M 82 LRGB

[wimvb]

Yesterday started promising. But when I had set up my gear, clouds started moving in from the South East. Nothing else to do but pick a target to the North: M 82.

Still testing my new setup, since astro darkness is only 2 hours between midnight and 2 am. (Can't start alignment till after 9.30 pm, due to lack of visible stars.)

Lum: 100 x 15 secs

RGB: 50 x 15 secs each

Camera: ASI 174MM-Cool @ -10C, gain 75, offset 15

200 bias, 100 darks, no flats

No guiding.

In retrospect, with these camera settings I could probably have doubled the exposure time, to get better SNR.

Processed Lum and RGB separately in PixInsight, then combined Lum with a- and b-components of RGB image in L*a*b mode.

(click on the image to enlarge)

[Allinthehead]

That's a nice start with your new camera.

[wimvb]

Thanks Richard.

I'm quite pleased with the camera, despite some shortcomings (amp glow mainly, but that can be calibrated out). It allows me to automate my imaging, and is a LOT faster than my DSLR. Hopefully by the time the nights get longer, I will have figured out how this camera works, and if I should go for loads of short exposures or fewer but longer exposures. I've seen good results with both techniques.

[Allinthehead]

My advice is go for longer exposures. As a user of the asi 1600 the short exposures are a pain. I had a recent image with over 900 subs and it took a crazy amount of time to stack/calibrate. I'm going to use minimum 60 second exposures with mine. Longer when possible. Longer exposures at lower gain should be easier to calibrate out the amp glow. With my camera it wasn't always possible to remove completely.

[gorann]

Yes, good start Wim. I have not bothered yet. Want more than two hours - I would most likely mess up the first one anyhow especially now when I am out of training.

Is the reddish tint on the right side amp glow?  I thought that would be taken out by the bias and dark frames, or is it just a sky gradient? I think I also see some vertical banding.

[wimvb]

Thanks, Göran.

I agree that 2 hours is too short. But I have so many modifications that I have to test/learn, and clear moonless nights are rare.

The reddish background nay very well be the last remains of amp glow. Darks take care of most, but I need to clean up the rest with dbe. There is also a read pattern, mostly horizontal stripes. These can be cleaned up in processing. But as @Allinthehead already noted, you get cleaner results with longer exposures. Next step will be to add guiding. But I don't know how indi will react to two asi cameras connected to the same computer. More testing to do. Hopefully, I will have sorted things out when real darkness comes.

[gorann]

What made you decide on the ASI 174MMC? The large pixels?

[Barry-Wilson]

Showing lots of promise Wim.  These newer cmos cameras really are becoming popular . . .

[wimvb]

3 hours ago, gorann said:

What made you decide on the ASI 174MMC? The large pixels?

 

2 hours ago, Barry-Wilson said:

Showing lots of promise Wim.  These newer cmos cameras really are becoming popular . . .

For such a short time on target and considering the absence of darkness plus a healthy dose of LP in suburbia, I'm quite pleased with the result. But I will need to add guiding.

The reason(s) I bought this camera is a combination of pixel size (5.86 um, 1.6 "/pixel), dynamic range, chip size and price. I did consider Atik for a while, but with filters and wheel, those were over my budget. The amp glow is something I can handle. Although the equivalent qhy model has built in amp glow reduction, I wasn't convinced it would work with indi/ekos.

This image also proves that my diy focuser works. (Autofocus based on a geared dc motor. Lots of backlash, but ekos seems to handle that just fine.) And unfortunately it shows that I have to adjust the spider vanes in my 150PDS.

[Gina]

These CMOS cameras work well with short exposures and high gain.  I haven't used the ASI174MM for DSO imaging - mine is an ASI1600MM-Cool.  Also, my experience with the ZWO camera is with NB and I've been using around 60s with the gain set at 500-600 (= 50-60dB).  I do have an ASI174MM but for Ha solar imaging - haven't used it yet due to lack of sunshine.

[wimvb]

1 hour ago, Gina said:

These CMOS cameras work well with short exposures and high gain.  I haven't used the ASI174MM for DSO imaging - mine is an ASI1600MM-Cool.  Also, my experience with the ZWO camera is with NB and I've been using around 60s with the gain set at 500-600 (= 50-60dB).  I do have an ASI174MM but for Ha solar imaging - haven't used it yet due to lack of sunshine.

I take inspiration from Jason Guenzel

http://www.astrobin.com/users/Thirteen/

His images from before June 2016 are taken with the ASI 174MM-C

http://www.astrobin.com/228415/?image_list_page=3&nc=&nce=

He uses the camera as you would use a dslr: guided long exposures at low gain.

I think you can use this camera either way. Longer exposures will suffer more from amp glow, shorter from read patterns (horizontal lines).

I'm still testing. Which, as for you, is going slow due to clouds.

[Gina]

Yes, I have seen these cameras used both ways.  The ultra low read noise means these cameras can be used with many short exposures at high gain which you can't do with a DSLR due to high read noise.  I have yet to image galaxies with the ZWO cameras as the last galaxy season was clouded out.

[MartinB]

You've got some very nice Ha data there despite the short exposures

[wimvb]

48 minutes ago, MartinB said:

You've got some very nice Ha data there despite the short exposures

Yes, and no Ha filter in sight. But there is an empty slot in my filter wheel waiting to get filled with one. I plan to go the HaRGB route.

[wimvb]

A reprocess with deconvolution of both RGB and L. In the LRGB combination I pushed the saturation to 0.3 (PixInsight)

Just about overcooked for the limited amount of data, but LRGB data can be pushed much more than DSLR data.

I'll definitely return back to this galaxy. If those .... clouds will ever go away.

(click to enlarge)