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ZWO ASI178MC for DSOs?

16 Aug, 2019 23:27
Hello out there,
Capturing Hubble images is not the intention, so I am wondering whether the ZWO ASI178MC would be good enough for DSO imaging on a 450mm refractor or 750mm newtonian. Not planning to fumble with a filter wheel. When using a barlow for planetary imaging the small chip size of the ASI178MC may not come in handy as the focal length grows. I own an ASI120MC-S which produces great images of the moon and gas planets with and without a 2x barlow, but this jewel is in planning for autoguiding. FOV aside, would the ASI178MC offer any significant advantages, say, over a Nikon D5300 DSLR, worth spending 400 USD for?
Thanks a ton,
17 Aug, 2019 16:23
Hey Robert,

i can not compare the ASI178 to a Nikon D5300 (i only own the ASI178, not the Nikon), but i can tell that the ASI is fairly okay for DSOs, especially at shorter focal lengths (due to its very small pixels). All of the images taken before August 2018 in my gallery where taken with the 178MC, but most of them at 1624mm FL. But don't take my images as a reference, i was an absolute beginner at that time (not that i advanced a lot since than :-) ). But if you want to see what the camera is capable of, look at Łukasz Sujka's gallery. He uses the mono version and his images are wonderful. The ASI178 is very sensitive, that is maybe the major advantage. If you would buy the cooled version you would benefit a lot more i think.

17 Aug, 2019 17:21
Hello Mike,
Thanks a ton for your prompt reply. These are fine references. Please don't be shy about your pre August 2018 images.
Atually they are the closer reference to my reality, considering that I am still an absolute beginner myself. It seems as if the
ASI178MC ranks at the border of hi-res planetary imaging and bright DSO imaging, which appears to me a fine compromise
also considering the reasonable cost tag of the ASI178MC. They are on sale right now, here in Japan, still 10% down until Aug 25.
I'm currently in Okinawa. Perhaps a good chance for a decent deal without regrets. In terms of chip size, the ASI178MC is believed
to match well with my TS-71SDQ (450mm/f6.3 Quad APO), currently for calibration in Parsdorf. TS are awesome when it comes to
Quality Assurance.

Dank Dir bin ich schon einen weiten Schritt auf das Ziel hingelangt.

Ein schoenes, wolkenfreies Wochende, wuenscht Dir
Edited 17 Aug, 2019 17:25
17 Aug, 2019 18:20
Hi Robert, I'm using the 178MC for deepsky as well and in my experience it's a good match with shorter focal lengths. The sensor is quite sensitive and you can go for 2 or 3 minute frames for weaker objects  with similar or better results than using  DSLR cameras. Lucky imaging is also possible with the uncooled version if you go for brighter targets like planetary nebulae. But be aware that the sensor is quite small compared to a DSLR. It's a bit harder to get the objects centered and although the sensor has small pixels you still need either bigger apertures or quite long exposure times in total to get a decent resolution and the detail you want from a nice image. I'm still experimenting with my one to check it's full potential though, but I'm happy with it. Nevertheless, I'd recommend a filter to get rid of IR and UV at least.
18 Aug, 2019 01:18
Thanks a lot for sharing your view, jolind.
18 Aug, 2019 09:06
Hi Robert,
a friend of mine uses the 178 in the uncooled version for both planetary and DSO. He is quite happy with results.  While it is undoubtedly a great camera for planetary imaging, DSO seems torequire a lot more effort on the imagers side.  I would see major issues with  the dominant amp glow it exhibits at higher gain settings.  Overall, it is quite a noisy sensor. If anything, I would opt for the cooled version. But if you are willing to go that route, I would recommend the ASI183 MMpro (but it costs a great deal more). So all that aside, if DSO is your main focus, then a good DSLR would in my opinion be superior to the ASI178.
18 Aug, 2019 09:51
Hi Christopher,
Thanks a ton for your opinion. Actually, I am living in a subtropical region. My ASI120MC sensor never gets lower than 30C, no major issue with planetary work
but for deepsky, as you say, this may be a major drawback for any DSO but the Orion. Too much effort on the imager and post processing is something I'd love to avoid  smile
18 Aug, 2019 18:00
Hi Robert!
For subtropical regions cooled CMOS or CCD is ideal. I am not sure if a modern DSLR will be any better if temperatures are above 25°C. For my old 300D anything above 15°C was an absolute nightmare. But that camera is ancient old. So, if you can afford it, do consider going cooled (or maybe save a while for that end). It will save you a lot of frustration. smile
Cheers, Chris
19 Aug, 2019 00:28
Hi astropical,

I have a ZWO ASI178MC-C and I'm using it for DSO and (eventually) for planetary too. It's a great astro camera and very superior to a DSLR camera.

Take a look in this M20 nebula done with this camera:

19 Aug, 2019 00:59
Hi Delberson,

Ah, this is amazing indeed! Appetite wetting. Exactly an image I'd expect to capture myself:-)
As Christopher recommended it has got to be a cooled version of the ASI178 or an upper version.

Thanks a ton, and my heartfelt appreciation to all who responded.

19 Aug, 2019 01:11
Hi Chris、
Thanks a lot! That does make sense to me. I think I will "cool" down  smile
My Nikon D5300 is a pretty good performer on noise. Even at ambient 30C (without any NR engaged) it produces fine results from further-processed stacks of more than 50 light subs at 30sec/ISO3200 each.
19 Aug, 2019 01:36
using a ASI 178 MC for deep sky imaging session ?
Honestly, been there and forget it . you will be disapointed.
19 Aug, 2019 03:18
Thanks so much, Mehdi!
19 Aug, 2019 16:28
Atik 428 or 460 ex are great ccd's.
software that comes with the atik is great
19 Aug, 2019 17:47

There is one area where every dedicated (CMOS or CCD) astrocam beats every DSLR: it is designed to fit into the telescope like an eyepiece. This has tremendous benefits compared to the DSLR which always needs some kind of adaptor and always has the sensor too far back in the optical path (things that cost in brightness, sharpness and FOV distortion).

