Jupiter seeing demonstration

[cgarry]

Just inside Monday morning I tried to do a run of captures with my DMK and RGB filters. The idea was to get some data to practice with WinJUPOS, instead I think I captured a good example of how quickly seeing can change.

Below are just the green channels from the 4 RGB capture sequences I did. Each run was 2 minutes long, the best 1200 frames have been stacked in AS!2 and exactly the same wavelets applied:

00:09

00:17

00:25

00:34

Cheers,

Chris

[sologuitarist61]

That is amazing Chris Great images as well

[BuzzBomb]

Very interesting.

In conclusion, we should only image Jupiter at 17 mins past midnight!

[JamesF]

In conclusion, we should only image Jupiter at 17 mins past midnight!

Or, we should image Jupiter for the entire night in the hope of getting three minutes worth of good data

James

[cgarry]

Yep, I shall only image at 17 past midnight from now on.

I guess a colour camera gives the best chance of getting a half decent image on a night when the seeing is so variable, not much chance of getting 3 sets of RGB images from a mono camera to run through WinJUPOS...

[Space Cowboy]

Ah yes that golden moment! How did the RGB come out on that good one Chris?

[BuzzBomb]

Or, we should image Jupiter for the entire night in the hope of getting three minutes worth of good data

James

Sent from my GT-I9001 using Tapatalk 2

[cgarry]

Ah yes that golden moment! How did the RGB come out on that good one Chris?

I have not had a chance to process it yet, work getting in the way of play yet again!

[neil phillips]

Thats a good example of the effects us mono imagers have to contend with. I could be wrong Chris. But using a C14 these effects will be somewhat exagerated compared possibly to the C9.25 users. and even us 10" Newt users.

So i belive you have your work cut out, with these rapid changes air cells affecting the C14s potentiall quite a lot.

I know its sounds rather odd, but would it likely be worth having a smaller SCT or Newt, for those nights where the C14 is getting hammered by these effects. Its a weird idea i agree. But im sure you know why i am suggesting it. Under great conditions the C14 should outperform smaller scopes. But i think your example here is showing how rapidly its struggling to do so.

Whats your local seeing like where you are Chris. Compared to say what youve seen from me ? I guess thats hard to answer. Because of the more consistent coping of these effects with smaller optics. But i am just wondering whats your thoughts ? On all this. You know to prove the more consistent theory with smaller optics, i should do a example like this and show you

on a few of the upcoming nights we might get. What would be interesting is, if our capture times matched. focal lengths were similar over a few of these nights. That would tell you ( us ) a lot about either your local conditions and or its effects on the large primary and design of the C14 Chris

[cgarry]

In fairness I probably would not have bothered imaging with seeing that bad, it was only because we have been starved of clear nights and I wanted some data to use for WinJUPOS practive that I persevered.

I am not convinced that using a smaller scope actually has an advantage over the C14 or whether bad seeing means the C14 is just unable to get any more detail than a smaller scope, which can look worse because of the C14's naturally large image scale.

I still have my C9.25 so that could be another thing to try on these iffy nights. Though currently I tend to use the DFK camera on the C14 if the seeing is all over the place as it gives me a half chance of getting an image if the seeing does briefly improve.

I have wondered if I might have bad local seeing, especially having the A14 just to the south of my garden. But nobody seems to have good seeing lately so it is hard too tell.

I like the idea of doing some comparison tests with your setup, I could possibly get the C9.25 in on the action.

Cheers,

Chris

[Space Cowboy]

I agree with Neil you would be better with a smaller scope. Maybe if we did a swap while this poor seeing is around. I don't mind making the sacrifice.

Look forward to seeing that RGB combo Chris!

[cgarry]

I agree with Neil you would be better with a smaller scope. Maybe if we did a swap while this poor seeing is around. I don't mind making the sacrifice.

Cheers Stuart, very selfless of you!

[Fossil Light]

• Chris,
  
• Damian Peach remarked how variable the seeing was on Sunday night when he sent out his images for that session. He found a freak period of decent seeing around 23.36 when he was imaging in the red.
  

Martin

[neil phillips]

In fairness I probably would not have bothered imaging with seeing that bad, it was only because we have been starved of clear nights and I wanted some data to use for WinJUPOS practive that I persevered.

