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AstroShader iOS AP app: Intro + beta-testers wanted

Smartphone AP Software Astrophotography
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#1 astrshdr

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Posted 30 December 2022 - 01:41 PM

Hi everyone,

 

This is a first post to introduce a free app I'm working on called AstroShader and to look for support with beta-testing and discuss ideas for improvements (...and bug fixes).

 

Download link (free) here

 

Docs here

 

What is AstroShader?

My aim is to make an end-to-end astrophotography app for iOS. Beyond this to also make the application mobile first, e.g. make it easier to take longer captures and stack images on mobile without using a laptop/desktop, and then also some tools to edit them as high quality images.

 

To achieve this the image capture process is a little different to standard AP workflow. The images are aligned and stacked live during the capture process so only a single image is generated, as 16bit tiff. The downside here is not having the subs data, however it means you can go from setup to final image very quickly.

 

AstroShader is aimed at anyone but more beginners looking to start imaging or people out travelling/trekking where you can't take loads of kit. Also giving iPhone users some more options, as there are some great images coming out of the newer Pixels, Samsungs and Xiaomis these days.

 

How to use it:

    1) With a tripod or attach to telescope, or lean your iPhone on something.

    2) Find focus, easier with shorter exposure time 0.1-0.2s.

    3) Set exposure time; ~4s for wide-field with main camera, longer for tracked AP with telescope, shorter for untracked.
    4) Set ISO and WB. Other settings; choose camera, timer and alignment function (helps where there is ++ light pollution).
    5) Set number of exposures to take.
    6) Tap capture, the images are automatically aligned during capture. When complete the image is saved as a tiff and the edit tools open up.

    7) The open image button on the bottom left of the main screen can be used to open and edit previously captured images.

 

How it works:

- The native iPhone exposure range is extended beyond it's max (if needed) by stacking raw sensor data without alignment.
- Per exposure the image is debayered and then aligned and stacked with the next image.

- The above approach is only possible due to modern iPhone GPU processing capabilities and is done to save disc space, each tiff is ~95Mb. e.g. per imaging run of say 150 images would otherwise take up 14Gb if saved and stacked from disc. Downside is you lose the subs data, I guess it's just a different "mobile" approach to AP.

- The data is saved as a 16bit tiff by default, this may not work with the photos app. But in AstroShader you can open 16bit images to edit.
- With the edit tools I tried to offer more than the photos app, so added curves, improved black point and a sharpness stacking tool (with radius and intensity controls). You can also choose png, tiff of heif save format.

 

Known issues:

- Focus... iPhone do this in a weird way so there isn't a predefined infinity point. You have to find focus manually, but I do save this for the next shot.

- Roughly 1 in 50 attempts to capture and image there's a crash on older devices. I think it's a video memory issue.
- On older devices using all the edit filters at once causes the OS to boot the app from memory.

- (Not a real issue but a TBA) iOS doesn't play nicely with 16it tiffs so the thumbnail preview is messed up and iOS Photos app will convert to a jpeg for editing. When sharing tiffs or pngs from iPhone always use the top "Options" > "All Photos Data" option, or iOS sends a jpeg.

- Another iOS TBA, when you edit images in the iOS Photos app you do not edit the original. Photos saves a jpeg version of the edited image inside a folder with the original. So if you open an image edited in Photos in AstroShader (or another similar app) you won't see any changes from Photos as they aren't reflected in the original full res image.

 

Current roadmap:

- Foreground extraction (trees, mountains, etc).
- Planetary imaging workflow.

- ...However looking for other suggestions from real people here too.

Any feedback would be greatly appreciated, whether bugs, UX improvements or major feature requests.

Thanks!


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#2 Pinac

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Posted 31 December 2022 - 04:55 AM

Sounds interesting.

Happy to try that out as soon as weather allows.

Pinac



#3 Pipiland

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Posted 01 January 2023 - 10:20 PM

Im already testing.



#4 Rabbanah

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Posted 02 January 2023 - 12:16 AM

I downloaded it and will test it out on my next session. It is super cloudy here for the foreseeable future though. I will run though what I can in the daylight to get a feel and give feedback as I go.



