Altocumulus

Weeps!

Brilliant .... Where's the envy sticker! 🤠

Thank you Nicolàs....I think!

I'll be honest, it's getting a bit too complicated! 

14 hours ago, Nigella Bryant said:

I only get around a two hour window here in the afternoon. 

And how very well you used that short window. Marvellous...

I need to move south! Sun's, barely over the yardarm these days!

4 minutes ago, vlaiv said:

Correct focus position does not depend on either of those two things and I don't really see why would either over or under sampling prevent anyone from achieving good focus.

It's a bit like saying that finding correct focus for visual needs very high magnification. I've never had issues where I could not focus at particular magnification. I did however have situations where seeing was so poor that I was not certain if I had correct focus.

Thank you for the clarification.

I'll put it down to seeing conditions, which means I ought to pay more attention to the atmospheric conditions - that I do.

7 minutes ago, vlaiv said:

Defocus is another level of blur that adds up - it reduces effective resolution of the image and makes it harder to sharpen it up (it attenuates high frequencies even more).

 

Taking that to a previous question, then - if the sampling ratio f and pixel size isn't correct, could that effect the ability to achieve focus easily. I know conditions weren't good the last twice I tried Jupiter/Mars but I just couldn't get focus - not even a hint in lucky imaging - and the 174 was motoring at ~100 fps.

2 hours ago, inFINNity Deck said:

Here is the analysis of the 20 December image. I have split the image into RGB, then processed each channel using ImageJ:

I have not resized the images, only show them here at 50% to make them fits the screen.

Clearly the FFT shows that the images are well oversampled. No detail is lost when reducing it to 25% and resizing it 400% again:

Nicolàs

What happens analysis-wise if one of those images (or a live image) is de-focused?

I just did a search in the plugin library. It was the first on offer.

57 minutes ago, geoflewis said:

Yes please, in English would be great, as I could not read your article when I opened the link.

I used a translate plugin on my Firefox browser. 

On a slight side to this, one guesses a mis-sampling could have an effect on focusing? (over and above seeing of course.)

Thanks all.

Tell it more times, and it might sink in!! Vladimir!

Reading your article Nicolàs, thanks.

Many thanks.

I've come across some accounts suggesting 7* for mc cameras because of the matrix, so you're good!

Where some confusion comes from is ccd compatibility in astronomy tools that suggests a barlow worsens. The 174 on the 180 is already to the left of the green band - adding barlow shifts it further to the left...mind it's over rather than undersampling.

Och - a side effect of getting old Brain's not what it used to be....

May I check with the Planetary Imagers on cameras.

Does the 5 * pixel size ~ telescope f-ratio hold? Or is there a better formulation. I keep reading all the bits on Dawes Limits and Nyquist, but nothing sticks on the brain cells, so if

someone has a simple easy to use guide, I'd appreciate it.

For instance I'm guessing - under the above rule of thumb - the 178 chip at 2.4µm ( 12 - bit low ) and the 462 at 2.9µm ( 14.5 - close, but the one I have is colour ) are within the native resolution of the SkyMax 180Pro f15.

Similarly the ZWO 174mm at 5.6µm probably needs at least a 1.5* barlow added to the imaging train? Not too sure I can get focus with a 2*.

I'm likely looking at f17-20 on the SkyMax with a Crayford and ADC in the train.

How did you know the shot wasn't taken as the tower was collapsing sideways?

Good going for that elevation. No way would I get anything decent up her, the sun's barely a couple of hands above the horizon .

A few firsts here - use of filters and winjupos de-rotation...

Couldn't find a place to add a luminance channel in WJ, it seemed it 'wanted' one of the rgbs?

16,000 or so frames on each channel.
Skymax 180 Pro
ZWO 174mm ( tried to use a 2 barlow, but couldn't focus )
Focus in fact probably could be 'better' but some thin high cloud around.
ZWO filter holder

Sharpcap/AS3/WJ

Versions for your enjoyment!

Almost a full night session - 

Three for you - Keogram image for the whole night - timescale along the bottom.

Horizontal Aurora watch cam - North is just about the tree edge on the horizon right.

Overhead Allsky - North at top, lights of Aberdeen at the bottom. Power poles aligned 085-265 degrees - East is on the left.

All produced using AllSkEye windows software.

Aurora.aviSky Aurora.avi

Neat!

Good slice.

Let us know when you've completed Jupiter and Mars.

Still stuck behind clouds here - last session I managed was 10 days ago!

Aha. The culprit!

Mind, I blame all those cables!!!!

OOUK, Orion Optics UK.

Does anyone own the 140 Mak? I'm trying to find a solution that would allow me to use this with a remote focuser. The fit for the back is AP 2.7" and SCT thread. An OVL Dual Speed 2" Crayford Focuser For SCT Telescopes should fit, I use this on my Skymax, but there's not enough space on the rear of the 140 as the focus knob gets in the way!

It currently has a Baader adapter to fit a dslr - see image. The standard eyepiece fitting, in my humble opinion, mars the quality of the rest of the assembly.

May I join in with the wows?

Wow!

Question or three, if I may.

Did the sequencer work?

How does one calibrate the changes in focus for filters?

Did you use autofocus and still have enough time to capture frames before Jupiter's spin affects the end stack?

I've come across winjupos but am still learning the ropes moving from both Solar and a single bad session with an MC camera. 

Well I came here to see if anyone had cleaned a Skymax 180 and walk away somewhat overwhelmed!  My Mak displays flakes peeling from the inside of the tube like leprosy, and the main mirror looks like it has black measles!

Still works, to a fashion, but if I have to take the plunge at least I have a bit of a guide unless I can find a decent repair service! 

Subscribed for future reference. 

Impressive.  Three moons too?

I've learnt a thing or two reading this, thank you.

Apart from the odd moonshot I've only done solar, so that experience I carried over into my first Jupiter earlier this week. I'd hazard a guess my first error was in only taking 1-2k fast frames. Next time it'll be in the 10-20k ball park!

Plus my first time with an OSC!