Goodbye DSLR/OSC?

[Stub Mandrel]

I'm about to take the nervous step from DSLR imaging to mono, with filter wheel, nb filters and lots more  complication.

Having used a DSLR (mostly a Canon 450D, modded and cooled) for about 5 years I have had some really pleasing results and some disappointing ones. In the last few months I have been using one of the new tri/dual band filters that lets through Hb, OIII and Ha. While I ahven't used it on many targets with a lot of OIII  it's results with Ha targets have been remarkable, exceeding the results I get with a 7nm Ha filter.

Last night I had a six hour session with my 450D - quite a venerable DSLR. I used it with my ED 66, guided, 5-minute subs and used the Optolong L-Enhance filter. I have suburban skies, allegedly Bortle 5, but I wouldn't class them that good. All of these have been processed quite simply: Stack in DSS using super pixel mode. Stretch using x^1/5 in FITS liberator, combine into RGB with photoshop. Use Noel's  'reduce horizontal banding' to get rid of slight effect in background of red layer (noticeable if background too light). Select background and use Gradient Exterminator to balance colour (no noticeable gradient to get rid of). Use Noel's  increase star colour action a few times. Select brighter stars, expand and feather, then use selective colour to turn red stars orange and cyan stars bluer (this corrects the effect of the L-enhance filter on stars). Run HVLG. Curves to set background level and boost mids without boosting stars. Save and open in Astra Image. Gentle denoise (Pacman and Monkey Head only, California with 3 Hrs didn't need any denoise). Multi-scale contrast. Save as 48 bit TIFF and 24-bit PNG.

My conclusion is that these new filters, by reducing light pollution and enhancing Ha in particular, offer a significant step up for DSLR users and do narrow the gap with mono imaging. Also, I think accepting the reduced resolution of super-pixel images helps reduce teh signal-noise deficit of OSC as well.

One experiment I tried shows that the l-enhance images make an excellent luminance layer on top of ordinary RGB images which may have better colour but less detail.

Here are last night's results:

Pacman Nebula, 22 x 300s

California Nebula, 31 x 300s

Monkey Head Nebula, 21 x 300s

 

Edited December 4, 2019 by Stub Mandrel

[Whistlin Bob]

Especially like the California Neil 😁

[tooth_dr]

I have to say those are really rather good Neil.  Looking forward to how you get on with Mono and NB. 

[happy-kat]

What's your shortest exposure length have you found that you get signal when using that filter please?

I'm toying with a tri band but my immediate limitation is exposure length.

Edited December 7, 2019 by happy-kat