Capturing faint details on the veil Nebula - Forums

Hello,

First of all, it is really amazing to see so many people doing such a cool hobby! Very important to keep the motivation going

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I was recently in la Palma, Spain where the skies are Bortle 1-2. I have a Redcat 51 with a Canon 1100d (Full spectrum with L2 luminance from Astronomik).
The following picture of the veil nebula has an integration of almost 5h with 2min sub-exposures and calibration frames (darks, flats, and bias): https://www.astrobin.com/7r7fuh/

IMO I was expecting to pull more details from the faint areas with such high-quality sky and "long" integration time. Especially left from the Pickering's Triangle[b].[/b] So I wonder the following:

- I have an L-extreme but didn't use it since it was such a dark sky. Would it have been better to use it?
- Could it be related to high noise on the subs due to long exposures on an uncooled DSLR? Meaning a dedicated camera would have made the difference?
- Maybe I suck at processing?

If there is a similar topic where this has been discussed, I'd be happy if you could point me in the right direction

Thank you in advance for your help

I think you did very well for the integration time you have. I don't image with a DSLR any more but when I did I would have been using closer to 300s subs and probably double or more your total integration time. The filter will help isolate and improve SNR on the nebulosity you are trying to bring out but will likely require even more integration time. The high noise I found typical of DSLR imaging especially on warm summer nights. For me that was what kept my sub exposures shorter on warm nights but they were never less than 180s or so on dim nebula. Again more total integration time will help smooth that out. Someone familiar with your camera may have some suggestions for settings that may produce less noise.
CS
Jeff

Jeff Reitzel:
I think you did very well for the integration time you have. I don't image with a DSLR any more but when I did I would have been using closer to 300s subs and probably double or more your total integration time. The filter will help isolate and improve SNR on the nebulosity you are trying to bring out but will likely require even more integration time. The high noise I found typical of DSLR imaging especially on warm summer nights. For me that was what kept my sub exposures shorter on warm nights but they were never less than 180s or so on dim nebula. Again more total integration time will help smooth that out. Someone familiar with your camera may have some suggestions for settings that may produce less noise.
CS
Jeff

Thanks for your answer! I had a feeling it was the limitation of the camera. I just thought with high-quality skies and reasonable integration it might be ok. The last time I tried the veil was with half the integration time and an unmodded camera and ofc fewer details popped up.
I get what you mean. I was surprised by the amount of noise it gets at 25C ambient temperature. I am used to shooting in Norway during the winter at -5 or less

I just finished a mosaic of the "batwing" portion of the Veil Nebula (https://www.astrobin.com/515gko/). The resolution of the system was 0.59 arcsec/pixel, and I think the image shows very good detail even though the subs were only one minute long (ASI1600MM). The total exposure was about 6 hours. The scope was a 10" reflector with a focal length of 1325mm. Could it be that your system does not have the resolving power to show the level of detail you are expecting?

George

George Hatfield:
I just finished a mosaic of the "batwing" portion of the Veil Nebula (https://www.astrobin.com/515gko/). The resolution of the system was 0.59 arcsec/pixel, and I think the image shows very good detail even though the subs were only one minute long (ASI1600MM). The total exposure was about 6 hours. The scope was a 10" reflector with a focal length of 1325mm. Could it be that your system does not have the resolving power to show the level of detail you are expecting?

George

Your picture just looks insanely cool! In my case, I am aware it is quite undersampled at 4.2arcsec/pixel which is a good point on bringing up detail. I am considering getting an ASI183 MC Pro which seems to fit well with a RedCat 51.
However, I guess I am not far off your image total integration time taking into account that a Redcat 51 is pretty fast at f/4.9 so I guess a dedicated camera would have made a difference.

Borja Serra:
George Hatfield:
I just finished a mosaic of the "batwing" portion of the Veil Nebula (https://www.astrobin.com/515gko/). The resolution of the system was 0.59 arcsec/pixel, and I think the image shows very good detail even though the subs were only one minute long (ASI1600MM). The total exposure was about 6 hours. The scope was a 10" reflector with a focal length of 1325mm. Could it be that your system does not have the resolving power to show the level of detail you are expecting?

