Mono images from OSC ccd

[jambouk]

Here is an image i took tonight with my new colour ccd, QHY8L, with reducer on an Ed80; IDAS light pollution filter before the reducer as the spacing will be wrong if i put it between the reducer and the sensor at present. IR filter on the camera.

600s sub of m31. Lots of moon light.

Saved as a fit and then run through fits liberator to generate this tif.

The tif appears monochrome, and stacking two of these images in dss, it looks monochrome too and there are no rgb channels at the end of stacking.

I've correctly identified the camera in EZCAP, and it has "colour camera" ticked, and i've seen colour in daylight looking at the horizon, so why am i generating monochrome images?

I set up gain (10) and offset (116) as per various threads on sgl, and did it with the LP on and off and the values were very similar.

Any ideas?

James

[Thalestris24]

Hi James

FITSliberator only processes and saves in mono, I think. You need to use another application to keep colour.

Louise

Edit: of course you can stack fit images in dss and save either as fit or tiff. I usually save in fit and post process in StarTools (cos I'm a cheapskate, lol)

[ollypenrice]

The image has not been debayered, which is to say the colour has not been extracted. Indeed the Bayer matrix is still clearly visible as a grid pattern on the image.

Olly

[jambouk]

Thanks both.

Seems a flaw of the ezcap software that it can't output a high resolution colour image other than a fits file.

James

[Thalestris24]

Hi James

Unlike dslr images, osc images need a separate debayering step. You can debayer 'live' images if capturing in APT. You can also preview (and stack, of course) in DSS but don't forget to enter 'GBRG' in the Raw/FITS settings. Mind you, Fits Liberator still only displays in greyscale...

Um, wondering if you've previously set the camera's gain and offset? Details in the manual! Download from here: http://qhyccd.com/ccdbbs/index.php?topic=4275.0

Cheers

Louise

[Spikey]

If you run the image through the deep sky stacker application there is a debayer setting specifically for the QHY8.

[Thalestris24]

If you run the image through the deep sky stacker application there is a debayer setting specifically for the QHY8.

Don't use qhy8 - it's a different camera to the qhy8l!!

[Spikey]

Don't use qhy8 - it's a different camera to the qhy8l!!

You're right - my mistake ! it's the GBRG setting.

[jambouk]

Yes i spent a few hours setting up the gain and offset over the weekend; the values with and without the LP filter were very similar, i think gain 9 and offset of 116 without, gain of 10 and offset near 116, can't remember the number off the top of my head but it's written down. I didn't add the extra 5% onto the gain which one description suggested as i wasn't sure if it was necessary and wasn't really sure if the units i have for gain are percent or something else.

All very confusing.

James

[Thalestris24]

Hi James

Well it's just about getting the max dynamic range out of the camera without it clipping

I've found mine quite a good camera - if only I could get to use it more. The weather forecast continues to be pretty grim

Louise

[jambouk]

I'm surprised there isn't any software which could automate and make that calibration make it more precise; "now direct the camera to the diffuse light source, thank you, now cap the camera, thank you, now direct the camera to the diffuse light source... Thank you, calibration is complete, your optimal gain is xx and offset xx"

I'm off to wales for a week and was going to take all my kit, but the forecast looks so bad i might just take books and a pair of binoculars just in case.

James

[Thalestris24]

Hi

I guess it would be open to be done with a script but since you only have to do it once...

Yeah looks like a miserable week ahead Mind you there might be some clear spells from about 3am this morning up here and again from 5pm tomorrow - fingers crossed!

Enjoy Wales!

Louise