As some may have read in the (show us your equipment) thread, I've bought a new 8" F4 imaging Newtonian. I got it mostly for comets but will probably make use of it for other stuff as well. Be interesting to see how it compares to the refractor.
As usual it's either cloudy or full moon when new toys arrive. Can't shoot much worthwhile in full moon except brighter open clusters. This is first light night with the 8" on IC2395, a little open cluster in Vela.
Details, 13 x 30 seconds unguided, Baader MPCC MKIII, Pentax K-5 at ISO400. This is a full frame edge to edge. It's not too bad for an F4 I think.
As for tracking comets, basically I don't. Though I used to back in the old film days. The trick for comets is to take many short exposures, say 30 seconds to a minute and stack on the comet. There is a feature in DSS that does this. However one of the reasons I got the F4 scope is that in many situations it will be big enough and fast enough to capture the comet in just a couple of minutes, making comet stacking unnecessary - except when the comet has very rapid apparent motion.
Thanks Justin. I'll be posting it's progress as clouds and moon allow.
Barry knows I've been thinking about a mono CCD as it would open up a world of some really nice big achro refractors for imaging. I love my refractors but I also love my DSLR, so I'm kind of chewing on the idea for a while.
I know the 8" F4 + DSLR is a great combo going by your pics and Richards. A bench mark for me to strive for. The difference with me is my camera isn't cooled, it's now summer and the hot pixels will really hit the fan. But we will see how I go.
Congrats on your new scope Kevin. You'll love it once you get to image some of tha fainter targets and you realise what you can get witb much less intergration time than your refractor.
Thanks Rex. I don't think the difference will be as much as most would think. Refractors are very efficient at what they do. Doing some comparison testing tonight and the refractors are not far behind. But then there is the moon...
Oh ok. I just asumed the larger arpeture and shorter f ratio would translate into shorter exposure times. I have never owned anything longer than an f/5, so I was definatley not speaking from experience. Will be good to hear the final verdict once the moon goes away for you.
Always a new instrument is a good news. And each instrument has its own performance. Reflector has different performance from refractor. Mainly with the luminosity and coma distortion.
For DSOs astrophotos I prefer reflector. Mirrors capture more light, and so, more informations.
About comets: you can use DSS in two basic different modes: stack by comet and stack by star. DSS offers, also, stack by both: that is a superposition of images from both kind of stacking. Some times the superposition of the two kinds by yourself in a graphic processor has better result.
Cheers Kevin, Ill have to give DSS a go I have been using MaxIm DL and getting use to it especially with the starry night pro plug-in as i can setup the CCD size and telescope FOV. I was thinking u were tracking the comets with starrynight. Once i get some post worthy pics ill post put them up lol. Cheers and have a good weekend.
Congrats on the new scope Kevin. Wish I'd saved my beans and bought one of those instead of the 6" F/5 I have now - almost the same focal length but half an F-stop slower in my case!
Here is a comet for you from last night Chris. C/2012 K1 (PanSTARRS). Taken during full moon with the 8" so it's a bit muted. I think it was about 18 x 30 seconds with an Astronomik CLS filter stacked on comet with DSS.
Don't underestimate a good 6" F5 Cam. Forget the figures, in reality there's really not much difference between them, and F5 is better in many ways. I'm thinking I should have went for the 8" F5 version. Well, it was an experiment. In the end I want both anyway! Hey they're cheap as chips these Chinese newts so why not.
Thanks Kevin, Ill have to upgrade my camera I'm thinking a 5D or Atik 383L+, to get the most out of my setup. I'm keen on the 5D with backyard EOS software and hopefully i can get much better drift alignment, as I'm still having problems getting that profected. Would love to have a permanent setup too or even a pier that was setup ready to go so all i have to do is bolt down the mount add the tube and away i go. Thinking something in the way of 2 machined surfaces one on the pier and one permanently fixed to the base of the EQ5 so alignment would be pritty darn close. Cheers, let me know your thoughts.
Thanks Jo! Have some cloud at the moment but when that clears off...
That's not a bad idea Chris, a permanent pier. I should do this for the backyard too. At present I just shoot out of the window lol. Doesn't give me much sky this way.
