Blowing out the core of M42

[SDB777]

I see images of M42(Orion nebula) that are well defined in the 'core', and I've done a few different things to get the core back under control....but no matter what I've tried to do, the core is just a blob of solid white, no individual stars.

 

I'm using: Sony a7ii on a Orion ED80 apo riding a iOptron ZEQ25GT

I post-process using: DSS3.3.4, Lightroom CC, PhotoShop CC

I can track to about 7-8 minutes without guiding. I usually set the camera on ISO1600 if the moon is out, ISO400 when it's dark. So.....what can I do to get my cores back?

 

Thanks....looking forward to learning something.

Scott

[wimvb]

How does the core look in a single (unstretched) sub, and in the stacked but unstretched image?. If the core is blow out in these, your exposure is too long. If the core is well defined, you can blend an unstretched image with a stretched one. Blend as layers in PS, with proper masking.

[almcl]

Extending Wim's advice,  a few much shorter subs, stacked and processed, can be layered in Photoshop underneath the burnt out core. If the white in the upper layer is then made transparent so that the  darker layer underneath becomes visible you may get the result you are looking for.

I am very much a non Photoshop user, but there's an example of this in my album here.  Others have done much better and can perhaps advise.

[ollypenrice]

I suggest doing three exposure lengths for this target though you might just get away with two. I used 11 second subs, 50 second and 10 minute ones. Process each to give a final image. Start with the long one and stretch away nice and hard, ignoring the burned out core. Concentrate on a good result in the outer part of the nebula and its dusty surroundings. Keep this handy on the screen for reference later.

Now stretch the mid length subs keeping in mind that, again, you can let the core blow out but you need to 'fill' some of the burned out part of the main image to bring good data further in towards the core. Stretch by eye accordingly.

Repeat the process for the core but this time the Trapezium must not be burned out. You still need to 'fill' all that is burned out in the intermediate image, though.

The best way I know of to combine the threee is explained by Jerry Lodigruss. http://www.astropix.com/HTML/J_DIGIT/LAYMASK.HTM  He's using an earlier Ps but the main difference is that once you have set up your two images and created the layer mask you go to Window -Arrange - New Window for... and this will show you your blend as it stands in real time.

I think it gives a nice result.

Olly

[carastro]

I always follow this tutorial for M42:

http://www.astropix.com/HTML/J_DIGIT/LAYMASK.HTM

Not all the processes work on my PS exactly how it says in the tutorial, but I still get the correct end result. 

HTH

Carole

PS: Ah, just seen this is the same link that Olly has linked to.  Great minds etc.......

[Filroden]

And for those looking for something similar using PixInsight, this is a good tutorial http://www.lightvortexastronomy.com/tutorial-producing-an-hdr-image.html

[ollypenrice]

2 minutes ago, Filroden said:

And for those looking for something similar using PixInsight, this is a good tutorial http://www.lightvortexastronomy.com/tutorial-producing-an-hdr-image.html

Sorry, but for me the final image just screams 'HDR Wavelets.' Following the tutorial down it seemed to be going nicely till the thirteenth screen grab and then, bang, it turns from a picture of M42 into a picture of Pixinsight! Plenty of people won't agree but I'm afraid I just don't like that result myself. I find the Ps appraoch more natural altogether, though I do use both programmes.

Olly

[Filroden]

11 minutes ago, ollypenrice said:

Sorry, but for me the final image just screams 'HDR Wavelets.' Following the tutorial down it seemed to be going nicely till the thirteenth screen grab and then, bang, it turns from a picture of M42 into a picture of Pixinsight! Plenty of people won't agree but I'm afraid I just don't like that result myself. I find the Ps appraoch more natural altogether, though I do use both programmes.

Olly

I agree. I only use the first two sections and process more 'normally' from that point.

[ollypenrice]

3 minutes ago, Filroden said:

I agree. I only use the first two sections and process more 'normally' from that point.

Good call.

