DSO Restart

[saiph]

Hi guys.

Recently I had the opportunity to restart my hobby with a short astro-imaging test run in the back yard - a nice quiet little playground actually, near the place where I live.

My setup consists of an eq mount (AVX), a dslr (EOS 550D), and either a classical M42 manual focus photo lens (anywhere from a Takumar 35 to a Tair3S 300mm, sometimes aided by a 1.5x or a 2x TC), or an ED refractor (C80) most of the time reduced with a 0.8x FF/FR. Since the area where my observing spot is falls within a +5 NELM around Zenith, I always use a LP filter (IDAS LPS P2 2", or Optolong CLS 1.25") for better results.

Unfortunately my mount isn't PEC'ed yet, but I'm quite confident that i'll soon be able to achieve this goal, as it is rather imperative if I am to get any useful >120s subs. Guiding is not my main objective, as I do not have all the possibilities to do that - technically, logistically, financially... etc.

A couple of nights ago I went for a test run with a rather unconventional "weapon" - the SW 127 MC.  Yes, that's right, a Mak for DSO. Now, I know some of you have already played with this kind of instrument before, and had some pretty decent results. I also know that many imagers with higher standards have the habit to blame this little scope for its limitations. But who cares..   It's all about experimenting and having some late night fun. I used mine with a 0.63x FR, set at 0.73x due to the actual chip-to-lens distance I got, which brings down the focal ration from an infamous 11.8 to a more usable 8.6, which is quite doable exposure-wise, but a little inconvenient when it comes to star shape and vignetting (although the latter can be dealt with by means of flat frames).

With a MC-SCT thread adapter and a custom made rotatable SCT-2"-M42 adapter, I could use both the Celestron reducer and the 2" LP filter with the dslr on the Mak127, for a couple of dozens 50/50 hit rate 30s subs for each object, along with a set of correction frames (darks, flats, bias). I really hope next time, with PEC, the hit rate (percentage of usable subs with round stars) will increase, and subs will be longer, so I can take better images. Until then, this is what I managed to get. Processing is done in a "keep-it-simple-son" manner: DSS & PS CS5. I didn't bother shooting RAW, although I am aware of the limitation of using JPG correction frames. Maybe next time  

 

Clear skies, everyone!

 

 

 

[ollypenrice]

Those are very good results. It's a shame not to shoot in RAW, though. Any processing in JPEG comes at a hgh price in terms of image degredation.

In the case of stars and small objects F ratio is over rated!

Olly