Seeing and what it can do to your images

[ballaratdragons (Ken)]

Geez some of you people are hard to bloody please.

Mike makes a simple thread to show how poor seeing can make imaging a bit harder than it already is and he is torn a new one because he claims to have discovered Fire, has nothing compared to the Planetary Imagers . . . sheesh!

Thanks Mike for giving us a visual example of the difference between good and bad seeing. Us oldies may know it but I'm sure the newbies would like to know and see it.
We read about it, so now it's good to see a side by side example.

[strongmanmike (Michael)]

Originally Posted by ballaratdragons

Geez some of you people are hard to bloody please.

Mike makes a simple thread to show how poor seeing can make imaging a bit harder than it already is and he is torn a new one because he claims to have discovered Fire, has nothing compared to the Planetary Imagers . . . sheesh!

Thanks Mike for giving us a visual example of the difference between good and bad seeing. Us oldies may know it but I'm sure the newbies would like to know and see it.
We read about it, so now it's good to see a side by side example.

All's good Kenny, I think the spirit and intention of the post was interpreted and responded to appropriately by most

Mike

[Paul Haese]

Originally Posted by ballaratdragons

Geez some of you people are hard to bloody please.

Mike makes a simple thread to show how poor seeing can make imaging a bit harder than it already is and he is torn a new one because he claims to have discovered Fire, has nothing compared to the Planetary Imagers . . . sheesh!

It's an academic discussion Ken, not a personal attack. People are allowed to discuss this and not agree, or have a difference of opinion, or even suggest that there is nothing really to moan about when imaging at native focal lengths. I am not ripping Mike a new one, I am discussing the topic and suggesting he has nothing really to moan about. That is a valid discuss point. I hear this business all the time from DSO imagers and it always makes me laugh.

Just for the record, seeing defects are multiplied many times over when imaging at 6000+mm. At 12,000 mm it is like watching something in a washing machine. Imaging at 800-1000mm has little effect and can only be seen via guide record generally. My point is to show that everything is relative. From my perspective talking about seeing at low focal lengths is quite humorous.

Next time I just won't bother.

[strongmanmike (Michael)]

My point is to show that everything is relative. From my perspective talking about seeing at low focal lengths is quite humorous

Yeh I guess so but even at the puny 1140mm FL, if you look at my comparison again, I think I know which of the two results you would prefer to have as the Lum in your LRGB

Next time I just won't bother.

Please do, no issues here mate, your second comparison was just as revealing as my Cen A's

[tornado33]

Some of the degraded seeing could be at the scope itself, a scope bought out of a warm building causes air currents, I always set up my rig as soon as the sun is no longer on it to give as much cooldown time as possible, and only use just enough anti dew heating to keep dew at bay.

A friend of mine into viewing with a 16 inch truss dob is installing a special low virbration fan and a special baffle that will draw air across the front of the primary mirror to hopefully eliminate any boundry layer turbulence. He says he doesnt want to capture starlight thats been travelling for hundreds or thousands of lightyears only to be degraded in the last few inches of its travel.
Scott

[Peter.M]

I might be asking the obvious but would it then be preferable to shoot binned rgb images on nights of poor seeing?

Just thinking that not only will the image scale be more forgiiving but blurring less noticeable when combined with a good luminance frame?

[strongmanmike (Michael)]

Originally Posted by Peter.M

I might be asking the obvious but would it then be preferable to shoot binned rgb images on nights of poor seeing?

Just thinking that not only will the image scale be more forgiiving but blurring less noticeable when combined with a good luminance frame?

RGB is very forgiving and can be taken in poor conditions and/or binned. It is the Lum, or what ever you use for Lum, that needs to be at it's best if you want the best resolution possible...but sometimes beggers can't be choosers . Of coourse if you take your RGB in good seeing and bin 1X1 you can always then use it as a synthetic Lum to augment your actual lum

Mike

[Poita (Peter)]

Originally Posted by Paul Haese

You're right I can remove a lot of the problems with frame selection and with gathering high speed frames. A better example of what I am trying to say is the following images. One is 8.5/10 and the other just barely 5/10. That is when it can be chalk and cheese. Remembering of course there are many nights I look and the seeing is 5/10 so I don't bother setting up. At least with nights of average seeing one can get reasonable data for DSO imaging. Maybe not luminence but certainly the RGB.

Great seeing

Average seeing.

Long and the short of it though and for those wanting to learn about seeing, Mikes point is well made. Luminence should only be gathered near the meridian and during good seeing. Likewise planetary imaging should not be conducted in poor seeing. If you are using one shot colour, well image when the seeing is best if you can, but if you have constant cloud, image whether the seeing is good or bad.

Thanks Mike and Paul for posting these, it makes us beginners feel a lot better knowing it isn't *always* our fault

I find for planetary bad seeing is amazingly awful, it makes it impossible to focus as the planet dances around like a cork in a washing machine. What do you do when it is like that, or do you just pack up and try again on a better night?

[Paul Haese]

Originally Posted by Poita

Thanks Mike and Paul for posting these, it makes us beginners feel a lot better knowing it isn't *always* our fault

I find for planetary bad seeing is amazingly awful, it makes it impossible to focus as the planet dances around like a cork in a washing machine. What do you do when it is like that, or do you just pack up and try again on a better night?

Go straight to bed and get that much needed sleep.

[strongmanmike (Michael)]

I have only once packed it in due to seeing and that was the night I took that Centaurus A image... I just lump the softer images

MIke

[Poita (Peter)]

After many futile attempts on the planets, I've been doing deep sky whenever the seeing is poor, as the planets literally look like a blurry earthquake, and I have no idea how you would set a focus point.
On a good seeing night, planetary is a joy, but in bad seeing I am baffled.