And so...variable optimization of c-sonnar (tutorial)

elmer3.5

elmer3.5

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Hi, many folks asked me how to make the trick i use ion my c-sonnar in order to get both opyimizations by moving the rear element of the lens.

I´ve tried to make a tutorial that i posted yesterday on my flickr account site.

http://www.flickr.com/photos/enzo-betinyani/

Visit and if you have any questions i´ll try to answer them asap.

I´ve meade this trick because almost every rf lenses i´ve had or have did show some focus shift or a wrong focus setting.
Since i´m in chile nobody could help me out with these troubles so i had to learn how to fix them.

Hope some of you will try this and benefit from it.

Bye!
 
This looks very interesting! I was considering sending my sonnar to CZ to have it optimised for 1.5 instead of 2.8 which would cost 130 euro, but with this it might not be necessary.. thanks for the tip!
 
Thankyou for posting.

By moving the rear element, you are changing the focal length of the lens. Focus shift when stopping down effectively shortens the focal length, ever so slightly- shifting actual focus towards infinity.

How is infinity focus at each of the positions?
 
Hi,

Brian, on both settings infinity is OK.

nakedcellist, it is possible to do so.

rxmd, the thickness of the shim is: 0.01 mm

Another strong reason to do this arrangement is the fact that the lens in f1.5 optimization is virtually unusable at f2.8 or f5.6.
The shifting is so brutal that you simply can´t overcome it to actual shooting,

The best optimization is 2.8!
You can simply move a liitle bit the lens to infinity and achieve perfect focus wide open everytime.
On the contrary (opt @ f1.5) the lens focus behind subject just too much it´s unusable for anykind of precise shooting from f2.8 to 5.6 (even at f16 in certain cases)

Old sonnars are all set to f2.8!
Because the bokeh fashion of present years, zeiss did the f1.5 optimization, i can´t find another better reason for this.

Cheers!
 
elmer3.5 said:
The best optimization is 2.8!
You can simply move a liitle bit the lens to infinity and achieve perfect focus wide open everytime.
On the contrary (opt @ f1.5) the lens focus behind subject just too much it´s unusable for anykind of precise shooting from f2.8 to 5.6 (even at f16 in certain cases)
Click to expand...

I just move focus a bit closer when shooting at middle apertures and it works on my f1.5 optimized Sonnar, no problem.

And I really don't understand how correcting for focus shift would be any easier when you are working with shallower DOF?
 
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