Cameras for deep space and planetary imaging

[Luna-tic]

Being new to the whole idea of taking pictures through my telescope, I'm trying to learn about the cameras available for it. I understand about using a DSLR, and have one (Nikon D3400) that should work well enough for me, but I'm also looking at dedicated astrophotography cameras. From my reading, I've decided on a color imager, rather than a monochrome, so I don't have to mess with the filter wheels and stacking the individual color images; I've also read that newer advances in camera technology make a color imager almost as good  (or as good) as a monochrome one. I also see that CMOS, for my purposes, is as good as CCD, unless that's a difference that makes for better deep-sky.

What I can't seem to find in general reading is why an imaging camera designed for planetary photography isn't suitable for deep-sky imaging, and vice-versa. A lot of what I've read says the DSLR is plenty good for deep-sky.  What I'm looking to do is doing multiple images at shorter shutter speeds (to avoid tracking error) and stacking them to improve resolution. I'd also like to have a camera that I can attach to my eyepiece or visual back (my telescope is a C6 SCT), and observe by putting the output on my laptop monitor. I can do that so some degree now by using an HDMI cable from my DSLR to my computer, but I wonder if I might not get better viewing from a dedicated camera.

What I'd like is a good primer on the similarities and differences in cameras made for deep-sky versus planetary imaging and what makes one better than the other for a particular purpose. I'm on a moderate budget, and not interested in Hubble-quality photos, just something I can wow the unwashed crowds with   around the home.

[spillage]

In short planetary images are created from a video and deep space are long single exposures stacked together. They are both different animals so require different bits of kit.

 

You can use your nikon for dso imaging and purchase a modified webcam for planetary work on the cheap.

[vlaiv]

Well, CMOS sensor can fulfill both roles at the same time.

In general requirements for deep sky and planetary differ in following:

1. Exposure length

2. Pixel size

Deep sky favors large pixel, while planetary needs smallish pixels to achieve needed resolution. It is not really about pixel size, but rather achievable resolution for given pixel size and focal length of instrument used. This is why both can be done with same sensor if different scopes, or barlow is used.

Exposure length is obvious difference, you want 1 minute + for deep sky, and order of 10ms for planetary imaging.

This translates into other characteristics as well. Planetary sensor can and should be small - less pixels to read, faster read rate - higher frame rate (good for planetary). Deep sky sensors should be larger - some of deep sky targets are quite large. Full well capacity for planetary can be really small, while deep sky favors bigger full well capacity (again, related to pixel size, there is so much space to store electrons given pixel volume).

And yes, there are cameras that can suit both roles, and you can have them in color as well

For example look at ASI178mcc - good example of camera capable of both (it will not excel in both roles, but it is capable).

[Luna-tic]

On ‎7‎/‎26‎/‎2017 at 12:26, vlaiv said:

Well, CMOS sensor can fulfill both roles at the same time.

And yes, there are cameras that can suit both roles, and you can have them in color as well

For example look at ASI178mcc - good example of camera capable of both (it will not excel in both roles, but it is capable).

Thanks much for the info. I looked up this camera, seems a good one and would probably meet my needs. I've also talked with a couple of guys from the local astronomy club who do imaging. They're going to give me a tutorial and show me what they have done with a couple of different cameras. Seems there is a ton to learn, but I still have some functional  synapses and a bit of "hard drive" space  left in this aging brain. I hope to devote more time to this when I retire in a year.

[vlaiv]

11 minutes ago, Luna-tic said:

Thanks much for the info. I looked up this camera, seems a good one and would probably meet my needs. I've also talked with a couple of guys from the local astronomy club who do imaging. They're going to give me a tutorial and show me what they have done with a couple of different cameras. Seems there is a ton to learn, but I still have some functional  synapses and a bit of "hard drive" space  left in this aging brain. I hope to devote more time to this when I retire in a year.

Yes, take a look at ASI178mcc, ASI174mcc and ASI1600mcc

Different pixel sizes, different size of chip, all are capable of high frame rates (when using appropriate ROI). You can also check out QHY - different manufacturer same sensors, also cooled versions. Not sure if one vendor is preferred over the other. There are small differences in cooling / drivers / etc.

