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edsplace
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Last Ganymede transit w/ASI120MM 1 resize 1.35X
      #5557881 - 12/06/12 05:02 PM Attachment (155 downloads)

I found the best capture from last nights transit and re-sized it 1.5X the image didn't hold up, so I downsized it 10%. It looked better. The albedo features on Ganymede are easier to see, but I am not sure there is any more detail to them. I found after processing all the videos that as I increased the gain edge artifacts would form, if I kept the gain below 50 they were much less noticeable or not there. I also found that in the green channel there were edge artifacts if focus was just a little bit off, or in poor seeing when there were no artifacts in the other channels. This was the only downfall I have found so far, and I am not sure I would consider them a problem.

Edited by edsplace (12/06/12 05:09 PM)


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Re: Last Ganymede transit w/ASI120MM 1 resize 1.35X new [Re: edsplace]
      #5558065 - 12/06/12 06:48 PM

That's a beauty Ed. Worlds in all sizes.

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Re: Last Ganymede transit w/ASI120MM 1 resize 1.35X new [Re: edsplace]
      #5558075 - 12/06/12 06:53 PM

Looks great Ed!

Artifacts can come from some kinds of really diabolical seeing types, the camera or the stacking process. What kind of edge artifacts are you referring to?

Glenn


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Re: Last Ganymede transit w/ASI120MM 1 resize 1.35X new [Re: DesertRat]
      #5558132 - 12/06/12 07:26 PM Attachment (37 downloads)

I have attached an image that I have used excessive wavelets on to show the effect clear. You can also see they are constant throughout images in the animation I made here https://dl.dropbox.com/u/12373054/jupiter-120612-0353ut.gif if you look on the edge you can see the line stays fair stationary throughout the 23 frames.

reminds me a bit of the Phillips 740K when excessive gain was used.


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Re: Last Ganymede transit w/ASI120MM 1 resize 1.35X new [Re: edsplace]
      #5558140 - 12/06/12 07:32 PM

.....I don't believe those are camera artefacts per se Ed - I could be wrong of course, but they look much more like low gamma to me!

I hope/presume you're using "Gamma=50"....?

As I said beforehand, I haven't experienced any such effects personally.....


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Re: Last Ganymede transit w/ASI120MM 1 resize 1.35X new [Re: Kokatha man]
      #5558168 - 12/06/12 07:50 PM

Yes, I had the gamma set at 50. They may not be camera artifacts, they could be from AS2!, from capture setting, or even from the capture program. I have been able to "find" these rings in every other camera I have had (Phillips Vasta, Pihillips 740K, Sac7b, LPI, Sac8, SaC 4.2, Homebrew FCLabs CMOS, DMK21, and now this) some were more apt to produce the rings than others. This camera seems like it may be a bit touchy. Again... this camera outperforms all other cameras I have used, and I have been able to work around the rings.

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Re: Last Ganymede transit w/ASI120MM 1 resize 1.35X new [Re: edsplace]
      #5558185 - 12/06/12 07:57 PM

.....I also meant to say that I've seen low gain create that effect also.....but you're saying that the higher the gain is, the more likely they are....?

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Re: Last Ganymede transit w/ASI120MM 1 resize 1.35X new [Re: Kokatha man]
      #5558192 - 12/06/12 08:03 PM

With the 740K I would get bad ringing with high gain and longer exposures if the object still remained dim. Filling up less than 50% of the histogram.

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Re: Last Ganymede transit w/ASI120MM 1 resize 1.35X new [Re: Kokatha man]
      #5558194 - 12/06/12 08:04 PM

You can make any camera yield these onion rings. Usual cause is incorrect gamma. And even for gamma 1.0 sometimes if the exposure is not suffiently pushed the limbs fall in a flat part of the response curve. In other words the effective gamma is not what its set to. What you then have is large parts of the limb separated by too few counts. Then you get the posterization or the ringing effect seen here.

Glenn


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Re: Last Ganymede transit w/ASI120MM 1 resize 1.35X new [Re: DesertRat]
      #5558197 - 12/06/12 08:06 PM

That makes sense. I will increase the gamma next time out and see if it helps.

