PadrePeace

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

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.

My polar align with the AZGTI tonight using the Skywatcher Wedge. No need for a WO upgrade here.

I agree with AdamJ, although I could not work out what his point was in that last sentence. Maybe an edit required. 🤷 My extensive experience with the SW wedge is that if I set the baseline RA and Dec wedge adjustment tensions correctly, for that read firm! then I can nail < 0.20a/s PA in both axis every time using Sharpcap PA. Given the focal lengths this mount can reasonably handle that is way better than you need to guide within pixel scale limits. The SW wedge is more than up for the job if you treat it right.

I have a homemade dew shield that sits 6cm forward of the end of the Askar scope with an exit diameter of 6.5cm and with an ASI294 4/3rds sensor have never seen vignetting on my Askar 180. It sits over the dew strap so is naturally a bigger diameter than the scope which means I get away with a longer dew shield and hence that little bit more protection from cold air and any stray moon or lamp light. It additionally warms being over the dew strap which gives added protection .

California Nebula from my Askar FMC180 in Optalong L Extreme dual band and straight ASI294MC RGB for stars and the IFN. 13hrs (4hrs NB and 9hrs RGB). I used my own Darks only calibration technique to get around the 294MC vs L-extreme Flats problem. See here for more. https://stargazerslounge.com/topic/388826-294mc-pro-l-extreme-and-a-bunch-of-flats/?do=findComment&comment=4197379

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?

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.

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.

That’s the same as me. For what it’s worth I have just stacked four hours of dual band Ha and OIII in the California Neb from my extreme with exactly the same flats system I used before and the flats just failed by adding rather than subtracting from my subs. I have successfully processed this work by using just dark frames and the LP tool in APP to clean up what little additional colour (greyscale) the flats should have dealt with. Completely confused by this now and won’t be bothering with Flats for extreme subs. They just don’t work. I’ll post the split Ha and OIII subs pre and post LP removal below. Flats work fine for OSC but are a liability for my extreme dual NB. I’ll not be using flats for E- NB going forward. Just darks and a friendly LP tool.

That’s the same as me. For what it’s worth I have just stacked four hours of dual band Ha and OIII in the California Neb from my extreme with exactly the same flats system I used before and the flats just failed by adding rather than subtracting from my subs. I have, however, successfully processed this work tonight by using just dark frames and the LP tool in APP to clean up what little additional colour (greyscale) the flats should have dealt with. Completely confused by this now and won’t be bothering with Flats for extreme subs. They just don’t work. I’ll post the split OIII subs pre and post LP removal below. In the plus side, just stacked 9hrs or 28GB of OSC to go with the above and all calibration frames worked a treat though it took most of the evening to do it. I now firmly believe that a single master flat won’t work with the extreme NB. I think both channels need different flats treatment and on flat is never going to work for both. I’ll be splitting my NB channels from now on and just use darks and APP’s light pollution tool as above.

That’s the same as me. For what it’s worth I have just stacked four hours of extreme dual band Ha and OIII in the California Neb with exactly the same flats system I used before and the flats just failed, adding rather than subtracting from my subs. I have however successfully processed this work by using just dark frames and the LP tool in APP to clean up what little additional colour (greyscale) the flats should have dealt with. Completely confused by this now and won’t be bothering with Flats for extreme subs. They just don’t work. I’ll post the split Ha and OIII subs pre and post LP removal below. I’m there was some bight stuff down the RHS and you may be able to just make out some shading in the top left hand corner. This is the way ahead as I just don’t think this sensor is compatible with the extreme filter and flats. I think both channels need to be dealt with in a different way by flats and a single common flat for both just isn’t possible. Finally, when it comes to OSC or RGB flats work a treat. Just stacked 9hrs of OSC to go with my ‘no flats’ California Neb NB and though it took most of this evening to crunch the 28GB of subs it worked a treat.