 

[newbie alert]

Ive not layer mask yet but have a few core shots of 2 and 4 seconds.ive also found lowering the iso burns it less

[RichLD]

10 hours ago, ollypenrice said:

Sorry, but for me the final image just screams 'HDR Wavelets.' Following the tutorial down it seemed to be going nicely till the thirteenth screen grab and then, bang, it turns from a picture of M42 into a picture of Pixinsight! Plenty of people won't agree but I'm afraid I just don't like that result myself. I find the Ps appraoch more natural altogether, though I do use both programmes.

Olly

I totally agree - I don't tend to find images with an overly compressed dynamic range visually appealing at all. This opinion also applies to music that has been overly "squashed" or limited in the mastering stage, although I know plenty of people who disagree!

[SDB777]

Still collecting data, but this is what I'm dealing with at this time....

 

Thanks for those great links guys, and I'll definitely be reading up on 'em!  With the moon and weekly rain chances here, I'll have time.  But at least I will know what to gather as far as data on my time under the sky.

 

Scott

[bottletopburly]

Startools alternative method of a multi exposure HDR composite ,so as not to blow the core http://forum.startools.org/viewtopic.php?f=7&t=247

[Alpollo]

I might be in the minority here, but IMO the core should look blown out, it's really bright.

There is no right way to do it, other then to follow a artistic consensus.

It would be like photographing somebody welding, if you adjust exposure to see the welding tip, everything else goes dark. If you expose for the whole frame, the arc becomes too bright to see the puddle.  Either of which would be acceptable, kinda natural, IMO. Now if you combine multiple masked shots of different exposures etc., it wouldn't look like the guy is welding any more, he would just be squirting red paste from a handle.

If you post processes so that you can see everything at once, it is an artistic interpretation more then an image, IMO, it depends what you are after. It's not that it's wrong, just that it is not more correct then a blown out core.

IMO M42 is quite dramatic, it has a huge dynamic range, why compress such a unique and "powerful" target.

Find a compromise that shows some faint outer detail being illuminated by this insanely bright arc-light of a core.

 

[ollypenrice]

2 hours ago, Alpollo said:

I might be in the minority here, but IMO the core should look blown out, it's really bright.

There is no right way to do it, other then to follow a artistic consensus.

It would be like photographing somebody welding, if you adjust exposure to see the welding tip, everything else goes dark. If you expose for the whole frame, the arc becomes too bright to see the puddle.  Either of which would be acceptable, kinda natural, IMO. Now if you combine multiple masked shots of different exposures etc., it wouldn't look like the guy is welding any more, he would just be squirting red paste from a handle.

If you post processes so that you can see everything at once, it is an artistic interpretation more then an image, IMO, it depends what you are after. It's not that it's wrong, just that it is not more correct then a blown out core.

IMO M42 is quite dramatic, it has a huge dynamic range, why compress such a unique and "powerful" target.

Find a compromise that shows some faint outer detail being illuminated by this insanely bright arc-light of a core.

 

I understand your point but don't agree with it. Our own natural senses (eyes and ears, at least, since I know nothing about our olfactory biology!) use natural, brain-powered HDR processing all the time.

Here's a picture:

Of what is this a picture? I would say it is a picture of two things. 1) the main body of M42 and the Running Man. 2) the limited dynamic range of my camera. Now quite honestly I have no desire whatever to photograph the limited dynamic range of my camera!!! Give me M42 any day:

Olly

 

 

 

 

[Alpollo]

Yes I generally agree, just I think it is too bright for our senses, if you know what I mean.

If our eyes stop down to see the core such as the second image, the faint outer detail wouldn't be as visible.

In other words, the second picture evokes less dynamic range, as far as the object is concerned.

What I say is more or less meaningless depending on the desired result. I was just trying to think of an analogy, of say a trying to film an airplane adjacent to Sun spots. A tricky proposition either naturally or photographically without multiple exposures.  With combined exposures, the relative brightness of objects is lost, though the results can be beautiful and interesting in their own rights. 

