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OK, don't laugh too hard....

This is my first go at imaging and processing the Orion Nebula. 30 x 35 second exposures (Canon 50D on prime focus on Celestron Nexstar 8"GPS). Stacked in DSS, then processed in Photoshop using this guide

th_451cc8d3.jpg

(Click for bigger image)

A couple of things that I need to do to improve,

  1. I don't think that my focus was all that great. I was using Liveview to focus, but wasn't happy. I am building a DIY electric focuser to help, and am awaiting delivery of a Bahtinov mask.
  2. I need a LOT more experience in DSS. The colours and saturation is a fair bit off, and doesn't look right to me.
  3. I noticed that the previous owner of my scope tried to "clean" the secondary. It looked OK straight on, but at an angle is was marked with a "fog". I have cleaned it since (distilled water and alcohol) and it is a million times better. I am hoping that this gives me a bit more sharpness.
  4. The collimation is a wee bit out on my scope. Another thing that I have gotta learn how to do.

Critique and criticism welcome.:)

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This is not as bad as you may think. In fact it's pretty good, so don't knock yourself. You recognise what needs to be done , and the Mask will cure one of them. Focus is a prime requirement, and the Bahtinov will ensure you crack that one.

You're on your way, and improvement is assured.:)

Ron.

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Well, first off - you have picked one of the hardest objects in the sky. It has high dynamic range and a million works of genius out there for you to beat yourself up about!

You don't mention Photoshop or PixInsight. I only know how to sort out colour in these programmes. It is not unusual to get a kind of semi monochrome straight from the stack, yours being a kind of reddish magenta. But in Ps or PI you can separate out the colours and make them discrete and contrasty.

You are doing fine!

Olly

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Well, first off - you have picked one of the hardest objects in the sky. It has high dynamic range and a million works of genius out there for you to beat yourself up about!

Olly

:hello2::p..Nothing like setting myself a challenge.:)

You don't mention Photoshop or PixInsight. I only know how to sort out colour in these programmes. It is not unusual to get a kind of semi monochrome straight from the stack, yours being a kind of reddish magenta. But in Ps or PI you can separate out the colours and make them discrete and contrasty.

You are doing fine!

Olly

I used DSS and Potoshop in the first image. Photoshop only in the second image. I don't have PixInSight (and don't know if I have any more capacity to start learning another program:eek::hello2:).

It did look very monochrome when stacked....I resorted to copying from DSS into the clipboard and pasting it into PS. I think that my biggest challenge is knowing what "looks" right TBH. With more experience I can know which way to tweak things to make it correct.

You are doing fine!

Olly

Thank you, I appreciate that.

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Well done on your first shot, it looks great for a first attempt to me, especially as you didn't have a Bahtinov mask to help, which hopefully is going to make focusing a doddle when it arrives.

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To bring out colour contrast I use this idea by Martin Bradley.

Image-Mode-Lab Colour.

Channels, Split Channels.

On channels a and b, Image-Adjust-Brightness and Contrast. Push the contrast to +20 or higher.

Channels-Merge Channels (option LAB colour, Lightness, a, b.)

If the effect is too strong paste it onto the original and adjust opacity in layers, blend mode normal.

Olly

Edited by ollypenrice
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Hey Zakalwe, wonder if your using a focal reducer on the 8" Nexstar?

F10 is pretty slow for deep sky - even although M42 is bright.