#5 astrshdr

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Posted 04 January 2023 - 09:47 AM

Forgot to post an example before... This image was captured, stacked and edited entirely on an iPhone with AstroShader.

 

Orion nebula from a B9 area with a SkyWatcher 130P.

AstroShader settings: x100, 10s exposures, ISO 400, WB 4k.

 

IMG_3120 copy.jpg


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#6 astrshdr

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Posted 05 January 2023 - 05:31 AM

Also for reference these here a couple of shots with no scope or other equipment, just an iPhone.
Both images also processed and edited on a phone, in the spirit of end-to-end mobile astrophotography 😉

 

IMG_3069 copy.jpg

 

 

IMG_3137 2 copy.jpg


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#7 Lyaphine

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Posted 07 January 2023 - 02:23 PM

Hi there!

 

First off, thank you for developing such an App. That's exactly what I've been looking for! However after testing it, I noticed it always seems to apply some sort of noise reduction to the image. I would like to have full control over noise reduction myself. Is there any way to do so?

 

Thank you in advance!


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#8 astrshdr

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Posted 08 January 2023 - 02:50 PM

Hi there!

 

First off, thank you for developing such an App. That's exactly what I've been looking for! However after testing it, I noticed it always seems to apply some sort of noise reduction to the image. I would like to have full control over noise reduction myself. Is there any way to do so?

 

Thank you in advance!

 

Hi there, thank you for testing it out!

 

There shouldn't be any visual changes that look like denoising and this hasn't cropped up with any other testers... yet.

Would you mind sharing the settings you used and iPhone model and maybe an example image affected by this?

 

There may be a little blurring if you're stacking a lot of images not at perfect focus, but shouldn't be too bad if everything is working correctly.

AstroShader doesn't apply any explicit denoising in the image processing. The debayer function I use does use the noise data to calibrate some parameters but the effects are very light—and after some testing today even at extreme values the image is not significantly altered.

However. I can definitely add functionality to a future release to control this.

 

I'm wondering if the visual artefacts affecting your images are from a different source—for example focus, stacking issues (exposure length and the default function can cause issues especially when there's a lot of light pollution).
One thing worth checking might be an image from a single exposure vs say 50. That might highlight if this is due to the stacking process.



#9 Lyaphine

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Posted 08 January 2023 - 04:27 PM

Hi there, thank you for testing it out!

 

There shouldn't be any visual changes that look like denoising and this hasn't cropped up with any other testers... yet.

Would you mind sharing the settings you used and iPhone model and maybe an example image affected by this?

 

There may be a little blurring if you're stacking a lot of images not at perfect focus, but shouldn't be too bad if everything is working correctly.

AstroShader doesn't apply any explicit denoising in the image processing. The debayer function I use does use the noise data to calibrate some parameters but the effects are very light—and after some testing today even at extreme values the image is not significantly altered.

However. I can definitely add functionality to a future release to control this.

 

I'm wondering if the visual artefacts affecting your images are from a different source—for example focus, stacking issues (exposure length and the default function can cause issues especially when there's a lot of light pollution).
One thing worth checking might be an image from a single exposure vs say 50. That might highlight if this is due to the stacking process.

Thank you for your answer!

I used an iPhone 14 Pro Max and my settings were 100 Exposures, 3sec Exposure and max ISO of the telephoto lens.
For some reason the file says its a tiff in the image details but as soon as I send it somewhere (no matter if per mail or discord or some cloud) it turns into a jpg.

I can't see any noise on the image, even in the app itself before exporting.

My target was Andromeda and my goal was to take many of these images and stack those again for a really deep phone image of Andromeda. Unfortunately as soon as any noise reduction is applied, this plan fails.

 

Here are the files because they are too big to upload to CN:

The tiff which somehow turned into a jpg and a screenshot of it being labeled as a tiff (for sanity reasons)

https://drive.google...iew?usp=sharing

https://drive.google...iew?usp=sharing


Edited by Lyaphine, 08 January 2023 - 04:27 PM.


#10 astrshdr

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Posted 08 January 2023 - 05:38 PM

Thank you for your answer!

I used an iPhone 14 Pro Max and my settings were 100 Exposures, 3sec Exposure and max ISO of the telephoto lens.
For some reason the file says its a tiff in the image details but as soon as I send it somewhere (no matter if per mail or discord or some cloud) it turns into a jpg.