George

Your picture just looks insanely cool! In my case, I am aware it is quite undersampled at 4.2arcsec/pixel which is a good point on bringing up detail. I am considering getting an ASI183 MC Pro which seems to fit well with a RedCat 51.
However, I guess I am not far off your image total integration time taking into account that a Redcat 51 is pretty fast at f/4.9 so I guess a dedicated camera would have made a difference.

Just agreeing with and somewhat amplifying the point that George makes. The fundamental problem is really the short focal length of the redcat 51. It is great for wide vista images but not so good if you want to resolve close in detail of some feature or another. As you say it will indeed help to use a camera with smaller pixels (2.4 um for the ASI183) but even then at f = 250 mm the image scale will still be above 2 arcsec/ pixel - so still undersampled for resolving finer detail at the sub 3 arcsec level . Also this level of extra detail possible at lower pixel sizes won't come for free since to get the same SNR as ypu have currently at twice the resolution will require ~ 4X the imaging time.

You do have one advantage over George's setup though. Your picture shows the whole object in one go whereas using the long focus instrument it has taken a mosaic to cover even a part of it.

Tim

Hello, I think your photo is an excellent starting point. Having a dark sky will allow you to capture more details. My first advice is to consider, when you can, the purchase of a dedicated cooled astronomical camera. This, besides increasing efficiency, will enable you to cool the camera and better calibrate your images. Looking at your photo, I see a blurring effect, perhaps due to an excessive use of denoise? There are various algorithms to reduce noise in post-production. I recommend you to explore this aspect further and also consider using masks, which allow you to preserve details even when applying noise reduction to other parts of the photo. Clear nights.

Thank you all for your answers! I guess I will have to buy a dedicated astronomy camera😅, preferably with smaller pixels if I want to combine it with the Redcat.

Borja Serra:
However, I guess I am not far off your image total integration time taking into account that a Redcat 51 is pretty fast at f/4.9 so I guess a dedicated camera would have made a difference.

You have received a lot of good advice. But you should know that there is a massive difference between your image and George's. George is using a 10" reflector. When you examine your image and his image at the same viewing scale (meaning features occupy the same size on your screen), it is not the f number that matters but the aperture. So, for every arc second of object, George is capturing 25 times the light that you are from each part of the object both of you are recording. To get the same SNR from the same size feature, you would need 25 times the integration time. Your advantage is that you are capturing a larger field. His advantage is that he is capturing far more light. Your advantage disappears completely when you blow up your image to be the same size as his and compare a common feature.

Yes, we are definitely comparing "apples and oranges" when comparing the two images. On the one hand, we have a large reflector (254 mm), and on the other, a small refractor (51mm). But the differences do not stop there... the reflector has a focal length of 1325mm, while the refractor is only 250mm... a factor of 5. The cameras are also very different in that one is cooled while the DSLR is not. This could be a problem, especially in the summer. I speak from experience! The pixel size of each camera also differs but is close, with the DSLR at 5.2 microns and the ASI1600MM at 3.8. And the astro camera is mono, while the DSLR is OSC. Both images were taken under relatively dark skies. The integration time was similar. So what is the single factor that accounts for the difference in detail in the two images? I would say focal length. It is the one factor that cannot be changed by sky darkness or integration time, or even a better camera. To get more detail, a scope with longer focal length is needed. True?

George

Borja,

the DSLR you use is more than 12 year old and has a quantum efficiency of only 35%.

This is no match for a modern dedicated astro camera.

CS
Chris

Thanks for the explanations. I agree with you both. As you mention George, both images are night and day and hard to compare due to all differences in setup, especially in your favor hehe. I think I was too hooked on the concept of the focal ratio and integration time as a rough "way to compare" similar images. What
@Arun H says regarding the aperture makes sense and it is something I was not paying attention to since focal ratio was what I was focusing on mainly.
But yea, I think I understood that my setup is limited and needs longer integration time if I want to reach a higher level of detail.

Christian Koll:
Borja,

the DSLR you use is more than 12 year old and has a quantum efficiency of only 35%.

This is no match for a modern dedicated astro camera.

CS
Chris

Haha yes, I am also aware of my camera is quite old. I am pretty new on the hobby and wanted to see how far I could push it before buying a dedicated one.

