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JSeaman

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    Melotte 15 / IC1805 ZWO ASI 1600 Narrowband

    in Imaging - Deep Sky

    Posted

    Thanks to Vlaiv for a little encouragment to get this one across the line!

    This is my first DSO with the ZWO ASI 1600mm, I feel like I'm not quite there yet but it's certainly an improvement for my pictures. This is a bit of an unconventional set up, waving a 12 inch Newotonian around as an imaging scope but it works and it is good fun. I have moved my Lakeside focuser onto the stock 300PDS focuser and it performed very well too which is a bonus.

    I was using 300 second/5 minute subs with 1x1 binning at unity gain (139) with an offset of 15 which gathered plenty of detail and meant fewer wasted minutes with any wobbles etc. Processing details are as follows:

    Hydrogen Alpha

    I got a little over 7.5 hours of good Ha data over 4 nights, this was stretched with a simple levels and curves adjustment intially and showed some good detail. I then masked off a few regions of interest (ROI) such as the bok globules, Mel15 itself etc. in Photoshop before using PixInsight to apply a light MultiscaleLinearTransform (2.5 to 0 in 0.5 steps over 5 layers) which smoothed out the really fine speckles on the background. 

    I applied a 0.44 MorphologicalTransformation star reduction with no star mask and then created a star mask for the larger stars using PI's tool (scale of 9 and 0.26 noise threshold) before customising the mask in PS to the big hitters only before applying a .040 MorpholocialTransformation. I pulled the black point a little with levels and called that my Green channel.

    Luminance

    I took the Ha data further with a minimum pass filter at 1px in PS and then pushed the contrast up. I used shadows/highlights to change the midpoint contrast and pull down some of the bright spots in the middle and then decided to do something a bit whacky which I hadn't done before, I dropped the image into Registax and ran a Wavelet sequence on it. I used all 6 layers:

    All Sharpen were set to 0.100

        Denoise    Preview
        0.20    8.9
        0.30    20.2
        0.40    43.5
        0.25    55.8
        0.00    72.4
        0.00    87.1

    This was applied to the whole image and brought out the details well. A small amount of speckling was introduced so I just popped my ROI mask back over it and ran another light MultiscaleLinearTransform to smooth out the background. 

    I then did a more agressive process as follows:

        Denoise    Sharpen    Preview
        0.40    0.100    100
        0.55    0.110    100
        0.40    0.130    46.6
        0.25    0.130    49.0
        0.00    0.100    60.7
        0.00    0.100    79.1

    I masked this off for the centre of Mel 15 to really make the details pop. I used these two luminance masks together and it really did transform the sharpness of the image.

    OIII + SII

    I imaged both OIII and SII during a full moon after reading a number of threads about narrowband in moonlight. Indeed I have tried narrowband in moonlight before and got passable results but it always felt like the moon was washing things out. This target let me know for sure it isn't worth gathering anything other than Ha when there is a full moon. There was about 10 hours of data and just enough to pull out the result below. I probably haven't done it justive in post.

    So this is it, my 33rd attempt at processing it (yes, really) and I'll probably hate it by this afternoon but it's where I'm at currently...

     

    33.thumb.jpg.cce1ab74539cfc83f5be657a771a513e.jpg

    • Like 26

    Filters + Gain + Binning + Exposure Time on IC1805

    in Discussions - Scopes / Whole setups

    Posted

    Hi all,

    I'm working on my first picture (IC1805) on the ZWO ASI1600mm Pro using a 12" 300PDS (1,500mm, f/4.9). I completed the Ha previously and got some lovely data but my 3-4 hours of SII and OIII were really weak. I put this down to the full moon and had another go tonight in the brief clear spell. I was expecting a good amount of OIII and SII for this target based on examples like this: https://www.galactic-hunter.com/post/ic-1805-the-heart-nebula

    I have been using unity gain (139) for the Ha and got some lovely data on 5 min/300s exposures. I am using a gain of 278 (I doubled it) and binning 2x2 and I still have very little OIII data. Has anyone got any thoughts or experience on this? I can go to 10 minute subs but I'm at a wildly different set up for OIII to the Ha (double gain, double binning and double exposure time) if I do this which feels a bit wrong

    Some images below to show the issue:

     

    1. Ha 300 second sub at unity gain (139)

    image.png.b079c30b39c96a45648a006b67414738.png

     

