I have forwarded this to Pete.

Hello, yes this was my mistake when collecting the darks. It is very easy with this camera to forget to set it to Darks as it has no shutter system. The frames are still dark frames but do show a filter name in the fits header as light frames.  If you are using an automated calibration and stacking some software will get the darks and light frames confused. This can be easily fixed by renaming in the fits header. Highlight the offending name, fill out the correct information and click replace.  Hope this helps you

Thank you for your quick response. First of all, I apologize for the fact that the content written last time was incorrect. It is FLAT file that contains LUM characters. Not DARK The file name is from (1) to (20) as shown by Flat-Lum (1) .Fit. When I see Fits Header, the image type seems to be correct. Because it is FLAT. Is this FLAT file for LUM?

That is perfectly fine - as it's a One shot Color with no filters, the filter is just called LUM Kind regards, Phil.

I hope you don't mind me interrupting your thread but if you get a moment could you email Pete re your Pier 6 order as he has some advice for you Steve