Two more experimental images with ASI1600mm-cool CMOS

[Shiraz (Ray)]

Originally Posted by el_draco

Mary, mother of someone else.... What a FABULOUS moon shot!

Originally Posted by gregbradley

Ah yes I can see the Moon shot now. Wow, razor sharp.

Greg.

thanks - yep that is my favourite image to date with the 1600 - when I had finished processing it, I spent about 20 minutes just looking around - had forgotten how interesting the moon is..

Originally Posted by Peter Ward

Hello Ray...the speckle is there alright...if it was just in the shadows I would not be fussed, but it is in the bright regions as well in your M16 shot.

Oddly... the Lunar image is very clean.

I've exaggerated it (with a high pass filter ) in the attached image.

Ah - OK, that is the fault of the processor of the image. In order to enhance the meager high frequency components in the scene (seeing was poor), I pushed the fine wavelet sharpening hard. Thought I had kept noise under control, but not quite enough by the look of it.
regards Ray

Edit: the enhanced noise can be a easily removed from your jpeg - actually that's not a bad enhancement technique - excess high pass followed by a non-linear filter to get rid of the excess noise that the high pass pulls out.

[Shiraz (Ray)]

Further to Peter's concern re the nature of the noise in the 1600 images, decided to have a closer look. The attached crops show part of a sub with linear "stretch" so that the bottom 0-4000ADU fill the screen DNR and also a 0-2000ADu version.

Then the light suddenly went on - this noise looks different to that which we normally see because there is practically no camera noise at all. This is what shot noise looks like in a narrowband image - more signal gives more noise and there is no camera noise (dark, read, FPN) to degrade the darker areas. I didn't think that I would ever see the day when we would have access to a high QE, essentially noise free camera - but here it is. And it is affordable. woohoo

[Peter Ward]

Originally Posted by Shiraz

Further to Peter's concern re the nature of the noise in the 1600 images, decided to have a closer look. The attached crops show part of a sub with linear "stretch" so that the bottom 0-4000ADU fill the screen DNR and also a 0-2000ADu version.

Then the light suddenly went on - this noise looks different to that which we normally see because there is practically no camera noise at all. This is what shot noise looks like in a narrowband image - more signal gives more noise and there is no camera noise (dark, read, FPN) to degrade the darker areas. I didn't think that I would ever see the day when we would have access to a high QE, essentially noise free camera - but here it is. And it is affordable. woohoo

Now that's better.... looks much more like what I'm used to seeing in a well calibrated sub

[strongmanmike (Michael)]

So Razzor, does this mean we are moving into the era where darks and dithering will no longer be necessary...?

I want a large (30mm+) high QE, tiny pixel, noiseless one shot colour camera that produces good colour and doesn't require 100's of frames to go deep and stars don't saturate easily. I want the option of using no filters and to say good bye to multiple night imaging on a single object....please? ...a return to the days of film when I could image as deep as anyone else in the world and on several fields a night.

Mike

[Shiraz (Ray)]

Originally Posted by Peter Ward

Now that's better.... looks much more like what I'm used to seeing in a well calibrated sub

but there was no calibration Peter - this is a raw sub with no corrections applied at all. Scarily, the camera really does not have any noise to speak of.

Originally Posted by strongmanmike

So Razzor, does this mean we are moving into the era where darks and dithering will no longer be necessary...?

I want a large (30mm+) high QE, tiny pixel, noiseless one shot colour camera that produces good colour and doesn't require 100's of frames to go deep and stars don't saturate easily. I want the option of using no filters and to say good bye to multiple night imaging on a single object....please? ...a return to the days of film when I could image as deep as anyone else in the world and on several fields a night.

Mike

Not quite sure yet, but maybe dithering will still be necessary to get the utmost sensitivity and flats will help if you have vignetting or dust, but darks/bias etc will possibly be a waste of time.

the problem with the new cameras is that we seem to have almost reached the theoretical limit - there is nowhere else to go but bigger, but that may not be quite so bad if you only have to use 20 second subs and don't need to make 50kg of scope guide perfectly.

One possibility that might be worth pursing is to set up a second automated system to take colour while you get luminance on your main scope - an EQ6 with a medium level small Newtonian and a 1600mc should be able to give round colour stars with 30 second subs.

regards Ray

[Peter Ward]

Originally Posted by Shiraz

but there was no calibration Peter - this is a raw sub with no corrections applied at all. Scarily, the camera really does not have any noise to speak of.

regards Ray

Yes, I got that.

I was referring to what my 16803 subs look like after calibration.

[Shiraz (Ray)]

Originally Posted by Peter Ward

Yes, I got that.

I was referring to what my 16803 subs look like after calibration.