Astronomy Notes

Today, the Malaysia Meade Distributor, Uncle Looi told me how do an illunimated reticle work and why was it invented.

Long exposure astrophotography will always suffer from some imperfect tracking because even the most precise man-made gears have some minute imperfections in them, the mounts can never be perfectly rigid (they are invariably flexible to some degree) and the atmosphere itself can cause positional shifts in images.

All these contribute to periodic and non-periodic shifts in the celestial object’s position that can be seen in the eyepiece, and if it is not immediately “corrected” by gentle tracking steering, they will blur the captured image. The reticle allows one to see the minor shifts and to make the needed corrective actions.

“Guiding” is one of the most important and difficult skills needed in long exposure astrophotography. These days computer guiding by CCD has made this chore much less challenging.

In order to use this eyepiece when imaging, you need to get an off-axis guider. If not, you can only either use the reticle eyepiece or imager at the same time.

It seems that this is a good gadget to invest. It can also help you to do the alignment more precisely as there is a crosshair for you to center the star in the eyepiece.Due to the rising of the autoguiding chip built in the CCD camera or autoguiding CCD camera, people are not buying this anymore.