Focusing Techniques For Lunar and Planetary Imaging

Focusing Techniques For Lunar and Planetary Imaging

Poor focused image of Saturn

Saturn 270411 v3.tif

Using a webcam to image planets and the moon is a great way to capture good images. However, if the images are out of focus to start with, no amount of post image manipulation will provide a satisfactory final result. It can be very difficult to achieve perfect focus when using a webcam as the changes in the seeing moment to moment, the need to touch the telescope to focus with the resulting wobble and the delay between focusing the telescope and the image on the laptop screen appearing all combine to make create a frustrating focusing problem.

 

Making a parfocal eyepiece by putting a parfocal ring around the stem of an eyepiece at the level that achieves the same focal point as the webcam is a cheap and quick method. Every time you want to use the webcam simply drop the pre-made parfocal eyepiece into the telescope and focus the telescope, then when you attach the camera it will be in focus immediately.

 

Another useful method for achieving focus on Jupiter is to use it’s moons to focus on first.

 

Other methods include the use of a motorised focuser, Bahtinov mask, Diffraction spikes and Hartmann masks. More information on these can be found here.

 

http://www.davesastro.co.uk/techniques/focussing.html



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