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Archive 2013 · Infinity Focus shift on Planar 100 f2?
  
 
Ezmo
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p.1 #1 · Infinity Focus shift on Planar 100 f2?


I bought a Contax 100 f/2 from Adorama a couple months ago and I've really liked it so far but recently I noticed that if I shake or twist it lightly when it isn't attached to the body there's a shaking sound that I believe is the aperture control that juts out of the rear of the lens. Now the infinity focus is miscalibrated. Focusing at infinity on the lens only focuses to about 40 ft away and I can't focus any further than that. I'm wondering if there's a way to fix this or a way to get it serviced.

Has anyone had similar issues either with this lens or others?

Thanks.



Jun 14, 2013 at 03:05 PM
edwardkaraa
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p.1 #2 · Infinity Focus shift on Planar 100 f2?


This is a typical Zeiss calibration philosophy. Lenses are calibrated to reach infinity at f/5.6-f/8. You can adjust the lens to reach infinity at f/2, but then you would have to pull the focus by 1-2 mm when stopped down.


Jun 14, 2013 at 05:59 PM
Toothwalker
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p.1 #3 · Infinity Focus shift on Planar 100 f2?


Ezmo wrote:
I bought a Contax 100 f/2 from Adorama a couple months ago and I've really liked it so far but recently I noticed that if I shake or twist it lightly when it isn't attached to the body there's a shaking sound that I believe is the aperture control that juts out of the rear of the lens. Now the infinity focus is miscalibrated. Focusing at infinity on the lens only focuses to about 40 ft away and I can't focus any further than that. I'm wondering if there's a way to fix this or a way to get it
...Show more

You are hearing a ball bearing. That is perfectly normal.

The calibration issue is unfortunately not uncommon. I had two 100/2 Planars with that problem. Fortunately, it is easily fixed. If you strip off the rubber grip, you will see six screws. After loosening them a bit, with a proper screwdriver, you can recalibrate infinity focus simply by rotating the barrel and fastening the screws again.






Jun 14, 2013 at 08:22 PM
Ezmo
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p.1 #4 · Infinity Focus shift on Planar 100 f2?


Thanks, is there a good tutorial about how to remove the rubber grip?

While it gets closer to infinity focus stopped down just because of the expanding depth of field it's still way off at f/5.6 and by f/2 I can't even shoot across a residential street. When I bought it I was at least able to attain infinity focus using live view at most every aperture.



Jun 14, 2013 at 08:32 PM
Toothwalker
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p.1 #5 · Infinity Focus shift on Planar 100 f2?


Ezmo wrote:
Thanks, is there a good tutorial about how to remove the rubber grip?


You can lift it over the edge and just slide it off.




Jun 15, 2013 at 09:43 AM
JimBuchanan
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p.1 #6 · Infinity Focus shift on Planar 100 f2?


edwardkaraa wrote:
This is a typical Zeiss calibration philosophy. Lenses are calibrated to reach infinity at f/5.6-f/8. You can adjust the lens to reach infinity at f/2, but then you would have to pull the focus by 1-2 mm when stopped down.


I'm not quite sure I understand this statement. Even for a M mount lens this doesn't make sense.

A lens that is calibrated to reach infinity at f/5,6 - f/8, is not infinity adjusted. A properly infinity adjusted lens is one that gives the sharpest infinity image at wide open. The C/Y 100/2.0 has the traditional infinity adjustment screws as has been mentioned.



Jun 15, 2013 at 07:23 PM
edwardkaraa
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p.1 #7 · Infinity Focus shift on Planar 100 f2?


JimBuchanan wrote:
I'm not quite sure I understand this statement. Even for a M mount lens this doesn't make sense.

A lens that is calibrated to reach infinity at f/5,6 - f/8, is not infinity adjusted. A properly infinity adjusted lens is one that gives the sharpest infinity image at wide open. The C/Y 100/2.0 has the traditional infinity adjustment screws as has been mentioned.


That is for lenses with some focus shift, and all lenses faster than f/2.8 do have some minor focus shift no matter how well corrected they are. Trust me, I've been shooting Zeiss for 25 years.



Jun 15, 2013 at 07:56 PM
 

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Ezmo
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p.1 #8 · Infinity Focus shift on Planar 100 f2?


Toothwalker wrote:
You can lift it over the edge and just slide it off.




Thanks, I didn't realize how the rubber was attached to the barrel and that it could just slip off like that.



Jun 17, 2013 at 12:59 AM
mpmendenhall
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p.1 #9 · Infinity Focus shift on Planar 100 f2?


edwardkaraa wrote:
[That is for lenses with some focus shift, and all lenses faster than f/2.8 do have some minor focus shift no matter how well corrected they are. Trust me, I've been shooting Zeiss for 25 years.


Focusing at 40ft instead of infinity isn't a minor correction for focus shift; it's a huge offset for the focus of the 100/2: not 1-2mm of focus ring adjustment, but ~15; way outside what the 100/2 should be doing.



Jun 17, 2013 at 01:09 AM
edwardkaraa
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p.1 #10 · Infinity Focus shift on Planar 100 f2?


mpmendenhall wrote:
Focusing at 40ft instead of infinity isn't a minor correction for focus shift; it's a huge offset for the focus of the 100/2: not 1-2mm of focus ring adjustment, but ~15; way outside what the 100/2 should be doing.


Yes, you're right. For some reason I read it as 40 m.



Jun 17, 2013 at 02:19 AM
Ezmo
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p.1 #11 · Infinity Focus shift on Planar 100 f2?


Toothwalker wrote:
The calibration issue is unfortunately not uncommon. I had two 100/2 Planars with that problem. Fortunately, it is easily fixed. If you strip off the rubber grip, you will see six screws. After loosening them a bit, with a proper screwdriver, you can recalibrate infinity focus simply by rotating the barrel and fastening the screws again.




Is there a particular screwdriver I should be using. I'm trying with one from an eyeglass repair kit that fits the phillips thread of the lens but the screws are in incredibly tightly and I haven't been able to move them and I don't want to force it too hard for fear of stripping them.



Jun 21, 2013 at 03:51 PM
Vox Sciurorum
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p.1 #12 · Infinity Focus shift on Planar 100 f2?


Toothwalker wrote:
The calibration issue is unfortunately not uncommon. I had two 100/2 Planars with that problem. Fortunately, it is easily fixed. If you strip off the rubber grip, you will see six screws. After loosening them a bit, with a proper screwdriver, you can recalibrate infinity focus simply by rotating the barrel and fastening the screws again.


Do the screws need to be precisely adjusted to avoid misalignment, or do they only hold the infinity stop in place?



Jun 21, 2013 at 09:34 PM
Toothwalker
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p.1 #13 · Infinity Focus shift on Planar 100 f2?


Ezmo wrote:
Is there a particular screwdriver I should be using. I'm trying with one from an eyeglass repair kit that fits the phillips thread of the lens but the screws are in incredibly tightly and I haven't been able to move them and I don't want to force it too hard for fear of stripping them.


I asked the same question many years ago, and as a result I bought a set of Wiha PicoFinish 261 P screwdrivers. The one that I successfully used was either the PH 0x50 or the PH 00x40 model. I cannot check it, because I sold the lens a few months ago. I think the 0x50 might be the one.

Vox Sciurorum wrote:
Do the screws need to be precisely adjusted to avoid misalignment, or do they only hold the infinity stop in place?


They only hold the infinity stop in place. You can adjust the barrel to focus beyond infinity if you like.



Jun 21, 2013 at 11:08 PM





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