Orion wide field reprocessed

[rcheshire (Rowland)]

I need to get a life.

This is a reprocessed orion wide field. This time with what I believe is proper bias, dark and flat frame calibration - except that the flat is at iso 800.

Canon 1000D, 247 frames, average 15 seconds, 200mm, f/2.8 - 3.2, approx 62 minutes - unguided.

It seems to me, that without overdoing the processing, this is about what to expect from an image of this size. Maybe someone else could extract more data - histogram attached.

[Octane (Humayun)]

Rowland,

Hope you don't mind, I had a two minute play in Photoshop with the attached JPG.

Note, the halo around M42 is not something that I've introduced -- it's in your data. Not sure where that's come from other than some kind of processing done in Pixinsight?

There's some data in there.

H

[rcheshire (Rowland)]

Thanks H. No problem, it's good to get a second opinion.

I have a feeling that it's a combination of the dithering issue, calibration, possibly the flat and the method of integration/pixel clipping, and the camera/sensor - or so I'm told.

I'll start again.

[irwjager (Ivo)]

Originally Posted by rcheshire

I need to get a life.

Seems to me you got a great life, practicing astronomy!

It seems to me, that without overdoing the processing, this is about what to expect from an image of this size. Maybe someone else could extract more data - histogram attached.

I think I got a wee bit more out of the JPG, but like you, I wouldn't want to overdo it with the processing.

Nice going!

[rcheshire (Rowland)]

That tool set is amazing Ivo. But I need to get some of the PI processes under control, particularly pixel clipping.

I found the problem. Basic really. The final combination of the exposure subsets required a different clipping algorithm. Having done that the quality of the image and any underlying problems is immediately evident in the L* channel. Unless I push it really hard, the streakyness and milky appearance is all but gone. Differential flexure is a large part of the problem, but I've managed to minimize that by integrating the images in the way that I have.

The lesson is dithering - reframing the subject periodically throughout an imaging run. This is true for unguided work, particularly with accurate polar alignment - a fluke.