Astrophotography

3239 readers

1 users here now

Welcome to !astrophotography!

We are Lemmy's dedicated astrophotography community!

If you want to see or post pictures of space taken by amateurs using amateur level equipment, this is the place for you!

If you want to learn more about taking astro photos, check out our wiki or our discord!

Please read the rules before you post! It is your responsibility to be aware of current rules. Failure to be aware of current rules may result in your post being removed without warning at moderator discretion.

Rules

I | Real space images only.

Astrophotography refers to images of astronomical objects or phenomena exclusively.
~~Images that show objects or people below the Kármán Line (100km) will be removed.~~ We won't be enforcing this rule for now, but as the community grows eventually we will split and have a separate space for just landscape astro.
Images must be an accurate representation of a real astronomical object.
See this page for more details

II | Original and Amateur Content Only

Image posts can only be images that you have captured and processed yourself, or discussion about capturing and/or processing your own images.
Images acquired from public sources, professional observatories, or other professional services are not allowed.
If you have done a drastic alteration or reprocessing of a prior submission, you may repost your edit - but only after a minimum of one week has passed.

III | Post Types

Image posts are to link directly to the image, not to landing pages, personal galleries, blogs, or professional sites. Link to these in the comments. (AstroBin and Imgur, are allowed)
Questions are welcome here for the time being.
Links to blogs, articles or external websites should be interesting and promote discussion about amateur astrophotography.

IV | Titles

All image posts should just include include the name of the object being photographed. Extra info such as equipment, it being your first image, or other information should go in a comment along with your acquisition info. Please see this page for more details.

If your post is removed, try reposting with a different title. Don't hesitate to message the mods if you still have questions!

V | Acquisition and Processing Information

All submitted images must include acquisition and processing details as a top-level comment. All posts without this information may be given a warning, and if not updated will be removed.
This includes the telescope, mount, camera, accessories, and any other pieces of equipment you used to capture the image.
You must also include processing details, i.e. the programs you used and a general rundown of the workflow/processes you used within those programs. “Processed in Photoshop” is not enough.

founded 2 years ago

MODERATORS

bigborpa@lemmy.world

lefty7283@lemmy.world

Awful (walking?) noise (feddit.org)

submitted 1 month ago* (last edited 1 month ago) by Linsensuppe@feddit.org to c/astrophotography@lemmy.world

6 comments fedilink hide all child comments

I recently took some pictures of Andromeda with a SA-GTI and a lumix g85 with the lumix 100-300mm, but the noise of the final image is really bad. Here is the first picture taken with a total of 2.5 hours (315*30s):

With this noise, I thought it was waking noise due to the almost perfect polar alignment. Since I don't have a dedicated computer and autoguider to dither, I just did it manually by moving the axis of the mount a bit to move the object on the sensor every half hour. For reference, the object stayed within the center cell of the grid of thirds, so I'd say I moved it a few hundred pixels every time in different directions. Here is the result (293*30s):

(Both pictures are processed in siril with green noise removed at the end) The noise stripes are smaller, but there is still a lot of noise in my opinion. It this due to the sort total exposure, or might it be walking noise? How can I reduce the noise without buying new equipment?

top 6 comments

sorted by: hot top controversial new old

[–] Thorry@feddit.org 4 points 1 month ago* (last edited 1 month ago) (1 children)

I don't think this is walking noise, that would result more in a blur across the image. This seems like you are pushing the sensor too much and its noise to signal ratio is getting poor. How many darks did you do? And how many light at what settings? I think you should decrease the gain and compensate with longer exposures. However this will increase how much the alignment matters.

My suggestion would be to bite the bullet and invest in a small guide scope with a cheap sensor. Make sure the guide scope is very fast, that way the sensor can be fast and cheap.

[–] Linsensuppe@feddit.org 2 points 1 month ago* (last edited 1 month ago) (1 children)

I did both of the images with ISO 1600, 30 sec. exposure and F7.1. My camera and lens are able to go to ISO 25000 and F4.9 at the focal length. For the first image I did 50 calibration frames of each darks, biases and flats, and for the second image 30 of each

I've had success with way worse settings. This was taken with ISO 6400 and F6.4: https://lemmy.world/post/25110033 Could it be the difference in exposure? Maybe ~1000 images at 5s is better than just 300 at 30s?

[–] Thorry@feddit.org 2 points 1 month ago

Hmmm yeah it's probably something internal to the camera that's not playing nice at 30 secs. Maybe the sensor getting too hot or a noise reduction system which isn't handling the long exposures.

Maybe 10 or 15 secs will fair better? Pretty sure the issue is camera noise, not the alignment.

[–] lefty7283@lemmy.world 1 points 1 month ago (1 children)

Are you moving the mount in just one axis? Or doing both RA and DEC movements at the same time? You might also want to dither more frequently, especially with how many 30” subs you can get in a half hour. Even that amount of walking noise will add up

[–] Linsensuppe@feddit.org 1 points 1 month ago

I did both axis every time, not following any specific pattern.

[–] skull@masto.ai 1 points 1 month ago* (last edited 1 month ago)

@Linsensuppe Been through that same experience with a "plain" SA, meaning motor only on RA, also meaning no chance of dithering:
https://masto.ai/@skull/113044962915561285

That it is walking noise indeed.

Later moved to an AM5N: autoguiding and dithering made it all go away, with same camera and lens 🤷‍♂️