The EQ3 DSO Challenge

[Nigel G]

1 hour ago, jjosefsen said:

Did a some processing on my little stack of the double cluster, 6x3mins at ISO 200.

This was my first go with guiding, and after spending most of the night getting everything working I had a little time to try and grab some light on this beatiful pair of globulars.

All in all it was a great night where I conquered a lot of the gear troubles I have been having lately.

• Polar Align with SharpCap - What a breeze it is to get good PA now!
• Guiding with PHD2 - Fairly easy to get working if im honest, but im sure it can be improved massively yet.
• Dithering with Backyard Nikon and PHD2 - Not 100% sure my settings are correct, but I think I'm aiming for a 15px dither.

Before I had about a 60% retention rate on 45sec subs (and they weren't great!), now I have 100% retention rate on the 4min subs I am taking of M33 as I type this.

Guiding certainly solves a lot of problems! I love it!

Thats a cracking double cluster, well done.

[Nigel G]

10 hours ago, Thalestris24 said:

Thanks! Sounds promising, though you have to bear in mind I'm a little old lady! I'm not very strong... But I'm desperate to get outside to do some imaging instead of having to put up with the indoor limitations. It only has to run for a couple of hours (after that I'd probably need to get back in! Haha). I wonder what it's unguided performance might be like? If I could run it unguided (no laptop) with a 200mm or possibly a 300mm lens, that would be good. I guess you run it with eqmod (like I do my heq5)?

Louise

Louise, I don't use eqmod, I use in camera guiding, the old way  The guide cam is connected st4 to the handset and data cable to the PC then good old PHD2 does the hard work.

I have not used mine unguided but other users here say 2 minutes seems a good keep rate.

With the mount on the tripod and the tripod closed I would say its portable.

I would say it needs re greasing twice a year to keep it smooth though in my opinion. 

Nige.

[jjosefsen]

Oh my bad, didn't see it was the syn scan model, thinking of my own..

The rest still applies I suppose. ?

[Thalestris24]

2 minutes ago, jjosefsen said:

Oh my bad, didn't see it was the syn scan model, thinking of my own..

The rest still applies I suppose. ?

No worries!

[wimvb]

1 hour ago, jjosefsen said:

Keep in mind it runs on 6v and not 12v, so some kind of converter is necessary.

 

1 hour ago, Thalestris24 said:

Hi

All the references I can find say the eq3 synscan pro runs off 11-15V, 2A?? e.g. this one

Louise

I ran mine off a 12 V leisure battery until I got a mains adapter. The synscan manual specifies 7.5 - 12 V.

With short the fl and low load, the mount performs very well. As is consistently demonstrated here.

The weak points of this mount are the aluminium tripod and the flimsy altitude adjustment bolts.

[Peco4321]

My latest Pleiades, 60 x 50 sec ISO 1600 darks and bias. New year resolution is to master the art of flats!!

[Stub Mandrel]

20 hours ago, jjosefsen said:

Before I had about a 60% retention rate on 45sec subs (and they weren't great!), now I have 100% retention rate on the 4min subs I am taking of M33 as I type this.

Guiding certainly solves a lot of problems! I love it!

 

It's a headache to get it working and to set up all those extra wires, but once it's working, it's a joy!

[jjosefsen]

50 minutes ago, Stub Mandrel said:

It's a headache to get it working and to set up all those extra wires, but once it's working, it's a joy!

Actually it was fairly easy to get going, but I'm an IT guy, so im used to all that tech stuff, on the other hand if something goes wrong I might be in trouble, as there are a lot of things you can change in PHD2.

But man is it cable hell! Already had one episode where I managed to the ST-4 cable clenched between the RA clutch handle and the RA axis, that didn't work too well.

I also keep forgetting to set the correct guide rate on the handset after framing, not to mention an episode last night where I accidentally switched to lunar tracking on the handset!

The number of things one needs to remember to do during a session is certainly starting to add up, but it's all worth it!

 

Stacking M33 from last night, already it seems I have a problem with the flats from the night :/

Edited December 17, 2017 by jjosefsen

[Stub Mandrel]

14 hours ago, jjosefsen said:

But man is it cable hell! Already had one episode where I managed to the ST-4 cable clenched between the RA clutch handle and the RA axis, that didn't work too well.

In the dark, a USB B will fit snugly into an ST4 socket...