Depending on your budget, take a harder look at ASI1600mcc - it is very good as deep sky camera (at least mono is, but I believe color is as well), and it is capable of decent fps (1280×960 73.6fps, 640×480 125.7fps) for planetary. This particular model, if used with C6, would need x2 barlow / powermate to do planetary at optimum resolution (well very close to optimum anyway), and will need field flattener for deep sky, so with popular Celestron F/6.3 reducer/corrector it will give you 0.83"/pixel which is a bit too much for average setup, but with bin 2x2 you will be operating on 1.65"/pixel which is quite ok.

ASI174 will probably need x2.5 - x3.0 barlow to get close to optimum resolution on planetary, but will give you "native" 1.28"/pixel with f/6.3 reducer - which is doable on heq5 / eq6 class mount without much problem (guided of course). Binning is not really an option on this camera as native pixel resolution is ~1900 x ~1200 so you will end up with smallish image if you bin (~ 950 x 600).

ASI178 might get by without a barlow, but would need ideally x1.2 barlow (not sure if there is any barlow like that) - it needs to operate on F/11.7 - F/12, so F/10 is close enough. On deep sky side of things it most certainly needs to be binned (that will produce ~ 1500 x 1000 px images), and when binned it will have resolution of 0.66"/pixel - now when I've done the math, I think I would not recommend it for use on C6 it probably needs small APO in range of F/5 - F/6 to be useful (or popular 130mm F/5 newtonian), resolution is simply just too high because of small pixels.

Asi178 and Asi1600 calibrate out really well (just don't use bias frames - shoot a lot of darks instead, but since you will be using short exposures and there is set temp cooling - this is easy to do afterwards) - have them both (178 color and 1600 mono version). 174 seems to have some banding issues that are bit difficult to calibrate out properly - at least that is what I've read (if I remember correctly) - no first hand experience there.

ASI224 and ASI290 will not suit you - their sensors are too small for deep sky work - but ASI224 is superb on planetary.

[Luna-tic]

Fantastic info, vlaiv, and I appreciate the time you took to explain it. I've been wondering what the advantages of binning would be; I know what it's doing to the sensor, but couldn't figure out why you'd want to do it. This helps tremendously.

Is there a book somewhere (like you see for so many other subjects), called "Astrophotography for Dummies"?

 

I messed around the other night, it was clear enough to get the scope out, and the Moon was low and early 1st quarter. I got some great shots with my DSLR at prime focus, ISO 200 and 1/5-1/6 sec. I then installed my sorta cheap 2x Barlow and turned the scope at both Jupiter and Saturn, and played with 1-3 second exposures and ISO from  3200-6400 for the planets. I wanted to see what the differences were in movement without tracking, and S/N with differing ISO's. I got passable single image photos of both planets, but was having a small issue with focus until I discovered I had dew formation on the corrector plate. Got in a hurry at the start since the Moon was low in the sky, forgot to put my dew shield on.

Anyway, I'm writing all my results down for later comparison and I learn a little each time. Hopefully, I'll live long enough to actually get some nice photos. :-)

 

I do have the 6.3 reducer/corrector for my scope, and have made some solar images through it, preparing for the upcoming total eclipse here in the US (Aug 21). I live in the 98% total region to the north of the track, and plan to drive to my brother-in-law's house 2 hours away, where I'll get 2 min 34 sec of totality. I plan to use the C6 and corrector for partial shots (I have a solar filter), and then use my 300mm camera lens for the totality. This way I'll have a wide field of view for the corona. I get a complete disc with sufficient extra room top and bottom in my camera field, through the C6 with the reducer in place. I'm shooting both RAW and jpeg for both. I've been out a couple of times to make solar images, to get my exposure times bracketed, shooting ISO 200 and 400. I plan to go out again this afternoon about 1600 local, and shoot some more, the air is much more clear today, not the usual midsummer haziness we normally have.

[serbiadarksky]

Well I'm a newbie but my advice for a camera is Canon 600D modified, its cheap,really really cheap

But better ask some some senior imagers becouse as I told you I'm just a newbie