The EQ3 DSO Challenge

[jjosefsen]

1 hour ago, Stub Mandrel said:

It took me four or five nights over two years!

My 'RGB Challenge' entry just uses the final night's data and seems to be better on its own!

What?! Ok I'll stop moaning about my 2 hours in one night. ?

Why did it take so long?

[jjosefsen]

1 hour ago, wimvb said:

Fwiw, here's my linear workflow. Maybe you find something you can use.

1. Crop edges - dynamic crop

2. DBE, using few but large samples. Place samples manually. Sample size 15 pixels or larger, the largest size that fits between stars. Correction method depends on cause of gradient. I always do a test without correction applied to examine the bg model. Depending on how it looks, I adjust the number, placement and size of samples. I always go for a background model that is smooth with no structure, and few colour variations. Adjust tolerance until all samples have a weight in all channels > minimum sample weight (0.75). Check normalise, discard bg model, replace image. Apply correction.

3. Define the largest possible preview in a bg area. Use this for background neutralisation. If there's very little background, I create several small previews and combine them using preview aggregator script.

4. Use the same preview for colour calibration as bg reference. Depending on target, use either with or without structure detection for white reference. If using an aggregated preview, this needs to be made fresh.

4 alt. Use photometric colour calibration with preview for bg neutralisation reference. This procedure gives good colour variation in star fields.

...

For stretching, I use Mark Shelley's arcsinh stretch. This is superior to any other stretch I've used regarding star colour. Don't overstretch. A weaker stretch followed by curves transformation usually gives better results than one aggressive stretch.

 

I hope that some of this may be of use.

Pretty much what I usually do, until I started to mess around with LF.

I did try arcsintretch, but could not get it to work. It's like nothing is really stretched even at max settings. But it's probably me not understanding how to do it, will try and find some tutorials on it.

[Stub Mandrel]

5 minutes ago, jjosefsen said:

What?! Ok I'll stop moaning about my 2 hours in one night. ?

Why did it take so long?

I have to image it after it climbs above the house and before it hits the tree, roughly limiting most objects to 2 hours a night.

I have vastly more data, but not all from the same scope and some of it is badly centred so only four nights have it more or less central in the FOV.

[Nigel G]

I have had a go at the Heart nebula in bi colour. Taking 6x15 minutes Ha and 6x20 minutes OIII. Not enough but not a lot of clear sky at the moment.

First I tried opening Ha as red and OIII as blue but didn't get what I was expecting, some good detail but not the colour I was hoping for.

So I tried the Ha & OIII blend to create a fake SII and opened....Ha as lum, SII as red, Ha as green & OIII as blue. Its more like what I was looking for but the heavy processing has taken its toll on the detail. More data needed as usual. There's a lot of colour in the image and colour variations are just a matter of changing the % ratio. I need to work on this but its a start and there's no red which makes a nice change  

Modified Canon 1200D, Astronomik 12nm Ha & 12nm OIII. 80ED EQ3 pro

DSS, PHD2 & StarTools.

Cheers

Nige.

[JemC]

On 18/12/2017 at 23:08, jjosefsen said:

I  tweaked it a little, and I think it looks better now, not so green.

 

That is a very good image, 

you could run HLVG in photoshop, it is a good little plug-in for removing that green cast, have a look here, http://www.deepskycolors.com/archive/2010/04/26/hasta-La-Vista-Green.html

hope you don't mind but i just ran your image through it, this is the result, 

BEFORE

AFTER

 

Regards

[jjosefsen]

@JemC

Thanks, looks good. Unfortunately I don't have PS, only PixInsight.

I think I figured it out though, I added the green back into it in my linear phase, due to an incorrect placed step. As someone mentioned earlier.

I will be redoing this image at some point, I just hope for more data to add to it soon.

but thanks again, I'm still quite pleased with it, by far the best image I have captured so far. ?

[Nigel G]

8 hours ago, jjosefsen said:

@JemC

Thanks, looks good. Unfortunately I don't have PS, only PixInsight.

 

Photoshop CS2 is a free download and excepts all plug ins , handy to have ☺

[jjosefsen]

7 minutes ago, Nigel G said:

Photoshop CS2 is a free download and excepts all plug ins , handy to have ☺

Oh I did not know that, thank you!

[jjosefsen]

Tinkered with my short 7x4min stack of M42 from a couple of weeks ago, too bad i didn't get more data, but battery died on laptop.

