Quote:
Originally Posted by awyong
Hi! Iceman,
Do you have good sky in your area? Any light pollution?
It seems it is impossible for me to take a long shot for more than 1 min. Even I have use the Light Pollution filter. My background will become very bright. Any suggestion for me?
- Televue NP101
- prime focus
- no dark or flat
- 1 min
- Light pollution filter
If I don't use light pollution filter, my image will become the second images.
- Target Comet Holmes
- 30 second
Aw Yong.
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Try taking many frames and stacking them, all night if necessary. Then you'll have enough signal you can subtract out the sky and still have a good image. You need a lot more time than someone in a dark sky would need but it can be done. Keep your exposure time short enough the object doesn't saturate and the background is less than half full intensity, less if using a 12 bit camera. Also narrow band imaging is virtually immune to light pollution. It limits the targets but is great for emission nebula as well as planetaries.
When it comes to fighting light pollution the added bit depth of a 16 bit CCD has a great advantage over a 12 bit DSLR.
I know an imager who gets great galaxy shots from down town Berlin using this technique but he does use a full 16 bit CCD (black and white).
Rick