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Jupiter, 6th Feb with the ASI120MC


JamesF
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It can be quite laborious getting to learn a new camera, and I've made it more tricky for myself by switching from SharpCap to FireCapture at the same time. I've been struggling with colour in my ASI120MC images with the 127 Mak, but Stuart suggested I should think about what gamma settings I'm using and I read some comments from Darryl a few days ago saying that the 120MC needs a very full histogram to work well. The wind was gusting and cold last night, but I couldn't pass up the opportunity to get out and do some more testing.

I've made a few "discoveries" as a result. Apologies if these come out in a less than coherent order...

First is that I need to be more careful about my use of the histogram tool in FireCapture. I've found that even if I keep the limit nicely below 100% there's quite an imbalance between red and green/blue that allows the histogram to show, say, 80%, when green and blue are completely blown out. I know there's not a lot of red in Jupiter, but I'm not sure there should be as little as I'm getting.

As a result of the above imbalance in colours I'm wondering if I shouldn't ditch the IR filter for at least some of my next set of tests.

I discovered that it's possible to turn off gamma altogether, but I'm not sure that yields as good a result as setting it to the minimum value (1). There's also a brightness setting which I set at 5, but I should perhaps experiment to see if that changes much.

For my setup at least, I don't think I can live with Darryl's suggestion to keep the histogram fairly full. Even running at 10fps I don't get anything like a full histogram and pushing the gain up beyond about 55 blows out the green and blue. At 30fps the gain needs to be quite high to get even close to a 90% full histogram and again I get the blue and green blown. Perhaps this will change if I remove the IR filter.

I'm really not happy with the "washed out" appearance of the colours. Perhaps more red would help with that too, but I'm just not sure. There's a definite lack of contrast.

These are all at a focal length of about 3.75m using my Revelation 2.5x barlow. I could drop that down a bit, but if I go much further than I'm not sure I'll achieve anything better than I have done with the SPC900 so there's little point. If I drop down to the Ultima 2x barlow then I think I'd probably get fairly close in terms of image scale per pixel to where I have been with the SPC900.

Overall I think more work is required, but I do wonder if I'm not getting close to the point where the scope is the limiting factor.

Anyhow, here are the images. My favourite is the bottom right as it's the only one that isn't obviously blown around the equator. The settings for that one are probably where I'll start next time, but if anyone has suggestions I'm all ears :)

montage.png

James

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James,

Have to agree on the colour, but an otherwise excellent set of images - what IR-CUT filter are you using? I'd definitely consider shooting without this to see if its this which is filtering too broadly and robbing the red from the image. Otherwise perhaps some of the debayering options in firecap, worth trying again in sharpcap or similar to rule this out. I find firecap very good, but the camera control settings are well hidden and dfifferent for each camera.

I wouldn't have thought this was an optical limitation of the Skymax, though the camera sensitivity may put a limit on this.

Frustrating when you finally get some good seeing and new hardware throws a spanner in the works.

Theres a good thread and images on this camera on Cloudynights http://www.cloudynights.com/ubbthreads/showflat.php/Cat/0/Number/5570298/page/1/view/collapsed/sb/5/o/all/fpart/1 no absence of red in this - though it was a C8!

Good luck resolving - Jake

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James,

Have to agree on the colour, but an otherwise excellent set of images - what IR-CUT filter are you using? I'd definitely consider shooting without this to see if its this which is filtering too broadly and robbing the red from the image. Otherwise perhaps some of the debayering options in firecap, worth trying again in sharpcap or similar to rule this out. I find firecap very good, but the camera control settings are well hidden and dfifferent for each camera.

I wouldn't have thought this was an optical limitation of the Skymax, though the camera sensitivity may put a limit on this.

Frustrating when you finally get some good seeing and new hardware throws a spanner in the works.

Theres a good thread and images on this camera on Cloudynights http://www.cloudynig...5/o/all/fpart/1 no absence of red in this - though it was a C8!

Some interesting comments on that page, Jake. Thanks for the link.

My thoughts on the images being partly limited by the scope are mainly that perhaps there's just not enough aperture to light up the sensor nicely. The C8 does have bags more aperture and 30% more focal length to go with it. Not that I'm complaining -- I think it's fun to see just how far the little Mak can be pushed.

James

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Some interesting comments on that page, Jake. Thanks for the link.

My thoughts on the images being partly limited by the scope are mainly that perhaps there's just not enough aperture to light up the sensor nicely. The C8 does have bags more aperture and 30% more focal length to go with it. Not that I'm complaining -- I think it's fun to see just how far the little Mak can be pushed.

James

James, I think you've hit the nail on the head there. Before getting choosing to get a DMK, I was looking at the kind of images that the ASI200MC was producing and came to the conclusion that every image taken with a scope of less than around 200mm aperture seemed to look washed out. The best picture I've seen to date was taken with a 250mm Mak. How about trying it in your 200P?

Damien

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I cannot offer technical advice, James, but I just wanted to say that these are very good images, especially for a camera and software with which you are not yet familiar. How long since you had them? It takes me many months and trials before I can get the best from anything new.

Chris

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I cannot offer technical advice, James, but I just wanted to say that these are very good images, especially for a camera and software with which you are not yet familiar. How long since you had them? It takes me many months and trials before I can get the best from anything new.

