Thread: Perfect focus each time using a Bahtinov Mask
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  #60  
Old 09-09-2008, 05:35 PM
Dennis
Dazzled by the Cosmos.

Dennis is offline 		 
Join Date: May 2005
Location: Brisbane
Posts: 11,820
Hello,

Here is a comparison using a single Bahtinov Mask for the following configurations:
  • Mewlon 180 at F12 prime focus, fl=2160mm (DMK21AF04.AS).
  • Mewlon 180 at F30 with x2.5 PowerMate, fl=5400mm (DBK21AF04.AS).
  • Mewlon 180 at F36 with x3 Barlow, fl=6480mm (DBK21AF04.AS).
  • Mewlon 180 at F12 prime focus, fl=2160mm (Canon 40D Live View x10 Zoom)
The same Bahtinov Mask was used in each instance; that is, the one calculated at 2160/180=12mm giving a 6mm Bar and a 6mm gap.

Cheers

Dennis
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