20 replies to this topic

[ghostlight]

I have used my S50 in a Bortle 7-8 with good results. I haven’t had a chance to get into a lower bortle rating and wonder if anyone has had a chance to compare results.

Can’t attach picture as it was rejected due to size. 

Thanks for any input

[Astronotrip]

I don t have pics to compare but there is a huge difference, especially if you start to get in Bortle 1-2 Vs 6-8

[Jethro7]

I have used my S50 in a Bortle 7-8 with good results. I haven’t had a chance to get into a lower bortle rating and wonder if anyone has had a chance to compare results.

Can’t attach picture as it was rejected due to size. 

Thanks for any input

Hello ghostlight,

The darker the skies the better, with one exception, when viewing the Moon and bright planets that benefit from a little light pollution. 

 

HAPPY SKIES AND KEEP LOOKING UP Jethro

Edited by Jethro7, 09 June 2025 - 02:33 PM.

[jprideaux]

For DSO, I find that it takes me about 3 times as long in bottle 7 to get something at about the same quality in bottle 3.5. So I experience one hour in bortle 3.5 is about equal to around 3 hours in bortle 7.

[marvindj]

For DSO, I find that it takes me about 3 times as long in bottle 7 to get something at about the same quality in bottle 3.5. So I experience one hour in bortle 3.5 is about equal to around 3 hours in bortle 7.

Some knowledgeable person had posted the amount of time required to get the same Signal/Noise ratio as a Bortle 1 sight for a given image. The graph showed that it takes 45x longer to get the same SNR in a Bortle 8 area compared to a Bortle 1. I can't seem to find the post with the graph. An eye opener (I'm in Bortle 8).... 

[ghostlight]

Thanks for the replies. I now have a better understanding of the time needed to achieve the same results in different Bortle zones.

[buramu]

That's interesting. That explains why some can get such impressive results (even straight out of the scope) in an hour and I often need 10+ hours on the same target to get anywhere close.

[BrickInTheSky]

Some knowledgeable person had posted the amount of time required to get the same Signal/Noise ratio as a Bortle 1 sight for a given image. The graph showed that it takes 45x longer to get the same SNR in a Bortle 8 area compared to a Bortle 1. I can't seem to find the post with the graph. An eye opener (I'm in Bortle 8).... 

this one? This chart does NOT say it takes 45x more but of course it takes longer….

Attached Thumbnails

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[marvindj]

this one? This chart does NOT say it takes 45x more but of course it takes longer….

No. This post:

 

https://www.cloudyni...4#entry14150479

[BrickInTheSky]

No. This post:

 

https://www.cloudyni...4#entry14150479

I am sorry but I have trouble to believe this chart. Not sure about its source but 1st of all I do not believe that you can archive same level from zone 8 as from zone 1 no matter how long you image (assuming zone 1 spent some decent time of at least few hours). Even 45 times that will not do the trick. 
 

the chart I listed above (colorful one) a bit more believable. Although I do not know the source of the data either but it shows that 1)you cannot get same results. From the zone 8 you can get as high as 80% of zone 1 (assuming zone 1 gives the 100% quality).  From zone 3 you need 2500 images to get to  ‘good results’ while from zone 8 you need almost double of that (4000) and after that doing additional images will not help much….

 

happy to hear your thoughts 

Edited by BrickInTheSky, 10 June 2025 - 04:13 PM.

[James Peirce]

I am sorry but I have trouble to believe this chart. Not sure about its source but 1st of all I do not believe that you can archive same level from zone 8 as from zone 1 no matter how long you image (assuming zone 1 spent some decent time of at least few hours). Even 45 times that will not do the trick. 
 

the chart I listed above (colorful one) a bit more believable. Although I do not know the source of the data either but it shows that 1)you cannot get same results. From the zone 8 you can get as high as 80% of zone 1 (assuming zone 1 gives the 100% quality).  From zone 3 you need 2500 images to get to  ‘good results’ while from zone 8 you need almost double of that (4000) and after that doing additional images will not help much….

