Thanks Erik, good to be back. For what I use these things for, the filter isn't even necessary. Just sweeping the Milky Way, clusters, etc. No moon or planetary targets for the f/5. A fast doublet would be a good choice for narrowband imaging, as well. Any uncorrected color isn't a concern. Like using a singlet for H-a solar observing. I built a few of the 5" for the club about what, 35 years ago? I wonder what happened to them. On 7/26/11, erikhansen@thebluezone.net <erikhansen@thebluezone.net> wrote:
Chuck,
Welcome back, the 5" F5 caught my eye too. I have the 6" version but did build a 5" tube assembly with the Jaegers a few years back. It is a great lens at a great price, add a V-block or Minus Violet filter and the chromatic aberration is greatly reduced.