LL .9 Stacking Attempt

[HiloDon]

Hi All,

I made my first attempt at live stacking with LL version .9 last night and thought I would share some results and comments. I only tried the sum stacking because I wanted to see if multiple stacked shorter exposures could equal or better a single exposure. The image quickly whites out, but if you adjust the white and black levels the image can be brought back. If you adjust them first, the image will brighten with each stack and will remain visible. Here are some results:

Ring Nebula

No stacking 30s

See below

Sum stacking 8x5s

NGC7331 (7321 is typo)

No stacking 30s

Sum stacking 10x10s

NGC7172 Hickson HCG90

No stacking 30s

Sum stacking 6x10s

Here are some things I noticed:

Hot pixel noise is reduced. I used no darks in any of these.

There are some horizontal lines or banding that is apparent in the stacked images.

The is some blurring in the stacked images as Paul has advised us.

Registration is very good.

I don't know if I'm using this properly, but any advice will be appreciated. I used my SW100ed with no focal reduction and no filter.

Here's the ring with no stacking. Couldn't get it to upload in the right position.

Thanks for your interest and help.

Don

[nytecam]

Excellent results Don :-) The many permutations of stacking in LL will keep you busy ! The banding on one image may be due to mains interference - keep all connections good and cables separated :-)

[HiloDon]

Excellent results Don :-) The many permutations of stacking in LL will keep you busy ! The banding on one image may be due to mains interference - keep all connections good and cables separated :-)

Thanks, Nytecam. The banding or pattern noise showed up in all the sum stacked images. The cable routing was the same for all my images, and I have never seen it in any single exposure image. Perhaps Paul has some ideas.

Don

[Paul81]

Nice set of results Don! I like the two NGC galaxies I have not observed before. I imagine sum mode will quite quickly saturate the ring nebula, but it is good for the really faint galaxies.

With regards to the noise you have noticed, sum mode will amplify both the noise and the signal, but the signal should increase more than the noise. This however might make some noise previously unseen visible (but the hope is it also makes some previously very faint detail more visible).

It would be worth seeing if the banding is present in median and mean modes.

I am also working on a hybrid mode which combines sum and median / mean which should hopefully offer the best of both worlds! Still tinkering with it though!

[HiloDon]

Nice set of results Don! I like the two NGC galaxies I have not observed before. I imagine sum mode will quite quickly saturate the ring nebula, but it is good for the really faint galaxies.

With regards to the noise you have noticed, sum mode will amplify both the noise and the signal, but the signal should increase more than the noise. This however might make some noise previously unseen visible (but the hope is it also makes some previously very faint detail more visible).

It would be worth seeing if the banding is present in median and mean modes.

I am also working on a hybrid mode which combines sum and median / mean which should hopefully offer the best of both worlds! Still tinkering with it though!

Thanks, Paul. I was thinking that may be a possibility and Nytecam's suggestion about the cable routing might be the culprit. I have my USB cable from the camera connected to an extender that runs through about 10 ft of conduit that also has my power cable in it. It's powered by a ac/dc power supply. Next time out, I'll power my mount separately and keep the power supply off. I'll also check the other stacking options, which I haven't done yet.

I'll update this thread once I figure it out so others will know if they have a similar problem.

Other than my noise problem, the new LL works great!

Don