I use an f/6.3 reducer (Celestron) on my 8" SCT and I push my camera (Nikon D5000) up to ISO 6400. This all makes imaging times shorter and easier tracking. I also use Deep Sky Stacker and it does often give a very grey result. I pop the image (keeping it in 16 bit Tif) into Nebulosity2 (free trial and well worth the $39 i think it was) and hit auto correct colour. It give a very accurate result. Also often windows live photo (comes with Windows 7 is surprisingly good with auto colour correct). Don't know if i can post a url here of a couple of M42 shots with my C8 - first one here (Orion Nebula / CelestronImages.com - astrophotography with optics from Celestron Telescopes.) is a stack of 5x30 second exposures with the reducer for f/6.3. The second one here (Orion Nebula / CelestronImages.com - astrophotography with optics from Celestron Telescopes.) is from a single RAW frame - and cropped slightly to look like it would at F/10. O.K. perhaps too much info here but one more thing, I found some apps like Nebulosity and occasionally Deep Sky Stacker produce better results if you use your camera software to convert your RAW frames into Tifs first. Your doing well - keep exploring

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... occasionally Deep Sky Stacker produce better results if you use your camera software to convert your RAW frames into Tifs first.

Just like to say that in my extremely limited experience, only 2 images so far, DSS worked much better putting raw files straight in. When I put in the converted 16 bit tiffs, it gave me a much worse image to work with as well as accentuated the slight vignette I had beyond all belief - Into a massive purple ring that I couldn't get rid of.

I won't be bothering with tiffs again. It's raw all the way for me.

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Hey Zakalwe, wonder if your using a focal reducer on the 8" Nexstar?

F10 is pretty slow for deep sky - even although M42 is bright.

I use an f/6.3 reducer (Celestron) on my 8" SCT and I push my camera (Nikon D5000) up to ISO 6400. This all makes imaging times shorter and easier tracking. I also use Deep Sky Stacker and it does often give a very grey result. I pop the image (keeping it in 16 bit Tif) into Nebulosity2 (free trial and well worth the $39 i think it was) and hit auto correct colour. It give a very accurate result. Also often windows live photo (comes with Windows 7 is surprisingly good with auto colour correct). Don't know if i can post a url here of a couple of M42 shots with my C8 - first one here (Orion Nebula / CelestronImages.com - astrophotography with optics from Celestron Telescopes.) is a stack of 5x30 second exposures with the reducer for f/6.3. The second one here (Orion Nebula / CelestronImages.com - astrophotography with optics from Celestron Telescopes.) is from a single RAW frame - and cropped slightly to look like it would at F/10. O.K. perhaps too much info here but one more thing, I found some apps like Nebulosity and occasionally Deep Sky Stacker produce better results if you use your camera software to convert your RAW frames into Tifs first. Your doing well - keep exploring

Thanks James4.

Interesting comments about the focal reducer. I was seeing oval stars at 2 minute exposure (or rather "jerky" stars- probably due to the less than smooth mount movements detectable at the long focal length). I was running at ISO800, which produces pretty good results. I might crank the ISO higher and see how much noise that introduces. To be fair, the 50D is pretty damn good at handling high ISO speeds.

I am interested in the focal reducer, and am researching it's benefits (I am cautious about buying more kit, as my knowledge is still very limited). Do you reckon that it is a worthwhile investment?

I'll also try using TIFFS as well. I was stuffing the camera RAWs into DSS, but will convert to TIFF and see the results.

To be absolutely honest, the more I mess with the images, the more I can see that I need to get the basics right. Focus, exposure time, ISO speed, tracking. If these are out, then all the processing in the world can't make the image perfect.

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Hey Zakalwe, yes the F/6.3 reducer makes a huge difference to image capture times. Its a 'double whamy' really - because F/6.3 will capture the same image as F/10 in approx half the time, and since focal length is reduced (from 2034mm to 1250mm on my C8) any tracking error is less visible. At present I don't guide at all. I keep all exposures below one minute. For deeper objects like M81 for instance I make up for short exposure by stacking many sub-exposures. The Signal to Noise (S/N) increases with the square root of the number of frames. E.G. 49 x 1 minute exposures will look the same as a single 7 minute frame (also the 49 subs will be smoother with less noise). You can pick up a F/6.3 reducer from Antares here in Canada for $99 last time I checked. The Celestron one is more expensive, around $149 U.S. I think they are comparable. Clear Skies!

