I recently had a chance to try out my new (to me) Nikon D5300 modded camera. I thought the Horsehead and Flame in Orion would be a good choice for trying out the impact the Ha mod has. Overall I am very happy with the image:
Autosave021HH ST.jpg (431.58 KiB) Viewed 5558 times
Unfortunately (?) the camera is more sensitive than the Canon I have used for the past few years. It picked up a fair amount of light from a streetlight that is near where the HH crossed the Southeast sky. It shows as that nasty glow in the upper left corner of the image.
Image consists of 43 180 second lights, 21 darks, 81 each of flats and dark flats.
I am wondering if there is a way to process that out of the image. This one would be a keeper for me and is a candidate for "the wall" if that area can be cleaned up. I have spent a little time with the color module and a mask in non-linear mode and have gotten close to where I want to be by using the dark saturation slider and adjusting the color channel biases. Is there a way to do this kind of process withing StarTools?
There's a good few ways you can tackle this (using the Filter module in Reject mode for example with a mask that includes the offending area, combined with a large Mask Fuzz), though it would really help if I could get my hands on the stack to see what can be done in the linear stage...
Ivo Jager StarTools creator and astronomy enthusiast
There's a good few ways you can tackle this (using the Filter module in Reject mode for example with a mask that includes the offending area, combined with a large Mask Fuzz), though it would really help if I could get my hands on the stack to see what can be done in the linear stage...
Thanks, Ivo. After I posted this, I discovered the Filter module (never used it before) and got some decent results. It wasn't quite as clean as I'd like, but I didn't spend a lot of time. It was definitely the best method I have tried so far. I will spend more time with it when I can put a block of time together.
I am happy! to have you take a look at the stack. You may note that I have done a fair number of stacks on this one - it is Autosave021. Here is a link to where you can find it. The ROI I used in Autodev include a portion of the Flame and all of NGC2023, which led to the nice (to me) display of dustiness. I am running ST 1.7.456.
You will notice that focus isn't that good and off-axis stars quickly get weird due to issues I had getting the camera/cc combo square in the focuser. I spent time with the Repair module in the image I posted.
Wow, Ivo, that is pretty amazing! I see I am going to have to mess around with this and see what it can do. StarTools capability and versatility continue to surprise me with just how much is built into the program! Thanks for taking the time to run through my data and find a better solution!
In the end, I wasn't happy with the color and level of detail that came out of the Wipe process with the Uncalib2 settings, so I went back to using the filter and mask on the original data. I will try some more processes and see if I can get the Wipe path to deliver everything I am looking for.
In the long term, I am going to reach out to the Town Engineering department and see about putting some shades on the two closest streetlights. There is an ordinance that states it is unlawful to shine a bright light onto someones property in town, and the Town needs to follow the ordinances as well as the people.
Here is what I came up with using the Filter module with an appropriate mask:
Autosave021HH ST.jpg (390.38 KiB) Viewed 5481 times
It could still use a bit of work, but it is closer than what I am looking for. Dang - I forgot to try it on that blob around Alnitak!
I was fairly comfortable with the Uncalib2 settings, as I found the dataset seems to have quite a few gradients in there that I wasn't quite sure were real nebulosity/detail. Perhaps it is worth cross-referencing whether all is truly accounted for in other images? (for instance the blue nebulosity at 6 o'clock extending away from NGC2023?)
Ivo Jager StarTools creator and astronomy enthusiast
Thanks, Ivo, will do. That particular are seems curious to me, too. I haven't had a chance to check yet but will do so - and will keep working the data!
admin wrote: ↑Sun Jan 24, 2021 10:18 am
Glad to hear you're getting it sorted Bob!
I was fairly comfortable with the Uncalib2 settings, as I found the dataset seems to have quite a few gradients in there that I wasn't quite sure were real nebulosity/detail. Perhaps it is worth cross-referencing whether all is truly accounted for in other images? (for instance the blue nebulosity at 6 o'clock extending away from NGC2023?)
Ivo - interesting that you mention other gradients in the data. I don't know if you have heard of an odd behavior with the Nikon D5300 where it will generate concentric rings in the image sometimes. I have seen a lot of articles about the "feature" including one that was started by Jerry Lodriguss over on CN, so I don't think I am imagining it. The D5300 has no anti-aliasing filter, and uses compression in its RAW format, these are potential suspects in the hunt for a cause. As I was messing with the data today, I thought I could see hints of circles in the temporary autodev presented by the Wipe module.
Here is an example of the circles when I used an underexposed set of flats:
rings in Wipe.JPG (277.32 KiB) Viewed 5449 times
I am going to start over on this one and collect a range of flat and dark flat exposures and see if I can find one that eliminates this effect. I think if I can start with a clean stack, it will reduce the amount of damage I am doing to the data running it through the uncalibrated Wipe process. This set of flats was 1/6 second and had a median ADU about 8K, where I expect to be with a 14-bit camera. I used bias frames to calibrate the flats, I would like to see what 1/6" dark flats would do to it. The stack I gave you was 1/4" flats and dark flats. The 1/6" flats didn't clean up the dust bunnies, (there is one near Sigma Orinonis) but the 1/4" did.
admin wrote: ↑Sun Jan 24, 2021 10:18 am
Glad to hear you're getting it sorted Bob!
I was fairly comfortable with the Uncalib2 settings, as I found the dataset seems to have quite a few gradients in there that I wasn't quite sure were real nebulosity/detail. Perhaps it is worth cross-referencing whether all is truly accounted for in other images? (for instance the blue nebulosity at 6 o'clock extending away from NGC2023?)
Ivo - interesting that you mention other gradients in the data. I don't know if you have heard of an odd behavior with the Nikon D5300 where it will generate concentric rings in the image sometimes. I have seen a lot of articles about the "feature" including one that was started by Jerry Lodriguss over on CN, so I don't think I am imagining it. The D5300 has no anti-aliasing filter, and uses compression in its RAW format, these are potential suspects in the hunt for a cause. As I was messing with the data today, I thought I could see hints of circles in the temporary autodev presented by the Wipe module.
Here is an example of the circles when I used an underexposed set of flats:
rings in Wipe.JPG
I am going to start over on this one and collect a range of flat and dark flat exposures and see if I can find one that eliminates this effect. I think if I can start with a clean stack, it will reduce the amount of damage I am doing to the data running it through the uncalibrated Wipe process. This set of flats was 1/6 second and had a median ADU about 8K, where I expect to be with a 14-bit camera. I used bias frames to calibrate the flats, I would like to see what 1/6" dark flats would do to it. The stack I gave you was 1/4" flats and dark flats. The 1/6" flats didn't clean up the dust bunnies, (there is one near Sigma Orinonis) but the 1/4" did.
Who says AP is easy?
Bob
Interesting! That is indeed what I spotted too with the Diagnostics Stretch/AutoDev in Wipe (it does its job! ).
Ivo Jager StarTools creator and astronomy enthusiast
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