Can I make my "Dark Frames" at any time of day???

[SlimPaling]

Hi ...

I have just upgraded my Mono CCD Camera and it is a long time since I made any calibration frames.

There was always something that I wasn't 100% sure about ..... can I make my Dark Frames at any time of day or night???

My camera has very efficient cooling ... and is set to -20 C.

Does this mean 20 degrees below the ambient temperature??? .... or .... is it really -20C below zero whatever the ambient temperature happens to be???

Cheers Mike

[Davey-T]

Temperature is minus 20 if that what it says regardless of ambient temperature, you can take darks anytime as long as you have no light leaks in the imaging train.

Dave

[symmetal]

The only problem may be the camera reaching -20C during the day when the ambient temperature is higher. Having a desk fan or similar blowing across the camera can get you an extra 5 degrees cooling or so. You may want to take the camera off the scope and fit the metal dust protection cap that came with it to ensure no light leakage. Assuming it is a metal cap. Black plastic caps do leak light.

Alan

[ollypenrice]

If it's the Moravian in your signature you should be fine so far as light leaks go because it has a shutter. You need to be sure your capture software allows you to keep the shutter closed for taking darks, though. I would still prefer to do them in the dark on the belt and braces principle, however.

Olly

[PeterCPC]

I suggest putting the camera in the fridge. It will help it to get to temperature and cut out any light (if you don't open the door).#

Peter

[kirkster501]

17 hours ago, SlimPaling said:

Hi ...

I have just upgraded my Mono CCD Camera and it is a long time since I made any calibration frames.

There was always something that I wasn't 100% sure about ..... can I make my Dark Frames at any time of day or night???

My camera has very efficient cooling ... and is set to -20 C.

Does this mean 20 degrees below the ambient temperature??? .... or .... is it really -20C below zero whatever the ambient temperature happens to be???

Cheers Mike

You can take your darks at any time of the day as long as the darks are taken at the same temperature that the lights will be taken at.  I too have the Moravian G2-8300.  The 8300 is a noisy chip and the chip gets much noisier as the temperature increases so it is important that the lights, darks and BIAS are all at the same temperature so that the subsequent image calibration is accurate.

If your intention is to build a dark (and BIAS) library, you should make them at all binning levels that you will use and the library should be rebuilt every six months or so to be an accurate representation of the chip's properties

[SlimPaling]

Hi guys ... many thanks for your thoughts and suggestions.

My new camera is a Moravian G2-8300 MkII ... with external 7 position filter wheel. I changed from my previous Moravian with 5 position internal wheel as I wanted to get into narrow band imaging.#

The end cap is made from metal and is a very light tight fit .... so I will be carrying out my darks probably in the early evening sometime soon what ever the ambient temperature might happen to be and see what happens 🙂

Cheers Mike

[glowingturnip]

just don't do what I did and try and take your darks with the camera in a suitcase to keep it dark - it got hotter and hotter and eventually couldn't hold its set-point temp !

[tomato]

On 10/09/2019 at 11:39, PeterCPC said:

I suggest putting the camera in the fridge. It will help it to get to temperature and cut out any light (if you don't open the door).#

Peter

I tried this with a Moravian 8300 trying to run at -30C, it didn’t work.

The amount of heat chucked out by the Peltier was too much for our fridge and the camera slowly warmed up. As it was winter time  I put the camera outside on a suitably chilly day and took them there, no problem.