Processing is getting better I think, need to learn how to better reduce star sizes and fix oversaturated stars (Arcsinhstretch) next.

As always - comments and tips welcome.

 

[Stub Mandrel]

Nice detail, but a bit short on colour.

[jjosefsen]

5 minutes ago, Stub Mandrel said:

Nice detail, but a bit short on colour.

Thanks..

I could always bump up saturation, but yeah star color seems to be lost in this one.

Any ideas?

[Stub Mandrel]

1 minute ago, jjosefsen said:

Any ideas?

A close look shows some stars against the nebulosity have dark haloes as well... sorry!

As for ideas, only photoshop ones... Noel's Increase Star Colour and the soft-light & luminosity trick

 

 

[jjosefsen]

Yeah like I said - I need to get better at star size reduction - causing me all kinds of problems :/

Had to go a little ham fisted with the noise reduction as it was a little low in the skye and of course not a lot of images to go with.

[Stub Mandrel]

It's really nice data, you need to keep playing with it

[jjosefsen]

12 minutes ago, Stub Mandrel said:

It's really nice data, you need to keep playing with it

hehe I am - so much to learn in this hobby.

[jjosefsen]

Could some of you, using PHD2 for guiding, post some of your settings and what RMS values you get?

Im trying to get a sense of what I should aim for with my settings and resulting guide graph.

While my subs currently look pretty darn good (compared to unguided), I do have pretty heavy fluctuations in the graph.

Included us a couple of guidelog graphs, would appreciate if anyone had some tips on improving EQ3 guiding.

I have done the whole strip, clean and regrease on the RA axis - haven't done the DEC yet.

 

Thanks

[mikey2000]

Hi jjosefsen.

 

I guide my eq3syscan with a QHY5L-iiC camera and with a 130mm guidescope.  I end up at about with the guide scope/camera combination similar to yours at 5.95arcsec/pixel.    With this, I can get overall RMS values at about 1.0" consistently, if not aiming too near the 0 degrees Dec celestial equator.  RA guiding gets a bit more wobbly then...   With careful 'polar disalignment' I can set up unidirectional Dec guiding to save me worrying about backlash and if I get the Dec guiding going the right way (either all north or all south, depending on patch of sky), Dec guiding sometimes stays as low as 0.5" RMS for extended periods.  (If I get the unidirectional guiding 'backwards' then I get occasional massive Dec excursions, I assume this is when the dec axis slips/drops a little.

 

I use Eqmod and Pulse Guiding.  I don't go via the synscan handset or ST4 port.   After experimentation, I found setting the Eqmod Pulse Guide rates to 0.7 for Dec and RA was smoothest.  (All other eqmod settings untouched from default). 

 

Balancing the RA axis a little bit East Heavy made a big difference - no more excessive RA lurches and leaps, just jagged zig zags. (Well, mostly.... I still get the occasional unexplained RA 'burp')

 

In PHD2 I have Dec in unidirectional mode, Agression 75% and MinMove as suggested by the PHD2 guide assistant.  For RA, I use Hysteris  0.120, Aggression = 0.700, Minimum move as set by Guide Assistant.   I don't use any backlash compensation.  Definitely use the PHD2 guide assistant before starting an imaging run.

 

One other thing to try is EQMOD Auto Pec.  I see in the second graph an overall long swing back/forth every 11 minutes in RA.  This is classic periodic error.  If you run EQMOD autopec (let it run about 6 cycles, ie 66 mins or so) and it gives a noteable improvement.  Eqmod can the smooth out the long slow periodic error (you can actually hear the motor speeding up and slowing down!) leaving PHD2 to chase the smaller glitches.

 

Going against all apparent conventional wisdom, I found short guide exposure most effective.  My EQ3 has some tracking errors that shift fairly quickly so Guide exposure of 0.5s seem to help the software keep up with chasing the mount....

 

What's your imaging scale?   With my setup, I'm imaging with pixels that cover about 2" of view so keeping RMS inside 1" is perfectly OK except for my annoying dec glitches.

[jjosefsen]

Thank you for that detailed explanation Mikey, you are a star!

I will definitely try the shorter exposures, see if more frequent guiding input has an effect.

As for eqmod - I only have the deluxe edition with motors and upgraded handset, not the synscan model. ? So I don't have a direct pc to mount connection, just an st4 port. I read somewhere too, that the non-synscan motors are lower powered, which would explain the 6v power instead of 12v. Maybe this impacts guiding.

