Correcting Noctilux focus shift

Kubilai, I used to think of myself as fairly competent with most technical aspects
of cameras and lenses, but I'm not ashamed to admit you sailed that one right over
my head. I'm sorry I have nothing contructive to add, but I felt badly about this
thread not generating any responses, so I at least wanted you to know the matter
you raised has been considered.

Regards,

Fred
 
The 72 micron 'shift' is so small as to be unnoticeable unless your camera is on a tripod shooting Tech Pan. This is something that only Mr Puts with all his testing equipment could probably detect. Anyway, who shoots a Noct at anything but F/1? The shift supposedly occurs when stopping down to f/2. I'm not sure I know how to find that aperture on this lens!

I use a Noct all the time, and that is the last thing I worry about in terms of the image quality chain. Camera or subject movement is likely to be a far greater problem, especially if you are using high speed film. Hell, using D-76 is likely to soften your images more than this!!
 
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As a matter of fact, nearly all high-aperture lenses exhibit some amount of focus shift. For instance all Summiluxes do, though somewhat less than the Noctilux. In terms of practical photography this is not very relevant. As most of Erwin Puts' tests, it is technically highly interesting, but not worth losing sleep over if you are happy with your results.
 
I don't quite get it. Even not after reading the original article. Do you mean that when you close down the aperture from f1 to f2, the plane of focus shifts? And that this corresponds to a lens extension of 72 micron?

If so, a reality check is in order.. If at this time of year you step from outside into a comfy room, the camera plus this lens combination undergoes a thermal expansion of approx. (62mm+28mm) x 17ppm/K x 25K= 38 micron assuming a brass barrel. When aluminium parts are used, this get worse (uptil about 50micron). Which although somewhat less than 72 is in the same order of magnitude.. Do people refocus in the cold? I haven't heard of it..
 
The book put out by G.Osterloh in the 80`s explains the problem. I memory serves correctly, the shift starts at 2.0 and continues to 5.6. If one were to compensate for it, the Noct will get Summicron performance at the smaller stops.
 
Ronald M said:
The book put out by G.Osterloh in the 80`s explains the problem. I memory serves correctly, the shift starts at 2.0 and continues to 5.6. If one were to compensate for it, the Noct will get Summicron performance at the smaller stops.
Click to expand...

Not really. Other lens "faults" like coma, CA, lower resolution, etc., all inherent for a super high aperture lens system will take over. The Noctilux' level of correction is lower than the Summilux and the Summilux lower than the Summicron at the same aperture. It is technically not possible to get the same level of correction for different aperture designs. Thus these lenses have different signatures.
 
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CLOSER focusing

CLOSER focusing

The question is simple and response must follow a plain binary logics

Most of these answers is noise. Talks known by everybody. Hence the topic may interest some.

Finally, in my public library I found a diagram. According to it, the positive and objective answer is : CLOSER.

Note this :
- Maybe there are circumstances when a four millimeters (f/5.6) rotation is not insignificant
- With little previous exercise, it is not difficult to make an approximative correction if you are not in a hurry situation.

Of course I don't think mysel fairly competent, and am ready to learn

Bests regards
Kubilai, grandson of Gengis

PS. I use TMAX system (4x5 and 35mm) since it exists. but think D76 deserve better advertising.
 
The answer is backward. Having owned one, I can attest to that. Personally, I wouldn't bother for the simple reason that this only improves dead center sharpness. Outside this small central core, shifting focus will dergrade field sharpness at a radius of roughly 6mm - 13mm from the center of the film at f/2. Since compositionally placement of the subject within the 'rule of thirds' is preferable, a focus shift backwards will degrade this subject sharpness.
 
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