 

happy to hear your thoughts 

It’s probably hard to break down into a S/N comparison in a reliable way anyhow. You can get some nice, clean detail and signal on bright targets under a higher Bortle, but as details get fainter, and become more and more buried underneath the ambient glow of the light pollution, it gets increasingly harder to bring it out meaningfully relative to exposure time. Even with meticulous calibration, normalization, excellent background removal, or even when using a tool like Mulitiscale Gradient Correction (which helps).

 

You can get data in a night under Bortle 1-3ish that would be hard to outdo with a month of shooting under Bortle 8 in terms of fainter structure, but the same wouldn’t be true of trying to resolve beautiful detail in the brighter regions of Orion.

 

S/N can tell a lot of the story, but breaking it down into a formula doesn’t do a very good job of describing a host of additional variables (e.g. dramatic variation in light gradients across exposures, especially where those gradients are non-linear) that end up adding additional complexity when the desirable signal is a very small fraction of skyglow that appears in every individual exposure.

 

I do believe the numbers are painfully large in comparison, though. It bears out with my own tests of Bortle 2-4 vs Bortle 8. Even in narrowband Hα, the value of data under Bortle 3 is considerably greater than the same setup under Bortle 8. And even this comparison, which is probably the most favorable for imaging under light pollution, ends up being quite a bit more than 3x.

[BrickInTheSky]

It’s probably hard to break down into a S/N comparison in a reliable way anyhow. You can get some nice, clean detail and signal on bright targets under a higher Bortle, but as details get fainter, and become more and more buried underneath the ambient glow of the light pollution, it gets increasingly harder to bring it out meaningfully relative to exposure time. Even with meticulous calibration, normalization, excellent background removal, or even when using a tool like Mulitiscale Gradient Correction (which helps).

You can get data in a night under Bortle 1-3ish that would be hard to outdo with a month of shooting under Bortle 8 in terms of fainter structure, but the same wouldn’t be true of trying to resolve beautiful detail in the brighter regions of Orion.

S/N can tell a lot of the story, but breaking it down into a formula doesn’t do a very good job of describing a host of additional variables (e.g. dramatic variation in light gradients across exposures, especially where those gradients are non-linear) that end up adding additional complexity when the desirable signal is a very small fraction of skyglow that appears in every individual exposure.

I do believe the numbers are painfully large in comparison, though. It bears out with my own tests of Bortle 2-4 vs Bortle 8. Even in narrowband Hα, the value of data under Bortle 3 is considerably greater than the same setup under Bortle 8. And even this comparison, which is probably the most favorable for imaging under light pollution, ends up being quite a bit more than 3x.

Precisely. The colorful chart does not show bortle 1-2 but starts with 3. But we can extrapolate that for lowest zones 1-2 it may take about 1000 images to get to the ‘best’ results while in the highest zone 8, after 4x of that you will reach the plateau at just above 80% and to get better results you need better skies and not more photos.

[James Peirce]

Precisely. The colorful chart does not show bortle 1-2 but starts with 3. But we can extrapolate that for lowest zones 1-2 it may take about 1000 images to get to the ‘best’ results while in the highest zone 8, after 4x of that you will reach the plateau at just above 80% and to get better results you need better skies and not more photos.

For my part, I don’t know how I’d extrapolate things into a number like 80%. It’s a tricky thing to nail down because the impact this has on an image, from the perspective of someone working with the data, is going to be pretty subjective. It’s a massive pain point for something like the Squid (Ou4) or bringing out other very faint nebulae, and especially for bringing up faint broadband signal, but much less so for the structure most of us focus on in our astrophotography.

 

So it seems like a question of... 80% of what?

 

That kind of ties back to breaking this down into a single measure of something like S/N. That’s not going to tell a complete story of how well faint structure is going to be resolved over those exposures because there ends up being so many more variables involved than just applying a S/N formula against some amount of skyglow which is assumed to be constant, and the result is going to impact different parts of an image in dramatically different ways.

 

The difference between Bortle 1-3 in terms of impact on imaging is pretty small compared to the larger Bortle levels. For my part, imaging under Bortle 2 hasn’t made a dramatic difference vs imaging at a low Bortle 4, but the difference between these and Bortle 6 is dramatic, and then again so to Bortle 7-8.

[jprideaux]

Bottom line, find a darker site and make plans to visit it from time to time. I have an hour-away site bortle 3.5) I go once every new moon (weather permitting) that is quite a bit darker than my home location (bortle 7). I try to do all my galaxy imaging at the darker site and tend to do only narrow-band emission nebula from my home location.