Subjectively speaking, I still prefer the first image. It reminds me more of my views through a telescope, in the sense that the centre bright spot looks like 1 or 2 big white blobs of undefinable light. That is my only frame of reference of course, but it is a visual reference nonetheless.

The second picture is missing the action were the stars are formed. It's one of the main character traits of M42, IMO. It's like a picture of people standing around a camp-fire, but the camp-fire is missing.

I won't lose sleep over processing when it comes time for me to take a serious crack at M42 again. I'll expose to make the core as small as possible until the peripheral starts to dim too much, then stop. That would be sufficient, IMO. There isn't enough to see in the core to worry about it anyway.

The first picture is the best picture and more of a feat in it's own right, compared to the second one.

 

[ollypenrice]

On 03/03/2017 at 20:59, Alpollo said:

 

The first picture is the best picture and more of a feat in it's own right, compared to the second one.

 

More of a feat? It's dead easy! Just expose and let the core blow out. I had to study for months to learn how to do the second one!!!  The last thing I am trying to do as an astrophotographer is replicate the eypiece view. If I want to see galaxies as little fuzzy grey smudges I don't use a camera, I use an eyepiece. I like visual observing but I use a camera to get vastly more information than can be discerned by the eye. That's the whole point - for me, at least.

Olly

[Alpollo]

Fair enough, but I did say many times, it depends what you are after, therefore I certainly cannot say it is incorrect.

The first picture is astrophotgraphy, the second picture is astroimaging.

Though very similar, perhaps overlapping at times, there is a fundamental difference that has been debated forever, so I don't expect to gain any ground here on that debate, though it is worth mentioning.

Artistic depiction vs a visual representation.

Auto-tune singer vs Pavarotii recording.

Webb telescope vs Hubble telescope. 

(Maybe the last one isn't a great example, but since it is filming the IR spectrum, this will have to be depicted in a way that we can see visually, though the Webb would still technically be "photgraphing" )

The fact that you studied for months to do the second image does not translate to the first one being less of a feat. It's almost arbitrary. I could think of many ways to make the first image more difficult, while at the same time others may be able to process the second data set in a fraction of the time with previous experience. They don't even need a camera.

Give yourself some credit.

The first picture is a beautiful photograph if original.

I can only speak for myself, but I won't put a graphic designer on a pedestal under the guise of astrophotgrapher, though that seems to be the trend these days. It's not a fair comparison in either regard..

Now I'm certainly not against all post processing, it is needed to a degree, I do it myself, but I stop short when I feel I am manipulating the data to be subjectively prettier then it is. For me, that would be multiple combined exposures with masks etc. May as well get out the paintbrush at that point, trade the tripod for an easel, paint some flying saucers in there too, now it's interesting!

To reiterate, I don't have a problem with astroimaging at all, I like it too, it's a valid branch of the hobby, just I feel there needs to be a clear distinction between what is a photograph and what is artistic imaging. It's a fairly wide blurry line I'll admit.

Also why do people call a store bought Newtonian telescope on a commercial ALT/AZ mount a Dobsonian?, ... think I'll leave that for another discussion.

Regardless of my persnickety viewpoints, both the contrived image and the photograph are stunning, my hats off to you sir.

[ollypenrice]

16 hours ago, Alpollo said:

Fair enough, but I did say many times, it depends what you are after, therefore I certainly cannot say it is incorrect.

The first picture is astrophotgraphy, the second picture is astroimaging.

Though very similar, perhaps overlapping at times, there is a fundamental difference that has been debated forever, so I don't expect to gain any ground here on that debate, though it is worth mentioning.

Artistic depiction vs a visual representation.

Auto-tune singer vs Pavarotii recording.

Webb telescope vs Hubble telescope. 

(Maybe the last one isn't a great example, but since it is filming the IR spectrum, this will have to be depicted in a way that we can see visually, though the Webb would still technically be "photgraphing" )

The fact that you studied for months to do the second image does not translate to the first one being less of a feat. It's almost arbitrary. I could think of many ways to make the first image more difficult, while at the same time others may be able to process the second data set in a fraction of the time with previous experience. They don't even need a camera.