I can't see any noise on the image, even in the app itself before exporting.

My target was Andromeda and my goal was to take many of these images and stack those again for a really deep phone image of Andromeda. Unfortunately as soon as any noise reduction is applied, this plan fails.

 

Here are the files because they are too big to upload to CN:

The tiff which somehow turned into a jpg and a screenshot of it being labeled as a tiff (for sanity reasons)

https://drive.google...iew?usp=sharing

https://drive.google...iew?usp=sharing

Great, thanks for sharing this.

 

Aha, I think I know what's going on here...

iOS shares the jpg preview image by default, not the actual tiff/png/raw image file. You still have all your original data from the image captures.

When sharing if you choose "Options" at the top and turn on the toggle for "All Photos Data".

(AstroShader will open the image properly to see the original data. I think iOS photos will too but you might need to make an edit before it shows the actual data 🙃)

 

Screenshot 2023-01-08 at 22.07.14.png



#11 astrshdr

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Posted 08 January 2023 - 05:38 PM

Oh also some random tips for shooting Andromeda I've noticed:
- To reduce the colour distortion try lowering the ISO a bit (e.g. ~2000) then edit using the "Low light" slider. (The image will initially look too dark but you can recover it amazingly in editing with AstroShader or something like PS.)
- If you're stacking >50 images try sharpening in AstroShader @ radius of 0.5-1.5 intensity of 10, and combining sharpening to bring out some detail.

 

Image below shows a lower ISO image with a before and after the low light slider edit:

Screenshot 2023-01-08 at 22.33.28.png



#12 wykbbb

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Posted 10 January 2023 - 06:34 PM

Also for reference these here a couple of shots with no scope or other equipment, just an iPhone.
Both images also processed and edited on a phone, in the spirit of end-to-end mobile astrophotography

 

attachicon.gifIMG_3069 copy.jpg

 

 

attachicon.gifIMG_3137 2 copy.jpg

What are you using to aim your iPhone to the right area in the sky?



#13 astrshdr

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Posted 11 January 2023 - 04:41 AM

What are you using to aim your iPhone to the right area in the sky?

I initially set the exposure time to ~0.1s and ISO ~5000 then aim by eye.

 

Pleiades I can see even in the city centre—and for the Andromeda galaxy I roughly aim between the Cassiopeia and Andromeda constellations. The Andromeda galaxy is visible even on a 4s test exposure in a B9 (iPhone 13), but I can't see it by eye.



#14 GeezerGazer

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Posted 14 January 2023 - 12:54 AM

Hi,
I've used the Long Exposure Mode in NightCap for iOS since 2017;  I've also tried Nocturne, Even Longer, Halide, Spectre and Reflex apps, but I'm hoping for more.  Here's a link to my small gallery of phone photos taken with either NightCap or Nocturne using just the phone or with supplemental optics.  The optical system used for each photo is listed below the image:  

https://www.cloudyni...-phonetography/

I've read your posts about AstroShader (AS) and it looks like you've done a lot of work to create it.  I am willing to be a Beta Tester and help if I can, but I have some testing to do on a different project first; by late February, I should be able to assist.  In the meantime I do have questions. 

 

1.  If exposure is set to 4s in AS, is it actually taking a 4s single photo or is it taking 4 x 1s photos?  The reason I ask is that iOS has always imposed a 1s (or less for older iPhones) limit for photo exposures.

2.  Can AS benefit from using RAW or HDR?    

 

3.  Does use of a tracking mount benefit the stacking/alignment process in AS?

 

4.  During the stacking/alignment process, are individual photos being averaged to help eliminate noise?  

 

5.  What is the highest practical ISO that can be used with AS?  

 

Thanks in advance, 

Ray



#15 astrshdr

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Posted 14 January 2023 - 12:53 PM

Hi,
I've used the Long Exposure Mode in NightCap for iOS since 2017;  I've also tried Nocturne, Even Longer, Halide, Spectre and Reflex apps, but I'm hoping for more.  Here's a link to my small gallery of phone photos taken with either NightCap or Nocturne using just the phone or with supplemental optics.  The optical system used for each photo is listed below the image:  

https://www.cloudyni...-phonetography/

I've read your posts about AstroShader (AS) and it looks like you've done a lot of work to create it.  I am willing to be a Beta Tester and help if I can, but I have some testing to do on a different project first; by late February, I should be able to assist.  In the meantime I do have questions. 

