Duo band filter test with Optolong L-Enhance

[RobertM]

Just a quick process of 6 x 15 min dithered subs with the ASI2600MC and Optolong L-Enhance (duo band) filter from this morning.  I think it's looking quite promising but will need far more subs for the final image and RGB.  No overly obvious haloes though may be there just aren't enough subs to show them properly.



2k: https://live.staticflickr.com/65535/50022577751_369ed200d8_k.jpg
6k: https://live.staticflickr.com/65535/50022577751_27b8419b78_6k.jpg

[The Thing]

Very interesting. I've just taken delivery of one of these.

[The Thing]

Is your filter in a wheel or drawer?

[RobertM]

I was going to use a drawer but managed to get the EOS spacing with wheel and QHY 10mm EOS adaptor.  All my stuff is now EOS fitting with the right spacing.

Robert

[Carole]

I have no proper experience with OSC cameras and these filters and don't even understand how they work, so can't make any constructive comments except to say it's a good image, but puzzled why you are using a OSC when you have in the past used Mono. 
Or are you just trying things out? 

I'd appreciate an explanation of what a duo band filter does, does it take Ha and Oiii all in one go? 

Carole

[RobertM]

Carole,

A duo band filter lets light pass in two bands, one around Ha and the other around OIII.  Designed for OSC cameras, the red channel captures the Ha band and the Green/Blue captures the OIII band.  I've just used the standard RGGB debayer pattern approach with this image but I think I need to split the red/green and blue pixels out and process them seperately as you would for a mono camera.

The advantage of recent OSC cameras is that the sensitivity is, hopefully, going to make them of use for narrow band as well as broadband targets - we shall see...

Robert

[Carole]

Thanks Robert, amazing what they can do these days.

Carole

[MarkS]

Wow - that's a great test!  There's so much detail in that image. Which scope were you using - the stars are sharp from corner to corner.

There are black dots in the background in the 6K image but that's a very minor criticism.

The new camera seems to be working very well.

Mark

[RobertM]

Wow - that's a great test!  There's so much detail in that image. Which scope were you using - the stars are sharp from corner to corner.

There are black dots in the background in the 6K image but that's a very minor criticism.

The new camera seems to be working very well.

Mark

Thanks Mark,

Scope was a Skywatcher Esprit 150ED with FF flattener - I've been lucky that everything is orthogonal !  I only spent 30 mins on processing including stacking.  There were also no calibration frames, just DBE and histogram with a bit of noise reduction so it won't be anywhere near perfect.  Will add a lot more frames when given the opportunity.

Robert

[MarkS]

I hope the filter works out OK - there are no signs of any problems in your image. 

Do you remember Astronomik replacing a whole set of filters a few years ago because of a problem with their anti-reflective coatings?  It's something Canon seems to have got wrong on its recent astro camera, the mirrorless Canon EOS Ra:
https://www.cloudynights.com/topic/712122-canon-eos-ra-star-problems/?p=10269293

To avoid red halo reflections it seems you are better off modifying a Canon EOS R than buying the Canon EOS Ra!

Mark

[julian]

That's is a really nice image Robert.
I have that filter just need the camera

[RobertM]

I hope the filter works out OK - there are no signs of any problems in your image. 

Do you remember Astronomik replacing a whole set of filters a few years ago because of a problem with their anti-reflective coatings?  It's something Canon seems to have got wrong on its recent astro camera, the mirrorless Canon EOS Ra:
https://www.cloudynights.com/topic/712122-canon-eos-ra-star-problems/?p=10269293

To avoid red halo reflections it seems you are better off modifying a Canon EOS R than buying the Canon EOS Ra!

Mark

I well remember the Astronomiks I had my set replaced for free.  Been following that Ra thread with interest, bit of an own goal not testing thoroughly - probably had some professional terrestrial photographer testing it (the type that gets their images published with all the abberations !).  Lets just hope that Canon are more responsive than Sony !

Thanks Julian  don't forget that you'll have to process the images after capturing all those subs 

Robert

[Carole]

I have been pondering since this thread on how the Duoband filter works.

So does it "sort of" have it's own "Bayer matrix" but instead of having 2 green, 1 red and 1 blue squares, it has 2 x Ha & 2 x Oiii, these operating within the spectrum of (Ha Red) and (Oiii green and blue)?

So although it is a coloured camera it is only letting Ha through the Red band, and Oiii through the Green and Blue band.

Well that's how my brain has worked it out.

Carole 

[Carole]

It would be even more interesting to be able to compare an image taken with the same OSC camera without using the duoband to see what a difference the duo band makes.

Carole

[RobertM]

I have been pondering since this thread on how the Duoband filter works.

So does it "sort of" have it's own "Bayer matrix" but instead of having 2 green, 1 red and 1 blue squares, it has 2 x Ha & 2 x Oiii, these operating within the spectrum of (Ha Red) and (Oiii green and blue)?

So although it is a coloured camera it is only letting Ha through the Red band, and Oiii through the Green and Blue band.

Well that's how my brain has worked it out.

Carole

In a word no.  If you look at for instance a uv-ir block filter, it blocks wavelengths at higher and lower wavelengths than visible light so it passes all wavelengths in between (uv and ir).   These new duo/triad/quad filters block additional bands much like a CLS does with light pollution.  The difference is that the bands passes are concentrated on picking out Ha and OIII in particular.

I will also be using the camera without the duoband and merging the two, well that's the plan.

Robert