Atik problem

[Carole]

Last night, it was working fine if I did 5min subs or shorter, but when I did 10min subs I got a total whiteout sub 650000 ADU, no detail, just as if I had done an overexposed flat. 
I went back to looping and a 5min sub and it was fine, so i did another 10min sub and the same thing happened again.  Went to try 7mins but the clouds came over.

No chance of stray light as back garden and too co-incidental to happen twice. 

My Atik314L is going back to Atik (when I go to Astrofest) anyway, as there is a really dark dust bunny that needs cleaning off and they offered to clean it for me.  (I don't want to tamper myself). 

But just wondered whether any-one has any ideas in the meantime.

Carole

[JohnP]

what happens if you try a 5min and 10min dark (you can try this in the daylight of course...)  John

[RobertM]

Is there a chance that the background count was over 50% (in the histogram) when you took the 5min frame ? if so then 10mins could flood the ccd.

Robert

[Carole]

I'll try both those things. 

10mins could flood the ccd.

I just took a look in maxim at the 5min sub and the sky background is about 39000 adu which would work as you said i.e flooded the sensor. 

I was puzzled as I thought I had done 20mins subs with this camera before, but just realised they were all narrowband.   

I have done 10min subs luminance at a dark site. 

Bummer, so I presume this means I can't do any longer than 5mins (still to try 7mins) with luminance from Bromley?

Does this sound about normal then?
Thought there was something wrong with the camera.

Carole

[JohnP]

cant remember what I have done - have you got a CLS filter or just straight L filter - if just L then yes I would suspect all the buckets are filling up.... I always use CLS even when doing L from Bromley

[Fay]

too much for around here, with L filter. did you use cls filter?

[Carole]

I can't believe it has taken me 2 1/2 years with a CCD camera to find this out. 

I just checked back all my images, and there were either done at a dark site, or with narrowband at home.

I must remember to use a CLS filter when doing LRGB from home, Bern told me I didn't need to when I bought filters from him, but more lately I have been advised to, but obviously not having done any from home in luminance I haven't got in the habit of doing so. 

I got a new set of filters when I went over to the EFW and apart from being Baader I'll check with Ian King what he sold me. 

I have got a CLS filter, so thanks for reminding me and no I didn't use one last night.

Well thanks for that, at least I know it's not because the camera is broken.

Carole