Borja,
I also shoot a redcat 51 and recently switched from a Nikon d5100 to an ASI533mc pro. In doing so I went from 3.96 "/pix to 3.1"/pix.
I'm extremely happy with the change and I'm accepting the sensor size puts me into mosaic territory. It was a leap and the conversations to get it through the "budget office" were touch and go but you'll be happy with the results. Also, ZWO makes it very easy to swap from DSLR to their dedicated cameras.
I have been dragging my feet on uploading a better image of my Orion Nebula shot but it was taken with the DSLR and the Andromeda shot of mine was the 533, in case you want to compare.
I'll work on that today and maybe message when I've uploaded if you're interested.
cheers, CS,
Astro

Astro:
Borja,
I also shoot a redcat 51 and recently switched from a Nikon d5100 to an ASI533mc pro. In doing so I went from 3.96 "/pix to 3.1"/pix.
I'm extremely happy with the change and I'm accepting the sensor size puts me into mosaic territory. It was a leap and the conversations to get it through the "budget office" were touch and go but you'll be happy with the results. Also, ZWO makes it very easy to swap from DSLR to their dedicated cameras.
I have been dragging my feet on uploading a better image of my Orion Nebula shot but it was taken with the DSLR and the Andromeda shot of mine was the 533, in case you want to compare.
I'll work on that today and maybe message when I've uploaded if you're interested.
cheers, CS,
Astro

Please do! It would be interesting to see the change! Thanks for the input🙂

Very similar experience, Borja. My first attempt at the Veil was disappointing. I was using my Canon Ra, which is designed for astrophotography. However, the lens I used was a stock lens and really distorted the stars in the form of chromatic aberration. In addition, the Ra is not cooled so initially there was quite a bit of noise. That, combined the preponderance of stars in the field, washed out much of the detail in the nebula. Even removing the noise and cleaning up the image with darks, flats and bias frame could not bring out the detail I was looking for. I really wanted a wide field of view to get the entire nebula framed so I ordered and received my new W.O. Redcat 71. First light of that scope, combined with my ZWO 2400MC-Pro, produced the crisp images you see on my astrobin page after applying Bill Blanchan's Star Reduction and Star Removal processes in Pixnsight. The difference was astonishing. Even with cropping different areas and enlarging them, this imaging train retained much of the detail and sharpness of the wide field image. My lesson learned: Invest in high quality equipment. In the long run, you'll save money and avoid a lot of frustration. Keep at it and remember…..progress, not perfection!

Patrick

I didn't realize how old the DSLR was. I looked at some other wide-field images of the Veil, and many show much better detail. Also, the image in question is just a bit out of focus when viewed at 100%, which does not help.

I agree that a new camera would do wonders for Borja's images. I used a Canan 6D for years and this year switched to an ASI533MC OSC camera. It is an amazing camera in spite of its small sensor. The noise is so low I have been tempted to do without darks (but didn't). It, combined with the ASIAIRplus, makes everything so easy, from polar alignment to finding a target and getting it centered just right.

But after spending the summer processing images from others (no imaging for me this far north), and mostly from mono cameras, I am ready to make the jump to mono. I really think the image quality is better. But admittedly, this is a subjective judgment with many variables affecting the final image.

George

I would love to have been able to shoot from those skies! Anyway, echoing others, the camera is a big factor. This is mine using the RedCat 51, a 2600MC-P, and NBZ filter, under Bortle 6/7 skies: https://www.astrobin.com/f7ffn0/ I also have a bit over 10 hours of capture time as well, though that is mainly due to my Bortle. I started with a regular DSLR, then quickly moved to a modified camera. I wasn't with that for all that long before I got tired of fighting the noise and sensor temps and moved on to the ZWO 533MC-P. I was (still am) quite happy with that camera. Long story short - start looking at a dedicated astro camera. You will be happy you did.

George Hatfield:
would say focal length. It is the one factor that cannot be changed by sky darkness or integration time, or even a better camera. To get more detail, a scope with longer focal length is needed. True?

The diffraction limited angular resolution of a perfect lens or scope (its ability to separate two objects a certain angular distance apart) is determined by its absolute aperture and not its f number or focal length. In other words, if you have two telescopes, with same focal lengths but differing apertures, the larger aperture scope will show better angular resolution. If you had a 51mm scope and a 254 mm scope, both with 1325mm focal length, the 254mm aperture scope would have superior resolving power.

I forgot to put in my previous post: using the Optolong L-Enhance filter helped, too as I was imaging from Bortle 6 skies.

