Hello all...
First run test of the "Hubble" 40D using my set of 12nm Astronomik EOS clip in filters.
Problems!!
1. Tried it out on Eta which wasn't the best idea as it's sinking fast and image run was done on the night of a nearly full moon.
2. Mismatched Darks have caused that speckled artefact too.
Anyway enough excuses - but I think results would be way better at the zenith/new moon.
Exposures were 45 mins per filter (no way near enough - sorry more excuses!!) arranged as per the Hubble palette...
SII as Red, Ha as Green, OIII as Blue channels.
2nd image is a rough Synthetic RGB using the Ha and OIII data only.
All comments welcome - be gentle, this is my first toe-dip!!
No need to be gentle, those two shots are Superb, nice tight stars not an egg in sight and the first shot has a captivating feel to it, it's contrast is perfect really draws you in, Brilliant work !!
I prefer the red one. The green one comes about commonly with narrowband even with CCD cameras. Its because these objects dominate in Ha. S11 is usually the dimmest and O111 is often not that bright.
What it takes is:
1. Longer exposure time and longer sub exposure times with S11 in particular and with DSLRs possibly try higher ISOs.
2. When combining you'll have to make S11 say 4 times and O111 say 3 times the amount of weighting compared to Ha.
3. You'll have to crank up the curves on red to bring out the S11 and get those nice mustardy colours otherwise all you'll get is green with a small amount of blue in spots.
Same with CCDs.
The red really needs to be pushed hard in narrowband processing and lots of exposure otherwise its all green from now on.
Geez, Doug, focus is out mate. You're going to have to take the next Soyuz up and move that mirror up the tube of the "Hubble 40D". Looks like a cut and paste job on the tube, at the very least
Seriously though...I like the red one too. Feels less processed in some respects than the green. The blue centre on the green shot looks out of place, like it's been pasted into the shot.
No need to be gentle, those two shots are Superb, nice tight stars not an egg in sight and the first shot has a captivating feel to it, it's contrast is perfect really draws you in, Brilliant work !!
Kind Regards
Shane
Thanks Shane - early days with this stuff as noted above.
Fun trying though, s'pose that's what it's all about!
Doug
I dont know how to weight in photoshop but I usually do is use something similar to the channel enhancement method from Starizona (I have a PS action on my web page to perform the method if required). Obviously it is a balancing act to keep sky background neutral.
I also play with after combination is the Sleective colour (saturation) tool in PS to boost reds (SII) in the hubble pallete but it can introduce a fair bit of noise.
Another cheat I use is to blend Ha with the SII at say 10 or 15% opacity prior to combination just to give it a little kick in the behind - the purists will hate it but it does assist in balancing the pallette.
I dont know how to weight in photoshop but I usually do is use something similar to the channel enhancement method from Starizona (I have a PS action on my web page to perform the method if required). Obviously it is a balancing act to keep sky background neutral.
I also play with after combination is the Sleective colour (saturation) tool in PS to boost reds (SII) in the hubble pallete but it can introduce a fair bit of noise.
Another cheat I use is to blend Ha with the SII at say 10 or 15% opacity prior to combination just to give it a little kick in the behind - the purists will hate it but it does assist in balancing the pallette.
Mark Bolton
Thanks Mark - I'll explore these points further. I'll check out your PS action too.
Doug
Doug, from what you said about the images I personally have no idea what you are talking about, however, other than the horrible green and the over bright red the shots are superb mate.
Doug, from what you said about the images I personally have no idea what you are talking about, however, other than the horrible green and the over bright red the shots are superb mate.
Errrr Thanks leon (I think)
But I think you're correct in some respects - just getting a decent colour image out of a DSLR is difficult enough sometimes without trying to be a clever bugger!!
Im not going to post it cause I hate that but to give an idea what to aim for a SII boost or weighting increase (if that is your intntion - I am not passing ymself off as an expert here) try just dropping the hue slider to about -25 (or to taste) on the master channel in Image->Adjustment->Hue and Saturation , duplicate the image - convert it to grey scale and adjust contrast to taste then paste it back in as a luminance and it will synthesis boosting the SII - its a rough and ready method but it may assist.
I mean its a danm good image for a DSLR nb anyway (in fact any nb) but regarding your question re channel weighting to balance pallette this might assist
Im on theobservatory computer at the moment (drove out last night) so im not sure of colour etc but this is rough and ready.
Again im not an expert - this is just what i've gleaned so far - I couldn't understand why SHO pallettes all looked pure green so I experimented and this is what i came up with.
First I converted your original to a greyscale and used carbonis lighten DSO action and blended at about 60% - obviously far more can be done if required - I saved this for the luminance
The first image I extracted your SII, Ha, OIII channels, converted them to 16 bit greyscale tiffs and recombined them in Maxim DL with weightings of SII (3), Ha (1), OIII (2) - the weightings should come from a G2V calibration but this serves for now - then I pasted the luminance in - as was said before I think this is the 'correct' way of doing it.
In the second I used Starizonas red channel enhancement action on your original image and blended the layer at 20%, tweaked some midtone levels and then pasted in the luminance.
Yeah there are magenta stars in the first and both could be processed more (especially the luminance) but it gives an idea of how (I think) the gurus balance their pallettes) - or a first step anyway.
BTW - Leon - I know what you mean - I lecture for 3 hours at uni sometimes and I have no idea what I said in that time when i'm finished - a bit like driving and have no recollection of it - damn i'm dangerous
I have now officially reached and shared the limit of my knowledge (or lack of it) - Hope you can improve on it.
using my set of 12nm Astronomik EOS clip in filters.
)
however, other than the horrible green 
and the over bright red 
