ollypenrice

The image is essentially great, to my eye, but that dusky magenta for the Ha doesn't sit well for me. Did you use a heavy dose of SCNR green? That would slew the hue towards magenta.

However, I think it will be more to do with how you blended the Ha. I keep it very simple and add Ha to red in Blend Mode Lighten. I prefer not to add it to luminance but, if I do, it is only at a very low opacity - 10% max. It can also be useful to boost Ha signal at any time in Ps by going to Selective Colour, Reds, and dropping the cyans in red.

Edit: I don't think your RGB is blotchy but it does show a mild trace of the tile pattern which sometimes arises from StarXterminator. Sometimes I don't get this at all and sometimes it's awful and takes a lot of fixing.

Olly

Great framing idea!

Olly

A belated processing note: when replacing the stars and keeping them small, I found that those in front of the bright nebula didn't show at all, giving the impression that the nebula sat in a stellar void. With the stars still as a top layer I used the Ps Colour Select tool to select the bright nebulosity and gave the top layer a gentle further stretch within the selection to bring them into view. In small format this doesn't show much but, when zoomed in, it looks more natural.

Olly

If you hadn't mentioned the moon, who'd have known? Nothing wrong with those.

Olly

Diffraction spikes are an artifact but, if you must have them, they can be created by cluttering your aperture with string or by using Noel's Actions in post processing. But why? Grrr!  

To be honest, modern post processing possibilities make star control so simple that it strikes me as being more sensible to concentrate on a system which gets the best object signal. I'm using a RASA 8 and a Samyang 135 at the moment. Native stars are not great in either, but does it matter? Star Xterminator gives me almost total control over them.

How does StarX work with Newt spikes? I don't know, but if it doesn't work with them I would would ditch the Newt straight away because star removal-replacement has revolutionized imaging.

Olly

13 minutes ago, sophh6699 said:

Unfortunately it is not motorised, it’s the manual one - where would I find where I can upgrade the stand? And yes I do already have a Nikon D300 I am planning to use. Thank you!

Ah, that word, the 'stand...'  I know it's a trivial business of words but nobody in astrophotograhy ever uses the word 'stand' to describe a 'mount.' That's because it doesn't stand, it tracks, and it is by far the most important part of the rig. First Light Optics, the sponsors of this forum, will sort you out with the bits you need and will see you proud in future developments.

My kit priority order has never changed. It is mount-camera-optics. Yes, optics last. 

Olly

48 minutes ago, matija said:

@ollypenrice,

I'm looking at the Mesu200 variant that has three screws in the middle of the angled wedge. No other form of PA. Is it still easy in that case?

 

Matija

I'm afraid I don't know. I've never seen one of these. Lucas Mesu is an excellent engineer, however.

Olly

I've polar aligned the original Mesus several times and a guest brings one here every year. However, these are not on the angled pier, which has a limited latitude range, I presume. Which one are you using?

Alignment is, in my view very easy. The Alt-Az adjustments bolt are beautifully made in stainless steel and are hefty and free from flex. Our guest just uses the Mesu polar scope, which is actually the Losmandy optical tube on a Mesu bracket which simply bolts on and off. He says it works fine and is all he uses. No need for drift refinement.

I've never had any issues with balance. I have no clutches but it doesn't seem to matter. Just balancing by feel has always worked fine. My oldest Mesu has the proud boast that it has never, ever,  lost a sub to guiding error and that's in commercial use over a ten year period.

Olly

You'd like to image 'galaxies and nebulae' but, most of the time, these require different telescopes or lenses. Most galaxies and small and most of the well-known and brighter nebulae are large. There are exceptions but I don't regard a nebula telescope as being the same as a galaxy telescope.

Ratlet makes the key point above. For a given camera, a shorter focal length lowers resolution, making tracking precision less critical. There is no point in putting a high resolution (long focal length) setup on a mount which is not tracking to a high standard. The resolution will be lost to the tracking error.

I agree that a camera lens is your best bet. Primes work better than zooms, as a rule, but check the astro performance of any lens you consider because stars are odd things where lenses are concerned. Some give good stars, some don't. It doesn't simply go with price.

The most important thing is getting your tracking as accurate as possible. A Box Brownie held still will easily beat a Hasslelbad that is wobbling around.

28 minutes ago, simmo39 said:

That's gorgeous! But when are you going to start trying? You make it look so easy!

