294MC Pro, L-eXtreme and a bunch of flats......

[PadrePeace]

3 hours ago, scitmon said:

The ZWO mini filter wheel that I'm using can be reversed.

Not the case if you mount a 1.25” into the ZWO adaptor that comes with the camera. There just isn’t enough thread left to mount the camera to the scope. Just found my filter to be ‘the wrong way around’ so not sure how to fix that without turning the glass around and I’m not doing that on a £180 filter. It will likely go back to FLO if it’s a factory mounting issue. 
 

Tried a fudge and the first is with threads toward the sensor (as one would expect and the only way I can mount mine. Second is the reversed filter with threads toward the scope. Major difference is down each side. 

Edited January 14, 2022 by PadrePeace

[Adam J]

1 hour ago, PadrePeace said:

Not the case if you mount a 1.25” into the ZWO adaptor that comes with the camera. There just isn’t enough thread left to mount the camera to the scope. Just found my filter to be ‘the wrong way around’ so not sure how to fix that without turning the glass around and I’m not doing that on a £180 filter. It will likely go back to FLO if it’s a factory mounting issue. 

Generally having the filter reversed will cause reflections as opposed to altering the underlying filtering performance. So not sure it would effect calibration to have it reversed. 

Adam

[PadrePeace]

I've cracked a way to get past FLATS issues with the extreme / ASI294MC combo.

Having now definitely given up the ghost on using FLATs with the Optolong L-Extreme Dual Band filter and my ASI294MC this is now my go to method for stacking and processing. The image here was a test last night with limited subs capture in 86% moon.  The filter was mounted 'threads toward the sensor' which Optolong say is wrong but hey, who cares as I cannot mount it the other way around.  

This was 15 x 360s dual band 1x1 subs cooled to -10C at 121 gain in 86% moon conditions which is far from great even for a 7nm filter. The subs looked pretty poor I must say but I wasn't looking for a keeper.   I first stacked Ha and OIII separately in APP with only darks which produced two greyscale images, I then pulled the minimal background LP and filter induced colour out with the APP Light Pollution tool, stripped the stars out with Straton, processed the starless Ha and OIII individually in PS, added on a synthetic green layer to get an RGB effect (optional) , added the stars back in and bingo....  This is how I'm going to deal with the Extreme filter going forward I think so the 294MC lives on for now. Thoughts?

Edited January 14, 2022 by PadrePeace

[scotty38]

Looks great to me that does! Going to give it a go today, thanks

Edited January 15, 2022 by scotty38

[scitmon]

On 14/01/2022 at 20:54, PadrePeace said:

I first stacked Ha and OIII separately in APP

Does this mean you went through every sub and split the RGB channels individually?

On the face of it that sounds time consuming but with Narrowband I suppose the number of subs isn't as much as broadband sub numbers.

[scotty38]

2 hours ago, scitmon said:

Does this mean you went through every sub and split the RGB channels individually?

On the face of it that sounds time consuming but with Narrowband I suppose the number of subs isn't as much as broadband sub numbers.

APP has the facility to extract Ha and Oiii from the stack. It's a two pass thing though, choose one then repeat and choose the other...

[PadrePeace]

12 hours ago, scitmon said:

Does this mean you went through every sub and split the RGB channels individually?

On the face of it that sounds time consuming but with Narrowband I suppose the number of subs isn't as much as broadband sub numbers.

 

[PadrePeace]

Just now, PadrePeace said:

 

Sorry if my explanation wasn’t clear. I put all of my dual band subs and associated darks into APP. I then make the selection as shown below for APP to draw out the Ha from the dual band data. I then set it running to integrate the subs. Repeat this process for oxygen and you end up with two files one OIII and the second Ha.

[PadrePeace]

Here’s my latest using this darks only procedure with a OSC 294MC and the Optalong l-extreme dual band filter. Enjoy. 

[scotty38]

On 13/01/2022 at 14:00, scotty38 said:

Oh well I was hoping I'd made a mistake and had an easy, if somewhat embarrassing, fix 🙂

In the interests of transparency it would appear I am a bigger idiot than I thought I was....

