cloudy? want to have a play?

[Aza]

I dont know this for fact.

But on a narrowband yahoo group I am a member of, a lot of the imagers use these filters, and produce stunning images.

Their choice in filters comes after years of experience.

What would be your choice Paul, and why?

[narrowbandpaul]

you are a member of the NBI yahoo group? me too......

i have heard reports that the astrodon filters lack contrast....

the baader ones get a good review from most, and they are far cheaper than the astrodons.

infact the astrodon O[iII] I use casts haloes, the baaders I believe do not cast these.

I would go with baader, or cust sci, for the narrower stuff.

[Aza]

Seems to be a lot of info around, some of it conflicting

I am a member of that group, but I was mainly referring to this one:

astro_narrowband : Astro_Narrowband

Unfortunately I dont have access to different filters, so I go by what is said by the people whose images I want to emulate.

I only have modest equipment, but I will do all I can to squeeze the most out of it.

And from all the reading I have done it seems that the filters I mentioned above are the way to go.

The astrodon you have, I assume its an older one. As the latest generation do not cast halos.

[Tim]

The blurb that comes with the second generation Baader filters makes an interesting read. You can read it on most sites selling them, eg FLO.

[Tim]

Rob, the link is still working, try it again, if it still doesnt work i'll put them elsewhere for you

[RobH]

Just had a play Tim, and it's very good data, just not enough of it

SII and OIII are very noisy, so I did some selective noise reduction before I started to stretch anything.

I'd say that 30% more Ha, and at least double the number of subs, plus longer exposures on the other 2 channels, would go a long way with this, and would be worth doing.

I tend to do my first batch of subs, then process them and see what amount of stretching I can do until they get too noisy. This gives me a good idea wher the weaknesses lie, and then I just keep shooting and processing until the image comes out easily. That does sometimes mean spending a month on a target though

I didn't try to push the SII or OIII beyond the noise limits, so the image tends to the green rather than being more yellow, but, as Martin said, there is no correct colour in NB, and I think a clean image is the most important thing.

Cheers

Rob

[Les Tilly]

Well I gave it a go but I dumped the SII and used the HA and OIII

HA for red OIII for green and Blue

Thanks for letting us give this a go now it makes me want a one shot Color CCD

Les

[Tim]

Thanks Les/Rob. I really like that softness without loss of detail Rob, must get together with you at salisbury and see how you do that.

I have some extra OIII data which has really helped, I was surprised how the colours alter so dramatically with the extra data. I think now I am going to stick with this for a while and just keep adding to it. I should think that with the SII filter in particular, subs of an hour or more would be reasonable. Maybe i'll add more to that band when the target is higher, it has a while to go yet.

Les, i'll try your method with my new OIII data, thanks for that.

[rich_t]

Hi Tim, Thanks for the data, I don't have narrowband filters at the moment so nice to have a play with some data.

I stacked the 3 files together to make a luminance layer and then applied the colours using LRGB technique, as an experiment really. I thought if I software binned the colour data I'd be able to stretch it more. Basically I made it up as I went along!

Thanks again,

Rich.

[rich_t]

Not sure if I'm allowed another go:) Think this has turned out better. Used the Ha as L and then applied the three files as rgb.

Cheers,

Rich.

[narrowbandpaul]

ha shouldnt be used as a luminance layer, as the O[iII] and S[iI] data may not align, in which case they are supressed.

keep plugging away, its how we learn....

paul

[rich_t]

My first ever LRBG picture (the crab nebula) was done with the L shot through the red filter, all my blue disappeared when LRGB was performed!

I guess you could get away with it if the Ha is very strong and covers all the areas where the other wavelengths are?

Cheers,

Rich.

[narrowbandpaul]

yes, but as you probably know adding an L layer can mute the colours, ie they are not so vivid.

in narrowband it is best to not use an L layer, and really shouldnt use an e-line image as an L layer

paul

[Cloudwatcher]

Reasons I don't do Nebulea, one,two, three. :D

[glennbech]

Here is my quick 20 minutes of play. Instead of going HST or something I tried R=ha, G=SII, B=OIII. I did some local contrast enhancement on all channels and a small tweak after combining them.

Hope you like it .)

[Tim]

Thanks all for your input! Very interesting to see what you guys make of the data.

Cheers

TJ