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james_screech
November 20, 2013, 16:37:03
Last night I tried my new DFK 31AU03.AS for the first time on some moon shots, for a first attempt and allowing for the fact that the moon was very low down and the air stability was not very good, I was very impressed with the camera. :-)

I was wondering if there is any documentation anywhere on the best procedure for setting the brightness and gain? At what gain setting does 1 e- = 1 ADU?

I have found some documentation for similar settings in another manufactures 16bit ADC cooled CCD cameras which I've used initially, but instructions specifically for the Image Source cameras would be better.

Have you considered providing some kind of user manual with these cameras? It might be a good idea.

James

Stefan Geissler
November 21, 2013, 11:29:55
James,

Unfortunately we are machine vision engineers, who build cameras, that astronomers use. We change some parts in the firmware to astronomer's needs, but we have no astronomy experiences on our own.

Therefore, I suggest to search in the appropriate astronomy forums for the camera and hints for making good astronomy photos.

james_screech
November 21, 2013, 12:12:16
Unfortunately we are machine vision engineers, who build cameras, that astronomers use. We change some parts in the firmware to astronomer's needs, but we have no astronomy experiences on our own.


But surely you must know how to use your own cameras and to configure them?
If you don't know the unity gain (controlled by your firmware and hardware) how can anyone else? :confused:

James

Stefan Geissler
November 21, 2013, 12:35:16
But surely you must know how to use your own cameras and to configure them?
If you don't know the unity gain (controlled by your firmware and hardware) how can anyone else?


I think, playing around with the controls in IC Capture is not as hard. The labels like gain, exposure, brightness and so one of the properties should be self explaining.

However, finding the ideal settings for planetary, moon, deep space or sun astronomy is a complete different skill than setting up exposure, gain and frame rate for a fast moving production line. Especially if you must take care of weather conditions and so on.

So please let me know, what do you not understand, I may can point you in the right direction.

james_screech
November 21, 2013, 13:59:01
I think, playing around with the controls in IC Capture is not as hard. The labels like gain, exposure, brightness and so one of the properties should be self explaining.

However, finding the ideal settings for planetary, moon, deep space or sun astronomy is a complete different skill than setting up exposure, gain and frame rate for a fast moving production line. Especially if you must take care of weather conditions and so on.

So please let me know, what do you not understand, I may can point you in the right direction.

I understand the effects of the different controls, however if the gain is above unity (1 e- = 1 ADU) dynamic range is reduced and the signal to noise ratio reduced. Therefore for astronomy the gain should ideally be set to unity.

As you cannot have half an electron, when the gain gives 0.5 e- = 1 ADU each electron contributes to 2 ADU and so 128 electrons will overload the 8 bit ADC (ADC output 255). At unity 255 elections will give a ADC reading of 255. With gain more than unity, more than 1 electron is needed for each ADC step, thus wasting electrons in an astronomical setting.

So as a general rule for astrophotography the camera should ideally be set to a gain of 1 e- to 1 ADU. A setting of <1 e- to 1 ADU reduces the dynamic range and effectively increase noise and a setting >1 e- to 1 ADU while improving signal to noise ratio will mean that longer exposures are required which in astronomy can lead to more image blur due to atmospheric effects.

James

Stefan Geissler
November 21, 2013, 14:26:40
James,

Thank you for this hint. I must admit, we do not know, how many photons give how many electrons and therefore it is hard to predict, which gain value has an equivalent to electrons.
The current gain settings have been requested by users. However, you can set the gain manually to you needs.

Also we are aware gain creating noise.

Maybe I am wrong here, but many astronomers use short exposure times, below 1/60 second and capture many images. From these images, the ones with less atmospheric disturbances are used for stacking. Doing so, the resulting image simulates long exposure times.

However, this is astronomy and I simply do not have the knowledge and skills for discussing this. I am very sorry for this.