Focussing tips for Canon 450D

[mswhin63 (Malcolm)]

Originally Posted by naskies

Another tip - I find it helpful to put a bright star in the centre of frame (Alpha/Beta Cent, Sirius, Canopus, Jupiter, etc) when focusing via AF or manually through LiveView.

Even on really expensive wide angle primes, the corners are often horrible with coma, CA, and other optical aberrations wide open. Being in the centre helps minimise the distraction.

Sounds like a good option, will try it myself once the cloud go away.

[skysurfer]

Originally Posted by naskies

Another tip - I find it helpful to put a bright star in the centre of frame (Alpha/Beta Cent, Sirius, Canopus, Jupiter, etc) when focusing via AF or manually through LiveView.

These objects you mention are too bright even for a 10mm on my 40d. The image is washed out to a blob when set to 10x magnification.
Use 2nd mag stars like the Orion belt stars instead.