Quote:
Originally Posted by von Tom
Hi Carl
I am not too familiar with the use of bahtinov masks as I use the live view on the 550D. Does focussing with the mask depend upon seeing conditions? I don't think the image could have been much sharper given the seeing and the field rotation.
Cheers,
Tom
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The bahtinov mask produces a spiked star like point when you use it to focus on an object. When you move in and out of focus, those spikes (diffraction spikes) move in relation to where you are in the focus. The object of the exercise is to get a well aligned middle spike. When it appear in the centre of the star, your focus is good. Use it on a bright star to focus, then slew to your planet you're imaging. You may need to give it a little tweak when you get the planet in FoV. Your seeing conditions will affect your ability to focus, no matter what you use. But the mask will improve what you can get, without the mask.
It will help with your planetary images.
http://en.wikipedia.org/wiki/Bahtinov_mask