Orion Nebula..2nd try

Well thanks to all those that gave me tips and ideas. I think these came out pretty good.

Thanks again to those who are helping learn astrophotography.

Now you're cookin'. You've got to be happy with those.
What was your setup, times, pp, etc

Steve.

Yeah nice ones! I'd love to hear how you did it too

Awesome! What scope did you use and was there a tracking mount in your set-up?

Keep it up .

Nice, Lloyd!

Don

Thanks for the kind and encouraging words.

Most of these were 30 seconds exposures. I used Bulb as I was near a road so I just would stop when cars came past.

I was using a Celestron Nexstar 6se with a canon 7d, f10 to f6 reducer, and t-mount attached to the scope. Post processing was done with Lightshop and Adobe Elements. I found in elements a tool that seemed to help clean up a bit...scratch and dust remover set to 2 pixel radius.

I am hoping once I get better at stacking and understanding the DSS that I can produce better results. I have found stacking frustrating. I did shoot 30 second flats and all that as well but they were not used in these.

Such a learning curve and once again I must thank those who have helped me.

lloydsjourney wrote in post #9853720
Thanks for the kind and encouraging words.

Most of these were 30 seconds exposures. I used Bulb as I was near a road so I just would stop when cars came past.

I was using a Celestron Nexstar 6se with a canon 7d, f10 to f6 reducer, and t-mount attached to the scope. Post processing was done with Lightshop and Adobe Elements. I found in elements a tool that seemed to help clean up a bit...scratch and dust remover set to 2 pixel radius.

I am hoping once I get better at stacking and understanding the DSS that I can produce better results. I have found stacking frustrating. I did shoot 30 second flats and all that as well but they were not used in these.

Such a learning curve and once again I must thank those who have helped me.

Your getting off to a good start.
The hardest parts are the stacking and post-processing.
Load all your files into DSS as RAWs then use settings that DSS recommends.
When it is finished stacking and loads the autosave.tif don't make any changes to color or luminance using DSS. Save it to a file with a name of your choice into a directory of your choice. When you save it, select to save it as a 16bit tif with the "Changes Embedded". Do Not save it with changes applied and do not save as a Jpeg, you don't want to dissolve any valuable image data.

Then comes the hard part. The post processing! A mistake many of us make is to clip the dark points too much. I have to keep reminding myself that space isn't really black. It's dark but not black! Especially in Ha rich areas such as the Orion Nebula Complex.

How many light frames, darks, Bias, flats and dark flats did you shoot?
Keep in mind, though it's not always possible, that more is better.
And Try to shoot all your frames the same exposure time, and shoot your darks the same as your lights.
Unless you're stacking two sets of images to later combine in Photoshop to improve the dynamics. E.g. one set to shoot the nebulous regions of Orion that will most likely blow out the Trapezium, and then another set of shorter exposures of core and trapezium without overexposing and blowing it out. But you don't want to stack those together using DSS.

lloydsjourney wrote in post #9853720
... I did shoot 30 second flats and all that as well but they were not used in these ...

Hi Lloyd,

You probably meant "30 second darks" instead of "30 second flats". Flats should be short exposures, usually less than 1 second. They are usually made at the same ISO as the lights and darks, but with the camera set to Av mode and the telescope pointed to an evenly illuminated, not too bright field such as the twilight sky. If they go over 1 second at ISO 400 or above, something's wrong.

Also, don't forget to shoot flat darks or bias frames, or both. If you don't provide either flat darks or bias frames in DSS the results will be unpredictable. Flat darks are shot in Tv mode with the telescope capped, and at approximately the same exposure time as the flats. Bias frames are shot in Tv mode with the camera body or telescope capped, and at the shortest exposure time your camera is capable of. They can be made at any time - the camera doesn't need to be attached to the telescope, and bias frames don't need to be repeated often, just once or twice per year.

Every frame shot with a DSLR contains a bias signal, sometimes called offset, that must be subtracted from the flats before the flats can be correctly applied. With DSS either bias frames or flat darks can be used for this purpose. Other image processing software may require one or the other, or both. I use both bias and flat darks, and there is an advantage to doing so even with more flexible applications like DSS.