Patrick

Astro:
Borja,
I also shoot a redcat 51 and recently switched from a Nikon d5100 to an ASI533mc pro. In doing so I went from 3.96 "/pix to 3.1"/pix.
I'm extremely happy with the change and I'm accepting the sensor size puts me into mosaic territory. It was a leap and the conversations to get it through the "budget office" were touch and go but you'll be happy with the results. Also, ZWO makes it very easy to swap from DSLR to their dedicated cameras.
I have been dragging my feet on uploading a better image of my Orion Nebula shot but it was taken with the DSLR and the Andromeda shot of mine was the 533, in case you want to compare.
I'll work on that today and maybe message when I've uploaded if you're interested.
cheers, CS,
Astro

Seems in the process of moving from a borrowed PC using DSS and Photoshop to my Mac with PI+RCAstro I've misplaced my originals.
sorry about that Borja, turns out I can't be of much help after all.
The transition to a dedicated camera however (IMO) was money well spent. I might pull the DSLR out this winter and do a side by side with the ZWO so keep an eye out.
good luck and CS,
Astro

Well, I can I think. I have an image taken last year, my first with a telescope and a goto mount, of the Veil using equipment somewhat close to yours and an image I am currently working on shot with the same scope and mount but a much better camera.

This first image was shot with my SharpStar 76EDPH reduced to a focal length of 342mm and f/4.5. I used my modified Sony A7R which has 4.88 um pixels and is a little newer than your camera but still about 9 years old and uncooled. The mount is the lowly EQM-35 and this shot is unguided with short 60s subs. Total integration is 5h 40m from my bortle 5/6 backyard. I used a Optolong UHC filter which is pretty wide but not as wide as a UV/IR. This is a re-edit about 6 months after the original data was collected.

This second image is a quick test edit of the veil that I am currently working on. This shot uses the same scope, reducer and mount but adds guiding and is shot with my QHY 294M in bin1 mode (2.36um pixels) using ZWO 7nm Ha and Oiii filters. The location was the same. This is a quick test edit of 4hr 35m of total data about equally split between Ha and Oiii. Not a careful edit and I intend on at least doubling the integration and adding 2 more panels and taking RGB stars.

You can see an incredible difference in detail and it is even more startling when viewed at the native resolution. Natively this crop is 37mp and well resolved to 100% viewing. I think it needs more integration and more time spent carefully editing it but I am happy with the project so far. Of course my scope is a little bigger and has some more focal length but it's not light years away like a 10" Newt is. I am also comparing an OSC DSLR to a cooled mono camera with narrow band filters which is worlds apart, but that is the point. How much can the camera change the result. I wish I had a 183 or similar to show you but I made the jump from my 2 uncooled SLR's straight to mono. I didn't see the point in spending money on OSC Astro cameras. If you want I can post some 100% crops of the mono channels to really show the detail.

Hello!
A suggestion for improving the present image: it might help to significantly reduce the brightness of the stars in post-processing, because they cover the fine structures of the delicate veil.

These two images have the same source material.

https://www.astrobin.com/uez27k/B/#r0

https://www.astrobin.com/uez27k/B/#rB

Best regards!

Markus Gorski:
Hello!
A suggestion for improving the present image: it might help to significantly reduce the brightness of the stars in post-processing, because they cover the fine structures of the delicate veil.

These two images have the same source material.

https://www.astrobin.com/uez27k/B/#r0

https://www.astrobin.com/uez27k/B/#rB

Best regards!

I agree, the fastest way to bring out more detail in the collected data is to reduce the stars. If you stretch the stars along with the object, the stars often appear too bright and distract from the object itself.

If you use PixInsight, I would recommend using StarNet (or equivalent) to separate the stars and the object before any additional processing (stretching, saturation, etc.) I believe StarXTerminator is available in Photoshop but you'll have to buy it. You can then stretch the stars seperately and apply star reduction techniques.

An image of the same object I did a few weeks ago for reference: https://www.astrobin.com/full/fkczl1/B/

Daniel

All great advice!
speaking of old cameras, I use an og Canon 6D. Pixel size is 6.54 microns,full well capacity of 74K e-, and 46% QE. not great by today's Astro cam standards, but I enjoy the challenge.
Here is the same shot taken with the 6D using a duo band filter and a 300mm focal length at f2.8. 15 hours integration.

Cygnus Loop Veil Nebula Complex
All solid advice above. More integration time really helped reduce noise, as well as removing stars before processing.