806 replies to this topic

[The Science Golfer]

If either of you have an original unedited version of the failed image, or even better a single exposure that would be really helpful to debug... Thank you!

 

Also have either of you tried the latest release? It may not have fixed it, but the last updated made some changes that might have helped

 

 

Overall, as Domdon says it's essentially down to signal-to-noise ratio. The other factor is magnification, but if you've successfully imaged at x40 then probably not this.

Here is the original, unedited. I attempted to do 70 frames at 10 sec exposure each, and ISO 800.https://ibb.co/Wz4jXF6

 

Afterward I tried playing around with the exposure time and number of photos to see if I could “wake up” the alignment function, to no avail. This is the closest I got to a single shot after the original failed. It is two frames, also at 10 sec exposure and ISO 800. https://ibb.co/D536hTH

 

I’ll be interested to see your analysis of those…

 

Clear skies,

 

Tyler 

 

[Domdron]

Got to go out and play tonight, just shot Orion again with hestia, left is gravity, center it using a bak mask on hestia and left is using the AstroShader app, still getting movement on stars during stacking no matter what app I use, I guess it’s just the movement in 1 sec

I'd suspect so. If you know the focal lengths of the Hestia and its ocular(or the f-ratio to calculate possible combinations of them from the 25x magnification), its aperture, and the phone camera's focal length, you could compute the effective focal length (or have it done for you).

 

Or, if you know the sensor's pixel size, you could use plate solving to get the image's FoV in angular size, and, using the image size in pixels as "object size", compute the effective FL from that. 

 

Then you apply the 500 rule to compute max. sub-exposure time for acceptable star trails. Though I think you'd still need to apply the iPhone's sensor's "crop factor", because the 500 rule has been designed for "full frame" (35mm cameras). And what is "acceptable" is subjective in the end, so you might come to use another value.

[astrshdr]

Got to go out and play tonight, just shot Orion again with hestia, left is gravity, center it using a bak mask on hestia and left is using the AstroShader app, still getting movement on stars during stacking no matter what app I use, I guess it’s just the movement in 1 sec

Interesting comparison - what were your exposure and ISO settings?

 

Also yes it might be that 1sec is too long for a single sub. Someone posted a link to the NPF rule to calculate exposure time a while back that might be useful here...

 

[EDIT: Just seen Domdron's comment which is a much more comprehensive answer)

Edited by astrshdr, 29 March 2024 - 06:43 AM.

[astrshdr]

Here is the original, unedited. I attempted to do 70 frames at 10 sec exposure each, and ISO 800.https://ibb.co/Wz4jXF6

 

Afterward I tried playing around with the exposure time and number of photos to see if I could “wake up” the alignment function, to no avail. This is the closest I got to a single shot after the original failed. It is two frames, also at 10 sec exposure and ISO 800. https://ibb.co/D536hTH

 

I’ll be interested to see your analysis of those…

 

Clear skies,

 

Tyler 

Thanks for sharing this.

 

My initial thought would be to drop the ISO to 100 or 200. It looks like the dark noise is adding up quite a lot in the extended exposures (beyond the hardware limit of 1 sec) - the magenta type hue in the background.

 

However, I think there is something I can do to help this in the long-term. I'll run some tests and see what can be done...

[astrshdr]

There is still 4.5 GB available (of 16 GB).

 

 

I tried re-booting my iPhone and re-opening the app, but I still experience crashes. Sometimes immediately after pushing the "highlight images" button, sometimes later on. And sometimes everything works just fine.

Anyway, thanks for the suggestion!

 

Without using this feature, I don't seem to have issues (except rarely, when using the Astroshader Tools. But that improved a lot after one of the updates where this issue was addressed).

 

Aha, sorry about this.

 

I'm 99% sure this is a memory (RAM) issue. Certain features are doing quite a lot of heavy lifting and although I've tried to optimise things I only regularly test down to a physical iPhoneX for performance.

 

I'll see if there's any way to resolve this...

[GSBass]

I think gravity is using 1 second and auto iso right now to keep it simple for people but hopefully they will open that up a bit in the future, meanwhile AstroShader gives me the ability to see what’s best for my iPhone 13 mini, so I’ll experiment further with shorter subs. The alignment/recentering did not work well for me last night, I guess I needed to be closer, I made the mistake of not leveling my tripod so the left/right movements of the video head resulted in diagonal movement of the target and also had a hard time moving it without over correcting. Anyway it’s obvious that recentering requires more than just getting the I just back in the fov, I’ll try this some more , should be easier when I am level

Interesting comparison - what were your exposure and ISO settings?

