Eta - now with bi-colour attempt

[rustigsmed]

First light for my new baader 7nm Ha filter, it was a crystal clear night in Melbourne (although some smoke around) - gee it is good to be able to image under a gibbous moon :thumbsup: and to kick off before 9pm, school night imaging is back :D

no shortage of issues, stars top left in particular really bad (tilt predominantly - I think) and also the focuser tube was protruding into the tube which I think gave the funny star shapes - still getting used to how far I need to place the RCCi into the focuser (more it seems - that would avoid the focuser intrusion). Also am going to have to get a bahtinov mask -focus is difficult even with live view - not sure how the gurus do it with 3nm filters.

still - some nice detail to be had, my second go at capturing NB - zeroing in slowly and reasonable for a dslr.

Exposure was around 2hours 20 mins at 7 minute subs (iso 1600).

Higher res

B&W
https://www.flickr.com/photos/80336656@N07/16979197685/in/photostream/lightbox/

Natural
https://www.flickr.com/photos/80336656@N07/16979197685/in/photostream/lightbox/


Cheers

Rusty

ps i'll no doubt reprocess tonight :lol:

[Paul Haese]

I have been collecting with this very same orientation. The Mono image looks good.

[strongmanmike]

Nice work Rusty :thumbsup: Eta really looks good in Ha.

yes having NB filters certainly helps in moonlit skies, using 12nm NB filters I have noticed that there is still a tad more contrast under moonless conditions and the moon can also shine down the tube at certain angles and create havoc too, especially with a Newt because the side light input is up near the end of the tube, although this is much less likely in a dome :) To hopefully help under the Moon, I have a full set of Astronomiks new line of 6nm NB filters on their way, this should improve NB imaging under moonlit skies..?

Mike

[Placidus]

Very nicely processed, Rusty.

With narrowband filters, if the moon is say in Pisces, then you can image bright objects in the deep south happily for all but a couple days either side of the full moon.

Any sort of moon at all say just 15 degrees away is as Mike says, a disaster, and for really ultra-faint stuff, one needs the new moon. Also thin haze, which often means good seeing, is bad if the moon's bright.

Nice work.
Mike

[rustigsmed]

thanks for that Paul - yes I thought the straight Ha colour was pretty intense.
Looking forward to seeing your version.



Cheers Mike :thumbsup: yes I was pondering the moonlight angle and was thinking either an extension tube was needed if not shooting south - or atleast a baffle (or dome). it also got me thinking about filters, one can take a photo of the moon in Ha no problem at all so I was thinking what is it that actually makes a NB filter so useful in moonlit skies - I've come to the conclusion (whether rightly or wrongly :lol:) that the filters generally only allow 'straight' light through the filter and onto the sensor so the stray moonlight while going down the scope is less likely to hit directly square - kinda like a polarising filter (I think). anyway that was my ponderings as I was sitting outside under the heavens.

I bet you're hanging for the 6nm's they're a new release I think? baader seem to have the best value nb filters I don't know how they compare with astronomiks - although the astronomik ccd cls is clearly superior in transmission than the baader equivalent.



cheers Mike - good to know to steer clear a few days around the full moon and to watch the haze - I wasn't too sure how close you could go. Is it also true the OIII is a bit more susceptible to moonlight than Ha (which blows my conclusions above out of the water :lol:)?

I think the tilt is a result of the OAG - as sometimes its there and other times its not, I don't really require the thinline anymore one so may have to start investigating more sturdy options.

Pretty happy in how the canon 600d handled 7 min subs - the sensor was at 29 degs most of the night.

I also took flats with the Ha - i'm not sure whether people do that or not - I was worried about noise. on another note I didn't use any darks for this just flats and dithering.

[strongmanmike]

Hmmm? not sure bout that..? I was talking about direct moon light getting down the tube and on to the front corrector lens in my Newt. When I was out doors I used a 200mm dew extension on the front of the tube and this helped and the dome makes it very hard now for direct light to get inside my tube :thumbsup:. As for the indirect sky glow from the Moon, I am sure it is simply a case of there isn't much coming through the few nm band width of the filter and the less the band width the less there is getting through?

I think Gerd ahs been working on them for a while and I know he is very happy with the result, very high transmission even at 6nm something like 95% or more I believe :thumbsup:

[rustigsmed]

I think I smell an upcoming side by side review (12v6) :)

[strongmanmike]

How funny, they just arrived now at work:eyepop: :thumbsup:

Ha: 6nm @ 97.8% transmission good to F3.1
OIII: 6nm @ 93.5% transmission good to F3.4
SII: 6nm @ 97.4% transmission good to F2.4

[rustigsmed]

ha! that is funny - looking forward to hearing how they go :thumbsup: they're good for quick optics too -nice.

[Ross G]

Great looking photos Russell.

Love the monochrome.

Good luck.

Ross.

[rustigsmed]

Thanks for that Ross :thumbsup:

Had some O3 data which was taken on a hot night, slightly out of focus, shorter than the Ha and just generally fairly bad. But thought i would have a go at making a bi colour nb image - my first of hopefully many.

used DSS to intersect and create the green channel from Ha and O3.
Then added a mono version of Ha to the red and a mono version of O3 to blue in photoshop. i had to move, rotate and warp to align the pics to the green.

experimented with attempting to remove the stars and reducing their size but the out of focus O3 was too much of a problem for my skills. this probably would have worked better if i did it wit the original O3 file before mixing with the Ha to make green ...

anyway my first nb bicolour - it seems to have worked somewhat :D

Vibrant version
https://www.flickr.com/photos/80336656@N07/17015235692/in/photostream/lightbox/

Normalish with no star reduction (edit: now see something had happened with flickr darkening the 32bit format ...)
https://www.flickr.com/photos/80336656@N07/17015826971/in/photostream/lightbox/


Clear skies

Rusty