Posted 03 December 2012 - 07:31 AM
This last pic shows the dialyte layout. With an overcorrected achro with very little power, the longitudinal color can be corrected to a large degree, and leave residual lateral color nearer the edge of the field. If an ordinary achro is used, it "becomes a Hypo" where longitudinal color also remains.
On the target on the barn, I used a piece of shelf-liner, and shot some black paint thru it onto a white background. It formed a matrix of ~1/8" dots---quick and dirty, relatively adequate for quick looks.
With a 40mm Plossl, i estimate the mag as somewhere near 40-50x. A bit much for what John Wall recommends, but it gave me something to look at. There was some aura around the dot matrix, but not too obtrusive considering what the optical layout was.
Now to the interesting part.
I swapped the 40mm for a 12, and the matrix exibited a rather very sensitive depiction of the longitudinal color. The dots first focused blue, with a red background in between them. As I brought it back thru focus, they darkened up somewhat, but showed a purplish aura. Even further, and the dots changed to red with a blue background.
This was extremely sensitive, and I was able to get a range from the blue dots to red dots of around 3-4mm~ (1/8"+) This effect will club you over the head! Very apparent, and very simple to do. I believe I can use it later when I get further along with development when checking the residual color issues with this design.