New ZWO issue

[Jpr78]

Just got a new ASI183GT and got out last night to take some test shots. I pointed my scope at the pelican nebula and went for a 120s exposure with gain at 400 using OIII. Absolutely nothing came out of the image except some Amp glow on the right and what looks to be dead pixels? At first I though they were stars so I stopped my mount tracking and took another exposure and they were all still in the same spot no trails. Tried again with the cover on my scope and same result. Did I receive a dud? Seems like something should have showed up. I am already missing my DSLR and wondering if forking over hard earned cash was worth it lol.

[Adam J]

11 minutes ago, Jpr78 said:

Just got a new ASI183GT and got out last night to take some test shots. I pointed my scope at the pelican nebula and went for a 120s exposure with gain at 400 using OIII. Absolutely nothing came out of the image except some Amp glow on the right and what looks to be dead pixels? At first I though they were stars so I stopped my mount tracking and took another exposure and they were all still in the same spot no trails. Tried again with the cover on my scope and same result. Did I receive a dud? Seems like something should have showed up. I am already missing my DSLR and wondering if forking over hard earned cash was worth it lol.

 

I would think that gain 120 would be the better option gain 400 is way way too high! Remember gain is not the same as ISO. I would also be going with 5min subs at least at gain 120. Offset 8 is too low try 50 maybe.

Also OIII is very weak. Better to frame the nabula in HA first to confirm that you are pointing in the right place and then after that switch to OIII. Sometimes you will only see weaker OIII after stacking and not in single sub frames.

Have you plate solved the image to confirm that you are actually pointing at the target? The pelican nabula has a bright star next to it and I dont see it in that image.

 

Adam

Edited July 26, 2020 by Adam J

[fwm891]

I'd go with @Adam J on this 400 is too high. I use 122 gain and 30 offset. Not the same ASI camera model. Like Adam I'd shoot with a different filter (luminance) to confirm target and framing before captuing weaker photons.

Edited July 26, 2020 by fwm891

[Craney]

Yes, the Oiii is much weaker than the Ha.

These were taken with the same rig on the same night, same exposure  (30mins)  .... not a ZWO camera though.

Ha left, Oiii right.

 

[SamAndrew]

Sounds like you're miles out of focus - how did you focus? it's very easy to miss the focus spot if you're moving the focuser all the way through it's travel trying to find the focus point.

[Jpr78]

The image I posted was with the cover on the scope. The white pixels are making me nervous.

[TerryMcK]

I use a gain of 111 (unity) on my 183 with an offset of 8. I didn’t know it could get beyond 270 and 400 is way too high.

Amp glow is a “feature” of CMOS cameras and can be easily calibrated out as can hot pixels.

Edited July 27, 2020 by TerryMcK

[Adam J]

10 hours ago, Jpr78 said:

The image I posted was with the cover on the scope. The white pixels are making me nervous.

Some hot pixels are totally normal. Especially if you are using very high gain. 

Edited July 27, 2020 by Adam J