 

Also yes it might be that 1sec is too long for a single sub. Someone posted a link to the NPF rule to calculate exposure time a while back that might be useful here...

 

[EDIT: Just seen Domdron's comment which is a much more comprehensive answer)

[GSBass]

Btw I hope no one minds me discussing gravity in parallel with my AstroShader experiences, it’s just that it’s so new I find it interesting, even after one night I think I have a better grasp of what they are doing by seeing my results with AstroShader.. so far their biggest things they are doing wrong, white balance is way off, Orion is super green befor you make an attempt to correct in post. Also a very major thing is they are saving everything in jpeg, it’s very obvious to me the tiff output from AstroShader is much cleaner and withstands post much better. The one thing that I did find helpful in gravity was when I was overshooting my target last night when trying to recenter, the navigation made it much easier to reaquire. It is constantly pkatesolving and the sides or corners of the phone light up with a blue glow indicating we’re the target is versus where you are actually pointed

Edited by GSBass, 29 March 2024 - 09:46 AM.

[GSBass]

I’ve experimented with AstroShader  so far I am not seeing any advantages using AstroShader although it does give you more controls to manipulate, the feature they announced that I was most interested in is to let you pause an exposure and recenter to continue stacking. Unfortunately all my test so far using that have failed, but it sounds great on paper if they can make it work. I think the target has to be very very close to where you left off for it to work but that has been a impossibility for me to align that closely by just manipulating my video head, I think I would need fine adjustment knobs or something precise like that. Hopefully he can make it work if you can just get the target back in to the inner third of the frame, that would be doable

[Domdron]

 

 

I’ve experimented with AstroShader  so far I am not seeing any advantages using AstroShader although it does give you more controls to manipulate, the feature they announced that I was most interested in is to let you pause an exposure and recenter to continue stacking. Unfortunately all my test so far using that have failed, but it sounds great on paper if they can make it work. I think the target has to be very very close to where you left off for it to work but that has been a impossibility for me to align that closely by just manipulating my video head, I think I would need fine adjustment knobs or something precise like that. Hopefully he can make it work if you can just get the target back in to the inner third of the frame, that would be doable

I had tried it quite successfully on Carina Nebula, and had posted about it here. I didn't do particularly close re-positionings on that one, just roughly in the area. So I think your difficulties might arise due to something else, maybe not enough bright enough stars in the image, as was discussed earlier. I had issues with that as well trying to shoot M83, unsuccessfully.  

 

So I'd encourage you to try a target which has some brighter stars in the FoV.

[GeezerGazer]

I’ve experimented with AstroShader  so far I am not seeing any advantages using AstroShader although it does give you more controls to manipulate, the feature they announced that I was most interested in is to let you pause an exposure and recenter to continue stacking. Unfortunately all my test so far using that have failed, but it sounds great on paper if they can make it work. I think the target has to be very very close to where you left off for it to work but that has been a impossibility for me to align that closely by just manipulating my video head, I think I would need fine adjustment knobs or something precise like that. Hopefully he can make it work if you can just get the target back in to the inner third of the frame, that would be doable

Questions for you:  

1.  Are you using the Hestia as the optical system and AS as the camera app, instead of the Gravity app, and is this system mounted to a video head mount?  

 

2.  Are you using the  binning toggle in AS?

 

3.  Have you tried AS, attaching your phone to an eyepiece in your AT 102, mounted to your M2 mount? 

 

4. Are you using AS settings to automatically stop the image for repositioning at pre-set intervals... or, are you manually stopping the image by pressing the button?  

 

5.  How long is your exposure time on the failed photos, and how many exposures are you stacking?

[GSBass]

Yes, using as on hestia with a video head mount, using the auto pause and reposition, I think I just had it set on 45 frames with pause set at 10 frames, tried 1 sec exposures snd 4 sec exposure, results were either a black frame or a double exposure. I’ll keep at it though, it will be a cool feature

—-

I have not tried as yet while hestia is attached to my refractor, I may be able to get closer alignment with that set up

Questions for you:  

1.  Are you using the Hestia as the optical system and AS as the camera app, instead of the Gravity app, and is this system mounted to a video head mount?  

