Another old Russian lens: Helios 44M-7

 The Helios 44M-7 is a 58mm f/2 screw-mount lens from near the end of the Soviet era.  Based on the serial number, this copy was likely manufactured in 1992.  I tested this lens with a Sony A7iii camera.  Like the previous tests with the 50mm Super-Takumar f/1.4 and Industar f/3.5 lenses, the results here show that this lens is not well-suited for astrophotography (and there was no reason to expect otherwise). 

Here is the lens mounted on the A7iii:

 

The following star images were obtained on 31 Oct.  There was some fairly strong red airglow that night, but it has been balanced out in post-processing.  Accurate focus was confirmed with a Bahtinov mask.

f/2.0

f/2.8

f/4.0

 This lens is horrible (for stars) wide open, just like the Super-Takumar 50mm.  It starts to become acceptable at f/4 in the center of the frame, but astigmatism is still present around the edges.

Here is a crop from the last image, at f/4:

 This shows three stars in the handle of the Big Dipper over the ridge line of Bristol Head.  Just up and left of center is a fuzzy patch which is the galaxy M101, the "Pinwheel Galaxy".  Based on star separations in this image, the true focal length for this lens is calculated to be 59.0 mm.

FYI, it seems Blogger has reverted back to serving up the original files, with correct filenames, for images uploaded directly from a computer.  I hope this persists.