DMK camera settings question

[StargazerX1]

With the Toucam we were advised to use a brightness setting of 50%. With the DMK I have just left the brightness at 0 since it appears only to be an offset, not required for planetary imaging. I use gain and gamma adjustments only, the exposure time being determined by the frame rate.

Is that correct?

Glenn Jolly
GIlbert, Az

[matt]

Yes. I have been wondering about the brightness level too and I suspect you are correct to leave it at 0.

I also believe it's best not to introduce too much gamma.

Gain and exposure are the important sliders for adjusting image brightness (I think).

[iceman]

Yeh I leave brightness at zero. I do run gamma at 18, which based on Bird's research (comparing it with the Pt Grey cameras) is a bit above "1".

I use exposure of 1/15 or 1/30s, depending on the transparency and brightness of the object, and then adjust the gain to get the histogram from 70-95% full.

[StargazerX1]

Thanks Matt & Mike.

With respect to bird's research, I was thinking we left that as waiting to hear further from bird on the DMK gamma question. I shoot at gamma register 10 (1.0) for Jupiter and was using 13-15 for Saturn. Compared to the color Unibrain camera I have it seems to me that 1.0 gamma is about right - I would be surprised if it were that far off.

According to bird, imaging at anything other than gamma 1.0 leads to some data loss. I understand that Mike shoots at high gamma and corrects it later in his IP. Would that not effect a loss off information?

It occurs to me to measure gamma, one would need a standard test target illuminated at a level to simulate an astronimcal object, as there may be an interdependence between gamma, gain and exposure time.

To clear this up, can an IceInSpace collective effort be made to resolve this issue? If anybody is in communication with bird, perhaps we could get some clarification.

Thanks guys for your help. The contributions by this forums contributors speaks highly of your love for this hobby (or livelihood in some cases).

Glenn Jolly
Gilbert, Az

[iceman]

Hi Glenn.

This thread (http://www.iceinspace.com.au/forum/showthread.php?t=19121&highlight=DMK+Gamma) is the last I remember on the issue.

In that thread, Bird thinks that a gamma of "10" on the DMK is actually 0.5 or 0.6. I now captured at gamma 18, which would equate to slightly above 1, giving me a brighter image that I can reduce in post-processing.

If your gamma is too low, you'll get more contrast during capture which could be losing you some detail, especially at the limbs.