Oiii on a modded DSLR

[Rico]

I have an astro modified 700D, which I've been using for the last few years, and while I would love to take the plunge and get a mono ... I can't substantiate the 2 grand price tag at the moment.

As well as the regular RGB images, I've been using an Astronomik 6nm clip filter, which has given me some wonderful images. Processing them isn't too difficult as it is all isolated to the red channel.

My question here is ... does anybody have any experience acquiring and processing oiii data on a dslr? Are you satisfied with the astronomik Oiii filter?

More than anything I'm intrigued about the fact that the wavelength sits right bang inbetween the blue and green filters on the bayer matrix. Does this mean that I need to extract both blue and green channels and combine them? Does that improve noise compared to the ha filter as I'm essentially using the other 3 elements of the bayer matrix (despite the fact that the blue/green filters only allow 50% of the light through at that wavelength as well)

Thanks

Edited September 24, 2019 by Rico

[Adam J]

50 minutes ago, Rico said:

I have an astro modified 700D, which I've been using for the last few years, and while I would love to take the plunge and get a mono ... I can't substantiate the 2 grand price tag at the moment.

As well as the regular RGB images, I've been using an Astronomik 6nm clip filter, which has given me some wonderful images. Processing them isn't too difficult as it is all isolated to the red channel.

My question here is ... does anybody have any experience acquiring and processing oiii data on a dslr? Are you satisfied with the astronomik Oiii filter?

More than anything I'm intrigued about the fact that the wavelength sits right bang inbetween the blue and green filters on the bayer matrix. Does this mean that I need to extract both blue and green channels and combine them? Does that improve noise compared to the ha filter as I'm essentially using the other 3 elements of the bayer matrix (despite the fact that the blue/green filters only allow 50% of the light through at that wavelength as well)

Thanks

here is some DSLR OIII data to have a play with (Canon 550D). Though its been a long time since I imaged with a DSLR now.

Something like 12x10mins so very little data.....but it was taken with a DIY cooled DSLR so just about sub zero temperatures. I am not sure how it would go without cooling. But if it was a cold night you would get similar performance.

This was a 8.5nm Baader OIII filter 2inch.

new oiii.tif

As you can see its teal so green is strongest, still significant signal in blue but less than green and red is just noise.

As for noise in comparison to Ha, no its much worse as the actual OIII signal strength is weaker than Ha.

Probably better to get a duel narrow band filter these days though if you want to image narrow band with a OSC sensor.

Adam

Edited September 24, 2019 by Adam J

[Rico]

Thanks Adam. The green channel definitely looks a lot cleaner than the blue and as I suspected, they're both receiving the oiii signal. Do most people scrap the blue and red channels and simply keep the green when doing a narrowband combination? A dual band filter sounds nice, but I like to image with 200mm lens, so a clip is ideal for me (which nobody does as a dual band anyway).