My SLR Magic HyperPrime LM 50mm T0.95 Review!

Started Oct 12, 2012 | Discussions thread
BSweeney Contributing Member • Posts: 903
Re: My SLR Magic HyperPrime LM 50mm T0.95 Review!

The Nokton 50/1.5 uses an aspherical surface to reduce focus shift, I am surprised the 50/1.1 Nokton did not. The 50/1.5 used wide-open matches the resolution of my Leica M9, will try it on the M Monochrom when received. My Nokton 50/1.1 back-focused when received, as did the 35/1.2 Nokton. I corrected the back-focus on both, and now they are quite good on the M9. A user reported having front-focus issues with his RF coupled SLRMagic 50/0.95 lens that was corrected by the company. My reply: "Milesab's lens was front focusing, meaning the optics were too far from the image plane to agree with the rangefinder. If the lens was calibrated as free-standing, that means it "leans forward" and the RF image registers a closer focus distance than when the lens is supported by the photographer. As the lens is calibrated in this position, the focus will be correct. As the lens weight is balanced, the RF pickup is pushed backwards, towards infinity. This means the photographer will move the focus of the lens Closer for the RF to agree with it. It should then front-focus. This is one possible explanation. If the RF image is observed to move as the lens is handled on the camera, then it is the reason for focus error. It could be the weight of the lens causing it to bow down, or it could be slop in the helical. From memory of the misfocused image, it looked like 0.02mm shift in the RF calibration.
The lens is an 11-element, all spherical surfaces. It is very long, meaning the light bundles travel through the lens at more shallow angles than they would in a "squat" lens like the Canon 50/0.95. This could be for two reasons: accommodate a digital sensor, and reduce spherical aberration/focus shift. BUT: this means the lens is long, and heavy and might not maintain good RF calibration. If it is a weight issue, not much can be done. If it is slop in the helical, then one with tighter tolerances is required.
There was an earlier 9 element version of this lens, shorter and lighter. This design should be revisited."

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