Best DSLR or ILC for Night Sky Imaging?

Started Nov 8, 2017 | Questions thread
JimH123 Senior Member • Posts: 1,906
Re: If you want the best, a dedicated cooled CCD cameras are far better than all the DSLRs and ILCs

rnclark wrote:

swimswithtrout wrote:

JimH123 wrote:

I have used many cameras for night sky imaging, but once I got a dedicated CCD camera, my opinions have changed. They are available in color or mono (I have both) and with the cooling, noise is greatly controled.

As an example using a mono Atik 460ex, here is one example of m27, the Dumbbell Nebula. This consists of 10 images stacked of 40 sec each taken with an Explore Scientific 102ed, a 4" objective with a focal length of 714mm. A camera like this far exceeds what any DSLR can do.

I totally agree !!!

But the OP and most everyone else here can't accept that fact.

Really? Compare the image below. Cooled CCD with 6 times more exposure (400 seconds), versus a single 60-second exposure with a stock DSLR uncooled.

The stock DSLR is already showing fainter detail with only 1/6 theexposure time. The point, however, is to not start a DSLR vs cooled CCD war. Both have their strengths. In short exposures, like in nightscapes, dark current isn't an issue except in extremely hot environments. If one wants to do RGB color imaging, then there is little difference because the mono CCD must time multiplex filters whereas the digital camera does spatial multiplexed images. Neither images all colors all the time at every pixel. The mono ccd or cmos works better for very broad band black and white, or narrow band filters, but at the expense of much added complexity. The digital camera does well at RGB color imaging and with the best sensors, cooling for reduce noise from dark current is less of an issue. It would be difficult to do nightscapes with a mono ccd and color filters as things are moving, sky relative to land. And more research is going into cmos, so the future will more likely be mono cmos versus digital camera, and cooling may not be needed.

Roger

Hi Roger,

I have a question regarding the above discussion. The Mono CCD image is actually ten, 40 second images. I was not auto-guiding and I didn't want to push beyond 40 sec. If my understanding is correct, the image is going to act like a 40 sec exposure, but that the S/N ratio will improve as well as the noise with the stacking. Is this a correct assumption? The mono CCD does show more stars within the nebula. Also, on that night, I was not using any filter at all. And with the cooling, there was very little noise and even less after the stacking. Also, the stacking was done with a Beta release of SW from Atik that allowed the 460ex to use the SW that was developed for the Atik Infinity. This was a very convenient way to capture the image. All I need to do is to let it stack for as long as I want and to then save a TIFF file (Or FITs if I want). When using the Infinity, which is not cooled, considerable noise can be seen which reduces with each additional overlay. In the case of this image on the 460ex, it was set to -15 deg C and I really couldn't see noise on the laptop screen.

M27 was not that low in the sky when this image was made as you also said that the color image was quite low.

Appreciated your previous post explaining things in detail.  But I also suppose I didn't fully understand everything you covered.  But I did understand that using a larger scope is going to produce better results than a smaller scope.

Thank you

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