[pushrod]

On ‎17‎/‎12‎/‎2017 at 12:47, Peco4321 said:

My latest Pleiades, 60 x 50 sec ISO 1600 darks and bias. New year resolution is to master the art of flats!!

Hi Peter, Newbie on this forum but have been messing with AP for a year or two and was interestingly reading this thread as i image with an EQ3 synscan when i came upon your image - and thought how similar it is to my recent attempt but from a totally different approach. Recently i have given up on stacking images and just gone for single long exposures - this is a  SINGLE 407s exposure, 130 pds scope with CC through a modded dslr with a cls ccd clip filter fitted, guided with phd, and then about 30seconds worth of tweeking of the raw image in an old adobe elements. I got a bit fed up trying to learn pixinsight(trial) and gimp as i'm not the quickest learner on a computer!

I would be very interested to hear what people think of my attempt - criticism gladly accepted

[Nigel G]

1 hour ago, pushrod said:

Hi Peter, Newbie on this forum but have been messing with AP for a year or two and was interestingly reading this thread as i image with an EQ3 synscan when i came upon your image - and thought how similar it is to my recent attempt but from a totally different approach. Recently i have given up on stacking images and just gone for single long exposures - this is a  SINGLE 407s exposure, 130 pds scope with CC through a modded dslr with a cls ccd clip filter fitted, guided with phd, and then about 30seconds worth of tweeking of the raw image in an old adobe elements. I got a bit fed up trying to learn pixinsight(trial) and gimp as i'm not the quickest learner on a computer!

I would be very interested to hear what people think of my attempt - criticism gladly accepted

A very good single exposure, nice and clean. 

20 or 30 of these stacked would make a great image. There's plenty of help in Stargazers lounge to guide you, just ask and help will come.

Nige.

[jjosefsen]

Here is my M33 from last night.

27x4 min for a  total integration time of 108 minutes.

 

My processing is still very raw - im definitely comming back to this data for a pass where i reduce star size before i start noise reduction.

One thing im quite please with is how I managed to heavily reduce the chromatic background noise my DSLR creates, even when dithering quite aggressively.

I did experiment a lot with the initial color calibration/correction. In this image i used BackGroundNeutralization -> DynamicBackgroundExtraction -> LinearFit -> ChannelCombination -> SCNR:Green -> ColorCalibration

Other examples i did without LinearFit, with DBE first, DBE last, etc. But this seemed to give the best result to my eyes.

[mikey2000]

 jjosefsen -nice double cluster!  M33 looks nice and clean too, if a little greenish for my personal taste.  Are those processing steps something to do with PixInsight?

Peco4321 - Yep, master those flats!   I took some more flats as I was trying a different ISO for an experiment.  I got something badly wrong and the stacked image ended up looking like a sheet of wet, crumpled paper :-)

pushrod - It looks good for a one-shot.  The darkening towards the edges could be fixed with flat files.  If you dare go back to stacking try 'DSS' then use a cheap bit of software called Startools to get the most out of the pic.  As ever, expect a bit of a learning curve but Startools is definitely simpler than PixInsight (my free pixinsight trial ran out before I understood anything at all.  The startools trial in time-unlimited but you can't save the end result except for by screengrabbing)

[jjosefsen]

13 minutes ago, mikey2000 said:

 jjosefsen -nice double cluster!  M33 looks nice and clean too, if a little greenish for my personal taste.  Are those processing steps something to do with PixInsight?

Yep it's PixInsight.

Yeah maybe it is a little green, could be fixed fairly easy I should think. ☺️

Edited December 18, 2017 by jjosefsen

[pushrod]

8 minutes ago, mikey2000 said:

 

pushrod - It looks good for a one-shot.  The darkening towards the edges could be fixed with flat files.  If you dare go back to stacking try 'DSS' then use a cheap bit of software called Startools to get the most out of the pic.  As ever, expect a bit of a learning curve but Startools is definitely simpler than PixInsight (my free pixinsight trial ran out before I understood anything at all.  The startools trial in time-unlimited but you can't save the end result except for by screengrabbing)

Hi Mikey, I am ok with DSS it is the post processing that used to get me a bit cheesed off. Yes i would agree that the vigneting should be fixed and i have never really got to grips with flats when i have stacked - usually just sticking with lights, darks and biases. The unlimited time of star tools sounds interesting - i might just give that a go

[mikey2000]

Startools does a fairly decent job to my newbie-ish eye.   As ever there is a bit of terminology and fancy sliders to get to grips with.  Google for 'startools forum' and get straight to the app's support site.  I'm sure I read a few 'what's your workflow for startools' threads here too.  That got me going and I'm no astrophotography expert, by any means.  Good luck!