 

1.  If exposure is set to 4s in AS, is it actually taking a 4s single photo or is it taking 4 x 1s photos?  The reason I ask is that iOS has always imposed a 1s (or less for older iPhones) limit for photo exposures.

Yes exactly - unfortunately there is a hardware API limitation. So if you choose 4s you will capture 4x 1s exposures where AstroShader stacks the raw sensor data. My thinking was to de-noise as high up the imaging pipeline as possible, and after testing different approaches this seemed to achieve the best results.

 

2.  Can AS benefit from using RAW or HDR?

The image data is captured in raw for each exposure (e.g. x4 1s images to make a single sub), then de-bayered into 16bit colour image data in order to align the images for stacking between subs. The final image is saved as a 16bit tiff, obviously not as good as raw but this is after alignment and stacking.
I could add a feature to save each sub as a raw, although this would slowdown the capture process, and users could easily use all available disc space on their phone, haha.
I'm also looking into a crazy feature that creates the final output image (e.g. all the aligned stacked subs) as a raw file... But this needs a bit of experimentation before I even know if it's possible.

 

3.  Does use of a tracking mount benefit the stacking/alignment process in AS?

Yes definitely. Depending on use of a telescope or without your subs are going to be <4s. My early testing with a SkyWatcher AZ-GTi in AZ mode I could get 25s subs without trailing in the output image. I'm sure someone with better kit could get this much higher.

 

4.  During the stacking/alignment process, are individual photos being averaged to help eliminate noise?  

Yes exactly. Using your 4s sub example and let's x150 subs the imaging pipeline works a bit like this: Start by capturing a single x4 1s sub as above, debayer, repeat to capture a second sub, then align and stack these 2 images, then capture a 3rd, align and stack and repeat 150 times. The final image will be the result of aligning and stacking 150 subs, with each sub being x4 stacked 1s. This all happens live during the capture - iPhone GPU getting a major work out.

The raw data from the sensor is in 14bit (for most iPhones) which I then bump to 16bit when doing all the aligning and stacking, so when editing you can push more detail out.

 

5.  What is the highest practical ISO that can be used with AS?  

Great question. I've found it differs between devices and cameras. On the iPhone13 main camera above ISO ~3500 starts to significantly affect the colour for long image runs, I assume from mostly dark current/thermal noise. However I've noticed the effects are very homogenous throughout the sensor area, so I have used ISO 7000 for a few captures and managed to recover the image a bit by altering the camera white balance and editing the colour heavily.

 

Thanks in advance, 

Ray

Great thanks Ray - that would be very much appreciated!

Great gallery - really shows what you can do with a smartphone these days!

 

I've tried to provide some answers to your questions above. Shout if you want any more info!


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#16 GeezerGazer

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Posted 17 January 2023 - 06:34 PM

Thanks so much for your explanations; they are very helpful in understanding how AS can be used effectively.  If I understand correctly, one exposure of 30s will take 30 photos and will average, align and stack them.  If I set AS to take three 10-second photos that are averaged, aligned and stacked, it is still taking 30 images.  Correct?

 

The NightCap app, is doing a very similar process in Long Exposure mode, but requires a tracking mount because it averages photos without aligning them.  However, NightCap does provide options for raising image brightness in two ways.  First, it uses a mechanism to double or triple the highest iSO (ISO Boost in Settings), that can be set (Off, Low or High).  Second, in the iOS camera app, changing screen brightness does not effect the exposure of a photo.  But in NightCap, changing image brightness in the Settings menu, does change the brightness of the image that is taken.  I don't know how these two mechanisms manage to increase image brightness, but I find both mechanisms to be of great value.  

 

Often, using my 5" ED refractor, I am working with ISO of 20,000 to 32,000 in NightCap.  For many objects, I can barely see them on the iPhone's screen without boosting the ISO, screen brightness, and maxing out the 1s exposure.  I find that even at ISO 32,000, most of the sensor/electronic noise can be cancelled out with longer averaging of 25-40s.  