Give yourself some credit.

The first picture is a beautiful photograph if original.

I can only speak for myself, but I won't put a graphic designer on a pedestal under the guise of astrophotgrapher, though that seems to be the trend these days. It's not a fair comparison in either regard..

Now I'm certainly not against all post processing, it is needed to a degree, I do it myself, but I stop short when I feel I am manipulating the data to be subjectively prettier then it is. For me, that would be multiple combined exposures with masks etc. May as well get out the paintbrush at that point, trade the tripod for an easel, paint some flying saucers in there too, now it's interesting!

To reiterate, I don't have a problem with astroimaging at all, I like it too, it's a valid branch of the hobby, just I feel there needs to be a clear distinction between what is a photograph and what is artistic imaging. It's a fairly wide blurry line I'll admit.

Also why do people call a store bought Newtonian telescope on a commercial ALT/AZ mount a Dobsonian?, ... think I'll leave that for another discussion.

Regardless of my persnickety viewpoints, both the contrived image and the photograph are stunning, my hats off to you sir.

As an English teacher (retired!) I have to say that the astrophotography/astro imaging distinction is a new one on me and I find it deeply unconvincing. Who announced to the world that these were to be defined as you or they suggest?

The technique I used to produce a high dynamic range M42 was a digital one, but it is entirely analogous with the darkroom method used by David Malin to make his photographic plate version of M42. It was in the darkroom that 'unsharp masking' was invented, back in the 1930s A blurred negative copy was used as a mask.

I don't use this technique in search of prettiness. I use it in order to be able to get closer to the truth about an object. M42 does inhabit a dusty wider region. M42 does have a Trapezium of four stars which lie within the resolution of my instrument. M42 does not have a large white blob at its heart!!

I'll assume that, when taking a picture, you don't just use any old exposure setting? You choose one which works for the target. Do you regard this as cheating or just using common sense? I'll assume the latter. When I shot M42 I did the same, but twice. Like this...

And like this:

 

Nobody has 'designed' anything in these pictures. They are just pictures taken with a camera. All I have done is use a digital equivalent of an eighty year old darkroom technique to combine them.

In time to come I don't doubt that cameras with sufficient dynamic range will appear and be able to do this in one go but, for now, the photographer has to do it in his digital dark room.

I'm always intrigued by discussions like this because they often seem to be predicated on the idea that the camera is a giver of some kind of 'truth.' The only truth it delivers is the truth about what it will and will not do with the light that goes into it. This sometimes has very little to do with the truth about what is out there. (No white blob lies at the heart of M42...)

Olly

 

 

[Alpollo]

4 hours ago, ollypenrice said:

 

Quote

 

As an English teacher (retired!) I have to say that the astrophotography/astro imaging distinction is a new one on me and I find it deeply unconvincing. Who announced to the world that these were to be defined as you or they suggest?"

It has been debated long before digital cameras were available. It is more of an observation of photography vs design throughout history rather then my opinion specifically.

"The technique I used to produce a high dynamic range M42 was a digital one, but it is entirely analogous with the darkroom method used by David Malin to make his photographic plate version of M42. It was in the darkroom that 'unsharp masking' was invented, back in the 1930s A blurred negative copy was used as a mask.

I don't use this technique in search of prettiness. I use it in order to be able to get closer to the truth about an object. M42 does inhabit a dusty wider region. M42 does have a Trapezium of four stars which lie within the resolution of my instrument. M42 does not have a large white blob at its heart!!

 

Hi Olly.

Yes you like imaging, that is wonderful. Nothing wrong with that.

I too will hopefully be a good imager one day, but first I need to work on fundamental photography and data collecting before I invest the time and money into the software venturing into imaging.

If may bring up the analogy again of a daytime comparison.

