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#276 Clouzot

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Posted 24 May 2020 - 02:51 PM

Stargazer.  That is exactly the way I have been doing it.  And I have been getting results similar to others I commonly see here.  Which is to say, worse than a DSLR (yeah, I know those might be fighting words, but honestly, that is the way I see it).  Clouzot got results very similar to my DSLRs.  The only difference I could see was in the way he used the histograms.  Going to give it a try.  I think the French may have an edge on us when it comes to making the images look nice.

Rick, thanks for the kind words. However I'm beginning to experience a serious imposter complex: I'm just an EAA rookie, and I shamefully stole that dual histogram trick from Master Steph (who finally turned to the dark side, but who still posts pure-EAA marvels that would put more than one seasoned astrophotographer to shame)


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#277 chilldaddy

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Posted 25 May 2020 - 10:11 AM

What I found most important in order to get a good color balance was not to stretch the live histogram too much, giving a wide berth to the "bump", and using the mini display histogram for the dirty work (cutting the sky background, and even more importantly, getting a decent contrast). That helps a lot.

When I first saw the live histogram, I wondered why it was so far left of the peak and thought maybe the image could be even better.  Then I realized how amazingly good it already was! bow.gif   I never would have thought that was why it looked so good.  I have always aggressively worked the live histogram first then the display histogram, so this is very interesting.  How do you determine the width of your black and mid points on the live histogram and do you always leave the white points untouched?

 

I'm beginning to experience a serious imposter complex: I'm just an EAA rookie, and I shamefully stole that dual histogram trick from Master Steph (who finally turned to the dark side, but who still posts pure-EAA marvels that would put more than one seasoned astrophotographer to shame)

Can you point us to some of his work?

 

Thanks!

 

Greg



#278 Clouzot

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Posted 25 May 2020 - 10:54 AM

His website can be found at https://astronomy-outcast.com
...but he only posts processed pics there. His EEA posts are on our small forum, but I don’t want to be accused of harvesting here, so...

As for the histograms, my usual method:
- auto stretch the Live Histogram
- auto stretch the Mini display histogram
- (the image will probably look horrible then)
- de stretch the Live so that the distance between the black and mid points is approximately twice the width of the bump (it’s difficult the strictly define what the width is, but have a look at one of my screenshots and you’ll see what I meant. If not I’ll annotate an image).
- unless the signal is really faint, put the (Live) white level all the way to the right. We don’t want to saturate anything, do we?
- balance colors so that the RVB curves are superimposed on the mini display Histogram
- then only adjust the mini histogram to your taste. Press and hold the Shift key before clicking on the histogram handles to fine tune. You can also do small changes on the Live histogram but try to keep them to a minimum

Hope it helps!
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#279 alphatripleplus

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Posted 25 May 2020 - 11:23 AM

Everyone, please remember this is NOT the thread for an extensive exchange on using SharpCap. If you want to have that discussion, please start a new thread. An occasional comment or question on a gallery picture is fine. I hope that is clear. Thanks.



#280 Rickster

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Posted 25 May 2020 - 02:32 PM

Here is a recent EAA shot of M63 taken with my 16in Newt/GEM, Astrotech (GSO made) coma corrector and ASI183MM pro.  29x10s Exposures.  No filters, flats or darks.  Moonless sky with average seeing.

 

Depending on your monitor settings, you can probably see what looks to me to be a path cut through the galaxy fringe by a small colliding galaxy.  The path shows up as a straight dark line running (more or less) horizontally (upper fringe).  If you extend this line to the left edge of the image, you can see what look like remnants (above the bright star).  At least, that is the direction (right to left) it looks to me that the colliding galaxy traveled.  The analysis at the link below seems to contradict what I think see, but I couldn't be sure.  Lots of speculation.  I will leave it up to you to decide.

 

 

Further reading:  https://www.cosmotog...ll_ngc5055.html

Attached Thumbnails

  • M63 29x10s 16SW CC ASI183MM 2x2 low black resize.jpg

Edited by Rickster, 25 May 2020 - 03:25 PM.

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#281 Rickster

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Posted 25 May 2020 - 02:37 PM

Same shot with less stretch/higher black point (prettier).

