Can I use a OSC as a mono camera?

[RugbyRene]

Hi,

I have a new ASI2600MC and was wondering if it is possible to use it as a mono camera by using narrowband filters. I mean we have the L-Extreme, L-Enhance and OPT Triad filters which do that, but can we use Ha, Sii and Oiii filters separately to achieve something like a mono camera. I realise it will take longer to capture the data but other than that what are the technical limitations?

Rene

[Startrek]

Rene,
I use the processing software Startools V1.7 ( latest ) which has a Compose module designed for processing OSC Duoband or multiband data
It creates a synthetic luminance file and combines with RGB to make a composite which can be used with many presets made consisting of Ha S11 OIII variations etc.....
It works pretty well but its not true narrowband like from a Mono and individual filters and will never be as good either , but at least you can image under horrible skies and create a decent image ( nebulas only of course)
Here’s an image/s of NGC 3372 Carina I captured in March under Sydney Bortle 8 light polluted skies and an 80% moon using my 2600MC and an Optolong L Extreme filter processed in Startools V1.7 Composite module OSC narrowband
Cheers
Martin

[RugbyRene]

Those look very nice Martin, and from Bortle 8 no less. I have the L-Extreme filter so thinking about it I’m covered for narrowband. The Ha would be picked up by the red pixel and the Oiii by the Blue/green? Then I just need to spilt the channel and throw away what I don’t need. If I wanted to go narrower though, say 3nm, I’d need the individual filter (Ha, Oiii & Sii). I realise I’ll sacrifice resolution and have to image for longer but it’s better than dropping another $3500 on a camera.

Rene

[Startrek]

Rene,
Thanks , the image turned out surprisingly good for only 2 hours of data ( 3 minute subs ) usually you need considerably more data when using narrowband filters
You can’t manually split channels using the L Extreme or even using individual filters with a OSC ( 2600MC ) because of the RGGB Bayer matrix, if you did your colours would be screwed up
The photons are collected by the sensors pixels in that format so it’s a set thing
So a OSC is a OSC , however the L Extreme allows the Ha at 7nm and the Oiii bandwidths ( bandpass ) with 90% transmission to be collected by the sensor and then using software like Startools V1.7 Composite module , it can synthetically create narrowband luminance and combine RGB to allow narrowband presets to be used , quite intuitive
I don’t know of any other processing software which can use OSC narrowband data and process like true narrowband and provide so many presets etc...
In Startools ( Compose ) when you load your data , you load your stacked fts file once into Luminance channel , once in Red channel , once in Green Channel and once in Blue channel.You just select the preset OSC R ( 2xG ) and B and the software does the rest.
Cheers
Martin

[Zuts]

I am probably wrong but here goes :shrug:

I used to shoot Ha narrowband on my SBIG 2000 XCM which is an OSC. The results were great, heaps of detail under light polluted skies.

I don't see why you you wouldn't get equivalent results with SII and O3, subject to the object having some.

You would probably have to extract one channel from each of the filtered images Ha, SII, O3 as the camera is an OSC but could then combine as a narrowband image?

My confusion arises because of the following. On a mono camera there are no channels to extract, you are supplying the 3 channels from 3 separate filters. If you put a filter on a OSC and extract channels then essentially you are saying Ha is Red, O3 is green and SII is blue. So when you combine what do you get, an RGB image or some sort of Hubble Palette image?

So I am not sure you can get narrowband looking images using the filters or just the equivalent of an RGB image.

So, if you want RGB under light polluted skies then maybe but not sure about getting the colours you see in actual narrowband images.

Sorry about the long winded waffle answer with many questions...

[Craig_]

A Ha filter will see photons strike the red pixels on the bayer matrix, an Oiii filter will hit G/B and Sii will hit red. Where you run into issues using a OSC for this is that you're only ever using, at most, 75% of the pixels in the bayer matrix to gather data so it is very inefficient (Remembering that they will have two green pixels.) Ha isn't so bad even though its only using 25% of your pixels since Ha is abundant and bright, but I'd expect Sii signal to be a challenge on an OSC and require very long integrations.

In theory if you used a single bandpass, good quality narrowband filter on an OSC, you should have no signal in G/B when imaging in Ha or Sii, and no signal in R when imaging in Oiii. In reality there may be some leakage between channels though so I'm not sure it would be as simple as there being 0 data in the opposing channels.




Sii is red wavelength light, same as Ha, so if you had a "tri-band" OSC filter you'd be blending Sii and Ha data together on the red pixels of the bayer matrix. If you assign Ha to red, Oiii to green and Sii to blue you will have a HOS palette, but to capture true Sii data with an OSC you would need a dedicated Sii filter otherwise it will just mix up with Ha on the bayer matrix. Not sure if this answers your question though :lol:

[Alchemy]

If you shoot Different single band filters, extract the luminance channel after debayering and call it Ha O3 or S2 and process as per normal narrowband. You will have lower resolution, but entirely doable.

[RyanJones]

Hi Rene,

Yes it is entirely possible. With each filter set of subs you will still get RGB data. Let say for example you’re using a 3nm Ha filter. Your blue and green pixels will still have data all be it very very low amounts and most of it will be noise. Subsequently your O3 filter will have data across the blue and green channels and very little on the Red. So remembering this it’s really up to you what you do to combine them. You can stack all three channels from each filter and save it as a gray scale image and associate the name of that image with which ever filter you were using to take them. Or.... you can use software such as Astro pixel processor to extract the channel from the RGB data and save the result as a gray scale image associated with the filter you were using. All you are doing which ever way you go about it is creating an gray scale image that you can then assign to a colour when you process. Remember that when imaging narrow band you are creating an image from data rather than “ taking a photo “. You are assigning data to a certain colour for no other reason that to create contrast between the different wavelengths so they can be clearly identified in the final image. The balance of these colours takes time to master and varies across different objects. Yes there is software that does a good job of doing some of the ground work for you but if you understand what the software is doing you can have much greater control of the final product and tailor your images to your liking. It will also give you a much greater understanding of what other images you see are composed of and help you to achieve similar results.

I hope this makes sense

Cheers

Ryan

[SB]

Hi Rene,
I use 3.5nm SHO filters with ASI183 MC Pro OSC. Mono would improve the imaging but for me OSC is the camera I have now.

Here is an example process for two targets:

* ASI183 MC , Esprit 100
* NGC 3576 5 X 300 sec Sii, Ha, Oii 3.5 nm Bin1 gain111 Temp -20C
* NGC 3372 10 X 300 sec Sii, Ha, Oii 3.5 nm Bin1 gain111 Temp -20C
* Darks, Bias, (No Flats)

Subs for each filter were individually stacked and converted to black and white, then followed the SHO integration process in Affinity using Hubble palate.

The process was easier than I thought and I think if I used a Mono camera I would get finer detail but happy with the outcome for such a short exposure time. Also the Sii signal was surprisingly strong for these targets.

see my post:

http://www.iceinspace.com.au/forum/showthread.php?t=191257

Chris.

[Nikolas]

Astropixel Processor works well for separating and extracting narrowband channels

[The_bluester]

I was going to write the same thing. APP does a far better job of extracting NB data from an OSC sensor either using true NB filters or the dual band filters than just shooting HA for instance and extracting the red channel. It adds to the workflow to make it really happen but it is doable.

I shot this last night (Image processing in Photoshop to assemble the bicolour by Andy01) using 6nm HA and Oiii filters with my ASI2600MC. 30 X 600 second HA and 20 X 600 second Oiii.