If I take a reasonably exposed photograph of a family BBQ at the beach, would I expect to see sunspots? If I presented that to a photographer stating it was a superior photograph, would it be unreasonable for said photographer to be upset?

I don't care either way because I know the distinction, I'm not in either camp since I like both imaging and photography. 

 

Quote

I'll assume that, when taking a picture, you don't just use any old exposure setting? You choose one which works for the target. Do you regard this as cheating or just using common sense? I'll assume the latter. When I shot M42 I did the same, but twice. Like this...

Well adjusting exposer is centric to the human response.  That is why I can't ever see sunspots with the naked eye or look at the bead from a arc welder.

 

Quote

Nobody has 'designed' anything in these pictures. They are just pictures taken with a camera. All I have done is use a digital equivalent of an eighty year old darkroom technique to combine them.

That is debatable.

Quote

In time to come I don't doubt that cameras with sufficient dynamic range will appear and be able to do this in one go but, for now, the photographer has to do it in his digital dark room.

It is not the camera, it's the human. The human cannot see the central stars and the outskirts at the same time. 

Your camera is doing a pretty good job at taking photographs showing what M42 would look like at various iris dilations or simulated physical distance.(Image scale) Depending on where we concentrated our vision, our exposure would settle somewhere between your two examples I suspect.

Quote

I'm always intrigued by discussions like this because they often seem to be predicated on the idea that the camera is a giver of some kind of 'truth.' The only truth it delivers is the truth about what it will and will not do with the light that goes into it. This sometimes has very little to do with the truth about what is out there. (No white blob lies at the heart of M42...)

Not at all, a camera is just a tool that has limitations, how it is operated is the distinction.

I'm not a hardcore photographer, but I suspect that if I photo-shoped a picture then flaunted it at some random shutterbug forum, they would lose their [removed word]. As I say, it's my observation not my opinion. The converse would also be true, a photograph would rarely be accepted as a superior oil painting at an abstract painting forum.

It is amusing. I myself know that it is a silly distinction at times.  Even with my  "long exposures", technically the target has morphed or moved to some faint degree, so even my images are contrived. I just chalk it up to not having a fast enough lens or shutter speed hence it's just a poor photograph again, rather then a depiction or a collection of data plotted to represent something for scientific purposes.

The dictionary definition of "photograph", the term "made visible and permanent" is used, not enhanced or altered. A good lawyer would say this excludes combining negatives. It is the human-centric context that a photograph attempts to reproduce. Everything else is just data plotted to represent something for some specific scientific, inquisitive purpose.

So while it's semantics most of the time, the word "photograph" already exists with a specific context, I think it's worth preserving the distinction, if not then Cartoons and would also fall into the category of photography.

"Motion Picture" used to be a real distinct thing, that has since been homogenized into a category with Pixar digital cartoons, now called "movies", which used to be categorized under "cinema" or cinematography which is an art form.

So if someone asked how to make a good movie, do they pick up a camera?, paint brush?, maybe  a computer?  Then you would have to sort it all out because they won't be able to film "Finding Nemo" with a camera. Finding Nemo is based on a real thing, it has data collected by filming real clownfish, but the result is a series of images, not photographs.

A photograph is not to be underestimated for the emotional, intimate connection it may provide to the viewer of the subject. IMO a bad photograph still feels more "real" then enhanced images. They are "genuine".

[AKB]

7 minutes ago, Alpollo said:

It is not the camera, it's the human. The human cannot see the central stars and the outskirts at the same time.

Does this mean that I'm not allowed to wear corrective lenses to improve my vision?

 

[Alpollo]

Sorry for the confusion AKB,  I'm talking in levels of luminance.

If your eye stops down to expose the core, it won't show the perimeter details as well.

Assuming you have tried to look at the sun, you may be aware of the physical limitations of stopping down on such a target. It's always going to be a blazing ~5500K white ball of fury at high noon with the naked eye.

