Amusing myself with a borrowed ASI533 MC and Optolong L-Extreme filter last night (Thanks Londoner!)
I took some images of the Tarantula (Ignoring the negative influence of the moon) through my 14" Meade SCT with Hyperstar before the clouds rolled in. The camera was guided but no darks or flats were applied - Basically, the images are just how they came of SharpCap using live stacking.
First up was a straight colour image with UV/R cut in place. Transparency was less than perfect and the stars were soft, and after 45 mins the detail wasn't really developing so I gave up.
I replaced the UV/IR Cut for the L-eXtreme and was instantly happy with the detail coming through and tightness of the stars, but needless to say, not best pleased with the over worked green pixels basking in all that OIII! The clouds rolled in after 17 mins and that was the end of the night.
So I decided to overlay the colour from the first image onto the detail in Photoshop, I often borrow colour from other images to make my monochrome images more appealing, and have essentially created an OIII, Ha and RGB image with only one filter change. TBH, I think it looks very promising as a technique and deserves a little more care in the acquisition next time.
Any one tried similar? I still find it conceptually odd to use a narrowband filter with a colour camera, but hey, it seems to work
I have actually done something very similar last night, whacking a HA filter in front of my ASI2600. I can probably afford to be less subtle with laying in the HA, but this is the first time I have tried it. The big challenge was getting the imaging software to focus it with the oddball looking results of having an NB filter in front of a bayer matrix, and working out what "Mean" value to use to shoot flats when all pixels are included in the mean calculation but the green and blue have very little data. I got it all to behave around midnight and went to bed to see what I would wake up to.
Nice result, what did your Ha image look like? I certainly seemed to get a fair amount of colour bleed into the other channels - That bayer matrix isn't quite built to astronomical standards
The HA looked pretty much as I would expect, similar to the red but with a lot of stuff showing that is swamped out in the red by stronger signal at other wavelengths.
I did it purely as an experiment, but I reckon it is worth pushing on with to broaden the detail I can capture. I could probably have laid into it a bit harder on the final image but I am just feeling my way at the moment. I was just pleased to get usable data.
Which processing software are you using? I find with Astropixel processor I extract the Ha and O3 separately then do an rgb combine in HOO that seems to work
You end up with something like this after finishing it with Photoshop, shot with the 294mc and L-extreme
In my case, it was very unsophisticated processing - I simply opened the L-eXtreme as the background layer in Photoshop added the full color image as a new layer, aligned and blended using color mode.
In my case, it was very unsophisticated processing - I simply opened the L-eXtreme as the background layer in Photoshop added the full color image as a new layer, aligned and blended using color mode.
I am using APP, given I have a HA filter in it I loaded all the HA subs, set the debayer to HA, loaded master dark and flat, calibrated then saved the calibrated (Mono) output files. Then I took the RGB lights I had, calibrated them with master dark and master flat and saved the calibrated results using the setting to split the channels so I ended up with approx 40 each of red, green and blue mono subs and 20 mono HA subs.
After all that I loaded them up and integrated by "filter" to get red, grren, blue and HA integrations and did an RGB combine in APP, saved the RGB image and the HA integration as Tif files and layered the HA in in Photoshop.
Any one tried similar? I still find it conceptually odd to use a narrowband filter with a colour camera, but hey, it seems to work
Well those filters like the L-Extreme are designed to work with OSCs after all. Since Ha hits the red pixels on the bayer matrix and Oiii hits green and blue, it works out nicely really.
FWIW I have a small amount of Tarantula data gathered with the same camera and filter combo (533MC and Extreme) and my subs shot with that filter stacked in APP would look very similar to your third image, without any broadband data included. The very strong green you had coming through in the Sharpcap live stack is not what I would call characteristic of this filter/camera combo.
I think the L-extreme (and similar duo-band filters) are pretty incredible options for OSC users. I've been very happy with the results I've gotten from mine and it certainly makes life easier when imaging from Sydney.
L-Extreme does suffer a small red shift with very fast scopes
So more 03 is collected than ha
Yes, you are quite right. The red channel is very sparse in the L-eXtreme with Hyperstar and digging around, that's not uncommon. The slightly wider bandpass of the L-eNhance seems to do much better at F2
I am in hibernation inside due to the heat today, so I spent some time working through various workflows to layer in the HA data on my M42 shot. I am sure I will hate it next week and want to do it again, but I settled on this.
I am in hibernation inside due to the heat today, so I spent some time working through various workflows to layer in the HA data on my M42 shot. I am sure I will hate it next week and want to do it again, but I settled on this.
Thanks, I am pretty pleased with the result, It is a fair bit more work than the straight OSC process but I reckon it is worthwhile for the improvement in the image. Not to mention expanding the moon conditions I could image under significantly. It would still be less work than an LRGBHA workflow.
I guess I better get looking in to a filter wheel, plate solving though the HA is a bit of a pain. I don't think I would be able to image "L" (Bayer matrix) and NB without changing equipment profiles due to what I had to do to the focus settings to get it to work with the lack of data in the green and blue pixels, but all that means is I have to either image RGB on separate nights to NB, or have to stay up and change profiles as needed. Better to just do RGB around new moon and NB on nights when I have less than three or so moonless hours.
Now the bit that annoys me! I seem likely to keep going down the same "Bitsa" rabbit hole I have been in for ages. The ZWO filter wheels look perfectly up to the task for me, only the 2" one seems the only one set up to attach to the camera in a way I like (I don't really want to go to a 2" wheel due to the cost of filters)
The 2" wheel you remove the tilt plate from the camera (Which the FW would block access to anyway) and use screws to attach it directly to the camera, the big ZWO OAG looks a good setup. But the 36mm required a male to male T2 adapter ring be screwed in to the tilt plate (Which becomes inaccessible) and the filter wheel spun on to that, ugly! And the QHY OAG-M has a much better attachment method rigidity wise.
The ideal would be for ZWO to put me out of my misery (Except financially) and make an ASI2600MM GT, with an integral 7 X 36mm filter wheel and a guider port!
Last edited by The_bluester; 24-01-2021 at 08:33 PM.
I has a tiny slice of clear sky and put the camera and filter on the 102 that rides piggy back to the main scope. I only captured by way of a photograph of the screen the results after two 4 min frames, and can confirm that the Ha was back at a leisurely f7
It went horribly wrong from there, but did demonstrate that the filter is awesome under a heavily moonlit sky!
