Leo Triplet - please help with problem

[troypiggo]

Not very happy with this result. It looked ok on the camera's lcd, but after stacking and processing it's apparent the bottom half of had a red or magenta tinge to it. I spent only a little time trying to get rid of it, but you can still see the horizontal line through the middle of shot. Any ideas what this might be caused by? Is this what's referred to as "amp glow"?

I was trying a couple of new things last night. I bought a light pollution filter - IDAS LPS P2. Comes highly rated. Don't think it would cause this.

I also bought an AC power supply for my 30D instead of the batteries. Maybe the different power supply could do it?

http://piggo.com/~troy/photos/2009/2009_03_24/leo_trio.jpg

[iceman]

I take you haven't applied any calibration frames? (darks/flats)

I suspect that the problem would go away with flats.

Though it does look odd. I doubt it's the IDAS LPS, and I doubt it's the power supply. Unless it's interference if the USB cable is too close to the power cable?

I think more tests are needed to isolate the cause. With/without scope. With/without filter. With/Without power.

[troypiggo]

Thanks Mike. I did apply darks, but not flats. 5x8min lights, 3x8min darks.

Taken with Canon 30D DSLR, not a CCD - if that's what you mean by USB cable being too close to power cable. Only cables connected to the camera were the AC power supply and remote timer. Couldn't see those sort of things affecting the image in DSLR camera?

I'm a bit bummed. Got some good results last month, and now this issue has come up putting a damper on my fun :)

[multiweb]

could it be a bit of amp glow from the camera?

[Les Tilly]

I would suggest more darks as well as flats Around 20 darks 20 flats if you use only a few darks it can add more noise to the image I find the more darks the better and Flats are a must

I have the 40d and I use the power supply and also the idas LP filter the only problem I see with the Lp filter is a slight Green color but that can be adjusted with color correction.
Also use a 20 sec break between taken the images

Regards Les T

[troypiggo]

I dunno. That's what I asked you guys in my original post. You're not allowed to ask me the same question ;) :)
What causes amp glow?

[troypiggo]

Righto. I only have a 1sec break between shots at the moment. I'll stretch that out a little in future. Wasn't aware it causes problems?

Flats - only new to this astro imaging and haven't done any flats at all yet. Only lights and darks. I'll try that next time.

Re: more darks. I was thinking that if that was the problem, the image would just be noisier all over, not from a dead horizontal line down.

Thanks Les.

[iceman]

More darks won't solve it, in my opinion.

I've stretched and attached your image.

The red glow in the bottom right corner is amp glow.

The dark area in the middle of the two red lines is what the problem is.
More darks won't solve that. Flats might, if there's an area on your CMOS that is acting funny.


They would affect a DSLR if you were downloading the images directly to the computer through a USB cable. If you were just capturing in-camera and saving onto your memory card, then this wouldn't be a problem.

[RB]

It's amp glow, caused by the amp circuitry associated with the sensor.
You need to take lots of darks, and lots of flats to help.
Glad to see you ditched the battery and bought yourself a 240v adapter instead. ;) :whistle:

Also what you see on the LCD will be a jpg version with any Picture styles and whatever WB you have set, it won't necessarily correspond to your RAW files.

[RB]

More darks will help a lot with noise.
Like Les suggests, I recommend a lot of Darks and Flats.

[troypiggo]

Thanks again guys.

So....

apart from it probably needing more subs, more darks, flats, combating amp glow, the LPS filter affecting the WB, noise, longer break between shots etc....

pretty awesome shot, hey? :rofl::P

[RB]

It's a good start. ;)

[troypiggo]

Good answer :)