Jupiter's White Ovals in South Polar Region using an 8" SCT
I imaged Jupiter with my DBK21AU04 and 8 inch SCT on Sept 1, 2010 at 4:19 AM EDT from Baltimore, Maryland. For the first time I was able to image Jupiter at F/30 with a 3x barlow. That enabled me to see two of the White Ovals in Jupiter's South Polar Region. Note that South points toward the top of my image. You may need to increase the brightness and contrast on your monitor to see the image at its best.
Not too bad Peter.
It looks a little under exposed, but I'm not sure if it's the capture or the processing?
What capture program did you use? And do you have more details of the capture? eg. #frames total/stacked, exposure time and frame rate, etc.
Great potential with a bit of refinement.
Thanks Clayton, yes the under exposure occurred when I was capturing the AVI file. I use IC Capture 2.1. The AVI file consisted of 3417 total frames and 1201 stacked frames with a low quality setting of 85% using Gradient2. The exposure time was 1/15 sec and the frame rate was 15fps. I forgot to change the "Hue" setting so I believe it was very low. Also I didn't know how to choose the proper gain setting to compensate for the reduction in light on the CCD sensor caused by inserting the 3X barlow. Which codec do you use? I was using RGB24 with the YUY2 color format.
Hi Peter. As promised I'm here to offer any assistance with this camera. Hope you have a current pilots license!
It is fairly complicated with all those codecs to choose from
I've experimented a lot with different codecs on the DBK. The most successful results right now are coming from the 'KISS' principle codec - YUY2 + unspecified. I was using Y800 + Y800 which gives you a mono live feed & it'll be mono data according to registax as well but that's where you need to activate the debayering option in registax. Registax 5.1 is best for this. With Y800 you'll be able to capture @ 60FPS uncompressed. You won't ACTUALLY be getting 60FPS but according to all your programs it'll be 60FPS (Don't ask)
Always use the histogram in IC capture Peter I'd doubt very much if you'd get a full histogram with your 8" running a 3X barlow without a low frame rate like 15. In order to get a half decent shot of Jupiter you need to capture as many frames as possible in the relatively short time frame available before planet rotation upsets the apple cart. 30FPS is the minimum I reckon.
...I was using Y800 + Y800 which gives you a mono live feed & it'll be mono data according to registax as well but that's where you need to activate the debayering option in registax. Registax 5.1 is best for this. With Y800 you'll be able to capture @ 60FPS uncompressed. You won't ACTUALLY be getting 60FPS but according to all your programs it'll be 60FPS (Don't ask) Always use the histogram in IC capture Peter I'd doubt very much if you'd get a full histogram with your 8" running a 3X barlow without a low frame rate like 15..
Any Q's, fire away!
Thanks for the help John. I've only had my DBK camera for about a month and I bought my first telescope 3 months ago. Still what I lack in experience I try to make up for in persistence!
I forgot to ask whether you're using a 3x barlow and also what focal ratio you're imaging at. Apparently it's possible to image above F/30 with a 3x barlow if one secures the barlow at varying points along the cylindrical adapter that attaches to the DBK camera.
Have you posted an example of a Jupiter image where you use the Y800 codec? You mentioned not getting 60fps; how many frames per second can one expect to get?
I just discovered the live histogram in IC Capture; am I correct in thinking that the objective is to fill up the histogram as much as possible between 0 and 255? Is the level on the Y axis of the histogram important or am I just trying to have as much coverage along the X axis as possible?
Thanks again John I really appreciate you taking the time to help me.
Looks like it has to much red. DBK needs an IR/UV cut filter to get the propper color balance as it pass IR and UV. I've edited the image slightly making it brighter and less red.
Ah yes, an important point riklaunim has brought up - Are you using one of these? It's a necessity in this game..
Well it depends on the seeing as to what image scale (focal ratio) you would use. With my C11 SCT I would only use the 3X barlow in good to exceptional seeing. The worse the seeing, the less the image scale you would want to be using. In nasty seeing I'll unscrew the 2X barlow elements & screw it onto the camera adapter giving me about 1.5X.
I've never bothered to work out exactly how many FPS I'm getting @ the supposed 60FPS rate actually. I will though later, & let you know.
