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Contax Zeiss Vario Sonnar 35-70 f3.4 Front Lens Wobble Play
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PostPosted: Fri Nov 01, 2013 5:23 pm    Post subject: Contax Zeiss Vario Sonnar 35-70 f3.4 Front Lens Wobble Play Reply with quote

I've been gathering lots of info from the forum related to Zeiss lenses. This is my first post to contribute. My C/Y Zeiss 35-70 Vario Sonnar 35-70 produces, as much discussed, very sharp images. However, sometimes not. I closely examined and found there's about 2mm play forthe front lens. Everything else works smoothly including zoom and focus. Put your 5Dm?+35-70 on the table. Grab the front lens only and try to pull and push. If there is a play about 2mm, you will have the same problem (focus shift, unstable, etc.).

I searched internet a lot and found some related post from FM. But, can't find answer. I read several post related the fragile zoom mechanism of C/Y Zeiss due to usage of nylon bushings and plastics. Since I took a part several lenses before, I decided to see inside of the 35-70 for the cure. This post is not to give you a step by step DIY. I want to share the findings because it was so hard to find the answer.

The reason for the front lens wobble or play that mess you up focus (and also shutter mechanism may shake the front lens part resulting in soft images) is a broken nylong bushing inside within the zoom barrel. It is not accessible from the back rear mounting. The lens needed to be opened.

I searched again long time to find a replacement for the nylon bushing. So far, it is impossible. So, I should agree with other's post about how fragile the zoom mechanism is. I opened up Canon 17-55L to fix the broken front barrel after its drop. All uses nylong busings I presume.

My cure was swapping bushings. When you remove the focus ring rubber, you will see two screws with nylong bushings. I replaced the broken one with one of them. Now there's no play or wobble. But I know I have to be very careful not to induce much force. Canon's internal parts are mostly plastic which is much lighter. So, the wear of the busings are much less than heavier metal barrels of 35-70. I think this is price to pay for the good optics.

So, if yours wobble or play, it is caused by a broken bushings and can be swapped like what I did. The one on the front lens will receive less force than the internal bushings due to the lighter weight of the front. So, the wear will be much less. If you are not experience, don't plan to take a part. It is relatively easy if you have some experience though.

I suspect the bushing will be cracked if the front lens got some sort of impact too based on its design. However, all other functions will be fine because there are many bushings controlling vertical and horizontal moves of the zoom and focus barrels. Like I said, only 2mm play was the problem. The 2mm, however, impacts a lot on focus and front lens shake though. Take good care of your 35-70 and ask seller if you plan to buy to do the same.... leave the camera+lens on the table, grab the front to see any play. Enjoy your T* zoom and be careful not to break any bushings since not known how to get a replacement.



PostPosted: Fri Nov 01, 2013 5:45 pm    Post subject: Re: Contax Zeiss Vario Sonnar 35-70 f3.4 Front Lens Wobble P Reply with quote

poldar12s wrote:


PostPosted: Fri Nov 01, 2013 6:48 pm    Post subject: Reply with quote

Welcome , nice entry thank you!


PostPosted: Thu Dec 05, 2013 8:19 pm    Post subject: Contax Zeiss Zooms Tested Reply with quote

I sent email to Zeiss. They responded ToCad will take of it for Contax. I sent email to ToCad for nylin bushings I need. They sent email that they only ship to Japan for repair. I asked contact in Japan. It is Kyocera. ToCad sent me contact at Kyocera. I sent email to Kyocera for parts. Kyocera responded that they stop servicing this type of CZ lenses since 2005 or 2008.

So, it is impossible to get parts for CZ lenses. So, with my hope, I purchased from ebay Yashica ML push/pull zoom (42-70mm) hoping they use the same nylin bushings. I opened up and found they don't use the same. In fact, the construction is better than 35-70 to me. So, I did CLA and took shots that I didn't plan. Surprisingly it is very sharp lens. As usual, I can't find much difference compared to T* for normal daylight shots I'm taking. I almost admit that Yashica might use the same coating by looking at landscape shots. But, low light skin tone test, as usual, reveals the difference. So, no point using non T* lenses.

With my mind for the fragile design of 35-70mm, I purchased other CZ zooms. Starting with CZ 40-80mm, 80-200mm, and 28-85mm. So, now I own most zooms other than 35-135mm. With my lens disassemble experience, I opened up all to see the inside and for CLA. Then, tested.