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Hi Zakalwi

That is a pretty good for the short exposure time and first attempt.

As has been said the Bahtinhov will be a great asset for focus. One thing that struck me was

I resorted to copying from DSS into the clipboard and pasting it into PS

This is not a good thing to do as you are losing a lot of data doing it this way. I assume you were capturing in RAW. Save the file in DSS and open it in Photoshop that way you'll keep all the data you've captured. Processing is another big learning curve but keep at it, read other people's threads, read up and surf to learn all the best tips.

Keep up the good work.

Carole

Edited by carastro
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Hi Zakalwi

That is a pretty good for the short exposure time and first attempt.

As has been said the Bahtinhov will be a great asset for focus. One thing that struck me was

This is not a good thing to do as you are losing a lot of data doing it this way. I assume you were capturing in RAW. Save the file in DSS and open it in Photoshop that way you'll keep all the data you've captured. Processing is another big learning curve but keep at it, read other people's threads, read up and surf to learn all the best tips.

Keep up the good work.

Carole

This is what is doing my head in. In DSS, I can get the image to look OK-ish, yet when i save the file to a TIFF and open it in PS, the image is so dark. All the levels are shifted right over to the left and I am losing the data. Any ideas?

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This is what is doing my head in. In DSS, I can get the image to look OK-ish, yet when i save the file to a TIFF and open it in PS, the image is so dark.

I never do anything to my images in DSS and I agree they look better there initially than in PS. However once you save the file in photoshop you can process them and they will look even better.

I am losing the data

You're not losing the data. It just looks like you have.

Save the image in DSS and then open it in PS.

Try a gentle stretch in layers to start with. Make sure the left hand triangle (the black one) is not moved any further than the start of the histogram. Then bring in the middle triangle slightly to reveal more of the object. (The left one darkens the sky and the right one will lighten it and the middle one deals with the middle areas). Then try curves all the while doing this a little at a time but don't overdo it.

In curves, if you click on an area of your image you will see a little box come up on the diagonal line (lets call it (a). This shows you where that part of the image is located. Click on that spot (a) , then fix the rest of the line by clicking before you move (a), move (a) both ways to see which way to want to change it. You can do this with lots of areas of the image in curves, and also there are the RGB, R,G,B drop down boxes at the top too to select individual colours.

Then go back to levels and do a bit more. You can also select colours in levels too.

Continue doing this until you are happy with the end result.

You can always step backwards if you don't like anything in Photoshop (under edit).

Give that a go, you will get better with practice.

Carole

Edited by carastro
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Sorry just re-read my post and noticed a "typo"

This should have said Levels NOT layers.

Sorry to confuse.

Carole

Thanks again carole,

I did pick up on that one after a minute's headscratching:icon_scratch:.

Steve

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Hey Zakalwe, yes the F/6.3 reducer makes a huge difference to image capture times. Its a 'double whamy' really - because F/6.3 will capture the same image as F/10 in approx half the time, and since focal length is reduced (from 2034mm to 1250mm on my C8) any tracking error is less visible. At present I don't guide at all. I keep all exposures below one minute. For deeper objects like M81 for instance I make up for short exposure by stacking many sub-exposures. The Signal to Noise (S/N) increases with the square root of the number of frames. E.G. 49 x 1 minute exposures will look the same as a single 7 minute frame (also the 49 subs will be smoother with less noise). You can pick up a F/6.3 reducer from Antares here in Canada for $99 last time I checked. The Celestron one is more expensive, around $149 U.S. I think they are comparable. Clear Skies!

I hope you are on commission...an Antares focal reducer is on its way to me:icon_salut:

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Good for you - you'll notice a big difference in how quickly you can pull down an image at f/6.3. Who are the best online astro stores in the U.K.? (assuming you are in the U.K.). Here in Canada I order equipment from OPT (California), Orion Telescopes (California), Island Eyepiece (B.C. Canada)

Edited by James4
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