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Re: Last Ganymede transit w/ASI120MM 1 resize 1.35X new [Re: edsplace]
      #5558206 - 12/06/12 08:16 PM

Increasing the gamma may not be the best approach. Not sure about this camera but if 0.5 is gamma 1 (not the best number in my view to assign gamma 1) I'd try bracketing at 0.4 and 0.6, and also different gain settings. Yeah I know its a lot of work, but somebody has to do it! The good news is you don't need a lot of frames to determine the best combination, and you could do the whole test in red light just to keep it simple.

Increasing gamma can mean two totally different things in the image processing world, depending on the program being used. For a camera increasing gamma should appear to lessen the contrast across the planet, pushing it even higher the planet should appear almost all gray.

Edit: If you choose to test gamma as written above, also select 0.5! I left that out in error.

Glenn

Edited by DesertRat (12/06/12 08:56 PM)


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Re: Last Ganymede transit w/ASI120MM 1 resize 1.35X new [Re: DesertRat]
      #5558347 - 12/06/12 09:51 PM

Doh! My gamma was set at around .25 (25) somehow in all the excitement I must have unknowingly moved the slider. It has been reset to .5 (50). Il. See how it works out next time. On a not great night ill run some gamma/gain test.

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Re: Last Ganymede transit w/ASI120MM 1 resize 1.35X new [Re: edsplace]
      #5558354 - 12/06/12 09:56 PM

Quote:

On a not great night ill run some gamma/gain test.



I'll take your bad night images anytime over my good night images! .


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Re: Last Ganymede transit w/ASI120MM 1 resize 1.35X new [Re: edsplace]
      #5558534 - 12/07/12 12:11 AM

Quote:

Doh! My gamma was set at around .25 (25) somehow in all the excitement I must have unknowingly moved the slider. It has been reset to .5 (50). Il. See how it works out next time. On a not great night ill run some gamma/gain test.




Heck, I pulled another one back from my C/T2 thread blooper in my own thread Ed .....tbh I really though that was the issue for you (hence my first response) but I didn't want to sound rude bout it..!

FireCapture's log texts do have a couple of furphies, but they're allways a good port-of-call first-up to check your camera settings.

But great to put a finger on something - we're expecting to see even better images from your next decent seeing session!

Edited by Kokatha man (12/07/12 12:11 AM)


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Re: Last Ganymede transit w/ASI120MM 1 resize 1.35X new [Re: edsplace]
      #5558543 - 12/07/12 12:20 AM

Good catch Ed! I would stick close around 0.5 (gamma 1 ?) and vary other exposure settings to see if there is an optimum. Those logs are handy. Writing up your own notes sometimes helps also! Its amazing what you can forget in a span of hours, but at least the logs are written.

Problem with finding an optimum is that seeing trumps everything else by such a wide margin that night to night and even minute to minute variations can be misleading.

Glenn


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Re: Last Ganymede transit w/ASI120MM 1 resize 1.35X new [Re: Kokatha man]
      #5558568 - 12/07/12 12:47 AM

Darryl,

Quote:

FireCapture's log texts do have a couple of furphies...




Let me know what entries you have in mind and I can try turning them into code of law

Torsten


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Re: Last Ganymede transit w/ASI120MM 1 resize 1.35X new [Re: TorstenEdelmann]
      #5558594 - 12/07/12 01:23 AM

Hi Torsten - I wouldn't want anyone to think that I have an ounce of criticism towards your supremely excellent software...particularly after all the work you did on the ASI120MM DirectShow camera (which types you'd already said to Sam and me were only kept viable on FireCapture by virtue of people's requests.....)

And tbh the only "furphy" I can now see is the exposure value in each log - it is perpetually "Shutter=1000.0s"

Many pardons if I seemed critical in any way....!


