Cooled ATIK CCD Icing up?

[rnobleeddy]

Picked up a second hand ATIK 383L+ which seems to be working well. However, on both the last couple of nights there's been a transient blob on the first few images, which has then disappeared. One is attached below. The night before, there was two similar spots on the opposite edge. In both cases they were gone 10-15 minutes later.

I'm guessing this is the sensor icing up? I'm going from ambient (10°C) to -20°C and then start imaging immediately. 

So was wondering:

- does this look like ice?

- is this normal, and can it be avoided by cooling in stages or just cooling then waiting 20 minutes?

- does it suggest I need to re-charge the desiccant?

 

[wxsatuser]

Change the desiccant.

Mine used to ice all down one side, after doing the desiccant it was ok.

Edited December 16, 2020 by wxsatuser

[rnobleeddy]

9 minutes ago, wxsatuser said:

Change the desiccant.

Mine used to ice all down one side, after doing the desiccant it was ok.

Thanks - I believe it's the oven rechargeable type.

I forgot to also ask, I'm curious if anyone knows by what process this disappears after a short time - my guess is the desiccant traps water vapor, but once there is ice and the CCD is at -20, how does it dissappear? 

[Richie092]

Had this with my 383, luckily I still had the spare dessicant tabs. Swapped them out and sorted it.

I wondered where it went (cleared after half an hour) but was too lazy to ask.

 

[tooth_dr]

I’m a long term user of a 383L and this is something that I need to address 1-2 times per year. For me it is resolved by baking the tablets and then putting them back into the camera warm.  I also the. place the camera in a sealed Tupperware container with silica gel overnight immediately after I’ve replaced the tablets. 

[rnobleeddy]

1 hour ago, Richie092 said:

Had this with my 383, luckily I still had the spare dessicant tabs. Swapped them out and sorted it.

I wondered where it went (cleared after half an hour) but was too lazy to ask.

 

 

49 minutes ago, tooth_dr said:

I’m a long term user of a 383L and this is something that I need to address 1-2 times per year. For me it is resolved by baking the tablets and then putting them back into the camera warm.  I also the. place the camera in a sealed Tupperware container with silica gel overnight immediately after I’ve replaced the tablets. 

Thanks both. I'll have a go at baking the tablet this weekend.

[tooth_dr]

5 minutes ago, rnobleeddy said:

Thanks both. I'll have a go at baking the tablet this weekend.

Just for information, there are three tablets in the camera.

[mihaighita]

There are 3 desiccant tablets in the camera. Just bake them @ 220C for 2 hours. Remember to put the screw back on the camera and keep the camera in a box, preferably with desiccant bags near it while you bake the tablets. 

[Richie092]

Mine had a piece of cotton wool at the bottom of the 3 tablets, I swapped that out too.

[Bukko]

I have the SBIG version and the dessicaant failed. Different design, there is a small bag secured in with the chip. Moisture manaaged to get into the miscolenses and changing the dessicand did not fix it.

After a lot of thought, I disassembled the glass cover over the CCD and put the camera in a warm oven at about 45 degrees C for an hour. Re-assembled with fresh dessicaant and it is like new again.

Not sure of the message, apart from don't ignore it, or if it does get really bad, there is a fix!!

Gordon.

 

[newbie alert]

How fast are you cooling the sensor,  best done in stages