    2. OIII 300 second sub at unity gain

    image.png.dc04e9cffc4c824d0a72dc88fc6aa88a.png

    3. OIII sub at 278 gain

    image.png.666847fadd52d28ca4f74b25dd564d4a.png

    4. OIII with 2x2 binning and 278 gain

    image.png.18c12ed6108a26c215605118bae6a915.png

     

    I'm just running a 10 minute exposure to see how that goes

    James

     

    How to overcome the problem of long usb 3 runs

    in DIY Astronomer

    Horror Stories

    in The Astro Lounge

    Posted

    Following on from another thread today about a scope crashing into the rafters I thought we could share our collective disasters. So what is the worst thing that has happened to you on a night imaging?

    My worst was when I had the time set wrong in CDC and tried to slew to a target which was somewhere below the horizon, the mount slewed and telescopes were trying to drive through the pier while I tried to hit the stop button. Sadly the wifi connection failed so I ended up pulling the power cable out the mount to end the chaos (and then changed to a cat 5 connection!)

    My Horror Story Warning !

    in The Astro Lounge

    Posted

    It seems you're not alone in this from the responses! It's not an issue I have ever had but I made my set up do a lot of the work for me - I have a single smart plug which is in the chain to everything. I have a dynamic timer on that which is set every time I am imaging but with a failsafe timer at 6:30 every morning which will turn the plug off. I haven't needed the failsafe yet (several years later) but it's nice to know it is there!

    • Like 1

    Top end Pixinsight computer specification

    in Discussions - Software

    Posted

    I built three PCs last year at the start of lockdown and had PI in mind for it (at least partially), building yourself costs dramatically less than buying in a shop (~£700 each for these)

    For RAM I went with 32GB Corsair Vengeance 3600MHz, two 16GB sticks, a nice balance on price versus performance (and it does perform well). I have run image processing, lots of PI stuff, software development tools and various other simultaneous activites and never come close to using it all. If you're wanting to load huge amounts of data into RAM for some reason then by all means go for 64GB but most people won't benefit from it. I just loaded 100 images (3gb worth) in PI and started monkeying with them and never ht 9GB RAM usage

    I went down the Ryzen 5 360 / Tomahawk route for motherboard/chipset and it is very capable so a good choice, you can spend a lot more and get only marginal improvements

    I chose 1 TB NVME PCIe card which is well worth getting, only ~£100 and very fast indeed

    Last year PI was not using GPUs directly (see here: https://pixinsight.com/sysreq/index.html) but I went for a Radeon RX580 which I also recommend as a good all rounder

    Chuck that little lot in a case with a power supply and you'll have a plenty capable machine and save a couple of thousand on buying it from a shop

    Narrowband integration time ?

    in Imaging - Discussion

    Posted

    I have been experimenting with this over the last few nights with a similar set up, well, near identical actually. I also have a 300 second exposure with unity gain (139) on a ZWO 1600 pro at f4.9 but I am using Baader filters and a 12 inch scope. That said, the differences are outweighed by the similarities. I have experimented with sub quantity, binning and duration and I am settled (on this camera/aperture) at 300 second subs.

    The attached video gives you an example of what stacking does, it doesn't halve the noise every time and it is diminishing returns but the invesment lets you do more with the data. I would say you need at least a couple of hours worth of data on each filter and up to 6 is great. 

    When you zoom right in on the pictures you can see the noise reducing but the difference between ~40 pics (3.5 hrs) and 80 pics (~6.5 hrs) isn't huge.

     
    • Like 1

    Trails when guiding

    in Imaging - Tips, Tricks and Techniques

    Posted

    Yep it's a 300PDS. The mirror wouldn't move at a consistent speed over 20 minutes so I can rule that out. The focuser was on my hit list but it can't be because it went back to normal after about 5 pics. 

    I do have the drift you show in your thread and always have, I'm considering OAG at the mo

    Thanks for the links, I will continue to look at moving to an OAG but that will inevitably lead to buying a CR2 focuser and it would be rude not to get a sceond lakeside at that point ... Here we go again!

    Trails when guiding

    in Imaging - Tips, Tricks and Techniques

    Posted

    :) I knew someone would say differential flexure. I sort of agree in that the guide scope thought everything was fine and the imaging scope disagrees but this was on the same target I did last night over the same time period and there was no issue. The guide scope is bolted to a 5mm metal plate I welded so there's not much room for flexing

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