I think I have fixed my issue and it seems to be down to offsets. This is all using ASCOM drivers and examining fits headers etc I found discrepancies where some show an offset of 8 and others show nothing. I recently built a new mini pc and on checking it's, of course, using the default offset of 30. This also explain why some of my l-extreme images were ok (not the ones where Vlaiv found a darks issue too but again that was the offset) but nthey were taken prior to building the mini pc.

Using matching offsets for all the files and all is good as you'd expect. What I cannot explain is why the offset was 8 as I have no reason why I'd have changed it and also do not know why some files have the offset in the header and some do not but anyway at least I know why now.

Sorry for the inconvenience and I can now get back to taking nicely calibrated but crappy images.....

[Budgie1]

Offset of 8 is the default for the ZWO drivers, offset of 30 is the ASCOM driver default.

Did you swap drivers at any stage or did the new PC use the ZWO drivers as default?

[PadrePeace]

3 hours ago, scotty38 said:

In the interests of transparency it would appear I am a bigger idiot than I thought I was....

I think I have fixed my issue and it seems to be down to offsets. This is all using ASCOM drivers and examining fits headers etc I found discrepancies where some show an offset of 8 and others show nothing. I recently built a new mini pc and on checking it's, of course, using the default offset of 30. This also explain why some of my l-extreme images were ok (not the ones where Vlaiv found a darks issue too but again that was the offset) but nthey were taken prior to building the mini pc.

Using matching offsets for all the files and all is good as you'd expect. What I cannot explain is why the offset was 8 as I have no reason why I'd have changed it and also do not know why some files have the offset in the header and some do not but anyway at least I know why now.

Sorry for the inconvenience and I can now get back to taking nicely calibrated but crappy images.....

So are you now calibrating Dual band flats with your subs and they are working? Thanks for your heads-up on offsets. I’ll check mine.

[scotty38]

5 minutes ago, PadrePeace said:

So are you now calibrating Dual band flats with your subs and they are working? Thanks for your heads-up on offsets. I’ll check mine.

Yes I am. My finished images aren't any better so if you can find a fix for that.... 🙂

Edited January 20, 2022 by scotty38

[PadrePeace]

1 minute ago, scotty38 said:

Yes I am, the images aren't any better so if you can find a fix for that.... 🙂

slightly confused Sorry. Are you saying your flats don’t do what they should? If so, what has aligning  the offsets done?

[scotty38]

2 minutes ago, PadrePeace said:

slightly confused Sorry. Are you saying your flats don’t do what they should? If so, what has aligning  the offsets done?

Sorry, no I was being flippant about my processing skils.

[PadrePeace]

If your flats are working could you kindly post shots of your master flat and the final image? You could well have dropped on a diagnosis for an issue that has plagued owners of this sensor for some considerable time.

[scotty38]

Just a screenshot.. I'll sort the files, give me a minute

Here you go, you'll have to ignore the gradient and the poor framing, I'm imaging right now to fix the latter at least....

Edited January 20, 2022 by scotty38

[scotty38]

Here they are:

 

Edited January 20, 2022 by scotty38

[PadrePeace]

6 minutes ago, scotty38 said:

Just a screenshot.. I'll sort the files, give me a minute

Here you go, you'll have to ignore the gradient and the poor framing, I'm imaging right now to fix the latter at least....

Now I have to work out why your master  flat looks different to the one I have coming out of APP? (As attached) what’s the yellow colour all about. Is this Flat neutralised?

[scotty38]

It's just debayered and stretched. It's about a 3.5 seconds exposure but no idea why it comes out that colour

[scotty38]

Same file in APP:

[PadrePeace]

4 minutes ago, scotty38 said:

Same file in APP:

Could you see what happens when you select the neutralise-BG box in the top right panel just under the green histogram?

[scotty38]

Yep:

[PadrePeace]

22 minutes ago, scotty38 said:

Yep:

Great. That’s what I’m getting but just a different pattern which is clearly a fingerprint of my specific setup. Thanks for helping with images. Paints a thousand words. Glad you got your kit working well. 

[scotty38]

Thanks and hope you get yours sorted too.