 

2.  Are you using the  binning toggle in AS?

 

3.  Have you tried AS, attaching your phone to an eyepiece in your AT 102, mounted to your M2 mount? 

 

4. Are you using AS settings to automatically stop the image for repositioning at pre-set intervals... or, are you manually stopping the image by pressing the button?  

 

5.  How long is your exposure time on the failed photos, and how many exposures are you stacking?

Edited by GSBass, 01 April 2024 - 09:47 PM.

[GeezerGazer]

Yes, using as on hestia with a video head mount, using the auto pause and reposition, I think I just had it set on 45 frames with pause set at 10 frames, tried 1 sec exposures snd 4 sec exposure, results were either a black frame or a double exposure. I’ll keep at it though, it will be a cool feature

—-

I have not tried as yet while hestia is attached to my refractor, I may be able to get closer alignment with that set up

OK, you probably need to be using sub-second exposures.  Four second subs on a non-tracking mount are not aligned, they are only averaged, so they are almost certainly striated.   You are taking 4 one-second images that are not aligned, and then trying to align and stack them.  When you drop exposures to sub-second, every image is aligned, stacked and averaged in AS.  I don't know what magnification you are using, so I cannot recommend a specific exposure setting, but you may want to start at .3 or .5 sec and move up from there.  Instead of 45 exposures, go for at least 100 without stopping to re-position the scope.  If that works, then increase the number of exposures to be stacked to 300 or 400 and put in an interval to stop and reposition the scope at every 100 or 120 images.  Unless you are at a very high magnification, you should be able to stack 60-100 sub-second exposures without stopping to re-position.  Crank up the ISO and if needed, try toggling on the binning function for increased brightness.  For a target, start with a bright cluster... they are easier for the alignment function and you can more easily tell what problems caused a failure.  If the video head mount is stable enough, it should work fine.  But to see if the mount is contributing to misaligned images, try it on your M2 mount.  

Ray

[GSBass]

Thanks Ray, I will try that, hestia is a 25x scope, I have not calculated f or fov , but here is maximum fov on Orion 

OK, you probably need to be using sub-second exposures.  Four second subs on a non-tracking mount are not aligned, they are only averaged, so they are almost certainly striated.   You are taking 4 one-second images that are not aligned, and then trying to align and stack them.  When you drop exposures to sub-second, every image is aligned, stacked and averaged in AS.  I don't know what magnification you are using, so I cannot recommend a specific exposure setting, but you may want to start at .3 or .5 sec and move up from there.  Instead of 45 exposures, go for at least 100 without stopping to re-position the scope.  If that works, then increase the number of exposures to be stacked to 300 or 400 and put in an interval to stop and reposition the scope at every 100 or 120 images.  Unless you are at a very high magnification, you should be able to stack 60-100 sub-second exposures without stopping to re-position.  Crank up the ISO and if needed, try toggling on the binning function for increased brightness.  For a target, start with a bright cluster... they are easier for the alignment function and you can more easily tell what problems caused a failure.  If the video head mount is stable enough, it should work fine.  But to see if the mount is contributing to misaligned images, try it on your M2 mount.  

Ray

 

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[GSBass]

Ya know the thing I can’t seem to wrap my head around, is since phones are limited to 1 second subs, if you tell the app to give you 5sec subs, then essentially it’s stacking twice, 5 times to get you to 5 secs x however many frames you tell it to take. I guess there is a difference in the algorythm of whether those first stacks are aligned or how they are averaged… but I’m just guessing, it seems like a weird way to do it since it’s not truly a 5 sec sub

[Thrifty1]

I have tried M51 twice with AS through glass eyepieces (no Night Vision Device) in my 8" Newt and failed to capture a satisfactory image both times from my home, a bright LP red zone, Bortle 7-8... using a non-tracking mount.  M51is relatively faint compared to point light sources like clusters and there are few bright stars in the FoV at about 76x.  I even tried using 640nm and then a 685nm IR long pass filters to block the majority of LP without success.  When using the non-tracking mount, the phone was working at a huge disadvantage with exposure times set to .3 second.  But even at 4-5 sec exposures with ISO set to 16,000 on the tracking mount, results from home were dismal, partly due to atmospheric dispersion (high humidity) combined with high levels of LP (this attempt just a couple of weeks ago).  

