Sun in Ha 19 Jul 2013

[Notty]

Crisp skies with no haze, so thought what the heck. My third go, and with only the most very basic understanding of Autostakkert and Paint.net not to mention my camera and capture program settings, things can only get better. I'm still having no luck with mosaics... Tried the Frankenstein approach in Paint.net but its above my pay grade so far.

The Newton rings are still there, but nowhere near as bad as before.

[allcart]

You will really struggle with mosaics unless you can control that hotspot. Try tuning for the most even disc as opposed to the brightest disc, and see if you can tone down the hotspot a bit. What is your stacking method.?.

[DrRobin]

Hi Andy,

A nice capture Andy, keep trying different settings and see what works best for you, it is all practice, focus, tuning, exposure and everyone has to go up the learning curve. Oh and then there is the whole stacking and post processing issues and techniques to learn.

Your last mosaic was working out quite well, hope you get back to those again.

Robin

[Notty]

Thanks guys. Regarding tuning to a degree I'm hostage to the rings of Newton....it's only really by tuning that I'm able to tone them down (yes I know, wrong camera! All I could afford unfortunately). Whenever I managed to get rid of the hotspot the fringes all went black. You're all telling me its possible to get the even disk but I'm struggling. On my capture software i've got three sliders. the top one hasn't got a label, but has units of %, I'm assuming this is gain. below that I have exposure, and below that gamma. Am i correct in my reasoning that all things being equal, we want gain and gamma at their minimum possible?

I'm stacking in Autostakkert, setting it to "surface", then choosing stacking the number of frames as a proportion of where the green quality graph hits the blue line from above. I have no idea if this is right or not. I manually select about 5 AP's on the disk relating to prominent features.

I'm beginning to get the feeling less is more with the sharpening. I prefer the image on the left. Thanks again for the tips.

[allcart]

Everything with the pst is a compromise Ant. I think we all have a sweetspot and from what I have seen, most people have a hotspot . With my Lunt and DMK cams it is usually on one side of the frame, so I image on the other side. I'm working on getting an even illumination across the frame, but its not easy. With my pst the hotspot is in the middle just like yours, so I tune the etalon as best I can and then twiddle the gamma and exposure to expose the hotspot correctly and then its all photoshop to even things out. I have no experience with Paint.net

I always try to keep the gain at a minimum and use the exposure and gamma to get the image how I want it. Its low gamma for full disc and surface details, but I increase it slightly for full disc and proms. Exposure is set according to how the histogram looks. I try to get a histogram that is wide and low. If your histogram has a large narrow peak in the middle then some part of the image is too bright. That will be the hotspot.

You will probably know that after analysing the avi, the best frame is shown on the screen and represents frame one on the top slidebar and is the 100% frame. The graph gives a good idea of the quality of the frames for the whole AVI, but is not useful for choosing the number of frames to stack. When choosing the number of frames to stack, drag the handle on the slidebar at the top of the image window to the right and watch the info numbers change in the top left of the image screen. The second line of numbers shows the quality percentage of each frame and goes down as you move the handle along the bar. Slide the handle along the bar until you get to 90%. The other number on that line tells you how many frames are above 90%. That's how many frames to stack.

I never stack anything lower than 80% and if its a good capture with lots of frames to stack, I stick with 90%. I think that anything lower than 80% only degrades the image and loses sharpness of detail. As with sharpening, sometimes less is more.

[Notty]

That is hugely useful info Allan, thanks very much indeed. Obviously now I've got a few clues, I'm not going to have the opportunity to try them out for a while, but try them I will.

Regarding mosaics... When taking them, how much overlap do we aim for between panes? Also, as I move about the disk I sometimes have to refocus... Will this confuse the mosaic algorithms into thinking the pics aren't of the same origin? Along with retuning the etalon to try and balance the disk? Im stuck between a rock, as i can nearly get a whole disk with just the cam with its extension tube in perfect focus, but using my barlow I can't seem to get any focus. Seems to be the opposite problem to the DMK.

Now I understand I've been using the stacking all wrong I'm going to try and reprocess my stuff again and see if its any improvement.

[todd8137]

Mosaics are a pain but you will get there in he end

pat

[JamesF]

Well done. I'm finding it tough starting out in Ha imaging with the PST too

James

[Notty]

Bit more of an even disk on this, but I've had to lose a lot of detail

[allcart]

Looking at your top pics Andy, you could pssibly do it in 2 panes if you can even out the brightness a bit. I would probably go for 4 panes and use the part of the frame that has the best detail. You can crop off the bad part of each frame before stacking. Its all a bit trial and error until you find what works for you. When I do a mosaic i set everything the way I want it then take all the panes at the same focus and settings. I am no expert at mosaics, but I have found that if I change focus or settings between panes, it causes problems.

As regards overlap, I think you will have to experiment and see what works. With a 4 pane mosaic you should have plenty of overlap.

[allcart]

I'm trying to work out why your background is such a light colour. Can you explain?

[Notty]

Haha yes, it's just me playing around with the colour levels in Paint.net, at the time I thought the red looked quite fetching!. The last one I posted is more like how I want it but I need to learn how to use gradients etc to blacken it more

[allcart]

DrRobin is your man for paint.net. I have never used it, so can't help there.