 

I'm looking forward to using AstroShader in February when weather begins to clear in Calif.  Thanks. 

Ray



#17 Domdron

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Posted 26 January 2023 - 01:05 AM

Hi. I'm new to telescopes / astrophotography and was intrigued to find this. Thank you for this nice app!

 

I've started playing around with it, but seeing your results with a SkyWatcher 130P, I can clearly do better lol.gif  (I've got the 150P). I didn't realise that one could use multi-second exposure time without getting blurring, will try that next for Orion.

 

Anyway, here's my first tries (all a bit post-processed in the iPhone photo editor) -- Orion, Pleiades, Moon. The moon was a single shot only, the others multiple and stacked. 

Attached Thumbnails

  • IMG_4642 2.jpeg
  • IMG_4644.jpeg
  • IMG_4656.jpg

Edited by Domdron, 26 January 2023 - 01:06 AM.

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#18 astrshdr

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Posted 29 January 2023 - 06:39 PM

Thanks so much for your explanations; they are very helpful in understanding how AS can be used effectively.  If I understand correctly, one exposure of 30s will take 30 photos and will average, align and stack them.  If I set AS to take three 10-second photos that are averaged, aligned and stacked, it is still taking 30 images.  Correct?

 

The NightCap app, is doing a very similar process in Long Exposure mode, but requires a tracking mount because it averages photos without aligning them.  However, NightCap does provide options for raising image brightness in two ways.  First, it uses a mechanism to double or triple the highest iSO (ISO Boost in Settings), that can be set (Off, Low or High).  Second, in the iOS camera app, changing screen brightness does not effect the exposure of a photo.  But in NightCap, changing image brightness in the Settings menu, does change the brightness of the image that is taken.  I don't know how these two mechanisms manage to increase image brightness, but I find both mechanisms to be of great value.  

 

Often, using my 5" ED refractor, I am working with ISO of 20,000 to 32,000 in NightCap.  For many objects, I can barely see them on the iPhone's screen without boosting the ISO, screen brightness, and maxing out the 1s exposure.  I find that even at ISO 32,000, most of the sensor/electronic noise can be cancelled out with longer averaging of 25-40s.  

 

I'm looking forward to using AstroShader in February when weather begins to clear in Calif.  Thanks. 

Ray

Hi Ray,

 

Apologies about the delay getting back to you, I've been away for the last couple of weeks.

 

On your first question... A single 30s exposure will capture x30 1s exposures and stack the raw sensor data without alignment (as well as doing some other brightness boosting). Then next x3 10s exposures will capture 10s exposures (each of which will made using the previously described unaligned stacking) and then each of the three 10s rgb is aligned and stacked.

 

This sounds like a bit of a strange way of doing things (and is) but is to make the most of the processing resources whilst trying to maximise signal-to-noise ratio.

 

On your second point—that's interesting thanks for sharing. I'm guessing NightCap is adding a gain to the image brightness, I may be mistaken but I believe this is how most of the ISO range in iPhone camera works too, e.g. digital gain rather than true ISO.
Also yes, also definitely get the issue where you can't see most of the target in the preview when shooting until the final image. I guess this is where it falls below the noise threshold for the preview and what we can see vs. a final image with a stretch (or even without sometimes).


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#19 astrshdr

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Posted 29 January 2023 - 06:50 PM

Hi. I'm new to telescopes / astrophotography and was intrigued to find this. Thank you for this nice app!

 

I've started playing around with it, but seeing your results with a SkyWatcher 130P, I can clearly do better lol.gif  (I've got the 150P). I didn't realise that one could use multi-second exposure time without getting blurring, will try that next for Orion.

 

Anyway, here's my first tries (all a bit post-processed in the iPhone photo editor) -- Orion, Pleiades, Moon. The moon was a single shot only, the others multiple and stacked. 

Nice thanks or sharing!

 

Yeah you will do better than me with the 150... Haha

 

For the deep sky targets like Orion nebula and Pleiades if you have a tracking mount you can do >10s subs. If no tracking mount you may need to do <1s subs or whatever the max you can achieve without blurring.


