First RGB image

[JB80]

Hey all,

Got a quick session on Saturn last night to try out my new filter set with the ASI120mm and I can certainly see the difference in the channels and finished image so it looks a excellent combination.

I only did a straight up session with no barlow in the 6" newt so the image is a little small and I'm not sure I combined the channels right as the finished image was a touch funky looking so I probably made it worse after by messing with the colour balance but it's all a learning curve so it'll come eventually.

Also when using the B it was a really dim image and I don't think I nailed the focus so you can see a really noisy B image, it was the runt of the avi's by a long way but it was the only one I had so I used it.

I have included the RGB originals so if people think that looks about right or if something is off then that would be good to know and also a resized version.

Any tips or advice is always welcome.

[JamesF]

Very nice, Jarrod

James

[David Smith]

Certainly looks like a great start Jarrod as it is nice and sharp.

[JB80]

Thanks all, I reckon if I can improve the focus and throw a barlow on it should improve things too.

Hopefully I can get some more chances before I lose the elevation on Saturn.

[simmo39]

V nice.

[Grotemobile]

You have got some good pics there.

They have come out very clear.

Steve

[RikM]

Well done indeed

[Pete Presland]

a pretty tough target and it has come out pretty well!

it does look a little to blue to be honest. you should be able to adjust that when you are constructing the RGB image, maybe reduce the blue channel slightly.

[DrRobin]

Looking very good Jarrod, I would have thought that Saturn was getting quite low now?

I had always assumed that my camera is most sensitive around the red, (I think my cooled CCD is), but the ASI120MM seems to peak just above the blue, so you need to reduce the blue quite a bit.  If you look at the sensitivity curve for the ASI120MM and assuming your filters have the same tranmission you could probably guess the exposure reduction for the blue channel.

I started off down the same route, balance everything up on the histogram, but actually it is better to set the exposure for one colour and use the same for all three colours.  I am interested to note that you have got the best detail in the green, I usually get the best in the red with the green a very good second.

One further thing you can do is to create an RGB, but then create a luminance channel from your best colour (green in this case).  Then combine the luminance and colour, it is amazing how much extra detail it pulls out.

A great effort, shows your scope is correctly aligned as well, so it will be also good for solar.

Robin

[JB80]

Thank you everybody.

a pretty tough target and it has come out pretty well!

it does look a little to blue to be honest. you should be able to adjust that when you are constructing the RGB image, maybe reduce the blue channel slightly.

Cheers Pete!

Yeah that will be something I will try out either on this one or the next time, I did do it but probably something went wrong(ie me).

Looking very good Jarrod, I would have thought that Saturn was getting quite low now?

I had always assumed that my camera is most sensitive around the red, (I think my cooled CCD is), but the ASI120MM seems to peak just above the blue, so you need to reduce the blue quite a bit.  If you look at the sensitivity curve for the ASI120MM and assuming your filters have the same tranmission you could probably guess the exposure reduction for the blue channel.

I started off down the same route, balance everything up on the histogram, but actually it is better to set the exposure for one colour and use the same for all three colours.  I am interested to note that you have got the best detail in the green, I usually get the best in the red with the green a very good second.

One further thing you can do is to create an RGB, but then create a luminance channel from your best colour (green in this case).  Then combine the luminance and colour, it is amazing how much extra detail it pulls out.

A great effort, shows your scope is correctly aligned as well, so it will be also good for solar.

Robin

Thanks Robin!

It's still reasonably high as darkness falls, if you get a chance try and find it tonight around 10:30-11. That's about my window because if I leave it much later I'll have to flip the scope and I can't be having that.

Yeah I was reading an article saying that the Red on the ASI120mm is considerably the least sensitive but they praised how good it was on the Blue and Green as Blue can be the trickiest of them all so the extra sensitivity helps.

I didn't change the exposure for any of the captures, I think. It was just the focus and because I could hardly see it for the Blue I guess I was off a bit. That is probably why the Green was the best as I think the focus was slightly off on the other two, next time I wont touch it.

I can try the luminance thing but it was mentioned as I have the Baader filters they have it already in the filter, I do have the separate L filter as well so I'm a bit puzzled by it all to be honest.

[JB80]

Hmmm, I had a go again last night and the seeing was admittedly poor but with the x2 barlow I couldn't get any more than 10fps on Saturn with the ASI120mm. The ROI couldn't get smaller, the exposure and gain I couldn't change any more.

Would changing to 16bit speed it up or am I simply at the limit.

[ArmyAirForce]

I also have the ASI120MM. I tend to set the exposure levels for each filter to expose the histogram to about 70% to 80%, then adjust the colour in processing of each colour channel. I often use the red channel as a luminance layer, as the luminance filter alone is usually spoiled by the quality of the blue light. The Colour balance was most noticeable on Mars, I had to drop the saturation to 85% on the Blue and 90% on green, to get the image to look right.

Regarding the frames per second, this season, Saturn barely managed 20 degrees altitude above the horizon. Looking through that amount of atmosphere, the blue channel really suffered, and was very dim. I was getting 10 to 13fps on Blue, 14fps on Green and 20fps on Red with a x2 TAL barlow.

Saturn is only going to get lower over the next few years, so getting a nice image is going to be hard work.

[Vox45]

Nice and crisp ! Well done