I just managed my first, real picture of M31 (Andromeda) galaxy. It doesn't really match what you see in those better amateur pictures of it, or professional.
But I do think it's quite interesting. You see the fuzzieness which is the galaxy.
The exposure was 30 seconds at 3200 ISO (from a Canon Rebel T2i) fl 55mm (from a non APO lens I think) no filter, tracked on a Meade Starfinder equatorial mount.
I need some recommendations on how to use DeepSkyStacker. Does someone here know the benefits of using several pics and stacking them?
Do they all need to be the same shutter speed and exposure?
Do the darks need to be done (with stacker) first?
Is there a good tutorial on all of this?
I'm usually kind of good at computers and even had some computer programming
in college.
But this seems a real technical adventure. And I guess that my intentions are more for aesethics than for a scientific (kind of proving theories) kind of thing.
Like if there was some place that I could post these RAW pics (that's the original format of my M31 pics) and someone could process them for me, but show me too that would be another great thing to me.
In the mean time I want you all to know that this is my first galaxy pic and it's a really neat feeling when I had wanted it, and even prayed to God for it. And then it happened. So when you're stuck, praying doesn't hurt either.
PS: What are bias frames? And how do I take/use those?
PPS: I think that if my polar alignment is okay, and then I'd like to go up to a longer focal length lens. Like I've ordered, and it's on the way, a nice 70-300mm zoom F4-5.6 APO lens. I believe that optically magnifying the subject (M31) will make a better difference than a whole lot of snazzy processing. But like while I'm at it: does someone here know how to do the median processing on Deepskystacker?
It's a good start, but if you want to take good shots of galaxies etc, you need to invest in a good scope and, more importantly, a mount.
The whole idea of taking a number of exposures and stacking them is to raise the S/N ratio of your resulting image so that more detail becomes apparent and the noise becomes less so. Running your camera at 3200 ISO is not the best way of recording a faint object like a galaxy. It introduces too much background and electronic noise into the frames. So long as you have your polar alignment down pat and a mount that can carry the load, you should reduce the ISO down to 800 or even lower (400 or 200) and extend the exposures out to a minute or more...preferably 5 minutes. Take 20-30 frames and then take the same number of dark frames of the same exp length, ISO and such. When you import these into DSS, it will subtract the dark frames from the light frames as you tell it to, or will run the default setup. Bias frames are those frames which account for the bias that is inherent in all CCD chips. The bias is the background electronic noise within the chip even when it's not being illuminated and recording a signal. To negate the bias, you just take quick snapshot frames with a cover on your lens/telescope. Take the same number of bias frames as you do with the others. DSS will also handle these in the same way as it does the other frames you've taken. To do median processing in DSS, you go into the advanced options menu and make your choice for median combine, or whatever parameters you choose.
Recommend you stay with the same exposure, ISO and aperture to start with. Put it all in DSS and DSS will take care of the rest.
Just remember, when DSS finishes, it will look quite dark and appear in greyscale. It isn't, DSS has increased your 14bit (or 12 in some cases) to 16bit and hence it will appear darker but the information is there.
Then you stretch the data. Took me a few mths to understand this concept.
I would also recommend you search around IIS as there are many good examples/guides from those with far more experience than myself.
Good luck and more practise will only improve your skills.
Let us know if you do need a more specific guide on DSS.
I started out at 3200 ISO at 10 seconds, there was no noticable trailing and could see M31. Then I started doing 1600 ISO and 30 seconds and still no real trailing (it seemed). Then I went 800 ISO and stepped up to 1 minute and then on trailing I could see trailing (looked like an upside-down L rotated 90 deg to left with bold short piece and longer, but thinner back, like a chair). And I wondered if that was from mirror shake because I believe I didn't do any touching of the thing while I was taking the photo. I could post a photo of it, but would have to reduce it and convert from RAW. Also after analyzing the first other photos (at 3200 and 1600 ISO) they too had a little trailing, but not that L shaped thing. These were arcs instead.
PS: My setup still isn't permanent. That is, in that I still whether it's my LX200 or my Starfinder mount (which is what I used this time) I will still take it down at the end of the session and it wastes my polar alignment, which only amounts to me roughly gun-siting it to Polaris (which is of course really rought).
PPS: Does someone here know of a way to delay the exposure (mirror lock) on a Canon Rebel EOS T2i to avoid this mirror shake?
Does someone here have any suggestions other that the one I have, to try to have enough money for an observatory (with concrete and things more permanent)?
I mean like, I was talking with my mom about it and I think she joked about I could sell my car. That's one possibilty, because there's the 3 of us (mom, dad and I) and we each have a car. My dad's actually going on 91. But has a car and I could drive that one. Mine's kind of neat and all (car, Ford Focus) so it would probably more than cover all the costs of my observatory. And/or could get a loan.
I have the canon 600d (rebel ti3) and the mirro lock option is available when you select manual mode, press the menu button, and then go into custom functions ( this menu option is not visible when you use auto mode or some other modes), on my camera it is option 8 (c.fn III:autofocus/drive, mirror lockup).
Once switched on you will need to press the trigger to open the mirror, then again to open the shutter.
Good luck with the imaging, I find using mirror lockup it takes about 10 seconds to stop shaking then you can trigger the shutter to open and start exposing.
