RZ67 65mm L-A Lens: Checking the Floating Element Position
Originally posted on Instagram. Notes from the repair bench, kept here as a searchable archive. View the original on Instagram
After any service on a Mamiya RZ67 65mm L-A lens, the floating lens position needs to be checked. While it is set at production, lens resolution may be degraded if the position is disturbed and not re-set. This post will show the process of checking the floating position and I will warn you that this is a bit technical!
Photo one shows all of the equipment needed: coupling gauge A and datum block base for front element group; coupling gauge B and datum block base for rear element group; block gauge (64.5mm) and datum base.
First, the coupling gauge A is set to zero while placed on its base as seen in photo two. In photo three, the coupling gauge is placed over the rear of the front element group and reads an offset of (+0.01mm). Next, photo four shows the coupling gauge B being set to zero on its base and then in photo five the gauge is placed on the rear element group and reads an offset of (+0.015mm).
Photo six shows the floating position block gauge on its datum base and this is used to set the indicator on the stand to zero. Then, the lens is installed on the base and a reading is taken on the floating barrel as shown in photo seven. In this case, the position (+0.025mm) of the barrel is correct and no adjustment is needed. This is the correct position because to find this measurement you take the reading of A and add it to B. In this case, (0.01) + (0.015)= 0.25
