esprit 120ed My first images with circles??

[MHaneferd]

Hi. Newbie question here;
I have just purchased a Skywatcher Esprit 120ED triple APO, and an ASI120mini, and today an ASI2600mc.

I first tried the ASI120mm mounted, and took some shots at the pinwheel galaxy a couple of days ago. I got a dot in every photo as you can see, but didn’t bother since I was waiting for the ASI2600.

Then, today I tried out the ASI2600mc (in daylight and cloudy wheather), and I got similar dots. I tried to clean the front of the scope, the flattener and the asi2600mc, but the dots keep coming. How do I get rid of them??

 

ASI120mm:

 

ASI2600mc:

[steppenwolf]

If you capture Flat frames and calibrate your images using these Flats then not only will your images be better balanced across the field of view but the shadows caused by the dust particles will also be removed. Assuming that you used filters, did you clean these as well?

[MHaneferd]

Thanks for answer.

For the ASI120 photo, I did not use filter. For the ASI2600, I tried with one filter and no filter. Same spots.
 

Are those rings created by dust? They seem so perfect round. I tought dust was more blurry.

[MHaneferd]

I did a new cleaning of the camera and the filter. Now I have everything on side, bright light and a magnifying glass… I really struggle to get all dust grains off, but I felt I was getting somewhere now..

It is still cloudy (will be that for the next 14 days), so it was blank photos. I notice that the  spots are more visible with long exposures. I took 1sec (no dots), 30 sec (faint dot upper left), 300 sec (clearly visible dot upper left.) Also moved the scope angles, but the dots where at same spots.

So, I guess I have to learn shooting flats?? 😳

asi2600mc, 1 sec (no dots):

 

Asi2600mc, 30 sec (nearly visible dot)

 

Asi2600mc 300sec (visible dot)

 

camera setting for the asi2600mc;

the gear. (I am still waiting for a dove tail to fit the asiair to, so it is a bit messy now). High angle to polar star (61degrees), since I am in Norway.

 

[tooth_dr]

10 minutes ago, MHaneferd said:

So, I guess I have to learn shooting flats??

As Steve says above, flats not only remove these dust motes, but will make it so much easier to process your data.  I dont think you will have much trouble learning to take them. You could use the sky with a white t shirt over the end of the scope, or even an iPad/tablet, or buy a cheap tracing panel, and just do some research into how to take flats in your capture program.  I'm not sure what you are using, is it NINA?

[MHaneferd]

7 minutes ago, tooth_dr said:

it NINA?

No, I am just using ASIAir for now. I have not dived into photo editing programs….yet. I do have Adobe photoshop and lightroom, which I use for «ordinary daytime photos». 
But, I’ll check out NINA. 
Thanks.

[tooth_dr]

52 minutes ago, MHaneferd said:

No, I am just using ASIAir for now. I have not dived into photo editing programs….yet. I do have Adobe photoshop and lightroom, which I use for «ordinary daytime photos». 
But, I’ll check out NINA. 
Thanks.

No worries. I dont use ASIAir, but NINA is just another program that is used to capture data, it's not an editing software.  I only asked because some capture programs help you to calculate the correct exposure for your flats.  I used APT and SGPro, and both make flat taking easy.

[tomato]

Unless you assemble your filters and imaging kit in clean room conditions you will get dust particles, it’s the ones on the camera sensor window which cause the black and dark circles. But it’s not a problem, properly taken flat calibration frames, as described above, will remove them.

You have an impressive equipment set up, may I suggest that if you are just getting started, please get a copy of “Making Every Photon Count” written by Steve Richards, @steppenwolf here on SGL, who posted earlier. It covers all of the required knowledge and techniques needed to carry out successful Astrophotography, definitely the best purchase I made in the first 6 months of starting out on imaging.

[Padraic M]

Fully agree with what the guys have already said - flats are an essential part of processing astro images, and aren't hard to do once you understand the process. All of the stacking software packages support applying flat frames.

