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Uranium235

Three telescopes = one HST image

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Yesss! Finally ive been able to put my new 2" SII filter to use and knock out my first HST format image for over four years! :)

Except this time, I've added a little extra spice from two other telescopes besides the Star 71. The Pelican area is from the 200pds which I shot last Autumn, along with the NA wall area taken with the 130pds - which was test data from last year that I never thought I'd need, but such is the apparent gain in sharpness and noise reduction when you downsample it that far - it turns out you dont really need much of it to make an impact (just two hours worth!).

Blending it all together with Ps was a bit of a fiddle, but there arent any obvious joins - just a few diffraction spikes poking through... though I can live with those I guess :D 

Star 71 20x900 (Ha_L), 8x900 (SII_R, Ha_G, OIII_B) 

130pds (8x900) Ha

200pds (20x900) Ha

 

Thanks for looking :)

24215436917_38350b3ddd_o.jpg

Fullsize: Here <- worth a look if you're a pixel peeper :D 

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Awesome image, thanks for sharing!

Which stacking software do you use to get the different scales to match up?

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1 minute ago, almcl said:

Awesome image, thanks for sharing!

Which stacking software do you use to get the different scales to match up?

Registar does the magic bit. But first of all I downsample in Ps so its quite close - otherwise if you do it straght from 1000mm down to 350mm in registar, the stars pick up some wierd artifacts.

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Thanks, I'll have to have a detailed look at that. (Going from 910mm to 200 may not be sensible but could be interesting.)

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12 minutes ago, almcl said:

Thanks, I'll have to have a detailed look at that. (Going from 910mm to 200 may not be sensible but could be interesting.)

Thats where you need to take it to a halfway house first before using registar. Just divide one focal length by the other and that will give you the reduction factor - which in your case is 21.9% of the original size, but I'd take it down to 25% then let registar do the rest.

Also you need to find a way to use the original stars from the lower focal length image, I used Ps layer masks for that task.

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A truly wonderful image Rob!

I am thinking of a similar approach with some images from my tripe rig (Samyang 135mm, Canon 300mm and a 5" refactor at 750mm). Have long been cloudy or moon-lit but tomorrow night finally looks promising here...

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13 hours ago, gorann said:

A truly wonderful image Rob!

I am thinking of a similar approach with some images from my tripe rig (Samyang 135mm, Canon 300mm and a 5" refactor at 750mm). Have long been cloudy or moon-lit but tomorrow night finally looks promising here...

That should work pretty well, just get the base image with the 135mm,  then target any regions of interest with the longer focal length instruments. 

To blend after registration, you need to part develop the images to roughly the same brightness, blinking between the two to see if it looks about right.

With the layer mask, I chose blend mode normal and used the eraser to cut back to the area I wanted - ending in a gaussian blur of the mask to smooth out any transitions. Takes a bit of experimentation, but you will get there in the end :) 

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Thanks for the suggestions Rob. I have experimented with a similar approach before but I had not thought of using the gaussian blur at the final stage. Now I only have to gather the data, hoping that I or the weather do not mess up....

I just found and clicked on the high-resolution link to you image. Fantastic details in there - should blow away even the most notorious pixel peepers.

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Wonderful image Rob! Barely recognisable from the visual object I see, it's amazing just how much is up there!!

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2 hours ago, Stu said:

Wonderful image Rob! Barely recognisable from the visual object I see, it's amazing just how much is up there!!

Cheers Stu, I managed to grab some SII on ic1396 as well before packing up so I'm hoping to give it the same treatment later on today. Had to stop at 9.30pm last night  (which is criminal on a winter night...lol), but my wife was on a 4am shift so I had to be there for the baby.

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