I hate to prolong your misery but was IC 1396 taken with the same scope and flattener, exposure, gain etc? I can’t see how it wasn’t there but is now. The general consensus seems to be long (> 3s) flats exposure. I tried sky flats and that made my issue (very bright glow left and right sides) worse. Whilst I know you’ve tried almost every option already is it possible you have your filter fitted in reverse which might give reflections back into the sensor. I fit mine to the scope side of the 1.25” adapter ring that then screws inside of the 11mm extension that comes with the camera?

Forgot to mention that I split the Ha and the OIII out from the dual band subs when I integrated them and calibration files in NINA, then applied the LP correction to the Ha and OIII output files (output in greyscale). Splitting the two bands may be key to processing the dual band subs. Just saying.

I think you’ll find that the red and green banding is a function of this sensor. It’s a common theme on 294 flats posted here and like a fingerprint varies between sensor examples. It is in each sub (though not visible in an unstretched RAW single sub) and needs to be calibrated out. It’s the bright stuff down each side that is my issue cos it’s not in the image subs. Try reducing your flats exposure to 5s at 23ADU and cool the sensor too. Good luck.

Scotty38, I have the 294MC and have had similar FLATs difficulties with the Optalong E-extreme Dual band filter (Ha and OIII 7nm) that being overcorrection down the left and right sides. I went through the same diagnostic tests you have and had gigabits of flats at various exposures and from different light sources including sky flats. My conclusion was that the filter is either leaking additional bright light source frequencies (suspected with sky flats) or the flats are compromised by trying to take a flat at one optimum exposure setting across two specific frequencies. As an illustration my other specific Ha and OIII filters used for NB with my mono need very different treatment to each other to produce working Flats, so why would there be one flat exposure to rule them all so to speak? Someone please come back and explain why I’m wrong if that’s indeed the case. So What? Having tried to get a single master flat that worked (using the Flats tool in NINA) for the 294MC and the e-extreme, I ended up stacking my image subs using a let’s say ‘compromised’ master FLAT taken at 5.63s exp and then removing the over corrected corruption around the edges of the integrated image using the light pollution tool in NINA. I’m sure the Flat is introducing correction where it was not required hence the need to remove it as LP. This worked well and as yet I have not seen a more definitive solution posted. Some report not to have this issue at all but then the variables from poor filter quality control through to those that just don’t see poor correction as an issue could explain that away. All I know is my 294MC has issues with my dual band filter or indeed the other way around. Bottom line is my technique produced the following image with a ‘compromised’ flat of 5.63s exp for an ADU of 23k also posted below. you may also wish to check out this thread

Just want to thank all at FLO for another year of outstanding support to the Astro community. Wishing you fortune and success in 2022.

When you say traditional pallet do you mean this one or the Hubble?

Agreed and I guess if one can live with the extra weight nothing says you have to cool it when mobile in the field. Anyone tried the colour version uncooled?

This is a good starter for ten though thermal noise is very low anyway. That’s all I have…..

My latest with the Askar 180, 2” L3 filter, and the ASI294MC cooled to -10 at 120 gain. Only 1hr 40mins of 30s subs with a 20% moon. Still a good image to support the L3 discussion here at the moment with some very bright white stars. Enjoy…. and clear skies guys.

AdamJ is your man for this one…..

Happy to help. Clear skies.

I have the Optalong eExtreme for dual band and a SVBony UV IR cut filter when shooting RGB. Both are 1.25” and mounted in the 11mm extension that accepts the filter mount (all comes with the camera). As AdamJ says you will have to remove the camera to change filters out but given that you are either Narrow or Broad band imaging that would be an initial set up action and won’t change until you have finished a project. I will warn you now that with that narrow band filter you are going to get some very odd blemishes in your subs and flats due to it being dual. This took me some time to find a way to get rid of those blemishes in post processing as dual band flat won’t hack it. Working with a Mac you will run into issues I’m sure as the software available is just miles away from what you can get for windows much of which is freeware. That’s all for another time I guess but just a heads up. Here to help if needed of course.