Sick to death of debayering so out with the mono DMK21AU04 + filters. Seeing was a bit iffy but generally ok. Good enough for this kind of test anyway. Bloody hard work but at least I was occupied! With the DBK all you do is sit there watching for 5.5 mins with not a lot to do except scan for incoming clouds.
Good fun
Be gentle, this is my 3rd ever RGB & as the title says, 1st Saturn
These look very good to me John – I’d be over the moon if I could produce Saturn images of this quality at that image scale. I guess the capture and processing workflow will get easier and a little less frantic once you get it down pat!
I think a good effort Asi and I like the colour, reckon the basis of it is to try for neutral ring colour, grey or white. The width of the CD is always a pretty good gauge as to the seeing and how much sharpening had to be applied.
There is a hint of the cloud structure in the NEB showing through, with better seeing I think you will get great results from the mono camera.
Not sure of the histo setting you used but if it is any help I have found the R & G at about 80% with B at about 60% works well for me.
As soon as I have my RGB & IR data I generally start running them through Castrator while keeping an eye on the live feed for any improvement in the seeing. It only takes about 10 mins to run it all through and that gives me ahead start the next morning with my processing.
Regarding the C ring, I leave the gamma at default with the gamma box unchecked.
Thanks Dennis. Yes it was a bit frantic at times. Once thing I'm still unclear about is should I be using that Astronomik L filter on my nosecone as a 'dust-bunny protector' for the chip. As far as I know, this L filter is just a UV/IR cut filter with another name but the RGB filters I use are already UV/IR cut...In which case I'm getting a double up of IR/UV cut...Or that's how I'm looking at it in any case. I don't want to waste valuable light!? Any advice in this area gratefully accepted!
Thanks Trevor. When I see a big fat, wide coal black CD that means to me it's been overprocessed. If I can't get a nice thin line & still maintain control on the amount of noise/grain on the globe I'll delete the data, no questions asked.
I had a couple of dry runs, just to test myself regarding camera settings & I'm still unclear as to what I should be really doing. I previewed each filter & fiddled with gain levels & found at my optimum FR (F15 based on 30FPS) I ended up using (by eyeballing the histo) a 55% histo for all 3 filters by giving R & G 55% gain & B 85%. The only other thing I can think of is to drop back to 15FPS on the B with a lower gain level.
...Once thing I'm still unclear about is should I be using that Astronomik L filter on my nosecone as a 'dust-bunny protector' for the chip. As far as I know, this L filter is just a UV/IR cut filter with another name but the RGB filters I use are already UV/IR cut...In which case I'm getting a double up of IR/UV cut...Or that's how I'm looking at it in any case. I don't want to waste valuable light!? Any advice in this area gratefully accepted!...
Like you, my RGB filters include IR/UV cut, so I reckon keep a nosepiece cover on the camera when not in use (to keep the dust donuts away) and don't permanently attach the L filter.
Particularly because I often use IR and UV filters and the L would have to be removed in that case anyway.
Well in this case Ivan, the images copped a double dose of IR/UV cut because I left it on. An old IR/UV cut (Baader) has been permanently 'welded' to the DMK nose cone for 4 years & the second I took it off last night, 1 million dust particles jumped onto the chip so I had to clean the thing before I could do anything. Screwed the L filter on pronto & imaged.
I had a couple of dry runs, just to test myself regarding camera settings & I'm still unclear as to what I should be really doing. I previewed each filter & fiddled with gain levels & found at my optimum FR (F15 based on 30FPS) I ended up using (by eyeballing the histo) a 55% histo for all 3 filters by giving R & G 55% gain & B 85%. The only other thing I can think of is to drop back to 15FPS on the B with a lower gain level.
Just wondering Asi how far off you are with using the 15", obviously would make a huge difference to the frame rate and gain. Even with my 16" at around 10m F/L, I run with max gain for the B channel, just looking at a recent FireCapture log its showing gain = 3318 at 31 fps.
No you don't need to have that filter in place and you are reducing your transmittable photons, so get rid of the extra filter. You should get a bit more light in as a result and that will help with frame rates.
I aim for 3/4 histogram and try to make every filter the same amount. that means different gain and exposure rates for each filter. That makes for easier colour balance. Astrodon filters are more evenly matched than the Astronomiks filters.
Yes, the big newt will make a difference. Still in process of making a linear fan & shroud system Trevor. Rather than peltier cooling, I've opted to try Alan Alda's idea of barrier layer displacement that I read about years ago & thought to myself "yes, that would work in theory" so I got in contact with Alan requesting info. To do it I have to have the skeleton framed OTA totally open, at least where the primary is for it to work, but then we have unwanted scattered light coming from bright laptops; kids turning outside lights on etc. that would disrupt things so I'm planning a special shroud as a light killer but full flow in an air flow sense. In the mean time, I'm still having fun with the C11. I love that scope.
very nice images Asi.
FWIW re histo, I use 30HzRG + 15HzB at about f28 at full gain and whatever histo that yields. adjust colour levels to pre-determined calibration ratios using multiplication function in IRIS before combining and sharpening. Final colour tweak in GIMP to get neutral grey rings and I normally try not to interfere with linear image value relationship (no non-linear curves adjustment and no gamma adjustment anywhere in the process) - unless needed to bring out a specific feature such as a storm spot. Alternative approach is to use about f20 at 60/30hz and super-res drizzle to recover resolution if fine detail is there, but local seeing will not support 30Hz - but this results in larger files and more read noise.
re dust, a routine cotton bud clean (or two) before each session.
regards ray