I am not convinced that using a smaller scope actually has an advantage over the C14 or whether bad seeing means the C14 is just unable to get any more detail than a smaller scope, which can look worse because of the C14's naturally large image scale.

I still have my C9.25 so that could be another thing to try on these iffy nights. Though currently I tend to use the DFK camera on the C14 if the seeing is all over the place as it gives me a half chance of getting an image if the seeing does briefly improve.

I have wondered if I might have bad local seeing, especially having the A14 just to the south of my garden. But nobody seems to have good seeing lately so it is hard too tell.

I like the idea of doing some comparison tests with your setup, I could possibly get the C9.25 in on the action.

Cheers,

Chris

Im not convinced either Chris, i may well be wrong. But i have seen C14s failing to deliver the goods over a extended period of time on occasion, But of course there can be more than one reason for that. Damien has talked about the advantage of the C14 not always being able to live up to its potential because of poor seeing, and other issues in the uk if i remember. Thats not to say a smaller scope will do better. But under certain conditions. The sharpness or distortion of raw frames can be better handled by a smaller scope.

What this means in the real world is hard to say. But like Stuart ( trust you Stuart ) i would do a swap for month or two.

I know under certain conditions the C14 will literally leave for dead scopes in the 9 to 10" range. Its the law of physics. But i guess my point is. If that hardly ever happens, it certainly would be easier imaging with smaller optics, and possibly about the same level of performance or even more affected than smaller optics im not sure ? And that the big gun will come into its own more rarely maybe. But of course when it does the whole ball game changes in a instant. How Damien does it so consistently in the uk is always hard to fathom.

[Space Cowboy]

Surely Chris would be better off reducing the focal length and increasing the shutter speed rather than reducing the size of scope?

Is that not the main advantage of large optics that you can run shorter exposures at lower gain settings to beat the wobbly seeing?

Last night conditions were windy and seeing was rubbish so I had exposure at 1/54 for a gain of just under 80% at f26.

For me anything over 80% gain with the dfk is too noisy. Now if I had a C14 I could have exposure at least 1/100 with lower less noisy gain probably?

[jimness]

This coincides very well with what I found that night - though I think my patch of good seeing was around 10 minutes earlier than yours! So I guess it was blowing north-east-ish...

Last night....not so good. Probably not helped my deciding to try imaging after stumbling back from the pub

[cgarry]

This coincides very well with what I found that night - though I think my patch of good seeing was around 10 minutes earlier than yours! So I guess it was blowing north-east-ish...

Last night....not so good. Probably not helped my deciding to try imaging after stumbling back from the pub

Hmmmm... I have noticed my seeing coming and going myself after coming out of the pub, but that was without looking through a scope...

[Hugechris]

Seeing from London was terrible last night, didn't make it past midnight, but waited for 3 hours for not a lot.

[cgarry]

Seeing from London was terrible last night, didn't make it past midnight, but waited for 3 hours for not a lot.

The stars here were seriously twinkling last night and it was pretty windy so I did not even bother to set up. Looks like I made the right call.

[budski]

From the comments made here, I too subscribe to the principle of the Law Of Diminishing Returns. When I moved from using an excellent 5 inch refractor to a C11 I assumed it would make a massive leap forward in terms of image quality, If anything, I've discovered the opposite - the C11 is wonderful at showing how bad the seeing is. Despite meticulous care in collimating the instrument and using the best filters etc I sit there sometimes and wonder what the heck's going on.

I live on the southern slope of one of the highest points in Somerset (my elevation is 99 metres/325 feet ASL) and am affected by the wind direction causing all sorts of swirls as it hits the very top of my hill.

I'm very tempted to dust off the 5 inch and attach a one-shot colour camera to it in the hope that I'll be able to get something worthwhile.

In the meanwhile, we await that one wonderful night ....

[JamesF]

I live on the southern slope of one of the highest points in Somerset (my elevation is 99 metres/325 feet ASL

Whereabouts are you out of interest, Bud? (Roughly, if you prefer. I'm not interested in lat/long

Out this way we're 125m ASL (or about six feet below the waterline at the moment As you say, there can't be too many places in Somerset where you can be 100m+ ASL.