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#20 astrshdr

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Posted 29 January 2023 - 06:56 PM

New super-budget pocket travel setup:

...iPhone13 + 8x42mm monocular + amazon adapter + Joby phone tripod

 

Orion nebula and running man

 

AstroShader settings: 150x 1s, ISO 3500.

Edited with AstroShader (light boost, saturation and sharpen) and iOS Photos

 

IMG_3550.jpg



#21 Domdron

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Posted 31 January 2023 - 12:47 PM

 

For the deep sky targets like Orion nebula and Pleiades if you have a tracking mount you can do >10s subs. If no tracking mount you may need to do <1s subs or whatever the max you can achieve without blurring.

Ah ok, thanks, I thought you were taking those 10s untracked. I don’t have a tracking mount. But from your other post I understand that there’s no alignment within „single“ >1s exposures, even if they’re really multiple exposures.



#22 astrshdr

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Posted 31 January 2023 - 06:42 PM

Ah ok, thanks, I thought you were taking those 10s untracked. I don’t have a tracking mount. But from your other post I understand that there’s no alignment within „single“ >1s exposures, even if they’re really multiple exposures.

Yes exactly—the exposure time per sub (before star trailing) will be determined by the focal length, sensor size, pixel size, etc. I remember reading about the 500 rule for DSLRs (or something like that) but not sure how it could be modified/applied to imaging with a phone through an eye piece.

 

I've found untracked deep sky targets to be a little fiddly with my 130P due to not being able to take long enough subs as the target moves in combo with being in a B9. It might work better from a darker site.

...I think AstroShader could also have some nicer features for stacking images when untracked. e.g. selecting from a library to stack after taking them to counter the shorter exposures available


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#23 Leafus

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Posted 01 February 2023 - 11:32 AM

I've downloaded AS and still not had a chance to use it, but interesting topic above. I already commented a few things on the previous smartphone thread but a few more questions/observations, if I may.

 

1) It does seem a bit odd to let the iPhone stack 4 shots (4x1s) to get a sub. I assume that the iPhone does not align and stack as well as Astroshader?

 

So if AS stacks better, then would it not be better to only let the iPhone do its 1s shot then AS does all the stacking? Please explain (I understand there might be data size issues.)

 

2) Does AS rotate the image to align it? Maybe not an issue if on a short duration, but in 300s the image would show rotation with any Alt-Az and that seems to be the case with the stars in that orion image, some look stretched and that will blur the rest of the stack. 

 

If AS stacked and rotated to align them (maybe a tick box option so EQ mounts don't get the processing overhead) it might improve things quite a bit.

 

3) I found with NightCap that things improved greatly in terms of clarity when dropping the iso to 400 and even 200. Perhaps overdoing the ISO is leading to the stars not being more point-like.

 

The app looks really great and hopefully I'll get a chance to give it an outing.


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#24 GeezerGazer

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Posted 01 February 2023 - 03:43 PM

I've downloaded AS and still not had a chance to use it, but interesting topic above. I already commented a few things on the previous smartphone thread but a few more questions/observations, if I may.

 

1) It does seem a bit odd to let the iPhone stack 4 shots (4x1s) to get a sub. I assume that the iPhone does not align and stack as well as Astroshader?  iPhone's native iOS camera app averages in Night Mode only, but it does not align photos.  AS can do both.  NightCap only averages photos.  Definitions are important in this explanation.  We know that AS is using at least one registration point in each photo to "align" images.  AS can also "average" several photos to eliminate noise in the final image, similarly to NightCap.  To me, "stacking" photos is a more vague term, that may or may not involve averaging or aligning multiple photos.  Some users call what NightCap does as stacking photos, but it only averages them, which is effective for eliminating electronic noise.  

 

So if AS stacks better, then would it not be better to only let the iPhone do its 1s shot then AS does all the stacking? Please explain (I understand there might be data size issues.)  In AS, settings permit the user to average longer exposures (up to 1s) at higher magnifications from a tracking mount only.  If using a non-tracking mount, shorter exposures of <1s (less than 1s) must be used depending on the magnification to prevent trailing.  In this way, AS allows better results from a tracking mount... like NightCap.  The benefit of AS is that the tracked subs with a longer exposure can then be aligned.  

