I purchased this tele for astronomy purposes. It’s a pre-AIS lens from the early seventies, labeled “ED”.
Check all my images made with it below. Usually I have an external IDAS LPS attached which brings the lens to F3.5, however I’m not sure what this does to the star quality.
There will be no diffraction spikes if the lens itself is set to F 2.8. However I tempt to use F4 or even F5.6 to increase sharpeness. I find focusing difficult as the exact focus point for infinity is not matching the visual best point when using live view to focus. This particular lens also has a tendence to sag away, loosing focus. So it needs to be clamped against a dovetail or equivalent fixture.
It has some residual blue-purple chromatic abberation in the corners
See all further comments on the excellent article that Jerry Lodriguss made:
Images with this lens: