chriscoles

Thanks for the book recommendation, for now i'm quite happy playing around with PI. May look at books when I get deeper into it.

Made improvements to my image, and because of all the clear nights I have started on the Cigar Galaxy too.

Wim, that's fantastic! Thanks, it shows me what to work towards with my image processing. I only installed PI on the weekend, so looking forward to achieving results like that

I kept trying with  Photometry-Based Color Calibration and got it working, I had incorrect pixel size.

On 12/04/2020 at 23:34, wimvb said:

A rule of thumb that I use is that if the main target looks noisy when only stf applied, but otherwise still linear, then more or longer subs are needed.

Okay, so last night was clear  And I have more subs. I have stacked them again. I also took more darks for good measure.

I combined the channels in Pixinsight, however don't yet know how to bring the colours out...?

Using the gimp I can, though would like to do it all in PI eventually.

I tried Photometry-Based Color Calibration but got errors, see below.?

Getting there... Thanks!

B_new.TIF G_new.TIF R_new.TIF L_new.TIF

9 minutes ago, wimvb said:

A bit noisy. Cmos works best with LOTS of subs. Try to collect at least 100 L subs. You can collect fewer rgb and blur the rgb image before lrgb combination.

My process in short:

• aligned the new r, g, and b masters with the first L master. The newest L has subs that were rotated too much, so I used the old L
• cropped L and R, G, B masters, then applied DBE to all.
• rgb combination

RGB:

• background neutralization
• photometric color calibration
• arcsinh stretch
• desaturated the background with a range mask to protect the galaxy and stars
• convolution 
• saturation enhancement

L:

• deconvolution
• histogram transformation
• hrd compression
• curves transformation

LRGB combination

Okay  Great result! Yes I agree, more subs.

I shall try your process. Still a lot more to learn but I'm getting there.

Thanks for the help, it means a lot!

Given your advice about B and G being the same, i have had more luck with the new DSS generated frames!

Still getting to grips with image processing, so happy to hear more suggestions.

31 minutes ago, wimvb said:

I can't get colour calibration working. The histogram also shows that your R and B masters are identical. Can you check that the stacking process produced the correct output.

Hi, I have generated new LRGB from DSS. As far as I can tell, they are using the correct files.

B.TIF G.TIF R.TIF L.TIF

15 minutes ago, wimvb said:

I can't get colour calibration working. The histogram also shows that your R and B masters are identical. Can you check that the stacking process produced the correct output.

Okay, interesting... I will regenerate them more carefully and repost them. Thanks again!

14 minutes ago, wimvb said:

I downloaded your data, and it seems that you have some calibration and stacking errors. For one, your luminance has an inverted vignetting pattern. Are your calibration files working ok? With cmos cameras, your darks MUST match your lights in temperature and exposure time. If you use 3 different exposure times, you need 3 different darks. Scaling darks doesn't work.

I'm processing your data, and will get back with the results.

Hi, all images are taken at -20. I have dark's for all my light exposure times. 

I will investigate the inverted vignetting, and double check DSS to make sure its using the correct files.

Thanks for you help!

Hi, I have taken mono LRGB images of M51 with my new ASI1600mm-PRO.

I have a mix of 30s, 60s, 120s subs. 100 darks, and 100 flats for each filter. About 4 hours total.

I Used DSS for alignment and stacking, then Pixinsight for LRGB combination.

My issue is that i'm not happy with the colours, the stars all appear white and the background is strange.

I have attached the Aligned LRGB images.

Can anyone point me in the right direction? Thanks!

Green.TIF red.TIF Lum.TIF B.TIF

Hey, thanks for everyones help. So 7 sheets of A3 and 10 second exposure. I have a flat!!

Now I just have to take 20 of each filter! 

🤩

16 minutes ago, tooth_dr said:

Thanks. I ask because my flats looked like that when light was getting in the rear of my reflector. I only takes flats at night now using a screen.  My pc screen works fine, but still needs 4 thicknesses of t shirt stretched over the scope (F2.8)

Something to experiment with. Do you know whether tshirts or paper work better? I may have to go cloths shopping 🤣

2 minutes ago, MarcusH said:

I'm away from home at the moment, but I'll have a look tomorrow to see if I can find some.

 

That's how I've done it too. But remember that monitors usually adjust the backlight by PWM (i.e. switching it on-off rapidly) to fast for the human eye but sometimes not fast enough for the sensor so keep your exposures long.

 

Well what do you know, here was I thinking that I'm the only one with an AST8300 paired to a C11 !!  😄

Thanks! no hurry. I will do some experimenting tomorrow hopefully, providing work hast zapped all my energy. 

Are you getting good results with your setup?

1 minute ago, tooth_dr said:

What scope is it?

Celestron C11 SCT with 0.5 focal reducer and Celestron OAG

4 minutes ago, MarcusH said:

The AST8300 has a mechanical shutter so make sure you have a long enough exposure to avoid shadowing from the moving shutter. Actually the shutter on the AST8300 is the eight position in the filter wheel so the shutter really is s-l-o-w (much slower than the mirror in a DSLR). I usually try to keep my exposures between 5 and 10 seconds to avoid any issues (I have the first gen. A-version) but that means you'll need a adjustable light source.

Thanks, markus, mine is also first gen. Do you have an example flat file you could share so I can compare?

I was thinking of using my PC monitor as an adjustable light source, do you think that would work?

Hi, guys. Sorry but I got a bit confused. Actually VNC did have an impact. This is a screenshot from windows. The image is stretched. 

This is the same 5 second exposure.

The second image shows the histogram range from 35000 to 38000 to try and show dust... but i don't see any. Any thoughts?

Hi, thanks for the replies.

The image was taken in the daytime and and the brightness should be relatively uniform as it isn't obstructed.

Reading about my camera,  AST8300, i put it in the title btw. IT apparently has a slow shutter speed, could the strange effect be the shutter? It isnt VNC, I just opened it locally.

I might bring the scope indoors and use my monitor as a light panel so I can experiment.

Hello, I have only just started taking flats. Below is a 5 second flat, using the white t-shirt method using the sky as illumination.

I have no idea if this image is suitable as a flat, and what the pattern means. Also shown is the histogram. Could somebody explain whats going on in the image and whether I should do anything to improve the process?

Many thanks in advance! 

Hey Geeklee! Thanks to your help, my guiding is all up and running.  The calibration works well with the rates changed to 0.5 and guiding is about 1/2 a pixel accurate. Now guiding is working, I can move on to my other issues

Hey Geeklee, thanks for your reply!! I have read the best practice guide however overlooked the guide rate. I wonder why EQAASCOM defaults to 0.1? I have increased to 0.5 and will try again.

The camera is set up correctly as far as I can tell.

I will update this post when the cloud clears.

Hi There, last night I calibrated PHD2 on my NEQ6. This calibration allowed guiding within two pixels. I think it can do better.

Can anyone see any likely causes of the bad calibration from the image? In particular the strange bump in the DEC.

My equipment is well balanced on bot RA and DEC. The backlash screws are set fairly well, I tried to get it as low as possible while allowing the motors to move freely.

I have a permanent set up in my roll off roof observatory so looking to get this tweaked!

Guide Camera: Celestron Skyris 445C

Guide Scope: 50mm aperture 190mm focal refractor

Main Scope: Celestron C11 SCT

Thanks in advance!