[marvindj]

I am sorry but I have trouble to believe this chart. Not sure about its source but 1st of all I do not believe that you can archive same level from zone 8 as from zone 1 no matter how long you image (assuming zone 1 spent some decent time of at least few hours). Even 45 times that will not do the trick. 
 

the chart I listed above (colorful one) a bit more believable. Although I do not know the source of the data either but it shows that 1)you cannot get same results. From the zone 8 you can get as high as 80% of zone 1 (assuming zone 1 gives the 100% quality).  From zone 3 you need 2500 images to get to  ‘good results’ while from zone 8 you need almost double of that (4000) and after that doing additional images will not help much….

 

happy to hear your thoughts 

That's completely fine. You could well be correct.

I'm no expert in any of this. I simply read various fora/threads and put together "best practices" based on input from people far more knowledgeable than myself. Another example, 20 second exposures was determined by someone to be the optimal setting for the S50. I just go with that information. 

[CraigR]

If it were possible to get the same images from Bortle 8-9 as from Bortle 1-2, we'd put JWST in my backyard instead of at L2. We'd save money and it would annoy the neighbors, so win-win.

 

Give serious consideration to sending your S50 to Starfront Remote Observatory in Texas if you want to get the best results. There is a growing number of Seestar owners hosted there now — probably 20-25. You've got 220 nights per year of clear Bortle 1 skies. About 15 minutes after you're set up and calibrated you'll have better data than your last 2 hours at home. :-)

[BrickInTheSky]

If it were possible to get the same images from Bortle 8-9 as from Bortle 1-2, we'd put JWST in my backyard instead of at L2. We'd save money and it would annoy the neighbors, so win-win.

Give serious consideration to sending your S50 to Starfront Remote Observatory in Texas if you want to get the best results. There is a growing number of Seestar owners hosted there now — probably 20-25. You've got 220 nights per year of clear Bortle 1 skies. About 15 minutes after you're set up and calibrated you'll have better data than your last 2 hours at home. :-)

Yea but maybe it is just me but I like the whole process of handling the scope, cleaning the lenses, making sure it sits right, etc. Maybe eventually I will ‘graduate’ to the idea of a remote scope and start chasing absolute best skies but for now I am staying at my backyard:-)

[Stevan Klaas]

The very rough calculation for integration time “multiplier” is 2.5^(mag2-mag1). Then many videos and posts of seasoned astrophotographers give much more color to it below.

 

There are also different tools to calculate SNR, Sharpcap or this one:

 

https://deepskydetai.../Calculate_SNR/

 

But long story short, the fainter the object, the less likely it is that a light polluted sky will ever reveal details, no matter how much integration time you dedicate. And nothing is that simple as a formula for the whole image, brighter areas do not benefit as much as fainter ones.

 

This youtuber has very nice videos:

 

https://youtu.be/OA8...VRqMiSk_Xbv8O6R

 

https://youtu.be/kiU...e-HCZtebpkQ45_v

 

 

This is a good CN post :

 

https://www.cloudyni...-skies-for-snr/

 

With a good article as well:

 

https://jonrista.com...phy-basics/snr/

 

Another post:

https://www.cloudyni...tegration-time/

 

And a video from Sharpcap’s creator:

https://www.youtube....h?v=3RH93UvP358

Edited by Stevan Klaas, 14 June 2025 - 11:16 AM.

[gooeytek]

This website allows you to compare imaging times between different Bortle locations, and it's more updated than the light pollution map site:

 

https://darkskysites.com/

[Starlancer]

I normally image from a B7 but get to a B1 when I go to the Nebraska Star Party, this is the first year I'll have my Seestar and Dwarf with my so it will be interesting.  I plan on trying some dark nebula.

 

I can say the difference between B1 and B7 is massive, even a B3.  I took a picture of Andromeda in Nebraska with 15m of exposure, that image would be hours in my skies back home.

[Stevan Klaas]

Just tested S50 in bortle 4-5 vs my usual 8-9. Very encouraging 4-5 hours integration time…

 

 

 

 

Edited by Stevan Klaas, 19 June 2025 - 10:56 PM.