Been mucking around with my GSO RC6 f9 scope. Here's one of my better efforts of late, 35 x 2min subs, 70mins total integration with a few dark's thrown in, guided on an Heq5 pro.
I have a question though, is there a point of diminishing returns, because I really can't see a lot of difference / improvement after about 30 mins worth of subs are taken and then stacked. My processing efforts / skills are still pretty much on a beginners level though.
Good job Rick. With a relatively dim object such as this, and a relatively
slow scope, you could do with longer subs, say 4 or 5 mins. The returns
from stacking do diminish, and how many you need depends upon how noisy your camera is at the time of imaging; with an uncooled DSLR the ambient
temp, as you are probably aware, is the main factor to consider. In summer
I found I needed at least 75-100 subs to bring the noise down to acceptable levels. In winter 40-60 did the job. My 1100D was obviously not as quiet as
the higher end models.
Incidentally, your focus looks good, so maybe a tiny bit of sharpening
would finish it off nicely.
raymo
Overall I am pretty pleased with performance of the RC6, only had to tweak the secondary collimation slightly out of the box to get a good field. Perfect focus is hard to achieve but on this night just seemed to snap, so I kept imaging till the trees got in the way. I'll have to try longer subs, now that I seem to have the autoguiding working well on a regular basis, but my biggest stumbling block is the lack of cloudless nights and winter is supposed to be the clearest here in the tropics? I am using a 1100d unmodded as my imaging camera which seems to do a good job, less noisy than my newer 1300d. I have been shooting at iso 1600 and 2 min subs which seems to be the best compromise for this setup.
I found that 1600 was good in summer, and 3200 on nights of sub
5 degrees in winter. you can reduce noise with long subs by using a
mains powered adaptor in place of the camera's battery. Batteries build up a fair bit of heat over a session. Its amazing what people can do unguided.You can do several hundred subs and short exposures of 30-45 secs. Cometcatcher [Kevin] often works that way.
raymo
I have been following Kevins work, he is producing some excellent stuff with pretty modest equipment. Its also good to see that dedicated cooled astro cameras are finally starting to become affordable to the average astrophotographer. The way the tech is going in a couple of years we'll all be taking those hubble shots but without the big $$ equipment.
Your image is very clean and reflective of the time spent in data collection. I sometimes wonder when to call it a day with the amount of subs taken in a given session, generally a good result is achievable with an hour or two as you have clearly shown with the addition of good flats and darks. It always comes down to what your trying to get out of it. The sky is the limit with integration time and the images produced with such always are worth it, they are spectacular. Personally I like to get a result from a single nights observation. I never seem to have the time to dedicate to multiple sessions on one object. I totally respect those out there that do though and aspire to one day having an observatory to assist.
You also referred to processing, i agree, there is much to learn in this area and I can appreciate how much skill it takes to get the most out of it. Keep it up, nice work Doppler.
Thanks Anthony,
Astro photography isn't the easiest thing to do but with a bit of practice and perseverance some nice result can be produced. I am like you I like to have a result at the end of the night, usually processed the next morning. There are far too many objects that I would like to capture so I can't dedicate multiple nights on just one, I usually go for 2 or 3 objects on a good night. (there are just not enough good nights each month).
Good Cent A Rick! Interesting to see what an RC6 can do.
There's no limit on subs. Just keep going until you wear the shutter out, or your patience. Whichever comes first.
Thanks Kevin, I have found the RC6 quite a capable little scope, a bit slow at f9 but with a bit of guiding to stretch the sub length it all comes together.
Quote:
Originally Posted by cometcatcher
P.S. I didn't even get a chance to try 5128 this "winter". I think we had more clear nights in summer.
Yea the cloud has been very persistent this year and frustrating, I don't know how many times I have set up on a clear afternoon just to be foiled by cloud cover, and even a single cloud can mess auto guiding right up.
Good pic Rick. I echo your comments about the clouds.
Here in Melbourne it seems an eternity of cloud cover.
Cant wait for clearer skies. However i have taken the an opportunity in the down time to build a stepper to go with my new moonlight focuser.
What a hobby hey? But rewarding when you take and process a good pic. Anyway that is what i say to my kids. taking a picture of a cloud of dust or gas hundreds of LYs away which cant be seen with the naked eye. Simply amazing.
John