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Re: Last Ganymede transit w/ASI120MM 1 resize 1.35X new [Re: Kokatha man]
      #5558742 - 12/07/12 07:13 AM

Gamma setting 50 on this camera is actually gamma 1. It is actually the default setting for the camera. Ah well, it brings a bit of variation to all the camera's out there, sometimes gamma 100 is gamma 1.0, or gamma 0 (for the good old vesta pro), and now it is 50

Edited by MvZ (12/07/12 07:13 AM)


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Re: Last Ganymede transit w/ASI120MM 1 resize 1.35X new [Re: Kokatha man]
      #5558756 - 12/07/12 07:34 AM

Hi Darryl,
Don't worry I was just kidding. I'm happy to receive any comment that helps me improving the program.

Quote:

it is perpetually "Shutter=1000.0s"




Is that only for the ASI or also for your other cameras ?
Torsten


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Re: Last Ganymede transit w/ASI120MM 1 resize 1.35X new [Re: TorstenEdelmann]
      #5558767 - 12/07/12 07:48 AM Attachment (25 downloads)

Hi Ed
The inner ring usually come from bad seeing .
here is a test I did.
I think short exposure can reduce the inner ring problem.


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Re: Last Ganymede transit w/ASI120MM 1 resize 1.35X new [Re: wenjha]
      #5558986 - 12/07/12 10:23 AM

Sam, I think you are correct about some ringing also being from bad seeing. I had average seeing the other night I am fairly sure the problem was my .25 (or .5 if you move 0 ganma to 1 where Emil likes it, personally I think that Gamma 32 should be 0 it maxes out at around 212 and bottoms out at -273)

I will dig through my logs and see when I moved the slider over, check images pre and post movment.


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Re: Last Ganymede transit w/ASI120MM 1 resize 1.35X new [Re: edsplace]
      #5559009 - 12/07/12 10:29 AM

Now I'm confused, but that is fine.

(as long as it is clear that you should use gamma 50 for this particular camera, because that is the most neutral/linear setting. This corresponds to an actual gamma correction value of 1.0: http://en.wikipedia.org/wiki/Gamma_correction).

Edited by MvZ (12/07/12 10:29 AM)


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Re: Last Ganymede transit w/ASI120MM 1 resize 1.35X new [Re: TorstenEdelmann]
      #5559074 - 12/07/12 11:07 AM

Quote:

Hi Darryl,
Don't worry I was just kidding. I'm happy to receive any comment that helps me improving the program.

Quote:

it is perpetually "Shutter=1000.0s"




Is that only for the ASI or also for your other cameras ?
Torsten




Hi Torsten - I'm pretty sure it's only with the ASI cam: I think it is fine and gives the correct exposure values on the Flea3.

Sometimes the Flea3 logs would give weird focal lengths and quite large variations between reds and the green/blues but atm the ASI cam values are nearly allways "5000mm" for red and "5050/60mm" for the other 2 channels.....but perhaps this is a natural result of diffraction etc altering image scales slightly between channels - I presume FireCapture does some simple measurement of the image to arrive at the log values...


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Re: Last Ganymede transit w/ASI120MM 1 resize 1.35X new [Re: wenjha]
      #5559282 - 12/07/12 01:15 PM

Sam, I do think the ring you show may be an artifact of bad seeing and the rolling shutter. I think that everyone else has it correct with my image that the ring was caused by a poor gamma setting. I'll run a couple of tests on the next night that is below average seeing with different gamma/exposure/gain and see if I can find anecdotal correlations.

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Re: Last Ganymede transit w/ASI120MM 1 resize 1.35X new [Re: Kokatha man]
      #5559419 - 12/07/12 02:39 PM

Quote:

Quote:

it is perpetually "Shutter=1000.0s"



Is that only for the ASI or also for your other cameras ?
Torsten



I just made a test for ASI120MM and DMK21AU618. FC 2.2 beta (Build:#35) gives the correct exposure values on the DMK. The logs for ASI perpetually shows "Shutter=1000.0s" independently of exposure.


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Re: Last Ganymede transit w/ASI120MM 1 resize 1.35X new [Re: edsplace]
      #5559469 - 12/07/12 03:08 PM

I don't think its seeing, although seeing can do some strange things.

