geoflewis

Lovely images Neil. I’m curious when you say the 462MC sensor has colour bleed. What does that mean and how do you recognise it, as I got that camera in part to try some colour lunar images?

27 minutes ago, neil phillips said:

yes, i think your right. wonder what causes the thinning ? is it a temperature thing ?

Maybe it's all the glass being pointed at it from Earth right now......🤔

Thanks Stuart, that's very kind of you; now that I've picked myself off the floor....!!

I guess it was that polished DP look that I was after, but I couldn't convince myself about it, they just seemed too smooth, so maybe something between is what I should try for. I asked Richard McKim, BAA Mars Section Director which he prefered and he said that he thought the sharper version had more merit from a scientific content standpoint, so I've gone with that. I will keep experimenting. Cheers.

3 minutes ago, Kon said:

I read your initial 2x6 min as 6 captures of 2min. Sorry. The new images look much better despite the edge rind.

No worries and thanks for the feedback on the later versions.

1 minute ago, neil phillips said:

Excellent Geof it's getting interesting now. Nearly full

Thanks Neil, I just wish the weather would cooperate. I've just looked outside and it's already foggy, with no stars or planets, to be seen....

1 minute ago, neil phillips said:

Cheers Geof, off to see your post

I put up 2 versions. The fisrt ones I went for a very smooth look, even with the detail still there, but then reworked them my usual method, which is a btter sharper and leves a more textured look. Will be interested to hear what you think.

That's big step up in quality. The colours are pretty much spot on and lots of details coming through. It is a tad noisy, so maybe capture an stack more frames, or hold back on the sharpening a bit. Don't forget to have a try at Mars at it's very bright, at a high elevation and only a couple of weeks shy of its opposition, after which it will be receeding againuntil it comes around again in a couple years.

That looks great Dave. I've said it many times before, because it's true; it's one of my favourite visual targets, especialy in my 22x85 binoculars and that's just about what i see with them.

58 minutes ago, Kon said:

The weather is not on our side at the moment. 

Is there a reason you don't shoot longer videos? With Mars my understanding is that we can go to 5min? This is what I have been doing. I should try some multiple videos and derotate (my attempts with Jupiter were not very pleasing but you seem to have master it). 

I was thinking the second IR looked softer but like you said it was weather dependent.

Hi Kostas, I'm actually shooting 6 min SERs, did I say something else by mistake somewhere?

I've also reprocessed the data, going back to how I've previously done it with a little sharpening included during AS3! stacking before Registax. I was trying for a smoother look hence tried something different, but I think the images came out too smooth and not revealing the detail that was there. Here they are again...

There's a more pronounced edge rind, but otherwise I think I prefer these versions. As always I am very interested in what others think.

1 minute ago, andy fearn said:

lovely images. hopefully the nights will be clearer and you can gather more data. Good luck.👍

Thanks Andy, I'm always hoping 😉🤞

9 minutes ago, Kon said:

Excellent images with really nice details coming through. The N polar cap is excellent.

Thanks Kostas, yes, the detail was good on screen early on when I was capturing the IR, but I noticed that the seeing already started to fall away in the 2nd IR run. I was intending to capture 3 x IR then 3 x RGB without the barlow, then rinse and repeat with the barlow included. However, things got progressively worse through the first set of RGB and by the time I'd added in the barlow lens and refocussed for the 2nd set it was getting really bad. I pressed on for a bit, then waited to see if it would clear, but it was no good. My observatory was full of fog with everything soaking wet dew, by the time I gave up.

Excellent image Neil. The seeing deteriorated here and I got fogged in as Mars gained altitude, but had a few reasonable runs early on.

Here's a look at Mars in IR and RGB from last night. The images are with the scope at it's native F11 with the ADC in train, so actually coser to F13 (FL = 4700mm).

I've resized both images from 96dpi to 192dpi (so x2).

The IR is a the best 10% from 2x6 min SERs, then de-rotated in WinJupos. The RGB is the best 10% of 3x6 min SERs, also de-rotated.

I had hoped to conduct some more experiments at higher amplification, which came out at F20 (FL-7400mm), so I possibly got the barlow lens slightly further away from the sensor than previous nights which reported F11 and F18 respectively, but unfortunately the seeing deteriorated and fog piled in. Nevertheless, here is a single IR that I did get, also the best 10% and resized as best I could to the other 2 images.

