Irregular production Sonnar lens comparison

[dexdog]

I posted a thread 6 days ago about a "fake" 5cm/1.5 Sonnar in LTM I purchased a while ago on eBay. I got the lens to focus on my Sony a7iii based on a suggestion from Sonnar Brian to grind down an LTM to M adapter. I thought it would be interesting to test the "irregular" "lens against a couple other lenses of similar vintage and heritage. The other two lenses are a genuine CZJ Sonnar of the 285 series completed in December 1945, and a 1948 ZK 5cm/1.5 assembled at the KMZ factory in USSR from barrels, mounts and lens elements seized as war reparations from the Zeiss companies. I took a bunch of pics, but for the sake of brevity will only include a sampling. Framing of the three pics are slightly different from having to readjust the tripod after swapping lenses, and also because the Irregular lens is appears to have a focal length of 5.8cm.
First bunch were taken wide open at a distance of 2 meters, straight jpeg conversion by camera. Point of focus is taller of two crystal candlesticks, using focusing peaking
285 series CZJ:


1948 ZK:


Irregular:

 

[dexdog]

This set of images were taken wide open at very close to infinity focus, I centered the frame on a truck about 90 meters from my front porch (truck is in shadows just to the right of the backwards STOP sign). I would rarely use a wide open aperture at this distance, but for testing seemed like a good place to start.
285 series CZJ:


1948 ZK:


Irregular:

 

[dexdog]

These images are a huge crop of the pics in the above post, looking at the front of the truck hidden in the shadows.

285 series CZJ:


1948 ZK:


Irregular:

 

[dexdog]

I was surprised that all lenses performed pretty well and had very similar rendering of images, especially the character of the OOF areas in the 2 meter pics. The CZJ and ZK lenses were built with Zeiss parts, and while I dont know anything where the lens elements in the irregular sonnar originated, the results look a lot like the other two.

 

[dexdog]

I have a number of the CZJ 5cm/1,5 and ZK lenses in LTM mount, and decided to use the ones that I have determined to be average in sharpness. I specifically avoided using a couple of 272 series Sonnars and one 1949 ZK that I think are outstanding, being a bit sharper than their brethren.

 

[Sonnar Brian]

The 5.8cm F1.5 is doing quite well! Someday one will fall my way.

The 14xxxx Serial Number- I still believe there is a tie in to the CZJ 5cm F1.5 prototypes. The lens was made after Zeiss was in the 2.8M mark, and before Zeiss Opton was anywhere near 1.4m. The lenses are Sonnar formula in LTM.