ZWO ASIAIR Preview function (color / black&white)

Hallthorr

Hi there,

got a short question about the ZCO ASIAIR Preview function.

A buddy of mine and me using nearly the same Astro-Rig
ZWO ASI 533 MC Pro; ZWO ASIAir; RC8" Telescope with 0.6x focal reducer and IR-Cut-Filter

We both did a 1000 Exp Preview on IC1396

This time he used a Skywatcher 70 ED + 0.6x focal reducer (Bortle 3/4)
I used my RC8" + 0.6x focal reducer (Bortle 5/6)

His result:

My result:

What is happening here?

Even my processed 50min Exp (10x 300 sec Lights; 10x 300 sec Dark; 150x 0.001 sec Bias; no flats) of IC1396 don't nearly look like the preview shot... quit disappointing

Stack: DSS with Debayer
Processing: SIRIL (background exctraction / photometric color calibration / stretching) & GIMP

Again -> What's happening, why tho?

Cheers!

johnpd

assume you have gotten color images before with brighter objects such as M8, M27, M42?
In looking at the Preview screen from you buddy, I noticed a couple of differences.
-a. He has the exposure set at 1000s. Was that what he was really using? I can't tell what you were using.
-b. He has stretched the white level back to 5552. Yours is sitting at 11722.
Have you tried opening one of the .FITS files in ASIStudio FITS Viewer? It will do an auto stretch and should give you something.

JohnD

Hallthorr

Hi there !
Thank you for the reply

Reply to 1:
Nope, before IC1396 I tried only M101 in Preview mode and it was B/W as well (I'm a beginner) 😃

Reply to 2:
a.) We booth used 1000 sec Exposure
b.) I've tried several stretching incl. Auto-strech - Nothing happend: Still B/W on the ASIAir Preview-mode

Reply to 3:
This is the 1000sec Preview-Save form the ASIAir opened and autostrechted in the ASIStudio FITS Viewer

Could it be that he have a special (narrowband) Nebular-filter like the Optolong L-eNhance? I've got only the Optolong L-Pro IR/UV-Cut Filter. But even if, IMHO it's still a huge difference between our single shot 1000 sec previews especially in colorization and details.

johnpd

I don't understand why you would want to do a 16min Preview. You should be doing a Live Stack if you want to go that long. You would be getting much more out of it. Galaxies typically end up with little color unless you are doing something like M82.

Since you are a beginner I suggest you start with something like M27 (the Dumbbell Nebula). That is very bright and it should be easy.

Do your polar alignment and focusing. Start the ASI533MC cooler on to "0" or "-10" degrees.
Use "Preview" to go to M27 and use short exposures to make sure the scope is positioned properly.
Wait until the cooler settles to the assigned temperature.
Go to "Live Stack" and set the exposure level to 10 seconds.
Put a cover on the scope and create about 10 darks.
Set the Lights for 10 seconds and select the master dark create by above step.
Start stacking. You can stack about 20 images. That's all it should take for a bright object like that.
Save the stack and open it in ASIFitsView and see what you get.

JohnD

AstroDude42

johnpd if i may add, the main camera‘s gain (in the settings) will also affect the exposure.

And to OP: yes, different filters will give different results.

Hallthorr

Late response: Thank you - That worked very fine for me! 😃