[excanonfd]

My latest acquisition from eBay (Carl Zeiss Jena 180mm f2.8 Pentacon Six Mount, 5 digit serial#) has problems. Either the aperture blades are stuck in the wide open position or someone removed the diaphragm assembly altogether. I am hoping the problem is the former, because at least that can be repaired. I am trying to determine the problem is not the latter - if any forum member has this lens of any variety (Zebra, Star-Wars, or MC), can he or she shine a small flashlight through the lens and move the aperture ring back and forth. I would like to see where the aperture blades are located, the colour of the blades and whether the blades are at all visible when the lens is wide open.

Here is a picture of my lens where I think the aperture blades are located, if anyone can either confirm or refute this, I can at least take the next step, keep or return the lens. I am sure many here are advising that I return the lens but cosmetically and optically the lens is near flawless, that I would like to keep this lens if possible.

Thanks,

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Last edited by excanonfd; 06-15-2011 at 09:01 PM.

[RawheaD]

The Sonnar is a pretty easy lens to take apart, all the way down to the aperture mechanism. You should look for disassembly guide and try it out.

My guess is that it's stuck, and you will have about 40% chance of fixing it; if it can't be fixed, you'd need to get a replacement, perhaps from an otherwise junk Sonnar. Good luck, it is one of the best lenses out there.

[georgweb]

I'd second Rawheads assumptions and try to shorten my always lengthy answers .-)

1.) Try the lens out wide open on your camera. If you like testing, do the brick wall and tripod and compare with similar lenses. As you can see here, Mother of Lens Tests there is quite some variety in the CZJ MC 180/2.8 lenses (assuming that you have such lens). If you give a damn for the brick wall do the nice portrait/flower shot with the sunny highlight background blur and enjoy .-) This lens won the Bokeh Test for a reason.

2.) If that was to your liking, disassemble the lens from the back. Take pictures of the lens before you start and from every step you do. I do not have the exact same lens as you, but again would say Rawhead is spot on. I have done this on the 180 Zebra and the MC300 and both were the easiest you can get.

Here's why I say like I do:
Zebra 180: does not look like your MC version, no spring to be seen from front or back.


MC300: Looks like your design. No blades seen when full open


Here come the blades:


Now there has to be some grain of salt added, so here it is: While the Zebra 180 was easy-peasy to disass, clean and put back together (and enjoy), the MC300 is stuck in the queue due to reassembly problems. This lens has a double helicoid and I did not take all those pictures like recommended in 2.) Still, I would expect your lens to have only one helicoid and you could also try just to take the back off, unscrew the back lens unit (which I could do with my bare hands on the Zebra) and get to the aperture and get it going with some zipper fluid.

I would never expect someone to take out a whole aperture unit, but rarely some bad tinkering on a lens and in the overwhelming majority the omnipresent gummed up blades.

Good luck, Georg
PS: Looking at your picture again I guess I see the round end of one aperture blade (light blue) in the 7.30 o'clock position

[excanonfd]

The Sonnar is a pretty easy lens to take apart, all the way down to the aperture mechanism. You should look for disassembly guide and try it out.

My guess is that it's stuck, and you will have about 40% chance of fixing it; if it can't be fixed, you'd need to get a replacement, perhaps from an otherwise junk Sonnar. Good luck, it is one of the best lenses out there.

Thanks RawHead,

Only 40% chance of fixing the lens - I think I will try to improve the odds a little bit by asking Ralph Innes to have a go at it's repair.

[excanonfd]

I'd second Rawheads assumptions and try to shorten my always lengthy answers .-)

1.) Try the lens out wide open on your camera. If you like testing, do the brick wall and tripod and compare with similar lenses. As you can see here, Mother of Lens Tests there is quite some variety in the CZJ MC 180/2.8 lenses (assuming that you have such lens). If you give a damn for the brick wall do the nice portrait/flower shot with the sunny highlight background blur and enjoy .-) This lens won the Bokeh Test for a reason.

2.) If that was to your liking, disassemble the lens from the back. Take pictures of the lens before you start and from every step you do. I do not have the exact same lens as you, but again would say Rawhead is spot on. I have done this on the 180 Zebra and the MC300 and both were the easiest you can get.

Here's why I say like I do:
Zebra 180: does not look like your MC version, no spring to be seen from front or back.


MC300: Looks like your design. No blades seen when full open


Here come the blades:


Now there has to be some grain of salt added, so here it is: While the Zebra 180 was easy-peasy to disass, clean and put back together (and enjoy), the MC300 is stuck in the queue due to reassembly problems. This lens has a double helicoid and I did not take all those pictures like recommended in 2.) Still, I would expect your lens to have only one helicoid and you could also try just to take the back off, unscrew the back lens unit (which I could do with my bare hands on the Zebra) and get to the aperture and get it going with some zipper fluid.

I would never expect someone to take out a whole aperture unit, but rarely some bad tinkering on a lens and in the overwhelming majority the omnipresent gummed up blades.

Good luck, Georg
PS: Looking at your picture again I guess I see the round end of one aperture blade (light blue) in the 7.30 o'clock position

Hi Georg,

Thanks very much for the pictures, they seem to confirm to me that my lens has stuck apertures rather than missing altogether, now I can think about getting the lens repaired rather than returning it. I have liked this lens even before I bought it and reluctant to return it even with the stuck aperture blades. I have the MC300 that I got with my P645 and I have been looking for a MC180 since then. I will ask Ralph Innes to handle the repair because my eyesight isn't up to par to handle a lens repair.

Thanks,