Yes that's correct regarding the histogram - You'll want to keep it as close to 255 as you can. You can tell if you overstep the mark, you'll be getting highlight burnouts (over exposure) in the equatorial regions in the center of Jupiter's disc.
Focus tip: Get jupiter on screen, adjust all your settings, & then lower your gamma to 55 & refocus. Don't forget to bump it back to 100 before pulling the trigger lol..
Ah yes, an important point riklaunim has brought up - Are you using one of these? It's a necessity in this game.
Yes that's correct regarding the histogram - You'll want to keep it as close to 255 as you can. You can tell if you overstep the mark, you'll be getting highlight burnouts (over exposure) in the equatorial regions in the center of Jupiter's disc.
Focus tip: Get jupiter on screen, adjust all your settings, & then lower your gamma to 55 & refocus. Don't forget to bump it back to 100 before pulling the trigger lol...All the best.
I have an UV/IR cut-off filter however I haven't used it yet; I'll try it next time I image. Thanks for the tips about over exposure when I'm monitoring the histogram and the method of lowering the gamma, refocusing, and raising the gamma back up. This process is really turning out to be an art form; I'm glad I had you here to give me some pointers!
Oh and what a great idea you had to target Jupiter's moons as the Jupiter system reaches its closest point to Earth in 47 years. I never stopped to think that not only is Jupiter at its closest in a half century but so are its moons. The surface detail on your Ganymede, Callisto, and Europa image is clear. It should only get better over the course of the next 2 weeks.
G'day Peter. Just thought I'd point out that you must have missed the bit where I said that the triple moon shot was taken 2 apparitions ago; June 2008 actually lol.
No problems on the tips at all. I'm glad to help - We DBK'ers must stick together. It's one of the finest one shot colour camera's around.
Two major problems here; Ringing & that grid pattern. I took 2 using this codec this morning & I'm about to delete both! I've spent a lot of time trying to figure out WHY - but the end result is I'm simply not going to be using it from now on, much easier..Actually I'll drop the other 'proof' in here as well. A direct comparison.
G'day Peter. Just thought I'd point out that you must have missed the bit where I said that the triple moon shot was taken 2 apparitions ago; June 2008 actually lol...
Oh ok well then the surface detail on the moons should be even better this month between Sept 19 and Sept 22 when Jupiter has an apparent size of 49.9 arcseconds (compared to 47.2 arcseconds on June 30, 2008). I'll be looking to see if you take any Jupiter moon shots in the next 2 weeks so that we can determine whether any new features appear that were not resolved in your 2008 image.
Here's one for you, using the Y800 codec @ 60FPS.
Two major problems here; Ringing & that grid pattern.
I don't know if it will help but there's a "Dering" function in Registax 5.1 (on the wavelet page). Speaking of Registax I noticed that there are 7 different "Quality settings" on the first page called "Classic, Human, Compress, Local Contrast, Gradient, Gradient2 and Blur Diff". Which one of these tends to give the best results? Below that there's a "Lowest Quality" setting. I've been using 85; is that a good value?
Hi again Peter. Yes I have tried that deringing feature & it does work to a degree. However it only works with mild ringing & I've seen examples with bad ringing (A lot of these rings) where it didn't solve the problem.
I've tried all the 7 quality settings & to be honest, I can't see a lot of difference. I use the 'gradient 2' function as I keep seeing claims (on the net) where it is the best to use.
As to the moons; I took a few of Io the other morning (9th Sept.) while capturing Jupiter. Io is 1 arc second dia. at the moment.
As to the moons; I took a few of Io the other morning (9th Sept.) while capturing Jupiter. Io is 1 arc second dia. at the moment.
Ganymede should be a good target too because it has an apparent size of 1.8 arcseconds with all sorts of differentiated surface features. Your previous image of Ganymede from June 2008 shows a number of sharply defined areas. At the time the moon had an apparent size of 1.7 arcseconds.