Rather at the lower gain the response was not as linear in that region (gamma NOT 1) as it was with higher gains. I've used lots of cameras over the years and have seen this before. At low gains the left side starting at zero intesnsity starts off flat with an effective gamma much less than one.

Glenn


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Re: Last Ganymede transit w/ASI120MM 1 resize 1.35X new [Re: Kokatha man]
      #5559724 - 12/07/12 06:10 PM

Hi Darryl,

Thanks, I will check the log entry for the ASI

Quote:

ometimes the Flea3 logs would give weird focal lengths and quite large variations between reds and the green/blues but atm the ASI cam values are nearly allways "5000mm" for red and "5050/60mm" for the other 2 channels.....but perhaps this is a natural result of diffraction etc altering



Please read these FL values in FireCapture as rough estimation. It's impossible to get an exact value on live data considering the error factors involved like seeing, orientation on the sensor, gain settings etc.

Torsten


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Re: Last Ganymede transit w/ASI120MM 1 resize 1.35X new [Re: TorstenEdelmann]
      #5559730 - 12/07/12 06:14 PM Attachment (21 downloads)

Okay I was not a WinJupos believer, I may be now. It seems as though with this image I have low noise and more detail when combining in Winjupos then if I do the color combine and luminescence layer. The polar areas and equatorial zone look to have more/finer detail while the whole image looks lower noise.

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Re: Last Ganymede transit w/ASI120MM 1 resize 1.35X new [Re: DesertRat]
      #5559773 - 12/07/12 06:33 PM

Quote:

I don't think its seeing, although seeing can do some strange things.

Rather at the lower gain the response was not as linear in that region (gamma NOT 1) as it was with higher gains. I've used lots of cameras over the years and have seen this before. At low gains the left side starting at zero intesnsity starts off flat with an effective gamma much less than one.
Glenn




...I'll weigh back in here - Glenn is definitely correct here imho and is what I first said to you Ed in a couple of posts after you posted that image (hopefully absolving me of any further "guilt" from losing my "C's & T's" )

Looking at Sam's images it might be hard to see absolutely clearly on my laptop (why I really don't like processing on it!) but definitely the bottom right hand image in Sam's 4 is identical and (again imho) caused by either gamma and/or lowish gain.

The others (and I can't see the same effect in them as in the bottom RHS image) are caused (imho!) by excessive wavelets and/or deconvolution (referring to the more pronounced edge that runs around the inside periphery of the planet's limb/circumference.)

Sometimes this one is quite hard to avoid unless one opts for very smooth and somewhat greater lack of sharpness/clarity in the end image - but if you want to remove said you can lasso the planet and then "Select>modify>contract" an appropriate number of pixels followed by "Select>inverse" and then apply a little Gaussian blur to remove this.....that and modest destaturating of that very edge are sometimes helpfull for both this and when RGB aligning the channels on detail in the central region of the planet leaves a slight misalignment on the limbs (which it can often do.)

This is all best done either before reducing the image scale back down to your desired size, or with the aid of the magnifying tool...I see many, many fine images here where that procedure or something similar has been applied to them

Not being argumentative on this Ed but I fail to see how you could prescribe any of these effects to "rolling shutter" - I've shot a couple of "hi-res" images now - the ones in my last thread and again last night (will post later ) and so far I don't see any of this.....which is why I challenge that assumption about the rolling shutter!

All good discussion material methinks!

# edit: corrected my text...

Edited by Kokatha man (12/07/12 06:39 PM)


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Re: Last Ganymede transit w/ASI120MM 1 resize 1.35X new [Re: Kokatha man]
      #5559817 - 12/07/12 06:55 PM

I agree with everything you say could be the cause of the rings Darryl.

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Re: Last Ganymede transit w/ASI120MM 1 resize 1.35X new [Re: edsplace]
      #5559859 - 12/07/12 07:38 PM

Good one Ed! We need to humble Darryl sometimes! But this time I think Darryl is on to something. In some seeing conditions its possible a rolling shutter could create some problems, but honestly I'm not sure we have seen an example of this yet.

