Staff note: This post may contain affiliate links, which means Pentax Forums may earn a small commission if a visitor clicks through and makes a purchase. If you would like to support the forum directly, you may also make a donation here.
I'm a fan of step-down "hoods." I received a PM asking about lens caps. I'd like to post the answer here.
For my FA50 F/1.7 and DA 50mm Macro, I use 49-28 step-down rings. The lens cap should be 28mm (such as
this eBay listing).
But I found out that a 51mm slip-on lens cap works too, especially if you can find the antique Pentax metal cap.
Any of the caps shown in this photo will work.
Note 1: For focal length of 50mm, using a 49-28 step-down ring will limit the max aperture to F/1.8 because 50/28 = 1.8. There have been threads discussing this.
Note 2: I use a 49mm empty ring (a 49mm filter with the glass removed) between the lens and the step-down ring.
Last edited by SOldBear; 05-11-2013 at 12:07 PM.