Saturday, July 31, 2010

It's a Smiley Face

I've had lot of lazy relaxing time during the days.  Some of that time I've used reading Ireland's Photoshop Astronomy but after a while it was just got too cerebral.  My brain needed something more hands on and tangible.  I decided to make a Bahtinov focus mask for the 200mm and 100mm Canon lenses.

I thought I might do this before leaving on this trip so I brought a printout of template and a few supplies.  I scrounged up some glue and tape from the library here and went to work.  The problem with a Bahtiov mask for small diameter lenses is that the pitch of the gratings needs to be rather small to pick up more of the diffracted orders.  Cutting thin bars out with an x-acto knife was not my idea of fun.  I'm not sure what I came up with was any easier but the end result was nicer.

I noticed that the bars were just about the width of a bobby pin.  I brought along a pack and went to work bending and snipping with the leatherman tool.  Then taping and more glue to put them in place.  A couple long hair-shirt hours later ... here is the result.
My bobby pin grating Bahtinov.
 A number of people came by curious, asking what I was doing and what a Bahtinov focus mask was.  I was challenged to explain but my 6 year old daughter satisfied them all with her answer.

"It's a smiley face".

1 comment:

  1. Cool! Hey...looks like some dark sky out there...ah..i mean clouds.