Ring and Dumbbell

[RSM]

Late summer nice weather with the nights drawing in and it's been a busy time. I captured a couple of Nebulae over the weekend, approx 4 hrs exposure time for each made up of 10 minute exposures at ISO. Subs were taken through my Powermate 4x, guided and with the EOS 500D. Might have a go a re-processing these as lots of noise in background (probably due to 10 min exposures and the effect that has on noise on the camera CCD). Usual Flats, darks and bias taken, stacked and processed in PI.

Clear Skies,

Richard

[wimvb]

Nice images of these PNs

The high magnification increases stars as well. You can try sizing them down by using deconvolution in the linear phase of processing, and adding a touch of positive bias in MMT in the non-linear phase.

Thanks for sharing

[RSM]

2 hours ago, wimvb said:

Nice images of these PNs

The high magnification increases stars as well. You can try sizing them down by using deconvolution in the linear phase of processing, and adding a touch of positive bias in MMT in the non-linear phase.

Thanks for sharing

Thanks for the tips. These are some of the first images I've taken under magnification and I've had to adjust a few things, most notably I needed to adjust the settings in the image registration process (star alignment) when building the image from the subs. I'll look into deconvolution (I presume by linear phase you are referring to processing steps before the first histogram stretch?). Can you expand a little on MMT?

thanks again. 

[wimvb]

Yes, linear phase is before any stretch.

MMT multiscale median transform, can be used for all kind of things.

In PI philosophy, images consist of layers. Each layer represents a level of detail. Layer 1 is detail on single pixel level. This is mainly noise, but also very fine detail. Anything that changes considerably from pixel to pixel, will be represented in layer 1.

Layer 2 is anything 2 pixels in size; layer 3, 4 pixels in size. For every next layer, detail size doubles.

In MMT you can control noise reduction, sharpening and blurring on layer level. By double clicking on a layer, you switch it of. By adding a bias that is positive, you amplify that layer, a negative bias will make it weaker. You can also do noise reduction on any detail level by setting the noise reduction parameters for that layer.

To sharpen an image, you would typically give low number layers (2, 3, 4) a small positive bias. Layer 1 is not used for sharpening to avoid increasing noise.

HTH.

[RSM]

13 hours ago, wimvb said:

Yes, linear phase is before any stretch.

MMT multiscale median transform, can be used for all kind of things.

In PI philosophy, images consist of layers. Each layer represents a level of detail. Layer 1 is detail on single pixel level. This is mainly noise, but also very fine detail. Anything that changes considerably from pixel to pixel, will be represented in layer 1.

Layer 2 is anything 2 pixels in size; layer 3, 4 pixels in size. For every next layer, detail size doubles.

In MMT you can control noise reduction, sharpening and blurring on layer level. By double clicking on a layer, you switch it of. By adding a bias that is positive, you amplify that layer, a negative bias will make it weaker. You can also do noise reduction on any detail level by setting the noise reduction parameters for that layer.

To sharpen an image, you would typically give low number layers (2, 3, 4) a small positive bias. Layer 1 is not used for sharpening to avoid increasing noise.

HTH.

Brilliant, thanks very much. I've been using MMT in my processing but more trial and error. Your note helps greatly in understanding what is s going on. ?

[Rodd]

What scope did you use?  And what camera.  A Powermate 4!!!!!  oh my.  

[RSM]

7 hours ago, Rodd said:

What scope did you use?  And what camera.  A Powermate 4!!!!!  oh my.  

Hi, I have a skywatcher 200PDS and image with a Canon EOS 500D. 

Powermate is giving me some great close ups meaning a lot more detail in fainter/smaller objects. There is some loss of brightness but I've managed to guide up to 10min exposures so that helps get enough light. Trouble is I then run into more noise in each sub (I feel that will be an expensive step to eradicate - cooling cameras doesn't look cheap!) Where I need to brush up is around sharpening the image. At such high magnification, focus is critical and the stars appear slightly more blurred. Some of wimvb's helpful comments might help me do that. Will probably look to reprocess the master stacks with some of those techniques.