You can have seeing of the gods and still get diffraction ring limb effects. Oversharpening makes it more obvious. In fact the better the seeing the more obvious they become. But in that case one should not sharpen as much. A scope out of collimation will make the effect worse on one side.

Actually in poor seeing these go away, you have a fuzzier ball with no clear edges which when sharpened would have shown a ring (single diffraction ring) effect.

The last image of the 4 that wenjha (is that Sam?) taken at lowest gain shows a different phenomena due to non linear response at the low end. This is something any camera can show under the right conditions unless fitted with very expensive electronics. If you carefully play with levels you can see it in the other images as well, but at a much lower level. The different phenomena I refer to is the multiple adjacent rings at the limb sometimes called onion rings.

For people starting out in this hobby I always recommend to push gain to almost uncomfortable levels. Then you can back off if you please. Interestingly it is often easier to focus a grainier image on the screen as it puts the eye-brain into a different mode. But the main thing it does is to put the bulk of your samples in the linear range of the camera, and besides the real payoff in lucky imaging is having lots of frames which will control noise when stacked. More gain usually means more samples as you generally increase the frame rate.

Glenn


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Re: Last Ganymede transit w/ASI120MM 1 resize 1.35X new [Re: edsplace]
      #5559874 - 12/07/12 07:47 PM Attachment (23 downloads)

I forget to attach one in good seeing
Yes, Ed experiment is the best way to prove it.
this is my test to find the best setting to capture jupiter.
From my test I think exposure below 20ms will be a good option.
And Emil is right that 50 of gamma will be the linely response value.


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Re: Last Ganymede transit w/ASI120MM 1 resize 1.35X new [Re: wenjha]
      #5559907 - 12/07/12 08:16 PM

I was not trying to humble Daryl, I do agree with him. Those are all causes for rings in images, and there is no arguing against his statments. My original statment was weak "ring you show may be an artifact" and I sure as the heck am not stepping out any further on that branch :-)

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Re: Last Ganymede transit w/ASI120MM 1 resize 1.35X new [Re: DesertRat]
      #5559943 - 12/07/12 08:44 PM

Hi Glenn
Yes, I am Sam.
I am not fully agree with you.
because the ring always apear in a poor image.not very good one.
Also I found that if I stack too many frames when seeing is bad can cause onion rings too.
So I am sure it come from bad images.

And it has no bussniess with gloable shut or progressive shut. because I saw it when I use spc900nc.


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Re: Last Ganymede transit w/ASI120MM 1 resize 1.35X new [Re: wenjha]
      #5559973 - 12/07/12 09:10 PM

Heh-hee fellas - I'm not averse to a little humbling and I make my share of mistakes and errant claims..!

I appreciate discussions where we can investigate various issues on the topic of our passion - planetary imaging.

On that note I agree to a certain point on "diffraction ring limb effects" Glenn, but I have almost never seen them per se personally on Jupiter (Mar most certainly!)

I say "per se" because I have no real idea whether those that appear with over-sharpening are in fact already there waiting to be "brought out" so to speak, but I do know in (say for example) the images I got last week that were in "good" seeing it was very hard to get any limb artefact, even pushing the wavelets or deconvolution OTT.

Anyways, "humble away" if it's necessary fellas.....as long as we all learn something!


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Re: Last Ganymede transit w/ASI120MM 1 resize 1.35X new [Re: Kokatha man]
      #5560012 - 12/07/12 09:44 PM

Hi Sam,

The images you just posted all show sharpening effects on the right side, the bright limb of Jupiter on that date. That is magnified by diffraction (its hidden in the stacked image). If a scope is out of collimation (in the 'right' direction) it will make them stronger. But you can also sharpen a computer generated perfect gray circle and get that effect as Darryl was commenting on overshapening.

The onion ring effect is a different phenomena caused by non linear operation. I've never seen that result from poor seeing when the settings are correct. Onion rings are multiple rings usually about the outside of a planet, but some of us have seen them so bad they cover the entire planet! I suppose if you had some kind of pathological seeing condition where the planet was throbing in size at semi-discrete sizes you could get something like that.