 

 

Attached Thumbnails

  • M63 29x10s 16SW CC ASI183MM 2x2 resize.jpg

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#282 alphatripleplus

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Posted 25 May 2020 - 04:47 PM

Very nice, Rick. I need to take a deeper look at the Sunflower galaxy.


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#283 Clouzot

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Posted 26 May 2020 - 03:16 AM

Stunning view of M63 Rick waytogo.gif. Coincidentally I was observing it yesterday evening as well, with no prior knowledge of the galaxy history. I only knew about its "flaky" apparence from prior observations. Then I saw that black streak (very, very faint on my image) and wondered if it was an artifact. Your post shows clearly it's not. I couldn't see the remnants on my C9 though.

 

The study you linked states that the colliding galaxy's whereabouts are unknown, so I want to believe the remnants on the left are what is left of the poor disrupted little thing lol.gif


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#284 Clouzot

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Posted 26 May 2020 - 06:41 AM

And here is last night session. I wanted to test the 294c at unitary gain (for some reason, this one gain, 400, gives an enormous amount of read noise: 5e-!).

With so little gain I knew that running at f/6.3 I had to use longer subexposures, so I settled on 60s. This is definitely too long for me, at least from an EAA standpoint, and with my frail AVX it mandates the use of an autoguider (PHD2 in my case). A bit too AP-like, I agree.

I also used darks and flats.

 

The weather was fine, with little to no clouds. No wild boars save for one grunt while I was polar aligning, and no badger

 

First, M81, before it was too low in the sky. I let it stack for 19 minutes.
M81-19x60s.jpg


Edited by Clouzot, 26 May 2020 - 06:46 AM.

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#285 Clouzot

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Posted 26 May 2020 - 06:45 AM

Next on my list was M97 aka the Owl Nebula. My aim was to capture the red outer rim (which I had never managed to see clearly with the 294 or the 183) while retaining some detail in the inner regions.

The red part is indeed there, but I lost some dark regions by stretching (perhaps) a bit too much.

 

This is a live stack of 16x60s.

M97-16x60s.jpg


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#286 Clouzot

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Posted 26 May 2020 - 06:52 AM

I passed on the Crescent Nebula (NGC 6888) but without any filter this was too hard a target for my setup.

 

So on to some galaxies, starting with M64 (the Black Eye). This one made me happy, because this was the very first time I could really see it in color with my gear. I spent 15 minutes livestacking, but I could probably have spent more (if it wasn't for that 8am business appointment)

M64-15x60s.jpg


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#287 Clouzot

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Posted 26 May 2020 - 06:59 AM

And finally, I slewed to its neighbor, M63 (the Sunflower Galaxy), which was worthy of its name this time.

 

While my observation was far less detailed than Rick's (see a few posts above), I could definitely see the black streak. And now that I know where to look, I think i can also see the "remnants" as well, next to the biggest star on the left.

M63-20x60s.jpg

 

It was a good session, but I don't think I will use 60s subexposures too often. 30s or shorter seem to give decent results, with less hassles (autoguiding etc).


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#288 chilldaddy

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Posted 30 May 2020 - 07:49 PM

After a long stretch of no viewing, I recently received my Evolution mount back from Celestron repair with a new HC.  They did an amazing job of turning it around quickly after having just returned to work in CA.  Last night was my first EAA session in a while and I was a little rusty, but these objects are pretty bright and always enjoyable. 

 

M81 & M82

AT60ED at F/3.8 (F/6.3 FR)

Evolution mount on wedge

ASI385MC, D1 filter

16sx139, 300G

Bortle 7/8

 

I'd like more detail in M81 for that long of an exposure.  Maybe I'm expecting too much for such a small aperture.

 

Screen Shot M81 & M82.jpg

 

M8

AT60ED at F/3.8 (F/6.3 FR)

Evolution mount on wedge

ASI385MC, D1 filter

16sx74, 300G

Bortle 7/8

 

This one never disappoints and it was good to see it for the first time this season.

 

Screen Shot M8.jpg

 

 

Greg


Edited by chilldaddy, 30 May 2020 - 08:12 PM.

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