 

On 11 April 2023, I used AS with my 8" f:4 Newt and a 2.5x Powermate with Night Vision in prime focus to collect a decent image at f:10, 76x from a tracking mount (ISO 250 with 60, 5 sec subs.  NV provides a huge advantage!  But just as important, this image was taken from a LP green zone, Bortle 4-5.  I have not been able to duplicate this image from my red-zone home even when using a tracking mount and night vision.  My conclusion is that AS was working properly to align the 60 subs in this much brighter image, and that signal to noise is the culprit for alignment failure at my red-zone home using glass eyepieces.   

 

IMG_9001.jpeg

I've been busy with some new equipment and testing things for the upcoming eclipse.  I look forward to trying AS in the next couple of months on some DSO... your M51 has motivated me.  While I don't have a night vision device, I can try longer exposures via guiding with my AVX mount to see how well AS does with decent tracking / guiding.  

[GeezerGazer]

Thanks Ray, I will try that, hestia is a 25x scope, I have not calculated f or fov , but here is maximum fov on Orion 

25x is pretty low magnification.   So try a .5 second exposure with a stack of 100 with no interval to reposition.  You will need to decide what ISO setting is best.  But try this with and without pixel binning to see the difference in results. 

 

Any time you are using Hestia on a stationary mount, keep the exposure in AS at or below 1 second so that every image is aligned and stacked.  Any time you push the exposure over 1 second, AS is averaging multiple 1 second exposures as your subs before they are aligned and stacked.  So if there is any visible trailing in the subs, it will show up in the final stacked image.  This is undoubtedly why your 4 second exposures failed from your non-tracking mount.  If you put Hestia on a tracking mount, then you can make your exposure as long as you like, because the tracking mount will keep the averaged, long-exposure subs aligned.  Does that make sense?

 

The brightness scale that is associated with an increase in exposure settings is imitating the long exposure of traditional cameras.  The longer light hits the film or sensor, the brighter the image will be.  If you want to brighten your images more, then move from a non-tracking to a tracking mount, which permits an enormous increase in light gathering for the subs.

 

So that you can see the difference that longer exposures can make in your subs, next time you are out with Hestia on a non-tracking mount, crank the Exposure up to 20 sec and wait for the preview screen to refresh (this may take several seconds).  You can't use this advantage with a non-tracking mount without causing trailing, but at least you can see the difference tracking can make when using AS... with any optical system.  

 

Android phones can take a single, long-exposure image up to 60 seconds like a regular camera, but they too are limited to much shorter exposures (usually sub-second) to prevent trailing from a non-tracking mount.

 

There is a difference between "aligning/stacking" and "averaging".   Typically, averaged photos are not aligned.  They are added to one another specifically to eliminate electronic noise in the final image; hot pixels not seen in all of the images are eliminated.  Averaging is what NightCap camera app does.  "Aligning/Stacking" uses specific registration points in numerous images to align them.  Some averaging also takes place during the "Aligning/Stacking" process.  The advantage of separating these two functions in AS is clear.  The longer that multiple images can be averaged, the better the final image will be with significantly less electronic noise.  Then aligning and stacking multi-second exposures permits a brighter image with greater detail and less noise.  

 

There's no free ticket to escape the laws of physics.  

Ray

Edited by GeezerGazer, 03 April 2024 - 05:45 PM.

[GSBass]

Thanks Ray for the explanation , I think it’s likely that most of the new users who like thier hestia will go ahead and purchase the tracking mount being designed for it, I know that some people will scoff a little as that starts to approach the pricing point of seestar… but I think it’s very fun to be on the cutting edge of phone astrophotography… it’s only going to get better and better, AstroShader and gravity are only the first of many to come, and I kinda expect more telescope boxes will come too because it really is pretty convenient to just plop your phone down on it and get right to business

25x is pretty low magnification.   So try a .5 second exposure with a stack of 100 with no interval to reposition.  You will need to decide what ISO setting is best.  But try this with and without pixel binning to see the difference in results. 

