9 replies to this topic

[cal1mero]

I am trying to take a photo from the leo triplet for the first time with my new camera asi585MC pro.

The system used is WO GT71 with 0.8x flattener (330mm Focal)  with ASIair. I am also using the L-pro filter and the set was taken in a bortle 7/8 a few days ago (no moon but 20mph gust wind and expected impact on the tracking). It was meant to test the camera.

I took the equivalent of 1h50mn made of 120s snapshots. I calibrated/stacked with dark, bias and flats using pixinsight. I used  the WBPP script to do so with the default values. CFA seemed to been properly detected. Performing a simple auto-stretch results in the following image which clearly exhibits a lot of background noise. Of course that can remedied toi some extend by working on the stretching.

 

But I am wandering if this is expected due to a poor signal/noise ratio (<2h with this refractor) or if I have an issue with the ASI585MC prop camera. Note that the camera was set with a gain of 252 to minimize the noise level. Photos were taken via an asiair.

 

Any help would be appreciated.

 

Eric

Edited by cal1mero, 29 April 2025 - 09:44 PM.

[TXLS99]

That looks pretty normal to me given the conditions and with less than 2 hrs total time.  It can be cleaned up to an extent in processing, but initial auto stretch will look like that.

[Yomamma]

PI can remove the noise or you can purchase NoiseExterminator it’s what I use and it is a no brainer

[rlmxracer]

That looks pretty normal to me given the conditions and with less than 2 hrs total time.  It can be cleaned up to an extent in processing, but initial auto stretch will look like that.

I agree and that has been my experience with galaxies from my Bortle 7/8 backyard. It takes a massive amount of time to get decent SNR on most galaxies with the conditions. Another more advanced imager that puts out great images from his Bortle 8 site only uses 30sec exposures on most targets with wide band targets. He said that the sky brightness overwhelms the sensor on longer exposures. 

Edited by rlmxracer, 29 April 2025 - 09:39 PM.

[cal1mero]

Thanks for your quick replies. As you all find that this is typical for the duration of exposure and the sky conditions, the camera is probably ok.

I have already taken care of the background noise by stretching manually. Of course noiseExterminator and similar suite of tools help greatly.

I was also trying to plate solve with Pixinsight without much luck due to the poor SNR. WBPP does not seem to forward the astrometric data and therefore cannot color calibrate properly.

it is definitely easier to do nebulae with narrowband than broadband in my bortle 8 neighborhood

 

 I will also try shorter exposures as mentioned by rlmxracer to see if that helps.

 

thanks again for your help. Will try to accumulate more time.

 

.

[EGregerson]

wind is pretty un forgiving;   u might go thru the individual frames and toss out the worst ones (bloated FWHM's, footballs, inchworms, seagulls) if u haven't already; or just  consider this a learning experiment and find a darker sight with less breeze next time.  As a camera test, it looks like it passes. 

Edited by EGregerson, 29 April 2025 - 10:51 PM.

[IanCass]

I too have a WO GT71 with the same flattener and an IMX585C. I'm in a bortle 6/7 area. Here's what I ended up with after about 2.5hrs. I usually do about 4x more on a target but this worked out ok with such short integration

 

 

 

 

[cal1mero]

Looks nice. Can you post a simple stretch from the stacked set to compare with mine. Just want to get an idea of bottle 4 vs 8 for the same exposure time. Were you able to plate solve on the stacked image?

[IanCass]

Looks nice. Can you post a simple stretch from the stacked set to compare with mine. Just want to get an idea of bottle 4 vs 8 for the same exposure time. Were you able to plate solve on the stacked image?

Yes I could plate solve the image. The preview autostretch of the original image doesn't look too different to yours

 

[cal1mero]

Sorry for the late response. I finally got some time to process my 2 hours bortle 8 stack. Note that it was just testing the camera in very poor conditions (high gust).

Consider this not too bad with the conditions I was given. Not as nice as IanCass's version.

Edited by cal1mero, 04 May 2025 - 08:04 PM.