Discussion in 'Ishtim' started by Ishtim, Jan 3, 2006.
Just a pic...
Looks a bit soft though, but still
Maybe we should have a moon shot competition.
But I think possibly only Ken and Ishtim will be able to take such pics.
Last night's... focused this time with Ronchi Screen...
Hmm.. Did a Google search. A Ronchi screen is just a piece of glass with many lines to aid in focusing, right?
This link has some explanation, but I'm not entirely sure how it works...
Link - http://www.astropix.com/HTML/I_ASTROP/I08/I0816/I0816.HTM
Is it like wearing spectacles with the glass replaced with a fine plastic mesh? That sort of corrects the focus.
The Ronchi screen makes lines appear by diffraction. When way out of focus, you see alot of lines. As proper focus is approached the lines become farther apart and eventually "disappear" once perfect focus is achieved.
To contrast this, the soft image at the top of this thread was focused by "eyeball" and guessing.
Oh, so it helps by telling you when the image is in perfect focus?
Yeah, I can see how that would be useful.
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