 

Any time you are using Hestia on a stationary mount, keep the exposure in AS at or below 1 second so that every image is aligned and stacked.  Any time you push the exposure over 1 second, AS is averaging multiple 1 second exposures as your subs before they are aligned and stacked.  So if there is any visible trailing in the subs, it will show up in the final stacked image.  This is undoubtedly why your 4 second exposures failed from your non-tracking mount.  If you put Hestia on a tracking mount, then you can make your exposure as long as you like, because the tracking mount will keep the averaged, long-exposure subs aligned.  Does that make sense?

 

The brightness scale that is associated with an increase in exposure settings is imitating the long exposure of traditional cameras.  The longer light hits the film or sensor, the brighter the image will be.  If you want to brighten your images more, then move from a non-tracking to a tracking mount, which permits an enormous increase in light gathering for the subs.

 

So that you can see the difference that longer exposures can make in your subs, next time you are out with Hestia on a non-tracking mount, crank the Exposure up to 20 sec and wait for the preview screen to refresh (this may take several seconds).  You can't use this advantage with a non-tracking mount without causing trailing, but at least you can see the difference tracking can make when using AS... with any optical system.  

 

Android phones can take a single, long-exposure image up to 60 seconds like a regular camera, but they too are limited to much shorter exposures (usually sub-second) to prevent trailing from a non-tracking mount.

 

There is a difference between "aligning/stacking" and "averaging".   Typically, averaged photos are not aligned.  They are added to one another specifically to eliminate electronic noise in the final image; hot pixels not seen in all of the images are eliminated.  Averaging is what NightCap camera app does.  "Aligning/Stacking" uses specific registration points in numerous images to align them.  Some averaging also takes place during the "Aligning/Stacking" process.  The advantage of separating these two functions in AS is clear.  The longer that multiple images can be averaged, the better the final image will be with significantly less electronic noise.  Then aligning and stacking multi-second exposures permits a brighter image with greater detail and less noise.  

 

There's no free ticket to escape the laws of physics.  

Ray

[GSBass]

Also thinking Vaonis purposely is only allowing 1sec subs and 30 frames initially because that gives newbies best chance for success even if stars are not pinpoint, in the coming months I think they will open that up a bit, probably not as much as AstroShader though, we will see

——

14000 is a lot if people to introduce to the hobby in one swoop, especially for a new device that has its own unique procedures… and quite a few newbies are struggling, trying to help them but the learning curve is a little rough for them, most of us here would not think so but some seems to not get it

25x is pretty low magnification.   So try a .5 second exposure with a stack of 100 with no interval to reposition.  You will need to decide what ISO setting is best.  But try this with and without pixel binning to see the difference in results. 

 

Any time you are using Hestia on a stationary mount, keep the exposure in AS at or below 1 second so that every image is aligned and stacked.  Any time you push the exposure over 1 second, AS is averaging multiple 1 second exposures as your subs before they are aligned and stacked.  So if there is any visible trailing in the subs, it will show up in the final stacked image.  This is undoubtedly why your 4 second exposures failed from your non-tracking mount.  If you put Hestia on a tracking mount, then you can make your exposure as long as you like, because the tracking mount will keep the averaged, long-exposure subs aligned.  Does that make sense?

 

The brightness scale that is associated with an increase in exposure settings is imitating the long exposure of traditional cameras.  The longer light hits the film or sensor, the brighter the image will be.  If you want to brighten your images more, then move from a non-tracking to a tracking mount, which permits an enormous increase in light gathering for the subs.

 

So that you can see the difference that longer exposures can make in your subs, next time you are out with Hestia on a non-tracking mount, crank the Exposure up to 20 sec and wait for the preview screen to refresh (this may take several seconds).  You can't use this advantage with a non-tracking mount without causing trailing, but at least you can see the difference tracking can make when using AS... with any optical system.  

 

Android phones can take a single, long-exposure image up to 60 seconds like a regular camera, but they too are limited to much shorter exposures (usually sub-second) to prevent trailing from a non-tracking mount.

 

There is a difference between "aligning/stacking" and "averaging".   Typically, averaged photos are not aligned.  They are added to one another specifically to eliminate electronic noise in the final image; hot pixels not seen in all of the images are eliminated.  Averaging is what NightCap camera app does.  "Aligning/Stacking" uses specific registration points in numerous images to align them.  Some averaging also takes place during the "Aligning/Stacking" process.  The advantage of separating these two functions in AS is clear.  The longer that multiple images can be averaged, the better the final image will be with significantly less electronic noise.  Then aligning and stacking multi-second exposures permits a brighter image with greater detail and less noise.  

