View Full Version : New owner of DFK 31AU03 with a question

April 27, 2009, 18:00:08
I just purchased this camera to replace my cheap SPC900NC for imaging the planets. I noticed when trying to image Saturn, that when using the camera and adjusting the gain and exposure, the Live view will become very choppy when increasing the exposure. If I set both to auto, it lowers both to become nice and smooth. As soon as I lower gain to half and increase exposure to brighten Saturn, the Live view starts to become choppy at around 1/9 to 1/30th exposure.

I have tried it on 2 different PC's with the laptop having XP and the desktop having Vista. Both have USB 2.0 and both have AMD CPU's of different types. Just read on here that AMD ******boards have an issue with using the max frames. Would it also have an issue with the choppiness I described here?

Any suggestions on Camera, software or OS settings? New USB cable?


Stefan Geissler
April 28, 2009, 08:49:17
Hi Trever

I have to admit, I do not understand, what you mean with "choppy". If the exposure time is longer than the frame rate allows, then the frame rate is reduce by the camera. Thus, if you want to exposure a long time, you should choose a low frame, e.g. 7.5 or 3.75 fps.

With these low frame rates, the AMD ******board problem plays no role.

April 28, 2009, 15:50:38
Forgive me. It may be my own inexperience with this higher quality CCD camera.

I probably need to research the optimal settings that others use for planetary imaging and not try to use similar settings I have used with cheaper webcams in the past. With other webcams, I have increased the exposure setting to the camera's limit and the live view frame rate remained unchanged. Of course, the exposure settings of the cheaper webcams are probably nothing like setting real exposure times on a CCD camera with the actual capability to use it.

This camera is worlds different than the older cheap webcams I have used so I will probably need to ask around and use the camera to gain the experience I need. Thanks for your help and I appreciate the time you gave to respond.


Stefan Geissler
April 29, 2009, 08:47:40
Hi Trever,

Of course I forgive you. I will try to answer any question, if I have a good answer (which I do not have in case). If the exposure time is longer than the frame rate allows, e.g you have 30 fps and exposure with 1 second, then the camera can only provide images with 1 frame per second. I think all the other camera providers and web cams, that allow long exposure times do the same.

But at least, this question is often asked.

There are many astronomy forums, in which astronomers exchange experiences. I am more in machine vision and not as much in astronomy. Thus I can only try to answer technical questions.