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Help derotating images in WinJupos please

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#1 Tulloch

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Posted 26 May 2019 - 12:16 AM

Hi all, I'm trying to de-rotate/stack images in WinJupos but I can't seem to make it work.

 

I've taken a series of 4 min videos over about 40 minutes and the individual stacks look pretty good  (to me anyway). More experienced people than me then take their stacked images and put them into WinJupos to combine and derotate the images which improves their images further. When I try to do this with my images I find that the derotation is not working as it should.

 

So briefly, I take the stacked and sharpened images, measure them in WinJupos then add them to the "Derotate Images" page. The measured images look fine, the moons line up where they are supposed to, but the stacked image is blurry and the moons (and the shadow) are not on top of each other as I would have expected.

 

Am I doing something wrong, or am I asking too much of WinJupos? 

 

Example photos are below, the first is an example of one image prior to de-rotating in WinJupos, the second is the image after stacking 8 such images in WinJupos. You can see the faint dots of Europa moving between images, and the moon's shadow forms a dark smear on the planet's surface. The derotate page showing my setup is also here.

 

Does anyone know what I'm doing wrong here?

 

Thanks in advance,

 

Andrew

Attached Thumbnails

  • 2019-05-17-1603_3-JUPITER_Tv140s_100iso_1024x688_20190518_02h01m09s_loop01_pipp photoshop_edited small.jpg
  • 2019-05-17-1603_3 copy.jpg
  • WinJupos derotate images page.PNG

Edited by Tulloch, 26 May 2019 - 12:21 AM.


#2 Lacaille

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Posted 26 May 2019 - 01:41 AM

Hi Andrew, a couple of quick pointers:

 

1.it looks as if you might be trying to integrate over too long a period. In general, you should derotate images collected over 15 mins - maybe 3 of your 4 min videos.  You can go longer than 15 mins but you start to get weird effects if integrating images over 25 mins (from memory - I did a comparison of this on CN last year).  

 

2.  The idea is you will end up in WJ with a derotated image which you can then sharpen and process further  - e.g. unsharp mask, increase saturation and adjust brightness and contrast to elicit more detail.  The WJ output  will often look a bit blurry, but there is often a greater signal there waiting to be teased out. I usually do this stage in GIMP(like Photoshop), or Fitsworks (Deconvolution) - others may go back into RStax. Often however the biggest thing you may notice is not so much more detail but rather a reduction in noise, which improves the appearance of the image. Occasionally, you will find that an individual derotated image is better than anything you produce from WJ - derotating that good image with the others just causes a loss of quality.

 

3. I quite often find the moons or moon shadows problematic.  Restrict the integration time to 15 mins as above, and be very meticulous with fitting and rotating the frame to the image.  Things may improve!

 

Regards

 

Mark


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#3 Tulloch

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Posted 26 May 2019 - 02:17 AM

Thanks for the useful tips Mark, looks like I'm trying to push WinJupos too much. Since the image measurements come out so well (the moons line up perfectly with the WinJupos outline), I thought there wasn't really any limit. Do you have a link to your previous CN post?

 

Since I'm actually recording jpgs continuously for 10 minutes, I could actually turn them into whatever video length I like. But at 20 fps max, I really need longish videos to get enough good frames. One of these days, I'll get a better camera, would you suggest a 224 MC or 290 MC?

 

Thanks again, Andrew


Edited by Tulloch, 26 May 2019 - 02:26 AM.


#4 Lacaille

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Posted 26 May 2019 - 03:53 AM

Hi Andrew, here is the thread where I posted some images following different integration times:

https://www.cloudyni...-winjupos-help/
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#5 Lacaille

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Posted 26 May 2019 - 04:56 AM

Oh, re cameras: both are superb. You won't go wrong with either. Both would perform better with an IR cut or L filter, and an ADC.

290 has a slightly larger sensor of 5.6 x 3.2 mm and pixel size 2.9 microns

224 sensor is 4.8 x 3.6 mm and pixel size 3.75 microns.

Working off optimal f = 5-7 x pixel size gives

290 opt f = 15 - 20
224 opt f = 19 - 26

Perhaps one or other of these ranges coincides nicely with your scope's f plus a 2 , 2.5 or 3 x barlow?

You can do a comparison of cameras on the Zwo website.

Edited by Lacaille, 26 May 2019 - 04:59 AM.


#6 Tulloch

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Posted 26 May 2019 - 06:07 AM

Thanks again, I really appreciate the help. I'm leaning towards the 290, larger sensor, smaller pixels, only $70 more. I have an f10 with 2x barlow which actually runs at about 2.6x when fitted to my scope, so maybe the 224 is better.

 

I have a Baader Neodymium Moon and Skyglow filter which also cuts IR, so might be OK with either.



#7 Lacaille

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Posted 26 May 2019 - 11:57 PM

Hi Andrew,

 

I just looked at that filter's specturm and it is similar to a normal L or UV/IR cut filter except for a big dip around 750 nm - I don't know what effect that would have on your image.  The blurb suggests it is fine for Mars and Jupiter though. On the other hand, if you don't cut the IR, you end up with some very weird colours, such as a hot pink Mars!

 

Re those cameras, I forgot to mention that they are USB3 - you can plug them into USB2 and they will work, but you won't get the max possible frame rate.

 

Mark



#8 Tulloch

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Posted 27 May 2019 - 01:52 AM

Thanks again, that filter is designed to cut street lighting but also cuts IR - my DSLR already cuts IR so no real benefit on that score.

 

I've tried it on Jupiter when the moon was very close, and it's quite clear that the yellow is removed (see below). Raw images only, but you can certainly see the effect!

 

 

 

 

Attached Thumbnails

  • Jupiter no Skyglow filter.jpg
  • Jupiter with Skyglow filter.jpg



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