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Posts posted by Prolifics

  1. I think I have the data now just not the skills for post processing via Photoshop. My 4th image. I may have over streched the image a bit :) If anyone else can do any better then I can post the data.

    Intermittant clouds.

    Data 90 x 1 min Lum
    30 x 2 min Red
    30 x 2 min Green
    30 x 2 min Blue

    TS 107 Triplet 700mm with 0.79 Focal Reducer F5.13

    Regards David







    • Like 1

  2. I just tried indoors with 1 layer of white T-shirt and a led dimmly lit led panel on top of the T-shirt and it seems to have sorted itself.

    It's managed 20,000 adu at 0.046 seconds exposure. Better than the 1m 36 seconds i got before :) Not sure what was going on maybe APT feaked out or partially crahed after a 8 hour session.


    Regards David






  3. Thanks for the info I am going to set up my light panel and test it indoors. I am thinking its a bug with the latest version of APT. Use to be less than a second exposure now 1.5 minutes. Somethings wrong but it producing good images still.


    I normally put a white t-shirt over the lens and a flat panel lit up by led on top. I have tried with and without the t-shirt but I will do some more tests.


    Regards David



  4. I am using a 107 Refractor Triplet 700cm F6.5 with a Zwo asi1600 Pro Camera and filterwheel.

    I take my flats in APT and set it from 0.000032 seconds to 2 seconds and it works well at around 20k ADU. Exposure times very short sometimes less than a second.

    However since I added my 0.79 Focal reducer bringing the scope to F5.13 and around 553cm Focal Length to reach 20k ADU exposure times are around 1 Minute 45 seconds each varying slightly dependant on filter.

    I understand there is more light going t0 my scope which is probably has something to do with the mess up I am having with the ADU.

    I worked out that a 12 bit ADC camera has the range of 0-4096 ADU so maybe trying 2,000 ish would work better?

    KIndest regards David




  5. On 25/07/2019 at 06:16, alan potts said:

    This is 93mins of 3 min subs on 3 nights, all the 3's.

    Well done looks great. I love clusters especially when done in 3's. So I will award you 3 out of 3 :)

    Keep them coming!


    On 25/07/2019 at 06:16, alan potts said:






    • Thanks 1

  6. I have been playing with numbers and will be doing 60 x 2 Min of Lum and 15 x 4 mim of RGB just about fit that in the darkness of August month.

    What formulae do you use for Narrow band? I guess the exposure time is double of RGB but what about the Lum?

    Another question my scope has a focal length of 700mm and i put this in APT so platesolving will work etc. When I get my x0.79 Flattener/Reducer do I put into my programs the new focal Length for example 700mm x 0.79 = 553mm ?

    This is the link to small spacers to get my backfoucs perfect I just need 1mm + or - :)


    Kindest regards David





  7. Haha -30 to keep everything constant  :) -1 and im already dead!

    Do your cables freeze up rigid in -30 + that must be a problem. Maybe a small wooden hand made shed with sliding roof would stop that add +15c to the temp :)

    I would make sure its all greased up well so really then you don't really need a cooler only to keep it constant. Bit like why you need a freezer up there in winter not to keep it cool but to stop everything from freezing.

    I guess in midwinter you can image for 17 hours of the day?


    Thanks for the link I will check that now. I am away Tuesday for a week so catch up with you then hopefully.


    Cheers David




  8. 29 minutes ago, wimvb said:

    The new field flattener should give you round stars, once you got it tuned (correct distance to sensor). Further than that, you can experiment with longer exposure times. When you image R, G, B the sensor receives only about a third of the number of photons as compared to L, so in theory you can expose up to 3 times longer. In your Iris image, the L frames seem to have a good exposure time, but the R, G, B frames could then be exposed eg 2 minutes. If you aim at 2 x as much integration time for L than R, G, B, you'd need 4 x as many L frames as colour frames.

    120 x 1 min L

    30 x 2 mins RGB

    Don't vary temperature and gain/offset too much, because you need darks for every combination of exposure time, gain and temperature. At low gain and longer exposure times, your camera has a larger dynamic range, and you'll need fewer subs to get to a certain level of signal to noise. If storage space and computer speed are a concern, you may need to factor this in.

    The total integration time you need to get to a certain result (signal to noise ratio) depends very much on your sky conditions. According to an article by Jerry Lodriguss, you need 2.5 times more integration time for every magnitude of sky darkness/brightness you lose. Eg, if you image 1 hr from a dark site (magnitude 21), you need 2.5 hours to get an equivalent result from a magnitude 20 site, and 6.3 hours from a magnitude 19 site. It pays off to look for dark skies, if you have that possibility.

    I played with "curves" after initial stretching to increase local contrast. I measured the lightness in two points where I wanted to increase contrast, then pinned one of those points and increased/decreased the other.

    Good luck.

    Thanks for explaining the exposure times for each filter. I was doing it half right. I always do double the Luminance amount but didn't relise about the RGB impact in light gathering. Now it all makes sense.

    Regarding Backfocu I will have 56mm I need 57mm so I bought some 1mm 1.5mm 0.75mm etc Baader adjustment rings so I can play with that. What is the best way to test your Flatterner? Guessing I would say take a 3 minute exposure of Luminance? Check for elongated stars at the edges and adjust back focus from there?


    My garden is a Bortle 5 site magnitude is around 20.27 for me.  So not terrible. I guess where you are is great because you get less daylight than anyone else :) Plus the cooler conditions means less noise and I guess the northern lights or Aurora may hinder you at time?


    I also have a friend who lives up there in the north of Sweden.


    Kindest regards David

  9. Hi Andy


    I got one of these last month. I got fed up going out all the time to refocus for my filters.

