What is possible with very short exposures and a phone

[sorrimen]

Hi all,

So I've recently acquired an 8" dob and have got some decent planetary and lunar images just using my phone and a phone mount. My question today is whether I will be able to get any sort of detail out of DSOs (specifically galaxies) by using 3-5s exposures with my phone. Given that my dob is manual, my strategy would be to realign the DSO each shot or after a couple shots so I could somewhat stack the target itself. Would I need so many shots that field rotation will mess everything up/is an iPhone 12 camera just too poor for DSOs? Let me know what you think and whether this challenge is even possible.

Cheers

Ross

 

P.S. I'm sadly well aware that proper astrophotography needs proper kit, but I'm looking to push the boundaries for what I own and challenge myself, rather than purchase further accessories.

Edited June 25, 2022 by sorrimen
Grammar

[happy-kat]

For some ideas you might like to see what's in this section

https://stargazerslounge.com/forum/283-imaging-challenge-24-android-vs-ios-now-closed/

Field rotation can be cropped away but if exposure isn't short enough the central target can become smeared.

Brighter DSO would be more suitable targets, globular clusters might be fun to try.

[Xilman]

21 minutes ago, happy-kat said:

For some ideas you might like to see what's in this section

https://stargazerslounge.com/forum/283-imaging-challenge-24-android-vs-ios-now-closed/

Field rotation can be cropped away but if exposure isn't short enough the central target can become smeared.

Brighter DSO would be more suitable targets, globular clusters might be fun to try.

Ross:

Note that it is often possible to restore distorted images with software.  Just because it is possible doesn't mean that it is necessarily simple.

In my experience, stacking is almost always best done by first plate solving each sub and then stacking on the WCS (world coordinate system) placed in the header of each sub by the plate-solver. The only exception (again IME) is when there are too few stars for the plate solver to succeed.

I second clusters. Open clusters might be even easier because their stars are generally resolved right the way through.

Good luck, and please report back on what you achieve!

(Added in edit: Actually, I have similar kit here but have never tried DSO imaging with it. Perhaps I should and we could compare notes.)

 

Edited June 25, 2022 by Xilman
Add final para.

[Elp]

My suggestion is always to try with what you have first. From experience, DSOs do need something like at bare minimum 30s exposures to reveal anything (star clusters can be captured in sub 10s exposures usually), ive used a 60mm refractor, 130pds and a C6. Only something like Orion nebula and possibly Andromeda you can get in sub 10s as they're so bright. Your camera has to be rock steady (ideally fixed to the scope). Galaxies I normally expose for 60s to 120s and stack hundreds of images shooting mono, you likely will capture more photons with your dob so just try it out. Getting more serious with imaging takes some doing and added cost and can be a black hole with your wallet.

[sorrimen]

That's great advice all, I'm actually yet to look for any clusters yet so this should be a nice little challenge and something to look forward to. I've snapped a couple pics of andromeda and M51 (only confirming it was M51 about two days later as it was my first DSO) and as you say there is some blurring, though from a bortle 7/8 it could be worse. 

Also would be thrilled if you tried it out too Xilman! I coincidentally go to university in Cambridge so I imagine we'll be observing from a similar area some of the time.

 

Edited June 26, 2022 by sorrimen
Fixing images

[Xilman]

4 hours ago, sorrimen said:

That's great advice all, I'm actually yet to look for any clusters yet so this should be a nice little challenge and something to look forward to. I've snapped a couple pics of andromeda and M51 (only confirming it was M51 about two days later as it was my first DSO) and as you say there is some blurring, though from a bortle 7/8 it could be worse. 

Also would be thrilled if you tried it out too Xilman! I coincidentally go to university in Cambridge so I imagine we'll be observing from a similar area some of the time.

 

We should meet up for a beer (or intoxicant of your choice) some time. I'm near Cambridge for 2-3 weeks, then off to La Palma for perhaps a month.

Drop me a line.

[OK Apricot]

Just seen this. For what it's worth, these are single 8s exposures on an A52S through a Skymax 127 (I forget the EP used), just tweaked a little with the phone editor. 

[sorrimen]

15 hours ago, OK Apricot said:

Just seen this. For what it's worth, these are single 8s exposures on an A52S through a Skymax 127 (I forget the EP used), just tweaked a little with the phone editor. 

Wow these are incredible and pretty much what I’m after. I’d have to guess that this would be a bortle 5/6 at the very brightest no? Samsungs seem to blow iPhones out the water when it comes to astrophotography usage. 

[OK Apricot]

4 hours ago, sorrimen said:

Wow these are incredible and pretty much what I’m after. I’d have to guess that this would be a bortle 5/6 at the very brightest no? Samsungs seem to blow iPhones out the water when it comes to astrophotography usage. 

Something like B5 yeah and good transparency. I couldn't comment on Samsung vs iPhone - I'm Samsung through and through 😂👍