What is going wrong here?

[AstroBogan (Jacob)]

Hi all.

Having issues with calibration frames (never has been an issue before).

Not sure what is causing my picture to look all messed up as the flats I took look relatively legit and the darks are just from a dark library I built.

Does anyone know what could have caused the image to resemble what it does? Not sure why it became even more grainy and the dust particles look even deeper and darker than without the flats added.

I took my flats immediately after the Lum data with a white t-shirt and a laptop screen over the top of the scope.

Any ideas?

I feel like I have some nice data (besides the collimation) and I want to get to the bottom of this.

FYI: Image best viewed at 50%-33%.

cheers,
Jacob

[Karlzburg (Karl)]

Looks like creases in the shirt

[RyanJones]

Originally Posted by Karlzburg

Looks like creases in the shirt

I'll second that.

[AstroBogan (Jacob)]

Originally Posted by Karlzburg

Looks like creases in the shirt

so if i was to re-shoot the flats it should be ok?

[Saturnine (Jeff)]

It is hard to say what the artifacts are, seems too many to be dust particles and the fact that they are streaked diagonally across the image is curious.
Have you cleaned the camera sensor cover and / or the filters at all recently. Definitely seems to be in the camera , filter system . I would be checking every glass surface in the imaging train to satisfy myself that everything is clean.
Re-doing darks and flats when satisfied all the glass is clean will help tell the story. The image itself looks nicely focused and is showing a nice amount of detail. If and when the dark streaks disappear you should end up with a good image. Good Luck.

[billdan (Bill)]

As long as you haven't moved the camera you could redo the flats.

However may I suggest just redo your processing without any flats first and crop the galaxy to get rid of any vignetting. (If anything it will prove whether or not creases in the T-shirt caused this issue).

Cheers
Bill

EDIT: How long have you had your ASI1600? I mention this because people over on Cloudy Nights who have had the camera for 18 months are now seeing rivers of dew forming on the sensor, as the internal desiccants are now saturated and need replacing.

[Saturnine (Jeff)]

That is interesting about dew forming on the sensor because of saturated desiccant because it does look like something slowly moving across the sensor rather than creases in the t shirt affecting the flats.

[billdan (Bill)]

Hi Jeff,

Well lets hope its not internal dew, so he has to pull the camera apart to fix it.

Here is the link if you are interested.

https://www.cloudynights.com/topic/6...1600mm-sensor/

Bill

[RyanJones]

As Bill mentioned, I'd stack it without the flats and deal with the vignetting by cropping and see what result you get. Unfortunately if you've moved the camera or your focus, you won't be able to redo your flats as they require the image train to be in exactly the same position as shot to deal with the artifacts that were present at the time of capture. On that note I found it interesting that you used darks from a file you've created. They also have to be taken during the session because the sensor temperature is part of the cause of false pixels.

It's a great pic. Stack without flats and see how you go.

[Stonius (Markus)]

Originally Posted by RyanJones

I found it interesting that you used darks from a file you've created. They also have to be taken during the session because the sensor temperature is part of the cause of false pixels.

...unless your camera has onboard cooling, which should enable you to achieve the same temperatures at a later time and not waster valuable imaging time shooting darks, correct?

[RyanJones]

Originally Posted by Stonius

...unless your camera has onboard cooling, which should enable you to achieve the same temperatures at a later time and not waster valuable imaging time shooting darks, correct?

Theoretically I guess. I don't pretend to know the myriad variables that contribute to hot or dead pixels but heat is certainly a large percentage of it. With my little understanding ( and I'm happy to be corrected ) I would assume that once a camera is powered down then powered back up again there is the opportunity that different pixels could error ?

[AstroBogan (Jacob)]

Originally Posted by RyanJones

On that note I found it interesting that you used darks from a file you've created. They also have to be taken during the session because the sensor temperature is part of the cause of false pixels.

It's a great pic. Stack without flats and see how you go.

Well I always use darks from a library i created and use the corresponding dark at the same temp/length as the sub. If any new hot pixels come through I just edit them out.
Thanks for the feedback on the image

Originally Posted by billdan

EDIT: How long have you had your ASI1600? I mention this because people over on Cloudy Nights who have had the camera for 18 months are now seeing rivers of dew forming on the sensor, as the internal desiccants are now saturated and need replacing.

Only 6 months. I think it is creases in the shirt as a few people mention as when I stack without flats it's only circles that represent the dust particles that are evident.

On a brighter note though, I've never had better guiding than with my EQ6-R pro!! it was clearly worth the jump from the belt-modded heq5 pro. so bloody smooth and easily holds the weight of my gear!

[rcheshire (Rowland)]

Step-by-step. Troubleshoot by elimination. Use a few light frames to speed things up. First inspect all your subs as well as calibration frames. Flats can be produced synthetically from light frames, if they cannot be redone for any reason... Google... Deconstruct the process.