Darryl, yes I was just joking with you. This kind of thread is what makes this forum useful!

Glenn


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Re: Last Ganymede transit w/ASI120MM 1 resize 1.35X new [Re: DesertRat]
      #5566826 - 12/12/12 12:05 AM

Update. Took the camera out tonight. I didn't notice that all setting in Firecapture were saved for each color channel, and the green channel was set at 12. I thought the Gamma setting was for all channels. I should have known better, the green channel was the channel that rings were occurring the worst. After changing the setting tonight, no rings at all. The problem did lie between the ground and the computer.

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Re: Last Ganymede transit w/ASI120MM 1 resize 1.35X new [Re: edsplace]
      #5566961 - 12/12/12 03:58 AM

Any decent images?

Seeing was supposed to be poor, so I didn't bother. Will probably get the scope out tonight if it stays clear like it says.


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Re: Last Ganymede transit w/ASI120MM 1 resize 1.35X new [Re: edsplace]
      #5567004 - 12/12/12 05:31 AM

Quote:

Update. Took the camera out tonight. I didn't notice that all setting in Firecapture were saved for each color channel, and the green channel was set at 12. I thought the Gamma setting was for all channels. I should have known better, the green channel was the channel that rings were occurring the worst. After changing the setting tonight, no rings at all. The problem did lie between the ground and the computer.




.....that's why Sam & me harassed Torsten so much to get FireCapture fully-compatible with the ASI120 cameras Ed.....it's the best capture software there is imho, and a real credit to Torsten..!


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MvZ
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Re: Last Ganymede transit w/ASI120MM 1 resize 1.35X new [Re: Kokatha man]
      #5567021 - 12/12/12 05:48 AM

Quote:

The onion ring effect is a different phenomena caused by non linear operation. I've never seen that result from poor seeing when the settings are correct.




I agree with this. I have processed many images (with other cameras), many under poor seeing conditions, but never found onion rings with correct camera settings. If it was caused by bad seeing, I would have seen them. I have not, so it is not caused by poor seeing. Perhaps it is only enhanced by the camera under poor seeing conditions. In that case I suspect adding more noise to the raw images (gain up) should deal with the problem, forcing the pixels to not have any quantization problems (basically increasing the variability of the pixels, allowing for a wider dynamic range after stacking).

In practice I have not found any of these problems at all though with the camera so far.


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edsplace
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Re: Last Ganymede transit w/ASI120MM 1 resize 1.35X new [Re: MvZ]
      #5567570 - 12/12/12 01:17 PM Attachment (18 downloads)

Z,

Nothing good. The images at capture looked fantastic, with little planet undulations. I was excited about the images, but in the end below was all I could get. there was considerable upper atmosphere scintillation stopping fine detail from coming out. Tonight CSC shows not so good, Calsky says above average.


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zAmbonii
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Re: Last Ganymede transit w/ASI120MM 1 resize 1.35X new [Re: edsplace]
      #5567772 - 12/12/12 02:50 PM

I would be happy with that image with my webcam on a less than average night . I'm a little bummed because when I got home there was a DHL sticker on my door. I missed the ASI120MC delivery by about 30 minutes and will have to wait until tomorrow to get it in my hands.

Doesn't look like there will be another decent night until next week .

Probably going to use tonight to experiment a little. I need to get the latest FireCapture loaded up so I can get used to using it, and mess around with the features some.


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edsplace
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Re: Last Ganymede transit w/ASI120MM 1 resize 1.35X new [Re: zAmbonii]
      #5567786 - 12/12/12 03:02 PM

You can drive to the DHL hub and they will give you camera. I have done that before, I think the courier is based in the Detroit Metro area.

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zAmbonii
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Re: Last Ganymede transit w/ASI120MM 1 resize 1.35X new [Re: edsplace]
      #5568003 - 12/12/12 05:43 PM

I gave them a call and could only pick it up in the morning. They said their drivers were out late for pickups because of the holiday season. Their hub is over by DTW so it wouldn't have been too far of a drive. I'll just wait till they deliver it again tomorrow :P

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