 

There's no free ticket to escape the laws of physics.  

Ray

Edited by GSBass, 03 April 2024 - 09:12 PM.

[Seawild]

Hello AstroShader Crew!  I grabbed this shot of M13 last night using AstroShader on my iPhone 8+.  102 with a 15mm eyepiece. (Cropped and crushed) 

 

First time using a tracking mount.  So cool!  Thank you for making this awesome App for iPhones!

 

iso_4169_0.999s_x80_06-Apr-2024_23.41.47.383

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Edited by Seawild, 07 April 2024 - 06:53 PM.

[Domdron]

Hi. I was out yesterday and shot these 2 images (of Omega Centauri and T Coronae Borealis and surroundings), and notice that it has some "star trailing", which seems to be quite a bit stronger on the right side:

 

 

 

Both were done with a 32mm 52° Plössl on an untracked mount, both 256 x 0.644 seconds. I think this is an alignment issue? But I'm wondering why the trailing seems to be stronger on the right side only?

Edited by Domdron, 10 April 2024 - 12:59 AM.

[GeezerGazer]

I recently purchased a 150mm Apertura CarbonStar f:4 Newtonian, made by GSO, and had it at my LP green zone site last night for some testing with AS.  Both the scope and AS performed very well, using night vision for the eyepiece with my iPhone 15 ProMax collecting the photons.  All my images last night were taken using an iOptron HAZ31 mount with GoTo & tracking, which is my normal way of taking images.  I imaged M42 Orion, NGC 2244 Rosette, IC443 Jellyfish, M51 Whirlpool, and M104 Sombrero.  I used a 6.5nm H-a filter for nebulae images.  All images came out great, comparable in quality to the image below, using similar settings.  By 01:00 hrs, the wind came up, which ended my session.

 

I was testing settings for image quality and wanted to see how the smaller file size of a binned image compared to images at higher ISO with a 12 MP size.  So I removed the Night Vision and attached my phone to a Delos 10mm eyepiece.  Binning did not work for me last night.   I got a satisfactory image on the preview screen, but when I took the photo, the images were very distorted.  See images with settings in my next post.  

 

So first, the good news.  The little Newt is excellent when used with my TS .73x reducer/corrector (actual reduced FL was 438mm) and AS performed flawlessly in non-binning mode on my tracking mount.  Settings were ISO 100, with 100 - 3s subs for this image of the Rosette Nebula.

 

Click on this photo to open in a bigger, more detailed image:

.  

Edited by GeezerGazer, 10 April 2024 - 02:04 PM.

[GeezerGazer]

I removed the Night Vision Device from the 6" Newt, attached my phone to a Delos 10mm, set ISO to 100, with 400 subs of .3 sec exposure, with binning toggled on.  I have the original TIFF image if needed, but this is a compressed JPEG to post here:

 

Using identical settings, I tried again and this time, saved it as a PNG instead of a TIFF:

 

Interestingly, as I closed these two distorted images in AS, at just the instant I pushed the close button after saving it, I saw what looked like a great image of M104 which only flashed on the screen as the distorted image was closing.  The good image flashed for perhaps 1/10th second, and was gone.  Only the distorted image was saved.  

Ray

Edited by GeezerGazer, 10 April 2024 - 02:03 PM.

[astrshdr]

I removed the Night Vision Device from the 6" Newt, attached my phone to a Delos 10mm, set ISO to 100, with 400 subs of .3 sec exposure, with binning toggled on.  I have the original TIFF image if needed, but this is a compressed JPEG to post here:

iso_100_0.3s_x399_09-Apr-2024_22.35.52.491.jpeg

 

Using identical settings, I tried again and this time, saved it as a PNG instead of a TIFF:

iso_100_0.3s_x400_09-Apr-2024_22.39.59.519.jpeg

 

Interestingly, as I closed these two distorted images in AS, at just the instant I pushed the close button after saving it, I saw what looked like a great image of M104 which only flashed on the screen as the distorted image was closing.  The good image flashed for perhaps 1/10th second, and was gone.  Only the distorted image was saved.  