CZ 40-80mm:
This lens is West German made. I wanted to own German Zeiss after Hasselblad lenses (I have CF 80mm and 150mm used for my wedding jobs). A long time ago, I opened up my Hassy 503 to fix something and still remember my impression of their workmanship like a watch. It can last forever by looking at all steel springs, etc. So, impressed. Anyway, CZ 40-80mm construction is totally different from 35-70mm. No nylon bushings will be cracked by accidental impact on the front lens. CZ 28-85mm utilizes similar design. The major design difference from other Japan made Zeiss zooms is that all lense elements are kinda sealed. So, it is hard or impossible to clean the internal sealed or glued glasses with a bit of haze over time in there. But as far as construction wise, it is the best. Images produce something mystic German glass feel (not scientifically defined yet). One note is that do not talk about sharpness unless you really clean the lens internally. Do the flash light test (beam flash light through rear) to see the lens inside is really haze free.

CZ 28-85mm:
The internal design is, to me, for pro use, except the open air rear lense elements. Over time, dust and others will deposit on top of these rear compartments (three of them). Probably need to open just the rear, remove the next one by unscrew for cleaning as a routine maintenance. No big deal. Push/pull barrels use metal bushings compared to nylon for 35-70mm. Internal barrels use nylon bushings though but those are involved with less weight though. Front lens design is not like 35-70mm but close to 40-80mm that no worry for cracking bushings. I love the construction of 28-85mm. It can take heavy punishment. But, 28mm corner performance is not there yet for 30x45 print but other than that totally useable with CA correction. We value other things than sharpness, right? For serious landscape shots, just carry your wide angle prime.

CZ 80-200mm:
Pretty close to 40-80mm design.

CZ 28-70mm:
Tested one day. Small lens. At 28mm, CA is much better than 28-85. Not sure but don't want to test more than a day. That is the feel probably because too small and feel its a toy. It can be a good travel lens for lighter and smaller but with sort of Zeiss feel images. Since its new, I didn't open up. It is metal outside though. Nothing much wrong with images. Feel like a cheap Japanese kit lens but made with metal outside and with T* coating.

So, 35-70 is the most fragile design after my search. But it gives you prime lens feel from its wide angle. 40-80 is very charming and feel much analog and affection, probably because German made.


PostPosted: Wed May 24, 2017 6:21 pm    Post subject: Reply with quote

I bought a 35-70 contax vario-sonnar last week which had a wobbly front element, had wrong registration distance, and could not enter the macro mode, of fully extend out to 35mm.

Sliding off the wide rubber grip from the focus ring there are a pair of slotted screws with white plastic bushes. Having removed them the front element (group) screws off it's helix. The previous technician had reinserted the front group into the wrong set of helices, so with a repeated attempt to find the right set it now focuses almost correctly, and enters the macro mode. The wobble is probably because there are three locking screws beneath the embellishing ring, to set the correct focus. The previous technician had removed the embellishing ring first in an attempt to dismantle the lens for cleaning.

The two slotted screws with white plastic bushes are rather delicate (one had its thread crossed) and the plastic wears down a flat. The last fault with my lens is a little fungus in the rear group but it is internal and this group is sealed shut, although it is easy enough to remove. I hope this fungus is dead; my experience of rear element fungus is that it has little effect.

Anyway, happy to report that a simple repair is possible with this nice little lens.

regards, Paul


PostPosted: Thu Jun 01, 2017 7:16 pm    Post subject: Reply with quote

Quote:
Kyocera responded that they stop servicing this type of CZ lenses since 2005 or 2008

bad news, maybe 3d printer can print the missing bushing


Quote:
If you are not experience, don't plan to take a part. It is relatively easy if you have some experience though.

if you have pics of disassembly the 35-70, it would be useful
I would like to clean mine


PostPosted: Sat Jul 01, 2017 4:07 pm    Post subject: Reply with quote




PostPosted: Thu Mar 25, 2021 10:22 am    Post subject: Reply with quote

Hi Smile

Does anyone know how to take the front group off? I've got the exact same problem and would like to change the bushing. There really is not much information about disassembly of this lens available.

I will probably make a new bushing out of bronze, if it's not too small for the lathe.

Thanks!


PostPosted: Thu Mar 25, 2021 12:22 pm    Post subject: Reply with quote

If it should, you can just make an hole in a brass rod, then cut it longitudinally, so that it will maintain a smaller rod in the chuck; like on this video: https://youtu.be/oJNfsMS_OG0

marius.zaech wrote:
Hi Smile

Does anyone know how to take the front group off? I've got the exact same problem and would like to change the bushing. There really is not much information about disassembly of this lens available.

I will probably make a new bushing out of bronze, if it's not too small for the lathe.

Thanks!