Thanks Clayton, yes the under exposure occurred when I was capturing the AVI file. I use IC Capture 2.1. The AVI file consisted of 3417 total frames and 1201 stacked frames with a low quality setting of 85% using Gradient2. The exposure time was 1/15 sec and the frame rate was 15fps. I forgot to change the "Hue" setting so I believe it was very low. Also I didn't know how to choose the proper gain setting to compensate for the reduction in light on the CCD sensor caused by inserting the 3X barlow. Which codec do you use? I was using RGB24 with the YUY2 color format.
Peter
Sorry Peter, I can't help you much with codecs as I have not the experience with those you quote or a DBK camera, or IC Capture.
As for the IR filter My experience is limited to Newtonian Telescopes, and so may not apply to SCT's.
I have been Imaging Jupiter for nearly 12 months (a relatively short time) and was advised by many that an IR filter was essential, and by others that it may help my colour balance.
Recently a generous friend, KM (thanks Darryl) loaned me one to use. Unfortunately (as is often the case with these things) it has been mostly cloudy since. But the one opportunity I have had to try the setup out was inconclusive (no visible difference) I am still hopefull that conditions will improve here so that I can perform a better comparison. I think that you can go a lot further than your promising early effort if you practise & practise getting basics as good as you can ie focus, collomation, exposure. etc. And when great seeing comes along (hopefully sometime near opposition) You will reap the rewards
As mentioned earlier My experience is with a Newt' and maybe SCT's suffer from a small ammount of CA that doesn't affect Newtonians
... I think that you can go a lot further than your promising early effort if you practise & practise getting basics as good as you can ie focus, collomation, exposure. etc. And when great seeing comes along (hopefully sometime near opposition) You will reap the rewards
Thanks again Clayton, I guess we're all racing the clock with only 9 days left until opposition I have a motorized focuser that lets me adjust the focus in fine increments; that's helped me a lot and I know my collimation is good because I recently tested it. My biggest problem is keeping Jupiter centered within the camera's field of view when I use the 3x barlow. When I use no barlow at all Jupiter does not drift within the camera's 11 arcminute square field of view; however I have not been able to center Jupiter close enough to the middle of that square because when I insert the 3x barlow to image at F/30 Jupiter is usually too far off to one side of the field of view where it can neither be seen nor imaged. That means that I have to use the hand controller to manually bring Jupiter closer to the center where it can be seen through the 3x barlow. That is when the clock drive of my scope begins to fail and Jupiter drifts off the field of view. I use a reticle eyepiece for the alignment procedure however it's difficult to hit the "Align" button at the exact moment when the alignment star reaches the center of the crosshairs. I have one of the least expensive go-to mounts on the market so I may have to upgrade my mount. In the meantime I've gone to the rather extreme measure of experimenting with an autoguider to lock Jupiter in place at the center of my laptop screen. I'm attempting to use Jupiter itself as the autoguider's guide "star".
(Don't ask) 
I'd doubt very much if you'd get a full histogram with your 8" running a 3X barlow without a low frame rate like 15. In order to get a half decent shot of Jupiter you need to capture as many frames as possible in the relatively short time frame available before planet rotation upsets the apple cart. 30FPS is the minimum I reckon.
I have a motorized focuser that lets me adjust the focus in fine increments; that's helped me a lot and I know my collimation is good because I recently tested it. My biggest problem is keeping Jupiter centered within the camera's field of view when I use the 3x barlow. When I use no barlow at all Jupiter does not drift within the camera's 11 arcminute square field of view; however I have not been able to center Jupiter close enough to the middle of that square because when I insert the 3x barlow to image at F/30 Jupiter is usually too far off to one side of the field of view where it can neither be seen nor imaged. That means that I have to use the hand controller to manually bring Jupiter closer to the center where it can be seen through the 3x barlow. That is when the clock drive of my scope begins to fail and Jupiter drifts off the field of view. I use a reticle eyepiece for the alignment procedure however it's difficult to hit the "Align" button at the exact moment when the alignment star reaches the center of the crosshairs. I have one of the least expensive go-to mounts on the market so I may have to upgrade my mount. In the meantime I've gone to the rather extreme measure of experimenting with an autoguider to lock Jupiter in place at the center of my laptop screen. I'm attempting to use Jupiter itself as the autoguider's guide "star".