    Comes with many springy metal adapters to fit your scope took me about 30 minutes to install it.

    Smooth as silk and can get better fine focus than by hand. Works flawlessly with APT. Make sure you downlaod the driver from their ZWO website and alter the ascom driver settings not on APT or SGP as driver overides it for me.

    You do not get a PSU with it! Any positive centre 12v power supply will do with 1.5A rating or above.

    If you want to go the extra mile go and fill in the backlash boxes you can determine backlash by movng the focuser until you see movement of your focus knobs one way then lower the amount from 10 to 1 and move the other way and record the Focus number just before it moves. This is your backlash. Mine is set to 8 units.

    My HWFM and HDR values are just around 1.3 wasn't acheivable before by hand. 

    Looks great on my scope (white). Would look great on black scope too, but not sure about bright red on blue or orange (Old Celestron).


    A worthy addition to my setup that now I can not live without. Go for it! I left you some pictures...


    Kindest regards David




    • Like 3

  10. Thanks Wim for that. You can see its like day and night compared to the one without darks.

    You have even got some of the black nebulae out from it even with only 2.2 hours of data. Not sure what to try next. I think its expreminent with gain next. Raising the from 1 Min to 3 Min exsposures will help bring a sharper and more detailed image as my tracking is good. Plus my Focul reducer/Flatterner will improve things. I also took 3 minute dark frames today while I did the 60 second ones :)

    Not sure what the white foggy stuff is? Did you set the black levels and grey and white levels? I know its zoomed in alot so will show a lot more noise and imperfections.

    Looking forward to any tips you may have.


    Thanks David




    1 hour ago, wimvb said:

    I've only downloaded the data, but I must say that it looks a LOT better. Just a slight vignetting effect left, no problem for PixInsight DBE.

    I just finally spent out and bought https://www.365astronomy.com/ts-optics-photoline-2-0.79x-4-element-reducer-and-field-flattener-corrector-for-astrophotography.html

    Cheaper than Pixinsight :)

    I did speak to my friend Zoltan there and he said I may be getting Vigneting because of the backspace 2 inch going to a 1.25 cone and into back of my scope. Thats the adapters that came with my filter wheel and camera.  So not only will this fix that but is a matched flattener for my scope and 0.79 reducer. So the Flattener should stop the elongated stars at the far left and right of my shots.

    Also the Reducer will lose 20% of my size because of the reduction of focal length but will gain x1.6 exposure time. Turning my F6.5 to a F5.13

    I am away all of next week  so I will keep you updated somewhere on this forum with the results :)

    Would be nice to compare the new data with the old if you get 10 minutes.


    Have a good weekend.


    Regards David



    • Like 1

  12. Hi Wim,


    I managed to do the darks same temperature gain offset and exposure time as my lights. I may have found something else I was doing wrong. I was using the same master flat frame for each colour. This time I done them all seperate.

    I have replaced the files and re-uploaded them. All with 30 frames of lights and 60 darks. I also saved them in 32 bit Tiff format as to not lose any data.

    Hopefully you will have time to look at these and see if its the darks not being added has caused this problem or something else I need to work on.



    Kindest regards David






  13. Wish I could afford that program :)

    My stars are not sharp and numerous like other pictures. I think it's more exposure time and gain settings that you were saying. Any good pointers would be appreciated but first I need to know if its my data or my post processing. I think its both :)

    Cheers for looking at it for me! Oh by the way there are no dark frames yet only flats. I still havent took them :)


    Kindest regards David


  14. 45 minutes ago, wimvb said:

    Very nice. What camera do you use? If you get 0.4" guiding rms, you should increase the subframe exposure time. But if your camera has low read noise (modern cmos), you should be able to stretch your final image harder to pull out more detail and colour.

    For example, this is what 3.6 hours of 30 and 45 seconds exposures got me.


    Compare the different versions.

    Hi Wim,


    I think I am a little out of focus but here is a link to my stacked LRGB files it would be nice to see what you can get from it, to see if my data is any good.




    Regards David

  15. 32 minutes ago, wimvb said:

    Very nice. What camera do you use? If you get 0.4" guiding rms, you should increase the subframe exposure time. But if your camera has low read noise (modern cmos), you should be able to stretch your final image harder to pull out more detail and colour.

    For example, this is what 3.6 hours of 30 and 45 seconds exposures got me.


    Compare the different versions.

    Hi Win


    All my equpment is in my signature. It's not far different from yours except the smaller scope :)

    I only had half your data and don't think I autofocused before the session as I was just playing with my new hypertuned mount. HWFM and HDR normall around 1.3 when i focus.

    I'm using unity game on my ZWO asi1600mm pro. 139/50 the 50 is so it shift the histogram to the right slightly and dosnt crop it. I was using gain 75/15 but saw a youtube video and decided to give the new gain a go.

    Plus my post processing is just basics. Adjusting curves and levels. Removng noise and making an RGB layer and adding the Lum channel.

    Thats about all I can do sa far. This is my 4th ever image :)


    Regards David




    • Like 1

  16. 8 minutes ago, wimvb said:

    In dss you should be able to set one subframe as alignment reference. Always use the same sub for this, eg one L sub, even for R, G, and B subs. Just exclude that sub from the stack.

    From the dss faq

    How do I align the resulting images of 4 stacks (red, green, blue and luminance)?
    To align the resulting images on the same reference frame just add the reference frame to the list even if it is not from the same stack, force DeepSkyStacker to use it as the reference frame (using the context menu) but left it unchecked. 
    This tells DeepSkyStacker to use it as the reference frame but to not add it to the stack.




    Thanks Wim I am going to try that shortly. I had already used a reference frame but one for each colour now I see the problem. I will let you know if it works for me.


    Kindest regards David

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