Wesley's Tool-Box

With the recent purchase of Celestron f/6.3 focal reducer (as mentioned in The Toon-Box) and the fine-tuning of the secondary mirror collimation, I've been quite eager to do some deep sky photography. Alas, the autumn sky at Naju has not been very cooperative.

For some reason, the days without clouds experienced thick fogs (and possibly smogs) and the days without fogs experienced cloudy sky. As the former at least provided some visibility near the zenith and because the constellation of Andromeda is currently very high up in the evening, the Andromeda Galaxy became the obvious target when the opportunity came.

The best three photos from the shooting session were manually stacked and processed, resulting in what you see above. It seems that the fog blocked much of the structural details of the galaxy, but you can still see a bit of it near the core. Also, the satellite galaxy known as Messier 32 (M32) are clearly visible in the bottom as well. I'll be trying on the Moon & Skyglow filter under a better weather condition to see if I can improve upon this.

(Note: M32 was misidentified as M110 earlier, and has now been corrected)

Telescope: Celestron NexStar 6SE + f/6.3 focal reducer
Device: Sony A5000 (prime focus)
Settings: (945mm) - ISO 1000 - 30s - (f/6.3)
Filters: None
Time: 2015-11-03 20:25-20:45 KST
Location: Naju, Korea
3 photos stacked

Using a Schmidt-Cassegrain telescope (SCT) like my Celestron NexStar 6SE requires the secondary mirror to be collimated properly to get a crisp image. I've done the collimation after fixing the screws, but I wanted to fine-tune further. The adjustment I will be making won't be the definitive for all the cases because the gravity affects the secondary mirror subtly with differing angles. But because the diameter (and consequently, weight) of the mirror is relatively small the deviation after the fine adjustment was hoped to be small.


Unfortunately, the real stars often look too shaky, so I decided to try the artificial star method for this tuning instead. An artificial star is basically a bright light source coming from a tiny hole. For the light source, I do indeed have one - an LED flashlight that I bought many years ago. It's actually an external battery for charging phones with a bright LED as a bonus feature, but it's so old that the charging port is a Korean 24-pin standard that was popular about a decade prior. Now it was time for this little gadget to be useful again.


I initially tried it out as is, but the LED part was too big. It was time for a little modification. After trying out different materials, I found that a sheet of back cover for making presentation handouts was effective at blocking light, yet did not require complicated tools to work with. A pair of scissors let me cut one up to make a cover over the flashlight. Next, I punched a tiny hole where the LED was supposed to be at.