Clip filters - do I understand this right ?

[AlistairW]

I have a DSLR and a CLS light pollution filter. However Astronomik make other filters such as 12nm Ha. So if I swap out my CLS and put in a Ha then I would be imagining in Ha. Then if i got other filters i could combine them in to a full colour image ?

[jambouk]

Yes, but unless your DSLR has been astronodified the intrinsic DSLR filter will limit your Ha sensitivity as it blocks some Ha. And if your DSLR is colour and has a Bayer matrix, only one in four pixels will be sensitive to light at the red end of the spectrum.

James

[AlistairW]

So i do have the Baader modification but it has not been debayered. Wondering what the results would be like.

[Owmuchonomy]

..you could go the whole distance and mono convert your DSLR . Not for the faint hearted.

[jambouk]

I'm not sure either. For your Ha data, you'd have a pixel worth of data surrounded 8 pixels of no data, but zoomed out no sure how this would look, though your other wavelengths data may fill some gaps, depending on what filters you use and what wavelengths the green and blue components of the bayer matrix allow through. I've also wondered before does 100% of Ha get theough the red component of the Bayer matrix.

Why not just get a large cooled mono CCD and stop messing around with DSLRs

James

[Pompey Monkey]

So i do have the Baader modification but it has not been debayered. Wondering what the results would be like.

Practice your art at multiple long exposures before moving to new cameras.

I managed this (as a newbie) with a SW 150P-DS and unmodded 600D (from a rather light polluted site):

And then the most obliging Mr Penrice (of SGL fame) offered some Ha data to the mix and, with minimal processing, I came up with this:

This image has 5 hrs Ha data and just shy of 5 hrs unmodded 600D data from two different locations. The key is guiding. Consistently and repeatedly.

Tonight, after reading another thread (with Mr Penrices' input), I tweaked the same image and arrived at this:

So yes. Better cameras capture more, but the key ingredient is integration time.

[D4N]

A modded DSLR with a Ha filter will only receive light on one in every 4 pixels, this isn't the end of the world though as you can change the weighting on the G and B pixels to zero or copy the R onto the G and B when you demosaic. This will greatly reduce the amount of noise you get.

Then do some RGB shots for star colour and combine to make a HaRGB image.

A mono camera would be better but you can certainly achieve a lot with a DSLR.

Sent from my iPad using Tapatalk

[laser_jock99]

My only advice on this on this would be to not bother with 'Canon specific' clip filters and buy the proper 2" filters from the the start. At least they can be used with any camera- DSLR, OSC CCD, mono CCD whatever. Avoid buying the same filters twice!

[AlistairW]

Thanks for the help - need to have a think

[Pompey Monkey]

Thanks for the help - need to have a think

There's a lot of think to be thunk in this hobby!