Pentax SMC-M macro f/4 & el-nikkor 50 f/2.8
This is a further comparison I did to follow up my thread at pentaxforums.com which compares a few Pentax 28 & 50 lenses reversed. The el-nikkor is one of the finest enlarging lenses that you can buy for macro reversal, sharp, contrasty and affordable. It is the go-to lens for a bunch of people myself included. But, I was pleasantly surprised when I tested the Pentax-M macro 50mm f/4 because the quality compares well.
Overall the Pentax loses about half a stop or so of light I'd say, but by upping the contrast in PP you actually get something that does well. In this case, the flatness of the older lens actually works in the photographer's favour because it means the dynamic range in the final shot isn't as tricky. The el-nikkor, being so fine, has presented me with hard-to-manage combinations of blown whites, muddy darks, or both. Your comments/thoughts would be appreciated. Both shots stacked using dmap ER=20, SR=10, CTPCT=20. El-nikkor is the newer version. Both shots @5.6, identical light & in-cam settings.