Even with all three frames attached I still struggle to achieve focus at times. Does anyone use four? I have vision issues at this range and I wonder if adding another would do the trick. If so where does one get another?

Yes i need four, but strange on my other viewfinder i only need two?

I have a couple of these ( 3 actually ) and it seems the older one on a 5DII, I only need two frames. On the Zacuto EVF or with the newer unit on the same camera I need 3 frames.

The 1.9x Zacuto optics are so poorly focused it's a shame.
The 3x works SO much better and focuses at about a third the distance but the image is enormous.

I'm using an Alphatron EVF for a true image.