Don

You are correct Don. It was darks I shot at 30 seconds.

I did try the flats but tried those wrong.

that part still has me a bit.

I keep taking notes from here though.

Eventually....lol.

lloydsjourney wrote in post #9858232
You are correct Don. It was darks I shot at 30 seconds.

I did try the flats but tried those wrong.

that part still has me a bit.

I keep taking notes from here though.

Eventually....lol.

Flats can be a bit tricky, and if you don't get them right you can ruin an otherwise good image. First off you want to leave the camera on the telescope in the same position and focus you had it while shooting your light frames.

An easy way of doing it is to use a Clean white t-shirt stretched tightly across the front of the telescope. Aim it at an evenly illuminated source of light. For that can either aim it at the clear dawn sky, or use some kind of backdrop to shine a light against. A white sheet about 6 feet away from the telescope works. Shine a couple lights onto the sheet making sure it's evenly illuminated. Then set the camera in AV mode and allow it to decide the exposure/shutter speed.

To be safe and to ensure a better image you should shoot as many flats as you did light frames. Then you will want to shoot Dark flats to go along with your regular flats. They are similar to your regular darks only shot at the same shutter speed as your light flats. Next you will want to shoot your Bias/offsets. All they are is dark exposures at the fastest shutter speed your camera is capable of shooting. Since your mounting your camera to a telescope you can set the camera in Manual mode and set the shutter speed as fast as it can go. For Bias/Offset the camera orientation and focus isn't important. In fact you can save your bias and use them for other images also. But, typically you will want the same quantity of Darks, flats, dark flats, and Bias as light frames (1:1 ratio). Your darks will have to be shot at the same exposure/shutter speed as you lights, and your dark flats the same shutter speed as you flats. And your flats must be shot with the camera in the same position/orientation and focus on the telescope.

Additionally, It's best if you can shoot you dark frames at the same operating temperture durring your light frame capture sequence. Easier said than done since the outdoor temp usually drops throughout the night. What some people will do then is shoot some Darks before starting your imaging run, then shoot more at the end. Some will even shoot some in the middle of the run. This will allow the darks to average out better for stacking and dark subtraction.

You will get there if you stick with it Lloyd.

IMHO learning DSS is the easiest part of the process. The two choices you have to make in DSS that make the biggest impact on your results are the stacking algorithm (average vs. median vs. kappa sigma, etc.) and the choice of whether to apply the adjustments made in DSS to the saved image. The correct choice for stacking algorithm depends on the number of light frames primarily, and DSS will suggest the best choice. The choice of whether to apply the adjustments or embed them is almost always "embed, don't apply". Embedding saves them in the image file so that next time you open the image with DSS they will be applied, but when you open the image in other software they will be ignored. Really, IMHO the best choice is not to make any adjustments in DSS after the image is stacked, but even then DSS automatically applies level adjustments which you don't want to apply when you save the image. When you open the unadjusted image in Photoshop it will appear very dark, but all the data is there, so you can start tweaking it. If instead you choose to apply the adjustments DSS makes when saving the image, you may lose vital data that cannot be recovered.

On the DSS home page there are links in the left navigation area called "How to create better images" and "Technical details". In addition to reading the user manual, these two sections should be read thoroughly- they may answer every question you have about acquiring images and processing them in DSS.

There are other astro image processing packages out there, but DSS is perhaps the easiest to use, it's quite capable and it's free. It's rudimentary post-processing capabilities are a drawback, though, and I have found that Iris software, also free, suits me better, mainly due to the light pollution I have to deal with. Iris includes some color balancing features that are much better than those in DSS, and easier if not better than those in Photoshop. Also, Iris has a very powerful feature called hyperbolic arc-sin stretching that I find makes it easy to get the most detail from deep space images. The trade-off is that Iris has a pretty steep learning curve and is not as user-friendly as DSS. Despite this, I use Iris almost exclusively now.

Don