You have a really impressive setup there! But, be really careful with all of that cleaning! You really don't need to clean optics or cameras AT ALL and are much more likely to do damage than to fix the problem. I've never cleaned mine. We all get spots and circles just like those on our images.

Flat frames are the solution to dirt, dust and shadows that can come from all sorts of sources, including dust, internal reflections, vignetting, etc.

[MHaneferd]

Thank you all for the answers. I really appreciate the help!

@tomato Thanks for the advice. I just ordered it from FLO. Also added in a book on preprosessing: «Dark Art or Magic Bullet» by Steve Richards.

Best regards,

Martin

[Adam J]

13 hours ago, MHaneferd said:

Thanks for answer.

For the ASI120 photo, I did not use filter. For the ASI2600, I tried with one filter and no filter. Same spots.
 

Are those rings created by dust? They seem so perfect round. I tought dust was more blurry.

Yes that is dust the size of the circle suggests on the filter. 

[steppenwolf]

1 hour ago, Adam J said:

Yes that is dust the size of the circle suggests on the filter. 

Yes, this is where I think the dust is too but if you could attach an unprocessed FITS file of the second image in your first posts (VASI2600mc), I can calculate pretty accurately where the dust mote is.

[MHaneferd]

7 hours ago, steppenwolf said:

Yes, this is where I think the dust is too but if you could attach an unprocessed FITS file of the second image in your first posts (VASI2600mc), I can calculate pretty accurately where the dust mote is.

Thank you @steppenwolf !! That is quite cool!! How do you do that??

 

I did not find the actual frame, but I took several turning the mount over and up/down, so attached a similar, same night- This is the preview image.

The original FITS (It is quite big!!

Preview_10.0ms_Bin1_1.fit

 

This is preview of another noe after trying my best to remove the dust. This one, I used binning (Bin4) Still have a spot in upper left:

Full FITS file (Bin4):

Preview_30.0s_Bin4_3.fit

 

[steppenwolf]

Unfortunately, I cannot find any artefacts or any other visible data for that matter, in the larger FITS data file you have uploaded so I can't do the analysis on it. If you process it, are you seeing the artefacts? If so, please do process it and save it FULL size, no cropping as a JPEG file, upload it here and I'll have another go!

Unfortunately, I am running out of time right now as I have an appointment with a surgeon and some sharp blades tomorrow afternoon so there may be a short delay in getting the distance results back to you! 😮

 

[MHaneferd]

Wow... Please just relax and make yourself ready for surgeon. I can wait, no need to rush.. The stars out there will probably be there next week also 🙂

I struggled a bit to find a program that could take one FITS file and save it to JPG. Many programs only displayed grey, and not the FITS image. The ASIFitsView from ZWO only views the file... Anyways, I found one software; "KStars FITS Viewer". That one displayed the FIT'file correctly and made it possible to save the file to both JPG and PNG. I uploaded both:

JPG (4.5 MB):

PNG (35.2 MB):

 

 

[steppenwolf]

Thank you for uploading those images. I make the distance from the sensor to the dust to be between 12.25 and 12.5mm.

I hope that helps you identify its location - surprisingly, this makes it more likely to be the cover glass than the filter.

It would be useful if someone else could confirm my findings!

[MHaneferd]

12,5 mm is exact at the protective glass of the sensor as I can see it. It also confirm some of my cleaning work, as it was the protective glass that had most particles on it.

I suspect that when I turn the filterwheel, it might whirl up and add additional dust since I must have 60+ degrees on polar alignment (Live up north) (Which also make the scope tilting upwards alot, and so making the sensor protective glass as a dust collector 😳 )

Here is the camera spec: 

I had to remove the 5mm on top to be able to attach the filterwheel:

[steppenwolf]

1 hour ago, MHaneferd said:

12,5 mm is exact at the protective glass of the sensor as I can see it. It also confirm some of my cleaning work, as it was the protective glass that had most particles on it.

I love it, my method works!! 🤣 Thanks for the confirmation and at least you know now where to direct a blast of clean air from time to time!