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ZWO ASI178MM Cooled CMOS camera

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phxbird's picture
ZWO ASI178MM Cooled CMOS camera

Just curious if anyone has used this camera, or another ZWO camera for photometry? At around 700 dollars it is on the lower end of the price scale but according to the specs it should do a fair job. Since you can use CMOS chips in DSLRs I suppose this camera could be used as well. I am using a loaner camera right now, so am keeping an eye out for a replacement camera. I would like to use the loaner on my LX200 eventually.  The IMX178 spectral response seemed to be similar to a CCD chip in efficiency. I do have a color ZWO120 MC (color) for planetary imaging but have done a couple of deep space objects with some success. I have attached an image of M 42 taken with the ZWO 120. It was shot using AVI with an AR 102 F/6.5 telescope. I also took several images of 30-40 seconds in JPG and got pretty good results from using the camera in a way that would be better for photomery. Here are the specs. 

Camera Type
Single Frame Camera

Color or Monochrome?

Camera Series

Sensor Manufacturer

Sensor Model

Sensor Type

Sensor Dimensions (mm)
7.4mm x 5mm

Pixel Size (µm)
2.4 um

Pixel Array (pixels)
3096 x 2080

Camera Cooling
Built-In Fan, TEC Cooling via Convection

Minimum Exposure
32 microseconds

Maximum Exposure
1000 seconds

Software Included

Computer Interface
USB 3.0

Includes Filter Wheel?
No, Not Necessary

Camera Weight (lb.)
14 ounces

OS Compatibility
Mac, Windows, Linux

phxbird's picture
I'll take that as a no!

A review came out today in Astronomy Technology on the ZWO 120 series camera. Hopefully it will provide some insight!

TRE's picture
no shutter?

Does it have a programmable shutter?


phxbird's picture
ZWO camera

It has a Pregius Global Shutter, which means that it does not have a physical shutter. Could explain the price. Not sure how much that would effect photometry?


phxbird's picture
After thinking about it...

Jeff Hopkins wrote a book on using the Meade DSI for photometry. Though I never used the info for the AAVSO database it did do pretty solid photometry. It is a non-cooled camera with no shutter. So I think the ZWO could provide low cost service for those who can't afford a more expensive camera. By the way the article in Astronomy Technology is on building a low cost All Sky camera. It is pretty good but does not answer the question that I posed. 



moont's picture
Photometry with ZWO ASI174MM


I am doing photometry with a ZWO ASI174MM. I have the uncooled version (so take regular dark frames) but there is also a cooled one. Both have global shuttering and there are color versions. Minimum of 12-bit required for photometry (Howell 2000) and important that FWHM of star images cover 2-3 pixels. ASI174MM achieves both these criteria (I use it with 150mm f/5 Newtonian reflector and 70 mm f/7 refractor). My friend has a ASI1600MM-Cool and is also using an ASI034MC on his guide telescope. We both find ZWO cameras easy to use and operate reliably. (I currently use SharpCap for image capture but plan to try Astroart in the next couple of weeks.)

Attached are B-V and V-I transformations I obtained on 26 January 2017 using this camera and BVI filters. I am using a Xagyl filter wheel (5 position, 248g) but have just bought a ZWO EFW (5 position, 300g) which I have tested; it also works well. The ASI174 has a full well depth of 32ke- and I have found it to have good linearity up to that (can send graph of checking of linearity if required). Happy to send further information via email and answer any other questions. I live way down under (Tasmania) but have good Internet bandwidth so can Skype if preferred.


File upload: 
SGEO's picture
CMOS cameras for photometry

I'm also making a transition from CCD to CMOS photometry with a ZWO ASI178MM. This thread is a year old; are there insights and lessons learned in the meantime that you can share?

A couple things that I've learning:
  - The camera has a dual nature: It can take timed exposures and it can also act like a video camera. Don't understand yet the transition.
  - The ASCOM driver allows tuning of the gain. What is the best setting if doing photometry.
  - The camera has a native driver and an ASCOM driver. Is it worth finding software that uses native driver? SharpCap does and also warns that that using the ASCOM driver reduces performance. MaximDL does not support the native driver. I've not thought of SharpCap as a photometric package. Suggestions?



spp's picture
Gain for photometry

What is your average seeing (FWHM), and what is the FL of your telescope?  I'll see if I can calculate at least a starting place for the gain setting which could be optimized by linearity testing.


JBD's picture
CMOS cameras for photometry

Hi All!
By the way...
Did anyone try APT (
I tried this low-cost software, but working very well and mading the plate solves with "platesolve2" made by Planewave. Compatible with Ascom, it allows many cameras in photo mode and video mode,
and can save in fits.
On the other hand, the photometric treatment is done with MaximDL.


phxbird's picture
Bad weather

I posted this thread quite a while ago with the intention of acquiring a ZWOASI mono camera and giving it a go. I did purchase a used ZWO ASI120 MM (Mono) CMOS and have used it as an autoguider with some success. Unfortunately, I am now living in Missouri (job change) and we have had about 12 clear nights since last March. I did get my 11" Celestron CPC setup, along with a SBIG ST-8E. Unfortunately, I am still working on getting the Meade 8" LX200 working. So have not had a chance to try out photometry with the 120MM yet since the LX200 would be the scope to be used. Having done some imaging with the 120 MM on a ST80 refractor, I think it would do excellent photometry. The big negative is doing dark frames and bias frames. You have to cover the aperture physically to take them. Since these are not cooled cameras you would have to shoot more dark frames if the temeperature shifted up or down. This is not a big issue unless you are doing multiple targets, with multiple exposures using a robotic setup. I think that these types of cameras can work quite well if you understand the limitations. 

B.P.Vietje's picture
Maybe a used SBIG?

I wonder how many used CCD cameras are out there, having been repleced by newer models?

Here's an SBIG ST7 on eBay:




Clear skies,

Brad Vietje, VBPA

Newbury, VT

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