Say you were being presented something as a photograph, wouldn't you want it to be a photograph?, not an image of how someone feels you should view it?  Wouldn't it be disheartening in some situations outside of astro? Are photographs no longer required for a drivers license where you live?  They might not be high resolution images but you aren't allowed to alter them, a third party needs to be able to ID you with it. Not an image that you applied a negative over of when you still had hair.

There are many valid contexts for photographs that are independent of quality to a degree. It's not just the resolution etc., it's letting the chips fall where they may that qualifies a "photograph".

I know when I was starting out, not that long ago, it was very annoying when trying to learn on google how to do astrophotography with my gear, I wanted to learn how take a picture. I would then have  to sort through what was "real" albeit stacked and stretched images, and what were pictures that required speciality equipment, techniques and extended software processes.  Did I really want to get into a hobby that required that much heavy photshopping? Fortunately it's not that bad, I tried it out, you can enjoy your own crappy photographs all the same while you learn how to image and use PI or photoshop.

I'm certainly no expert, but I can tell you the guys with the best Pixinsght images are probably the best photographers, experts of photon gathering. The chicken is the egg.

[AKB]

28 minutes ago, Alpollo said:

I'm talking in levels of luminance.

Ah, the number of photons.  Yes, got you, our eyes have their limitations.

...so what about energy of the photons, that is to say, their colour?    Is an IR image valid for you, or not?

[Alpollo]

2 hours ago, AKB said:

Ah, the number of photons.  Yes, got you, our eyes have their limitations.

...so what about energy of the photons, that is to say, their colour?    Is an IR image valid for you, or not?

Hi AKB, good example.

A IR image is valid, an IR photograph is invalid, because I can't see infrared.

Who is to say IR is actually "red"? Designating any visible colour to infrared or the ultraviolet spectrum would be valid for imaging purposes. It would be like applying a colour to a FM radio broadcast. What colour is FM? It's not any of the colours we can see so you'll have to choose one.

Is colour really real? Would an alien recognise a red light as "red"?, or would their evolution have applied a different colour to red? That I don't know, maybe they can't even see the "visible" spectrum. Maybe we can't find aliens because we can't see them? Quite possible. Sound crazy?, well it's certainly more plausible then the "big bang" nonsense going around.

Herschal ran into this problem in 1800, he wanted to know what colour the "heat" from the sun was. 30 years later, Ampere figured out that heat was in fact light, just a different wavelength. Maxwell penned it to paper in the 1860s but IR spectroscopy never really took off until the early 1900s. While a X,Y plot of absorption frequencies is not much to look at, it is just as valid of an "image" as the geometric IR plots that we expect from the James Webb telescope in the near future.

[ollypenrice]

We come back again to the idea of a photograph which tells the truth. Some kind of primordial innocence before anyone invented Photoshop. No such photograph has ever existed. The world in the 19th centrury was not sepia coloured. The world in the first half of the 20th centrury was not greyscale. The colours recorded by colour film are not 'natural.' They are as they are because armies of chemists have made decisions about the colours that will appear on their transparencies and papers. The geometry of a portrait, the spacial distribution of the features, is as it is because opticians have made decisions about field curvature. Two lenses will produce two geometries. That which is in focus and not in focus arises from decisions made by the photographer. My point is that a camera is a machine made by human beings who have, in constructing it, made thousands of decisions which dictate the nature of the final picture. There is no fundamental truth in any of this. No 'intervention-free' photograph. We even have to learn to read photographs. People who have never seen them before do not recognize photographs as representations, though they can soon learn to do so. There is no natural camera, nor will there ever be. The only true portrait would be three dimensional because the orignal is three dimensional. Maps of the world - Peter's Projection or Mercator?

The work we do in asto image processing is not like adding hair to a bald head. We are trying to extract what is buried deep in the data. There is (there really is) a tidal tail emanating from NGC3628. It will not be seen in a linear capture. It will not be seen clealy unless it is carefully and specifically stretched. But it is there. Nobody invented it and it looks pretty similar in different people's renditions. I'm into this game because I find it thrilling to discover that there is usually something in my captures that I had not expected to find.

Olly