Yet another DIY all sky camera thread

[Gina]

The next question is about cooling the camera.  I know I said there's a small hole in the PCB behind the image sensor in the ASI185MC and presume the ASI178MM is the same but this hole is a lot smaller than the sensor chip so a cold finger in this hole would only cool the middle of the chip.  The other question is whether it's worth bothering, particularly as adding anything inside the camera case risks damaging the camera!  I've already "deaded" one camera and I done want to kill another!  Cooling the case seemed to work well enough for the ASI185MC so should be adequate for the ASI178MM.  Also, any moisture that does get into the camera case would condense on the inside of the case rather than the image sensor chip or window.  Unlike the cooled ZWO cameras, these do not seem to provide a sealed enclosure which was a surprise.  There is no desiccant to remove moisture in these cameras.  Damp or even water (as I know to my chagrin) can get into the camera.  Whether it gets in around the window or one/both of the connectors (USB and ST4) I don't know but get in it certainly can!!!

Thus the extra £300 for the cooled versions is far from just a double step Peltier TEC and heat radiator plus fan, but a whole different case and internal construction with a sealed chamber for the imaging sensor.  The sensor chip presumably has a cold finger leading to the cold side of of the cooling system.  The upshot of all this is that the uncooled ZWO cameras are not really suitable for cooling by external means other than to reduce the temperature to a few degrees below freezing. 

In conclusion, my idea of adding an Ha filter into the ASC for providing a narrow band ultra widefield imaging system would seem to be a non-starter without a proper cooled camera.  I just don't think there would be enough light coming in through an Ha filter to give an adequate image with an ASI178MM camera with it's small pixels.  But I guess I could be wrong.

[Gina]

I seem to have succeeded in soldering the wire back onto the Peltier TEC.  One more small step...  back to where I was.  Well, sort of!  I would only be back where I was if I had a colour camera with 1/2" image sensor.

Clearly, I need to redesign my ASC to prevent wet getting into the camera if I am going to resurrect it!  There would seem to be no way of stopping horizontal rain drenching it every time we get a storm so the casing will need sealing very well to prevent wet getting in.

[Dr_Ju_ju]

Don't forget freezing conditions, which also takes moisture out of the air & then deposits it on every thing as frost, which then melts to heavy dew....