I've had the camera since Christmas, but I've only managed to get out with it three times since then and one of those was really cloud-dodging.

Getting my head around the SPC900 cost me quite a few nights of otherwise wasted data, so I'm not expecting miracles straight away. I know it's more a case of gradual refinement. Would be nice if we had rather more clear nights to spend on it though.

James

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James, I think you've hit the nail on the head there. Before getting choosing to get a DMK, I was looking at the kind of images that the ASI200MC was producing and came to the conclusion that every image taken with a scope of less than around 200mm aperture seemed to look washed out. The best picture I've seen to date was taken with a 250mm Mak. How about trying it in your 200P?

As soon as the obsy is built I shall be trying it in absolutely everything :)

James

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You're so right about the weather making very frustrating trying out anything new with real stars. I don't have the possibility for an obsy, but have been seriously considering an indoor planetarium! Focussing might be an issue......

Chris

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I've just discovered the camera controls pop-up in FireCapture (from the gear wheel icon next to the exposure settings menu).

The most interesting settings are on the "Color" tab which has sliders for red and blue and options for "auto wb" and "RAW output".

The default has the red slider at 52 (from 1 to 100) and the blue at 95 which might go some way to explaining the imbalance in the histogram. I have "auto wb" off and "RAW output" off though I guess the latter might be interesting to play with but for the fact that FireCapture will only do it for Y800 video formats and the camera doesn't appear to support that.

I've also found out how to get a red/green/blue histogram by having it in a separate window, so that will come in useful.

James

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They look pretty good to me James when you consider Jupiter is now 2 months past opposition. I'd be encouraged by these results for a 5" scope they are darn good. Getting to grips with Firecapture and a new camera is a steep learning curve for sure.

Thank you :)

James

Edited by JamesF
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I've just discovered the camera controls pop-up in FireCapture (from the gear wheel icon next to the exposure settings menu).

James

They certainly do tuck the controls away and I find the interface generally quite fiddly - but they're the only niggles I've had thus far with Firecap. Hope this resolves the issue and hopefully that old Skymak will continue to provide great images for many years yet!

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.....been busy lately and to tell the truth others would be much better at the colour cam controls than me, but it looks like you've found some more tips! (I posted the Win interface controls settings on Sam's website about 3 months ago...)

Sam reports that using red @ "59" and blue @ "100" gave very nice Jovian image colour renderings, showing a very nice example using that combination.

Do not adjust the gamma away from "50" which is linearity or "1" - doing so will result in problems of one sort or another: it can be usefull for focusing to drop the gamma right down as long as you remember to return it to that value of "50" after focusing.....the images allways looked quite "washed out" onscreen and this is the same with the mono camera also.

Sam is allways veryy ready to assist you with his experience and replies to any emails.....of course I was referring to the histogram with the colours when I spoke about "fairly full" histograms but naturally you have to watch for EZ "blowout" onscreen when adjusting this setting.

Brightness is a new one for me on the newer FireCapture builds (I'm a bit of a luddite and use a pre-brightness version but will update soon).....I'll speak to Sam about this feature personally because there was a lot of discussion about installing this when we were doing all the initial development - I may be wrong but suspect this is a "blackpoint" control which if it is can confuse a lot of folks.....but I'll enquire further!

Lastly, as Stuart and others have said, these images are really quite remarkable for a 127mm scope.....if you have a bigger baby then notwithstanding this little fella's performance so far I'd definitely use the bigger scope, regardless of what your average etc seeing might be......it's nonsense imho to think that you'll get better images with a smaller scope in poorer conditions - the bigger one will allways trump it but of course you do have to adjust it for the conditions, going for broke with it will possible create poorer images than the smaller scope and is probably where this absolute myth started..!

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As has been mentioned James, Nice images.

These cameras really are something else for performance and value. Think i would like to get a single colour shot version. And keep my DMK. Though i know Darryl, prefers these cameras to the 618 chip. But as i want a single colour camera. it makes the most sense to my pocket. I wonder how the single colour version pans out against the DBK ?

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Thank you everyone for the positive comments, and thanks for the additional information (particularly about gamma) Darryl.

Current forecast is for some clear patches on 14th, so I shall try to have another go then.

James

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Want to do some mentoring lol?!

I'm very happy to help however I can. I think there's a lot to be said for persistence and sheer stubbornness though. Being prepared to get things wrong, often on several nights in succession, on the grounds that you're actually learning from your mistakes, getting a better understanding of what you're doing and coming up with new ideas to try goes an awful long way :)

James

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I'm very happy to help however I can. I think there's a lot to be said for persistence and sheer stubbornness though. Being prepared to get things wrong, often on several nights in succession, on the grounds that you're actually learning from your mistakes, getting a better understanding of what you're doing and coming up with new ideas to try goes an awful long way :)

James

I also find that covering things in thick rubber is useful for preventing damage when they are thrown across the patio in a fit of frustrated rage!

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I also find that covering things in thick rubber is useful for preventing damage when they are thrown across the patio in a fit of frustrated rage!

:D

Learning when it's time to walk away for a while is definitely useful, too :)

James

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