Sky Fog Limit

Hi, I'm trying to determine my "Sky Fog" limit. I added two images to the
Analysis Gallery page two:

http://digitalastro.skyinsight.net/g...nalysis&page=2

One's a 15 sec exposure at f2.8 with my 50mm f1.5 lens, the other a 30 sec
exposure. The images were taken in Raw with white balance set to AWB and
Parameter set to 1, converted to Tiff in IP, and dark subtracted in IP,
nothing more. All image taken with a Digital Rebel 300D. Can some of the
experts tell me if I'm at my limit at 15 seconds without a filter or is it
closer to 30 seconds? I do plan to buy an IDAS filter, but would like to
calibrate my sky (looking East-South East from my deck). Due South is
much better, East is worse and North about the same as these exposures.

Thanks much,
Chuck

A follow up question: can a Lumicon NightSky H-Alpha Filter be used on a
Digital Rebel to image the Luminance portion of an image, using a normal
unfiltered image to record the color portion? I'm looking at ways to deal
with my light pollution.

Thanks,
Chuck

"Chuck" wrote in message
...
Hi, I'm trying to determine my "Sky Fog" limit. I added two images to the
Analysis Gallery page two:


http://digitalastro.skyinsight.net/g...nalysis&page=2

One's a 15 sec exposure at f2.8 with my 50mm f1.5 lens, the other a 30 sec
exposure. The images were taken in Raw with white balance set to AWB and
Parameter set to 1, converted to Tiff in IP, and dark subtracted in IP,
nothing more. All image taken with a Digital Rebel 300D. Can some of the
experts tell me if I'm at my limit at 15 seconds without a filter or is it
closer to 30 seconds? I do plan to buy an IDAS filter, but would like to
calibrate my sky (looking East-South East from my deck). Due South is
much better, East is worse and North about the same as these exposures.

Thanks much,
Chuck