My new workflow using StarX is the most consistent I've ever followed. In the past I'd do things differently at each stage, depending on how the image was progressing. For the first time since I started I can say that I do actually have a predictable workflow now.  Processing really is easier than it has ever been, though Paul's meticulous pre-processing has a lot to do with that.

Olly

12 hours ago, WolfieGlos said:

Most images I see of this don’t show the orange hues around the Garnet star. Stunning.

This was one of the best parts of processing the data. On earlier versions I've always worried about whether the orange colours around the Garnet Star were just bloat from the star's light.  In this version I can feel confident that the gasses themselves do have this colour.

Olly

Imaged with Paul Kummer who did capture, stacking and mosaic construction. I post processed. RASA 8, ASI2600 OSC, EQ6, based here in SE France.

I've image IC1396 several times but never like this, with the super-fast system and the X-suite to liberate the nebula from the starfield. Very exciting! In the top right is the start of the Flying Bat nebula.

It's a big image, best seen here:  

https://ollypenrice.smugmug.com/Other/Emission-Nebulae/i-5ZjzWhw/A

Olly

This is great. The region cries out for a piece of work like this and you've done it proud.

Olly

I think I knew what to expect when I opened the thread! M27 has, I think, been put to bed for at least a decade...  Beautiful.

No green?

Olly

On 12/08/2023 at 14:03, aleixandrus said:

Some posts ago, after dealing and (mostly) resolve backfocus issues, I said I deserve some fun with the Samyang. Well, this is my upcoming project:

The pic above is just a test-shoot to make sure I can fix anything in planning prior to the actual shooting. This is a 4x3 mosaic with just 1x300s Ha, calibrated with darks and processed with Pixinsight (GradientMergeMosaic, DBE and manual stretch). It went much smoother than I expected... which scares me as hell as it could be just good luck 😅 The initial plan is to add 12x300s per filter (SHO) per panel (4x3=12). This is 36h total to build a 'base' mosaic and, then, add more integration where needed up to 3h/filter (108h).

What do you think? Any advice from those with more expertise? It seems ambitious for my skills -never did a mosaic before-, for my sky conditions -clouds and rain most of the year- and many things may go wrong but... hey! it seems fun!

That is a truly magnificent framing.

Olly

There is no ionized hydrogen in the Pleiades field so the modding of your camera should not, in principle, affect your result one way or the other. It will be good on emission nebulae though. This target will give you something even in a short integration time because the main stars are bright.  After that, it will give and give and give and give as you do more integration. The extended faint nebulosity rewards patience!

Olly

It's not clear what we are looking at, here.

The green-magenta top image is the subtraction map for background extraction?

What we need to see are the original image screen stretched, the background extraction map and the image screen stretched after the map has been subtracted. JPEGs will do fine for a first look.

Olly

23 hours ago, saac said:

Had you enjoyed one too many and entered the quantum realm Olly?

Jim 

I can't afford one Hospice de Beaune, let alone one too many (whatever that might be.)

lly

8 hours ago, vlaiv said:

Well, you can't get around physics, and it says that whatever affects stars, affects the whole image.

 

We are not just talking about optical physics in discussing an imaging rig, we are also discussing the interaction between the optics and the camera and the data with the processing software and, as Andrew said, the role of other variables like the atmosphere.

I don't assert that what I observe derives from the optics. I don't know where it comes from - it is just what I observe...

Olly

7 minutes ago, vlaiv said:

I don't know - to me it looks all mushy and without distinct detail. I pulled 3 different images here from SGL, did not pay attention to aperture, and sure, some of them are narrowband or enhanced by NB data - but feature should still be there and should be sharp:

OK, I've probably zapped that feature in processing but, then again, I can see features in ours not seen in the others. The question marked feature is there in ours but softer - as you'd expect from broadband.

Of those posted, I think ours has the most information. This may be down to different ways of looking, of course.

Olly

16 minutes ago, tomato said:

Certainly if you go by the number of scopes being used for DSO imaging, then an 8’ Newtonian must  be close to the top of the list, but there are a lot of 80mm refractors out there also. However, I think they tend to be favoured by nebula imagers, small galaxies, it seems to me, are a less popular group of targets to image.

Perhaps the title of my original post was misleading, I did mean it to apply to DSO imaging (all objects) only.
 

 I tried DSO imaging originally back in the 80’s and 90’s with an 8’” F4 Newtonian, and the frustrations I experienced with that scope persuaded me to buy a refractor when I took up the hobby again 35 years later.

Another great DSO imaging scope which I think deserves a mention as a candidate for a one stop scope is the MN190, but I will stick stick with the RASA11, aperture is good.