[Peco4321]

@pushrod, I fully appreciate what you mean about the comparison between single and stacked images at my level. Sometimes after hours of imaging, stacking and processing I can't notice much difference but I think as I improve, that difference will become greater and in the meantime I am getting better and quicker at that side of things. The main area that lets me down is my inability to get good flats, something I'm working on. Also, I'm thinking of getting a filter for my camera in 2018, but that's another story. 

Great image by the way, the Pleiades is simply stunning to both look at either through a telescope or bins, and a very beautiful thing to image. 

[jjosefsen]

1 hour ago, mikey2000 said:

 jjosefsen -nice double cluster!  M33 looks nice and clean too, if a little greenish for my personal taste.

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

 

[wimvb]

10 hours ago, jjosefsen said:

 

I did experiment a lot with the initial color calibration/correction. In this image i used BackGroundNeutralization -> DynamicBackgroundExtraction -> LinearFit -> ChannelCombination -> SCNR:Green -> ColorCalibration

Lovely image. I'm a bit confused about your process flow, though.

1. Do you separate colour channels of your dslr image?

2. Colour calibration after scnr:green may very well put green back in again.

Personally, I always do colour calibration immediately after background neutralisation. Otherwise the neutral background that cc needs, may not be neutral anymore.

[Stub Mandrel]

@jjosefsen that's very nice. I'm banging my head against 6 hours data for M33 and I can't get a decent colour balance.

[jjosefsen]

8 hours ago, wimvb said:

Lovely image. I'm a bit confused about your process flow, though.

1. Do you separate colour channels of your dslr image?

2. Colour calibration after scnr:green may very well put green back in again.

Personally, I always do colour calibration immediately after background neutralisation. Otherwise the neutral background that cc needs, may not be neutral anymore.

My process is highly experimental at this stage ?

1. Yes I actually did linear fit for my dslr images, for some reason the color channels are in no way aligned, and I found this process to help bring out more variable star color, other wise my images have a distinct blue tint. Even without a filter..

https://jonrista.com/the-astrophotographers-guide/pixinsights/linearfit/

2. That's a good point, I will have a look at experimenting with that.

So many different approaches to processing, it's hard to find "the right way" and I probably have to find "my way" instead.

But any tips is highly appreciated.?

[jjosefsen]

6 hours ago, Stub Mandrel said:

@jjosefsen that's very nice. I'm banging my head against 6 hours data for M33 and I can't get a decent colour balance.

I would love to have gotten more data, but my view of the sky is quite narrow, limiting me to shooting only the western half, so I get on it quite late..

[wimvb]

1 hour ago, jjosefsen said:

My process is highly experimental at this stage ?

1. Yes I actually did linear fit for my dslr images, for some reason the color channels are in no way aligned, and I found this process to help bring out more variable star color, other wise my images have a distinct blue tint. Even without a filter..

https://jonrista.com/the-astrophotographers-guide/pixinsights/linearfit/

2. That's a good point, I will have a look at experimenting with that.

So many different approaches to processing, it's hard to find "the right way" and I probably have to find "my way" instead.

But any tips is highly appreciated.?

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.

[Filroden]

20 hours ago, jjosefsen said:

I did experiment a lot with the initial color calibration/correction. In this image i used BackGroundNeutralization -> DynamicBackgroundExtraction -> LinearFit -> ChannelCombination -> SCNR:Green -> ColorCalibration

I'd recommend looking at the new PhotometricColorCalibration process as an alternative and an improvement to BackgroundNeutralization and ColorCalibration. It calibrates the image to that the background is neutral and the stars match their BV values. I've found this gives much better starting points for star colour. You could also try the ArcsinhStretch process for at least some part of the stretching as it is better at retaining colour. I find it bloats the stars so I use it in combination with one or more of MaskedStretch, HistogramTransformation and CurvesTransformation.

I'd recommend the following order whilst linear:

DynamicCrop -> DynamicBackgroundExtraction (sometimes twice) -> ChannelCombination -> PhotometricColorCalibration -> (if necessary, and not always at 100%) SCNR:Green 

[Stub Mandrel]

2 hours ago, jjosefsen said:

I would love to have gotten more data, but my view of the sky is quite narrow, limiting me to shooting only the western half, so I get on it quite late..

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!