Is a 2.7" focuser really necessary?

I plan on eventually doing CCD and/or digital astro-photography. Would a 2" focuser be ok or do I need a 2.7" or 3" focuser. I never plan on doing medium format astro-photography.

Clear Skies,

Debbie

Debbie,

For CCD or digital camera astrophotography, a 2" focuser will work just fine. For full frame 35mm film prime focus astrophography, a 2.7" is preferable to avoid vignetting at the corners of the frame. What is most important is that the focuser is solidly built with no slop in the mechanism or sag in the drawtube when holding equipment. A lock screw to prevent creeping of focus after it is set is also essential.

Clear Skies,

Joplin