Helix NGC7293 done last nite ..Saturday.. using two Lumicon Minus-Violet filters , one was a 2in. and the other was a 72mm filter attached to a TeleVue .8XReducer/Flattener thru a 152mm A+M Refractor . I was trying to see if the Minus-Violet filters would suppress the 373nm Sky Glow . The first image was 555secISO1600 and it was a yellow-white over-bright .. so I then did a 195secISO1600 and that was easier to see the Helix and I did seventeen of them . This is another try as CR2.s put into MaximDL Pro V6.16 and I used an ISO1600 BiasMaster and then "Convert Color Red-45 Green-75 and Blue 180 for Scaling" because PictureStyle Faithful 5200K was used and can make the images yellow-red when using Minus-Violet filters . I stacked them using Sum ... one 9minISO1600 and sixteen 195secISO1600 CR2.'s . It took awhile to get the haze that was trying to get into the reddish eyebrow part out of the image .. and here is the result . I don't know which images show the reddish area outside of the main Helix but all together they seem to show it a little bit . The Moon was rising for the second half of the exposures and light was entering the images .x The FITS is a "Resize" from 3.72micron to 6.555micron pixels and then "Half Size" two times . I did a Two Star Align with Enif and Marfak and both have small stars in the image to 'Live View' focus on like I did with Enif and then to the Helix .x Next time I'l add to the two Minus-Violet filters a Baader UV-IR Cut-off filter that they say is like a Minus-Violet filter and try 260secISO1600 images for as many as I can get for e few hours , but I'l be able to tell on the first image if it is getting good content instead of hardly any .X I was cleaning the Orion Sky Glow 2in. filter I have that I was using with the 'stock' Canon EOS 6D ..thinking it was the same thing as a Lumicon DeepSky filter I have but the paper for the Orion Sky Glow shows it to be like an OIII filter that also allows 'red' ... and the Deep Sky filter graph I found on the Internet shows about the same type of color graph but a lot of 'blue' is also being allowed to enter ...so that might be why it looks darker . When I looked at the TV set with a 'blue' background on a news channel with the DeepSky Lumicon it was 'blue' where there is 'blue' and with the Orion SkyGlow the 'blue' was a pale 'green' instead ... so the Orion Sky Glow filter is more like an OIII filter which I don't have but the Orion SkyGlow might take it's place ... I'l see eventually when there is some clear sky .x