James

[cgarry]

From the comments made here, I too subscribe to the principle of the Law Of Diminishing Returns. When I moved from using an excellent 5 inch refractor to a C11 I assumed it would make a massive leap forward in terms of image quality, If anything, I've discovered the opposite - the C11 is wonderful at showing how bad the seeing is. Despite meticulous care in collimating the instrument and using the best filters etc I sit there sometimes and wonder what the heck's going on.

I live on the southern slope of one of the highest points in Somerset (my elevation is 99 metres/325 feet ASL) and am affected by the wind direction causing all sorts of swirls as it hits the very top of my hill.

I'm very tempted to dust off the 5 inch and attach a one-shot colour camera to it in the hope that I'll be able to get something worthwhile.

In the meanwhile, we await that one wonderful night ....

Sounds familiar. What I do wonder though is this; is it the case that a smaller scope will produce a better result than a big scope in bad seeing conditions or is it just the case that the big scope is being brought down to the same level of detail by the seeing? I am very doubtful that I could get a better image from my C9.25 than I can from my C14 under any conditions, it is just that the C9.25 produces a smaller image where all the issues with the image cannot be seen. If we had clear nights to spare I would set both scopes up and run some tests just to satisfy my curiosity.

And yes, lets have that wonderful night...

Cheers,

Chris

[budski]

Hi James, I'm on the northern edge of Yeovil, on the south facing slope of HundredStone Hill.

I agree with Chris's point about average seeing being a leveller of 'scopes - it's like owning a Ferrari but being stuck in a traffic jam.

However, 3am on a deserted motorway and no traffic cops is a different story ....

[JamesF]

Hi James, I'm on the northern edge of Yeovil, on the south facing slope of HundredStone Hill.

Ah. Totally the opposite end of the county to me then...

James

[neil phillips]

Surely Chris would be better off reducing the focal length and increasing the shutter speed rather than reducing the size of scope?

Is that not the main advantage of large optics that you can run shorter exposures at lower gain settings to beat the wobbly seeing?

Last night conditions were windy and seeing was rubbish so I had exposure at 1/54 for a gain of just under 80% at f26.

For me anything over 80% gain with the dfk is too noisy. Now if I had a C14 I could have exposure at least 1/100 with lower less noisy gain probably?

That is a fair point Stuart, and yes lower gain with bigger optics is certainly desirable. Lowering focal length though may not sort all of the issues with big scopes i dont think, It will help but likely not cure them.

I think i am saying that the C14 can suffer from a number of issues that can affect its performance, cooldown and currents to name some Chris has been working with and commenting on,and that smaller primarys might cope with better.. ( though of course will still be affected by ) when i say smaller optics i am talking between 9 and 12". A 6" will just be outclassed for the most part. well a 6 " SCT or Newt anyway, a 6" Tak refractor will have a certain quality appeal of course, contrasty razor sharp images. Though resolution will be affected.

Falling temperatures will upset a C14 probably more than Smaller optics. As will rapid seeing changes. Of course i am not suggesting for 1 minute. Someone shouldnt work with all these issues. Ive said for a long time I want a C14 to work with. I am just giving my beliefs as to how sometimes large optics can be very frustrating to work with in the uk. At the end of the day if there is consistency problems. Then over a extended period of time it will show.

I will say again under the right conditions a C14 will blow smaller scopes out of the picture. How Mr peach does some of the shots he produces in the uk so consistently is a mystery to me. Chris gos new C14 is producing unbelivable shots from hes location. Which is why i think what Damien says about the C14 being used in the uk for the most part is valid. What ive read about hes comments, and my direct experiance with 12" optics has made me realize there is often more too it than just large optics. Pete L has also produced some mind blowing images in the uk. So yes we know its worth working on issues. I would personally use a SCT fan, Pelter coolers is also another option. But more drastic than a sct fan.

None of this will affect seeing. But would help some with falling temps. I always switch my fan on between captures, and it does help control some of these issues. Scopes often stabillize doing early morning shooting. And i think theres more to it than better seeing in the morning. Ive started to feel rising temps can stabillize a scope for a short period. Well thats what ive often seen doing morning imaging with the sun rising.