I already balance east heavy, but haven't tried reducing DEC backlash via. Balancing.. Something to look at...

Will try to fiddle more with settings along the lines of your settings, but I suspect that each eq3 mount is a bit of a different beast due to the less than desirable build quality. ?

Now I have a reference point which was what I was really hoping for.

My image scale / sampling rate is 1,94"/pixel - does this equate to me wanting for RMS smaller than 2" for "good enough" guiding??

[jjosefsen]

On 22/12/2017 at 23:34, Stub Mandrel said:

A close look shows some stars against the nebulosity have dark haloes as well... sorry!

It's the deconvolution process! - my masking is not good enough.

Was pretty much just confirmed by @alacantin another post.

[Peco4321]

Currently snapping away at the festive Christmas Tree Cluster, probably going to call it a night with 120x 45 sec. Work at 7 so can't stay out much longer. 

[mikey2000]

On 27/12/2017 at 19:06, jjosefsen said:

Thank you for that detailed explanation Mikey, you are a star!

My image scale / sampling rate is 1,94"/pixel - does this equate to me wanting for RMS smaller than 2" for "good enough" guiding??

No problemo!   I try to aim for RMS about half of the imaging scale.  I think many of the guide wobbles are at least 2x the rms, averaged out by 'direct hits' with zero error.  So, the 50% goal seems sensible to me.

Have you looked at the PHD2 scattergraph? (View menu, Show Target).  It plots all the exposures in a nice view that builds up a pic over time, showing the general accuracy of your guiding.  I find it to be a nice visual tool to see how it's going.  (eg is DEC is much much worse than RA, you can get an idea of how oval the stars are going to be etc etc)

[jjosefsen]

I did not know about that no.

Forecast for tomorrow says scattered clouds but no rain, so might just do some testing tomorrow, as it probably won't be good enough for proper imaging.

[Nigel G]

On 27/12/2017 at 14:24, jjosefsen said:

Could some of you, using PHD2 for guiding, post some of your settings and what RMS values you get?

Im trying to get a sense of what I should aim for with my settings and resulting guide graph.

While my subs currently look pretty darn good (compared to unguided), I do have pretty heavy fluctuations in the graph.

Included us a couple of guidelog graphs, would appreciate if anyone had some tips on improving EQ3 guiding.

I have done the whole strip, clean and regrease on the RA axis - haven't done the DEC yet.

 

Thanks

 

Here's a good night with PHD2, 30 minute exposures going on.

The PC date is way off as this is my imaging PC and is not connected to the internet and no internal battery  

I don't really know much about the settings, the first lot I entered has work well so I don't change anything but some of them are at the bottom of the screen 

Nige.

[jjosefsen]

3 hours ago, Nigel G said:

Here's a good night with PHD2, 30 minute exposures going on.

The PC date is way off as this is my imaging PC and is not connected to the internet and no internal battery  

I don't really know much about the settings, the first lot I entered has work well so I don't change anything but some of them are at the bottom of the screen 

Nige.

 

Thank you, you are also under 1 sec total, looks like that is the goal then. ☺

I see you are running shorter exposures as well, gotta try that. Hoping for a hole in the clouds once my boy is tucked in, but doesnt look good.

[JemC]

Well i managed to get out last night(Sat) to do a little grab and go session on Orion, and it was only little.

My set up was, 

EQ3-2 on aluminium tripod (first time using this)
Canon 600d (unmodified)
Skywatcher 130P-DS (WITH CURVED SPIDER)

At the moment this is not the ideal set up as i only have one counter weight, which is not enough when using the 130P-DS, so to improvise i ended up balancing one of my power drills on the counter weight bar  (not ideal)

I could only do a rough polar align (by eye) as i do not have a polar scope for the EQ3-2 at the moment

So after a little messing around i ended up taking (according to DSS)

30 light frames @ 45 seconds (best i could achieve) total of 22 mins 54 sec

i then cheated a little and used a set of dark and bias frames i had from previous session  

it was then processed in Photoshop cc using some of @steppenwolf tips from Dark Art or Magic Bullet (really need to read this again)

As is understandable the image is really short on data and proper set up, but overall quite happy with what i got, 

 

1st Image is my set up with balancing power drill 

 

 

2nd image ORION

Edited January 7, 2018 by JemC
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