Ray

Oh weird... This sounds very similar to the issue with TIFFs and iOS Photos - it may well be related.

 

If you could send me the original TIFF that would be really useful, thank you!

[joezerneem]

As promised, I tried M51 again. It may be too faint to capture anything decent in this setup with an iPhone 6S, but this test was mainly to show the alignment/stacking issues I got.

 

- 10 inch Dobsonian (manual)
- Celestron Nexyz smartphone adapter
- iPhone 6S
- 30mm eyepiece (magn. 40x).
- Bortle 6

 

I didn't use the reposition interval setting here:

 

- The first image is a single exposure:
iso_16000_0.333s_x1_10-Apr-2024_22.02.20.506
- The second image is a 2x exposure:
iso_16000_0.333s_x2_10-Apr-2024_22.03.27.056
- The third image is a second try with a 2x exposure:
iso_16000_0.333s_x2_10-Apr-2024_22.04.06.501

 

Then I played a bit with the binning setting and lowering the ISO. Only the next day I noticed that using binning combined with lowering the ISO to (approximately) 8000 showed a better result (16000 instead didn't work well. Unfortunately I didn't try lowering ISO without using the binning setting):

 

- iso_8038_0.333s_x5_10-Apr-2024_22.11.03.071

 

So I could try to crank up the number of exposures with these settings next time.

 

I also tried M13 and seemed to have the same kind of issues.
In the first and second image I zoomed in a bit with my iPhone:

 

- The first image is a single exposure:
iso_16000_0.333s_x1_10-Apr-2024_23.59.54.747
- The second image is a 2x exposure:
iso_16000_0.333s_x2_11-Apr-2024_00.00.46.642
- The third image is a 5x exposure:
iso_16000_0.333s_x5_11-Apr-2024_00.22.30.520

 

To verify, I tried M82 with which I had decent results before. Again, the results were decent.

 

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[astrshdr]

As promised, I tried M51 again. It may be too faint to capture anything decent in this setup with an iPhone 6S, but this test was mainly to show the alignment/stacking issues I got.

 

- 10 inch Dobsonian (manual)
- Celestron Nexyz smartphone adapter
- iPhone 6S
- 30mm eyepiece (magn. 40x).
- Bortle 6

 

I didn't use the reposition interval setting here:

 

- The first image is a single exposure:
iso_16000_0.333s_x1_10-Apr-2024_22.02.20.506
- The second image is a 2x exposure:
iso_16000_0.333s_x2_10-Apr-2024_22.03.27.056
- The third image is a second try with a 2x exposure:
iso_16000_0.333s_x2_10-Apr-2024_22.04.06.501

 

Then I played a bit with the binning setting and lowering the ISO. Only the next day I noticed that using binning combined with lowering the ISO to (approximately) 8000 showed a better result (16000 instead didn't work well. Unfortunately I didn't try lowering ISO without using the binning setting):

 

- iso_8038_0.333s_x5_10-Apr-2024_22.11.03.071

 

So I could try to crank up the number of exposures with these settings next time.

 

I also tried M13 and seemed to have the same kind of issues.
In the first and second image I zoomed in a bit with my iPhone:

 

- The first image is a single exposure:
iso_16000_0.333s_x1_10-Apr-2024_23.59.54.747
- The second image is a 2x exposure:
iso_16000_0.333s_x2_11-Apr-2024_00.00.46.642
- The third image is a 5x exposure:
iso_16000_0.333s_x5_11-Apr-2024_00.22.30.520

 

To verify, I tried M82 with which I had decent results before. Again, the results were decent.

Thanks for sharing - these are some really interesting results.

 

In the M13 images you can see it coming through - I wonder with greater integration time (even the most images is less than 2 seconds in total) and then really sharp focus if it would improve things further.

 

You might need to play around a lot with the editing too (background removal, black points, curves/levels, etc). I occasionally test on an iPhone7 but don't have access to a 6 - one of the changes since iPhone11/12 has been much improved signal-to-noise ratio (much less noisy images with a greater sensitivity), I've found it can be really fiddly to tease details out of images on iPhone7 as the noise is similarly bright as the target itself. One way round this is long integration times, e.g. >10mins however this may not be possible with untracked setups.

 

These are great images for me to test with so thanks again for sharing!