 

If using a stationary mount, depending on the magnification being use, exposures must necessarily be kept very short to prevent trailing in each frame.  For a stationary mount, ISO will need to be set higher to accommodate the very short single frame exposures.  If the single frame exposures show star trailing, the aligned final image will also show trailing.  

 

2) Does AS rotate the image to align it? Maybe not an issue if on a short duration, but in 300s the image would show rotation with any Alt-Az and that seems to be the case with the stars in that orion image, some look stretched and that will blur the rest of the stack.  (If AS is using more than one registration point for alignment, then it is using rotation to align, but I do NOT know the answer to this question.)

 

If AS stacked and rotated to align them (maybe a tick box option so EQ mounts don't get the processing overhead) it might improve things quite a bit.

 

3) I found with NightCap that things improved greatly in terms of clarity when dropping the iso to 400 and even 200. Perhaps overdoing the ISO is leading to the stars not being more point-like.  In NightCap, I have used ISO up to 32,000 with 1s exposures with decent star results.  In NightCap, the higher the ISO, the longer averaging needs to occur on a tracking mount, up to about 45s on my alt/az iOptron AZMP.  

 

If using a stationary mount, then longer averaging is not an option because NightCap does not align frames... from a non-tracking mount, short exposures with very short periods of averaging are necessary, AND higher ISO is not a good option because it increases electronic noise that cannot be averaged out of the final image in shorter intervals of averaging.  

 

The app looks really great and hopefully I'll get a chance to give it an outing.

Hi Leafus,

Thanks for posting your questions... they seem like a good opportunity to see if I have understood what AS actually is capable of doing.  So I've answered some of your questions above in red (hoping my answers are correct).  I know NightCap quite well... just starting to understand AS.  I cannot answer your question #2 though, because I do not know how many registration points AS uses to align photos.  

 

I will begin to use AS very soon, using the iPhone's optics and with the phone attached to my telescope on my AZMP mount.  I know from experience with NightCap, that using the phone at magnifications higher than about 10x becomes exponentially difficult, without a tracking mount.  Without tracking, individual exposure times are necessarily kept so short that it limits photos to the brightest subjects.  Tracking permits longer exposures and the accumulation of multiple photos to average out electronic noise.  But as subjects become increasingly dim at higher magnifications, even with a tracking mount, they reach a threshold where exposure times and/or ISO cannot be pushed higher.  

 

I too, am looking forward to using AS.  I think AS has expanded the capabilities of phonetography, but testing is the only way to find out.  

 

I hope astrshdr can confirm or correct what I've written above.  I just want to make sure I understand correctly before I start using AS.  

Ray


Edited by GeezerGazer, 02 February 2023 - 12:28 AM.

  • brroberts, Leafus and astrshdr like this

#25 GeezerGazer

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Posted 02 February 2023 - 02:16 AM

A couple of observations.  I haven't started taking astro photos yet... weather in N. Calif has not been helpful.  But, I have opened the app and taken several photos indoors to familiarize myself with the controls.  

 

First and foremost, I find the app controls and settings very intuitive; the photo editing tools are also very easy to use.  It seems to be a far better user interface than NightCap.  

 

Second, I set it up to take several multi-second photos and moved the phone on the tripod slightly between the exposures.  The alignment function performed very well.  The final image was in perfect focus with no blurring.  Bravo!  

 

Third, I like that the settings are held/maintained between completed photos.  They appear to be lost if the app is closed... so it will be important to keep track of what settings perform best for astro subjects.  

 

Finally, the exposure must be reduced to about 1/10th second (0.1 secs) before manual focusing can be accomplished without the 1 sec delay of a longer exposure.  So if you are planning a multi-second exposure, first put it on 0.100 or perhaps 0.200 sec before attempting focus.  After focus has been set, the appropriate exposure setting for the image you want to take can be made.  However, when I first opened AS, I was able to focus manually.  Later, a note appeared above the focus slider that read, "Focus: Fixed for this camera type" which seems to have locked the focus slider so that manual focusing is impossible.  I'll have to see if the fixed focus is perfect for infinity.  

 

I'm looking forward to getting this app out with my scope, under the stars!




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