ASI294MM Pro speckle problem

[andrew s]

I have been getting a speckle issue with the camera I have been testing . I get a hot pixel surrounded by some cooler ones, see attached. Anyone come across this before? Latest software etc. Any reports at @FLO?

 

Thanks Andrew

 

PS this is intermittent sometime its fine but I can't find any way to consistently cause or cure it.

Edited September 2, 2022 by andrew s

[paul mc c]

I seem to get the same thing with my 533 mc pro,never had it until recently,I thought it may be condensation,but don't know.

[andrew s]

Here is when its ok

[andrew s]

28 minutes ago, paul mc c said:

I seem to get the same thing with my 533 mc pro,never had it until recently,I thought it may be condensation,but don't know.

Inside on a test rig definitely not condensation as it's as dry as a bone here! Regards Andrew

PS I will look at the sensor to check if and when it happens again as water could be trapped in the camera..

Edited September 2, 2022 by andrew s

[scotty38]

What happens if you try cooling more slowly or don't cool so much?

[andrew s]

1 hour ago, scotty38 said:

What happens if you try cooling more slowly or don't cool so much?

I took a series of images from ambient to -5 c all was well until -5 when the speckle pattern appeared.  Ha ha thought I. Returned to 0 c no speckles. Reduced it in 2 degree increments to -10 c no speckles!  Then to -15 c no speckles. 

Will try drying the desiccant just in case.

Regards Andrew 

[scotty38]

I must admit I only ever cool my QHY294 to -5c anyway. I think I looked at the graphs and it seemed like not much to be gained by going cooler.......

[paul mc c]

Read a post on cloudy nights about the same problem,seem if the camera cools to quickly frost can form on the sensor,I only noticed this on my camera when I started using the Asiair.

[scotty38]

Yep that's why i was suggesting to cool more slowly to see if it made a difference in this case.

[Anthonyexmouth]

2 hours ago, andrew s said:

I took a series of images from ambient to -5 c all was well until -5 when the speckle pattern appeared.  Ha ha thought I. Returned to 0 c no speckles. Reduced it in 2 degree increments to -10 c no speckles!  Then to -15 c no speckles. 

Will try drying the desiccant just in case.

Regards Andrew 

I've been having frost issues with my 294mc. Tried new tablets and a dew heater. Spoke to zwo and apparently they've been seeing it a lot this year with the heat and humidity. I wouldn't bother opening up just yet, wait until it gets a little cooler at night. 

[andrew s]

This is the proposal from ASI

"Usually we recommend slowly cooling the camera to solve the problem, which like the way you tried.
Before letting it cool down to target cooling temp, please keep it at 5℃ for 5 minutes, then cool it down to target temp and if this continues to appear, it will basically disappear in 5-6 minutes."

 

It seems to work for me.

 

Regards Andrew

[Adam J]

On 02/09/2022 at 11:18, andrew s said:

I have been getting a speckle issue with the camera I have been testing . I get a hot pixel surrounded by some cooler ones, see attached. Anyone come across this before? Latest software etc. Any reports at @FLO?

 

Thanks Andrew

 

PS this is intermittent sometime its fine but I can't find any way to consistently cause or cure it.

you need to renew your desiccant. Simple.  All this talk of cooling more slowly may help but it's just delaying the inevitable. 

Edited January 27 by Adam J