However, the ZWO ASI178MC is very low end with a really tiny sensor and the D5300 is exceptionally good for astrophotography as far as DSLRs go so I don't think there will be any spectacular difference one way or another, especially for DSOs. It is the quality of your seeing conditions, optics, guiding and tracking which will make all the difference. And number of subs, I guess smile DSOs have very different techniques compared to planetary.

Personally I prefer DSLRs because I do a lot of daytime photography and because I like it that the DSLR is 100% standalone (does not require a computer during the session). Since you already have the equipment for driving a dedicated astrocam you might  prefer the ZWO.
Edited 19 Aug, 2019 17:47
06 Feb, 2020 18:01
Revisit: having both a `178MC and a Nikon D7500, I will more or less stand by what I said. The single biggest benefit of the ZWOMC are its physical attributes: it fits to the telescope more naturally, it is much ligher which makes things easier for guiding/tracking and it has smaller pixels/sensor size which is a good fit for smaller or more remote DSOs such as galaxies and planetary nebulae. Literally the only practical plus of the Nikon is I can focus fairly quickly and accurately with live view. Looking at a computer monitor next to the camera and going back and forth to make adjustments is not as convenient, actually it is very frustrating.

Now, the ZWO sensor is super-sensitive but the quality of the DSLR's sensor is simply unparalleled. The D7500 has no amp glow, the offset frame is near zero and darks are necessary only above 20 degrees or so, and only for exposures longer than 60 seconds. Even then, their value is questionable if you are limited by sky glow/light pollution and it is usually a much better idea to just use a bad pixel map.

On the contrary, the ZWO cannot be used without calibration frames. Its offset has visible patterns even at very high gains and normal frames have a horrendous amp glow which is like a star the size of Mintaka complete with diffraction spikes [!] at the top right corner of the  image, as well as several hot pixels which are *not* the same in every frame (so you need to dither tens of frames to get rid of them). I have also seen strange, ghost like artifacts close to bright light sources which I am not sure where they come from (some kind of reflection phenomenon I would guess).

Now all this is not exactly bad. It is the price you pay for the insane quantum efficiency/sensitivity since a sensitive CMOS will not react only to your desirable signal but also to other sources such as its own heat. I have seen the same phenomenon with the D7500 itself. Compared to the D3300 I had before, the sensor has more hot pixels, more visible thermal noise and a slightly "dirtier" image feeling overall. But it is way more sensitive, I have captured the same targets with the same ISO and the difference is obvious, well worth having to create a bad pixel map once every two years or subtract the occasional dark frame when it's really hot smile The ` ``178MC simply takes this many steps farther, you get a raw 80% QE completely unmodified which means you *have* to do serious calibration.

And as everyone here will tell you, serious calibration is realistic only with cooled cameras, not so much because lower temperature reduces noise but because it cooling = regulated temperature = you can very easily create calibration frames that are a precise match for your lights.

In a nutshell: for a small target the 178MC will allow you to frame and capture better quality signal, but  significant effort will be required to remove the unwanted stuff and everything will be easier if you go cooled. For wide field and the larger/brighter messier objects, the DSLR will give you results of much better quality with much less hassle.
06 Feb, 2020 23:15

I use a 178MC almost exclusively for small DSOs and planets on my 150mm  F10 Mak Cas.  For DSOs, I typically  use a .63 focal reducers which puts my FL at 945mm.    With that focal length, you have to track pretty well to avoid star bloat.  I added a DIY external Peltier cooler to help bring the temp down.    The 178 does have a lot of amp glow that dark frames handle pretty well.   I prefer using it with  Sharpcap Live Stacking for my DSO imaging over using raw frames and DSS to stack.  I also have an 80 mm 500fl refractor that I typically use with my Canon T2i (550d)  when I want to capture wide field areas of the night sky.  For instance when I want to shoot M31 I use my Canon and my 80 mm refractor.  When I want to capture the Ring Nebula or Whirlpool Galaxy I use my Mak and the 178.   So I would say if you can only have one imaging camera simply decide how big the DSO objects are that you want to capture.  The free program Stellarium has a feature where you can enter the dimensions of each sensor you are interested in, along with the FL data of your telescope. Once entered and it will then allow you to zoom in on the DSO of your choice and show how much of DSO will land on your sensor.  I highly recommend doing that to help you in your decision.    For comparison the 178 sensor is only 7.4 mm x 5 mm while the Canon is 22.3 mm x 14.9mm.  Hope this helps.
Edited 07 Feb, 2020 19:45
07 Feb, 2020 06:46
Thank you so much for the revisit and details, dkamen.

In the meantime, I decided to stay with my Nikon D5500 for DSOs and ASI290MM for the Moon. With a DSLR I do not need to fire up a computer unless for autoguiding, and I do agree, the DSLR sensor performs better with less post-processing hassle. Frankly, processing is still a pain in my neck in that I am trying to suffice with a minimum.

Just for curiosity, I'm planning to hook the ASI290MM up to a Samyang 135mm with an IR-cut filter in between to see how it performs on popular DSOs.

By the way, I also own the TS 60mm/360mm with flattener. No need for a larger APO :-)

All the very best to Athens.

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