swich on the lens then you should look for a stop pin, that has to be located at the back side of the lens and when the aperture is set when you press that pin the blades should jump.
if hat doesnt happen there could a couple of reasons, but you should try looking for those thing in your lens and see if thy react accordingly

if the focus ring alligns at 3M when focused to infinity, or as you said the rear element protrudes untill a halt, then it could be that the lens was dissasembled at some point of its life, and reassembled without care for small details, the important thing to check in this case, is weather you can recive focus at infinity or not, and if you do, then it means that the lens was reassembled carelesly and the distance indicator ring need to be re aligned. really not a big deal.

adent · Joined: 06 Oct 2011 Posts: 304 Location: United States

Does the lens look like this? (ignore the EOS adapter and cover)

If so the little lever on the side puts the lens in auto mode when you cock it. Pushing on the pin on the mount should take it out of auto and put in manual where you can see the blades move. I also had a problem getting mine to focus correctly. I had to switch adapters and then it would work fine. Does it move through it's focus range OK when you have the adapter off of it?

venkys52 · Joined: 05 Apr 2011 Posts: 8

Thanks, I have the same model of the lens.

I tried moving the lever and aperture still doesn't move.
But it is in mint condition with no scratches.

Outside of the adapter, the focus ring goes all the way to infinity.

. Maybe its a faulty lens Sad

. For now just shoot wide open.

Wink

adent · Joined: 06 Oct 2011 Posts: 304 Location: United States

On the mount of the lens there is a little pin sticking out. If you push this pin in you should get control of your aperture. You will have control as long as you don't cock the little lever on the side again.

venkys52 · Joined: 05 Apr 2011 Posts: 8

hi adent,

Thanks for the time with the photo - I tried again with your suggestion - still its stuck.
I will try to get another lens and see if it works.

If I open it is it an easy fix?

Venky

adent · Joined: 06 Oct 2011 Posts: 304 Location: United States

I will have to defer to others on that question. I have never had mine apart. If the blades are stuck open then it may be more than just an open and clean situation.