The MN190 deserves a makeover with quality hardware around the optics. 1000mm FL and F5 is right on the money for galaxies and nebulae.

The joy of widefield and a fast system, though, is that you can do something new or rarely seen. Whatever you do on M51 will have been done better by the professionals. That doesn't stop it from being satisfying but getting a new perspective on a region is an incomparable buzz for me.

Olly

On 24/08/2023 at 21:23, saac said:

Yes there is, Newtonian at least. The water is a viscous liquid, a Newtonian liquid indeed. As the bottle falls (follows a straight path (geodesic) through the curvature of spacetime) the currents in the water will experience and exert viscous shear forces. Impart a spin on the bottle before you let go and these shear forces will present a delightful vortex in the water. Now how about we replace the water with supercooled liquid Helium! 
Jim 

I knew it!  I had a glass of Hospice de Beaune the other day and saw the waiter half drop the bottle on his way to our table.  I couldn't put my finger on what was wrong with the bouquet but now I realize that it was a nasty dose of viscous shear! (It had separated the berry notes from the truffle.)

Olly

11 hours ago, vlaiv said:

As far as I understood Olly - he claims that star size don't correlate with background detail in RASA data - that somehow stars are being large / soft (sign of high level of blur - high FWHM) - but that detail is still there in the background.

Here's a close crop at full size from a work in progress. The stars are lousy but, in my view, Trunk details are good.

I can fix the stars very easily, however, and get them good enough for my own taste. They are still not the best but I can live with them...

I'm not concerned by how much of this arises from my processing workflow because it's the workflow I use and it does what I want it to do. What you see above is the working reality of using RASA data. The non-stellar parts of the image neither had nor needed any intervention. RASA stars do need attention, though. They also needed it when I was using an earlier workflow.

Another example,. Before:

After

In this case the difference is slight, seen as a crop, but an extended starfield looks much better with the adjustment.

When using good refractors the stars needed far less attention and I've had to come up with efficient solutions for adjusting RASA stars.

Olly

1 minute ago, vlaiv said:

I can't really convince you that this is indeed so if I don't start with highly technical stuff and math.

Best I can do to show you that this is in fact true (without going into technical stuff) is to do the following:

I do hope we are in agreement that for all intents and purposes stars in astronomical image are in fact point sources (before the light reaches earth's atmosphere and aperture of telescope).

Imagine following scenario to understand what a blur is - there is only one star in the sky and nothing else - no light pollution, no nebulosity, nothing. Photons from this star always arrive from same angle in the sky - from same point, and in perfect world - they would all be focused into same spot, right?

However, we have atmosphere, we have aperture of telescope and we have aberrations. All of these conspire together against our poor photon so it does not land on a single point but gets thrown randomly around this point. Every photon that comes from this star gets the same treatment - majority of them are thrown off course just a bit, some are thrown off course a bit more. When they all accumulate - we get nice bell shaped distribution of photons with certain FWHM. In some scopes it will be nice gaussian like shape - where seeing dominates over diffraction effects, while in other scopes we won't get nice gaussian type shape but it will still be sort of bell shape but little distorted - this is where aberrations dominate seeing (seeing should be fully random and produce true gaussian shape - others are predictable and produce different shapes and result is combination).

Ok, now that we know how star light behaves - it gets scattered in particular way around that single point - we will call this "blur" as it blurs star into some non point like shape.

Punchline - atmosphere, telescope, sensor - all of them have no idea if that photon came from a star or from nebulosity or from some galaxy. All photons will receive the same treatment. Every point in the image will be blurred regardless of the source of photon - it is just important that photon arrives from same spot in the sky and it will get scattered around in that bell shape.

Do this with every point of the image and you have blurred image - that is how blur works - it performs above operation on every single point of the image.

Again - all the participants that scatter photons around from its true position have no clue if photon is coming from a star or from somewhere else - they will treat it the same.

Perhaps we should be talking about camera-telescope systems.

I will take a moment to send you a crop from a RASA 8 image, given a basic stretch, which includes both stars and detailed nebulosity. It will not be at all difficult for me to find such a crop which shows poor stars and good nebulosity. It won't be tonight: I'm old and tired out!!

lly

14 minutes ago, vlaiv said:

What affects the stars equally affects the nebulosity. Star is just "shape of the blur" affecting the whole image.

No, I do not believe this. I cannot believe it. I spend many hours per week working from linear data and every minute of those hours tells me it is incorrect.

Olly