The rotation angle is as captured with the north polar cap around 11 o'clock position, wheras WinJupos corrected the earlier images to display north up. It's also slightly more sharpened, hence the darker dark regions, so it's difficult to draw any conclusions. However, on my working screen, there is finer detail all over and especially in the brighter areas of the globe in the lower sampled (F13) image. Hopefully one of these nights I'll be able to get a long enough run to perform some more meaningful comparisons, including in RGB.

Nice capture Kostas

On 12/11/2022 at 16:12, Magnum said:

on the Down sides  the f25 image took much longer to stack and takes up much more disc space and was dimmer so had to use higher gain, yet the final image still looks smoother to me. 

The downside of the huge file sizes and processing overhead is something that's putting me off the higher sampling rate, perhaps other than in excellent seeing, if we ever get that...🙄

Thanks @vlaiv, that actually made more sense to me than I expected when I first saw the post.....🤯

5 minutes ago, Magnum said:

That an interesting and good to know, luckily by chance I have been using 5ms as my default in colour images of Jupiter and 2-3ms on Mars. Can get get that speed at any f ratio ive tried upto f25 with the 12" scope, I remember previously I had a C9.25 but always felt limited by the amount of light that could put onto the sensor so had to use longer exposures and higher gain. Since moving to the 12" scope I don't have to worry about using slow shutter speeds except for Uranus and Neptune or imaging in deep IR and Methane.

Lee

Hi Lee, I have say, this is another area where theory and reality do not align. I've had a few discussions with Anthony Wesley (Bird) and Niall MacNeil, both imaging from Australia and they do not capture at anything like those high rates. Both have done a lot of their own analysis and Niall suggests that optimum is 13ms / 76fps  (hence why I used that) and Bird even slower at 65 fps. Here's is what Bird wrote about it in a discussion with Niall, which he shared with me, so I hope it's ok for me to repeat here.

Well it all depends on the seeing of course, there are so many variables that effect the seeing. Personally I run at about 65fps, that seems good enough for me, but I could also believe that your test of 75fps makes sense in the seeing that you had. At 65fps I can reach max hardware gain in the camera quite easily and still have a relatively low noise image. I've tried speeds up to about 90fps in the past, but 65 seems just fine for me on most nights. I've had nights in the past where fog reduces my speed to about 10fps but the seeing was excellent and I didn't have any trouble with blurring.

Something to remember is that the data gets noisier as you shorten the exposure - AS!3 somehow has to lock onto and align features on each of these raw frames and noise in the frames will directly affect its ability to get an accurate alignment, so increasing noise (ie shorter exposures) will likely make it harder to get the best alignment. It's a tradeoff to find the right value, short enough to remove the blurring and not so short that AS! can't get a good alignment. There's no magic bullet, if the data is too noisy then you'll get penalised by AS! not being able to accurately lock onto the features.

You could broadly speaking divide the "seeing" into two components - ie the stuff that can be corrected in post-processing by AS!, and the stuff that can't (ie global jetstream blurring). No amount of high speed fps can remove the nasty jetstream blur, that really needs the sort of adaptive optics that you only find on large professional telescopes. Post-processing software like AS! can remove the simpler lateral-motion modes that come from seeing cells large enough not to destroy the high frequency component, these cells are mostly located in air masses close to the scope, at most a few hundred metres above, and sometimes a lot closer, and so they change all the time and vary from night to night. 65-75fps should be fast enough to handle that when you consider how little motion this allows for between successive frames.

There is something to watch out for - and something that I've experienced in the past - where short exposures can give you the illusion of more contrasty images, due to the lower number of shades in each frame. This is due to data loss, and is roughly the same effect as if you apply a lot of gamma darkening while capturing to make the image look "better", but then you pay the penalty later in processing. This is also one of the reasons I always use 16 bit mode on the camera so I can have more headroom during processing if I need it.

The high quality of their images speak for themselves. Take a look at what Niall is posting on AstroBin.....https://www.astrobin.com/users/macnenia/ I was going to pick out some examples, but there are so many that you can take your pick....

I decided to process the earlier 3x6 min RGBs captured at F18, then de-rotate and stack the 3 images. NB I did not de-rotate the individual SERs, so some loss of fidelity will have occured due to rotation over each 6 min period.

Nice capture

Nice set of images

Nice image Kostas, I’d say that’s a bit more than ‘some detail trying to come through’, there’s lots on show here.

5 minutes ago, Space Cowboy said:

That's a beauty!

Thanks Stuart

Lovely images and excellent animation.

Nice capture Lee, definitely worth putting up, even if a tad late 

Nice capture Peter