Originally posted by nater In that review it says under Specifications "other features 1:1 macro adapter", which is why people are saying to make sure to get this lens with the matching diopter.
This is very true, though the lens itself is spec'ed at 1:2 and Klaus tested it without the diopter attached. Adding the auxiliary close-up diopter will indeed allow closer focus to 1:1 in much the same way that adding the Raynox adapter will allow a close-focus zoom to support 1:1 or greater magnification. I would expect that the Cosina diopter will provide similar functionality on the Pentax-M 100/4 (another 1:2 macro lens) or any other 1:2 macro lens having 49mm filter threads. The nice thing about a diopter is that you get magnification without loss of speed. The not-so-nice thing is that there is potential for a quality hit.
If a 1:2 with the option of 1:1 with adapter is acceptable, I would suggest the Pentax-M 100/4 Macro, Pentax-M 50/4 Macro or the older version Tamron (1:2) 90/2.8 Macro with its matched doubler. All are available at the same price point or lower than a new Cosina, but with somewhat better build. Auxiliary close-up lenses to boost the magnification to 1:1 are readily available or a simple short extension tube (the more common solution back-in-the-day) will also do.
Here is the link again to RioRico's excellent "cheap macro" article. He gives a quick summary regarding auxiliary closeup lenses.
https://www.pentaxforums.com/forums/pentax-lens-articles/152336-cheap-macro-b...lose-work.html
Steve
FWIW, I have a set of Hoya close-up filters capable of doing a +7 diopter stack. They are great fun and yield a quite workable image.
Last edited by stevebrot; 08-10-2013 at 08:45 PM.