Continued issues with ASI071MC-Cool

luling_skies

I continue to have issues cooling my ASI071MC-Cool to -10C. I installed the extra desicant tablets and I have learned to cool the sensore very slowly, but I continue to experience a large black spot in the center of the FOV, see attached. When I warm the sensor, the spot goes away. Has anyone learned to successfully avoid this issue? I'm tired of it reuining my images.

Tim

ndb

Hello Tim,

I experienced the same issuproblem. This is dew (not frost), forming when the sensor is cooled in humid air. Here are some solutions to get rid of it:

- to add a warming resistor

https://astronomy-imaging-camera.com/products/accessories/anti-dew-heater/

- OR do not too much cool the sensor, that is +5°C. Given the extremely low thermal noise and amp glow of the 071MCC the solution is valid (my 178MMC demands stronger cooling).

- in all cases, check "anti-dew" feature (depends on the software; or choose ASCOM driver)

By chance, the problem appears only with the large sensor protection window of the 071 which has one of the very smallest thermal noise amid all ASI cameras.

Nicolas

PS: please see

http://zwoug.org/viewtopic.php?f=21&t=6961&start=10

Sam@ZWO

this is dew on protect window

please follow Nicolas' instruction which should be very useful

luling_skies

Nicolas & Sam,

I always turn on the dew heater on the sensor window via SharpCap. The ASI071 already has a heater on the sensor window, so the provided link to the ZWO webpage is not needed. I believe that product is for other ZWO cameras.

I can limit cooling to above zero to help avoid the issue but this reduces one of the primary advantages of this camera over my DSLR. If the sensor chamber is sealed with no leaks and contains desiccant tablets, there should be minimal moisture in the chamber to create dew on the sensor. So the only dew formation should be on the external side of the sensor window and the dew heater should mitigate that. So why are so many people reporting this issue?

Tim

Sam@ZWO

Hi Tim

I suspect the heater didnot work very well or not powerful enough to get rid of dew completely

we need to change the resistance smaller to make the heater more powerful

the heater for 1600 works for 071 too

this can be a temporary solution

https://astronomy-imaging-camera.com/products/accessories/anti-dew-heater/

luling_skies

Thanks Sam. I've ordered the dew heater and will apply it to my ASI071 and advise how it works.

Tim