I've recently started taking a few pics with a dslr and I'm after a bit of advice.
I've been using a Canon 600D to take 30 second exposures at ISO 3200 through an Esprit 80. Should I be using different settings?
Also how much less noisy/more sensitive are the newer cameras like the 6D and A7S? Are they dramatically better?
I'm thinking of getting a Lacerta stand alone autoguider as I'm reluctant to add a laptop and CCD camera - prefer the dslr simplicity at the moment.
Personally I think that you may be better off using 120s exposures at ISO1600. As for comparing sensors, I find http://www.sensorgen.info a good place to start. I found it relatively accurate with my Nikon D700 but you can always expect some variance camera to camera.
Without auto guiding 30 secs at iso 3200 seems to be the sweet spot for canon dslr crop sensor cameras. I keep the display turned off to keep the sensor a bit cooler.
The 6D is a fair bit less noisy than the 600D at the same temperature, but you'll still get noise speckle in your images on warm summer evenings, the 6D is just more tolerant of it. Just beware that a full frame sensor exceeds the imaging circle of the Esprit 80, so you might do just as well with a less expensive competing crop chip.
For your 600D...try dropping the ISO down to 800 and see how you go. The gain is quite high at 3200, with the unity gain being around 200. For the 6D it's closer to 800, so there's less amplification going on when using 1600 or 3200.
Thanks for the replies. I guess the first step is to get the guider and try the lower ISO's.
Colin, according to the list the 600D isn't too bad - not quite the dinosaur I though it might be.
Good point about the chip size and image circle Dunk. I also have larger refractors but the Esprit 80 is a nice setup - I'll have to look at prices of full frame vs APS-C and keep an eye on the classifieds.
I'm using an Advanced VX and had thought about a higher quality mount but the ease of use of the Celestron mount has me hooked. It takes me longer to physically set up the gear than it does to get the mount fully aligned including polar alignment.
I've got a GPS module and the StarSense accessory: StarSense aligns the mount automatically, then I do the All Star Polar Alignment routine, then another automatic alignment via StarSense - saves eyeballing and centering 8 or more stars.
I'd say save your money and get to grips with your 600D. There are less noisy sensors on the market now but it's constantly changing.
A mate of mine has the Lacerta and uses it with refractors large and small as well as SCTs and it works as well as a computerised setup as far as I can tell. It's not any cheaper than a computerised setup though. If you've got a laptop already all you'd need is a suitable guide cam and a guide scope, the learning curve is more or less the same IMO.
The 6D is renown for it's low noise, but most of the Canons are pretty good when the ambient temp is below 10C. But come Spring/Summer, oh boy, the noise can be atrocious.
Darks frames are essential. At the end of each session I would pop a fresh battery in the camera and let it take darks until the battery runs out. Add those darks to your library and add more the next night and the next. Turn them all into one master dark frame to add to DSS.
Take them at all the ISO's you will use.
So I ordered the Lacerta MGEN autoguider today along with an adapter for a 50mm finder and a camera control cable.
Will I have to bother with PEC or will the guider take care of it all?
The guider should take care of it, at least for short exposures. The MGEN also supports dithering to help cancel out the DSLR pattern noise, etc. It's a pretty sophisticated box of tricks!
I've not imaged with my AVX beyond DSLR and a wide lens, but at f/5 you shouldn't need particularly long exposures. Aim for ISO800 or 1600 and see how you get on. It'll depend on how dark your sky is as much as anything else.
The Lacerta MGEN is fantastic! I got one for my CGEM last year. I was thinking of getting a better mount but I got a better stand alone guider instead and now I don't really need a new mount. Easily control PE in RA and has some good features to control DEC backlash. Usually I disable the DEC guiding in one direction so it just corrects for drift. My stars are usually tight circles now and there is virtually 0 movement from the first image to the last.
That's good to hear Tony. While looking around the 'net at comparisons the only negative comment I found related to it being a bit pricey, but everyone seems happy with how the MGEN works.
The MGEN guider arrived today and I used it tonight. Having never done any guiding before I had to read the quick start guide but it was fairly easy to use. It controlled the AVX well giving round stars in my esprit 80 with exposures up to 4 minutes. It seemed to be making adjustments constantly on either axis judging by the flashing LED's.
I also used the MGEN hand control to operate the 600D, setting it to take sequences of exposures of different lengths while I went inside and warmed up.
Nice little gadget and a good way to learn another increment in imaging without risking getting overwhelmed and discouraged.
Here's a 2 minute exposure at ISO 800 through the 600d using a 50mm finderscope for the guide camera.
That's next on the list of new things to learn. I've got half an hour or so of Lagoons from tonight to play with; been forgetting to take dark frames but, one step at a time
Enabling dithering and no darks sounds like less work
After stacking in DSS I end up with a really bright background, due mostly to light pollution I imagine? What's the easiest to use processing software?
My Son has Photoshop on his school computer so I put a 20 minute stack into that and used the levels pipette thingy to get rid of the bright background, then stretched a little and it's not looking too bad.
The original looks much sharper but it's 182 MB; not sure how to resize but keep it looking better.
Yeah all you need to do to start with is adjust the black level so that the background looks darkish. I say "ish" because in this particular scene there are just stars everywhere, so not a true dark then adjust the white level so that they're not overblown (or "clipped").
try the dithering function on the MGEN and forget about the darks.
