Freddie

Nice. I think you have still got some room to reduce gain and hence reduce overall exposure on the prom shots. Do you use flats on the surface shots?

That’s been an interesting discussion, thanks for your input and comments. As someone who has done plenty of solar imaging, practical experience shows that 16 bit capture gives no observable quality improvement in the final processed image but can slow down capture speeds (which can cause issues in high res imaging of active areas such as proms) and certainly takes up more storage which may or may not be an issue depending on the individual computer being used. Some interesting theoretical points though.

Sorry, badly worded on my part. We were obviously originally talking about 16 bit SER. There is no real world advantage to capturing in 16 bit SER Vs lower bit but I neglected to state 16 bit above.

I don’t know if FC and SC capture in different ways when set to AVI mode but the overwhelming evidence from actual captures from many different imagers (at least when using FC) is that there is no observable benefit to capturing SER, it just takes up more storage and potentially slows achievable capture speed.

I would, and do, go with AVI every time. (though in FireCapture) https://pdfs.semanticscholar.org/657f/7ee24526277d5a9da3dbc6bdf0826c864a64.pdf

There is no point in capturing using SER as once you have stacked there is no advantage over capturing using AVI.

Interesting tutorial, thanks for putting the time in to produce it. One question though. Why do you blur the fine detail in imppg only to then sharpen it in PS?

The GONG website gives Ha views of the sun updated every minute. https://gong2.nso.edu/products/tableView/table.php?configFile=configs/hAlpha.cfg

I don’t know if EQMOD makes a difference and allows different settings etc as I don’t use it but straight PHD always moves 25 pixels during calibration and the step size (in ms) that you select will change the number of steps it takes to move those 25 pixels. So in terms of calibration, guiding and the graph showing pixels, it makes no difference if you add a FL, put an inaccurate FL in or just don’t bother it will still calibrate and guide the same with or without FL.

During calibration, PHD always moves a set number of pixels (can’t remember the number) and then uses that calibration to determine how to guide. It only ever uses the focal length to calculate the arc sec figure, so you could completely miss out entering a focal length or put in a completely wrong by a factor of ten figure and it would still calibrate and guide in exactly the same way as when a focal length is entered. With the wrong FL the graphs would not be accurate in terms of arc sec but they would still be accurate in terms of pixels.

Do you mean do both well or do both ok. Plenty will do both ok, none will do both well.

One last shot of the prom before it disappeared. No colour this time. Captured using FireCapture, stacked with AS!3, processed with imppg and PS.

Nice work.

You can set that in the sequencer, the icon with 123 on the top toolbar.

Makes sense you are getting the fps rate you are with that setup. Sounds like you are exposure duration limited rather than camera speed limited then.

No problem, glad it was of some help. I'm assuming that your 2000 frame captures are only taking about 10 seconds so the movement of the proms over time will not be an issue over that timescale and image scale. Merlin 66, the numbers you are quoting would indicate you are only getting ~40 fps, that sounds slow if you are using your ASI. Let us know how you get on with the adaptive settings in imppg.

What are you going to get?

I agree that of the shots posted, the 100 stack is the best. I however think the 50 stack approach has more potential with the changes I have suggested. You need to keep the Barlow in to achieve the image scale required so I would leave that. A larger frame size will make no difference when it comes to gain it will just slow down the FPS you can achieve as it is having to download more data. I still think you have room to lower gain as you look a touch over exposed so lowering gain will sort that and a slight increase in exposure by a couple of ms to allow a further lowering of gain will generate more benefits from reduced noise than you will loose by having exposure a few ms longer. Anything even up to 10ms really won’t cause you any problems. Once you are getting the best from captures and stacking, you can then concentrate on improving post processing with careful sharpening but only where you have bright signal that can cope with it and not the dark low signal areas.

As suggested, the more frames in the stack the more poor quality ones in there which will blur the detail. I think we can ignore the 10 stack as that isn’t realistic for a final image (fine though for an experiment) but I think the 50 stack would be the best with a few adjustments during capture and processing as I think the noise in the 50 stack is masking detail. Still looks like you have quite a high gain setting and the overall exposure is still quite high. I would reduce gain further until you get a slight darkening of the edge of the disc. If at that point gain is anywhere close to getting up to 200, I would increase exposure by a couple of ms until gain is well below 200. Then in processing, do try the adaptive settings to stop sharpening the background. With these changes, I think you will further improve on your images.

That video clip is really misleading and completely misses the point. As said above, if you ignore the pixel size as he does in the vid, just cropping the image produced by the larger chip will achieve the exact same result as using a smaller chip. If he wants to “zoom” in on specific targets he would actually be better off with the larger chip, capture the two targets in the same FOV of the larger chip and crop out each target and you have two images but taken in one go on the larger chip instead of having to do two completely separate imaging runs. He either doesn’t understand what he is talking about or does a really bad job of explaining what he is doing.

Chicken and bacon pie with assorted veg. Very nice!! The difference in detail (particularly between the 10 frame and 100 frame) is quite hard to see because of the noise and is only really easier to see in the brighter parts of the image. A couple of things I would change in your capture to make processing easier would be to really try and get your gain down. I see you have reduced it to 262 but I would really get this well below 200. Raising the exposure a couple of ms really won’t make any difference which will allow you to reduce gain to achieve the same level of histo but I would reduce further as the edge of the disc is over exposed which is burning out the small spicules. Reducing the overall brightness and increasing the exposure a few ms should give you plenty of scope to reduce the gain quite a bit. Stacking 10 frames was good to show the difference for the experiment but I think stacking 50 would be more realistic. I always think that setting a number rather than a % is a much better approach to stacking. What has happened in the post processing in imppg is that the sharpening has been applied globally. At least that’s what it looks like to me. You will have to correct me if I am wrong. What has therefore happened is that it has sharpened the proms but as there is plenty of bright signal there, the sharpening has not shown up the noise so much. However as the sharpening has been applied globally (I assume) the same amount of sharpening has been applied to the background and as this has very little signal, it has pretty much sharpened the noise, resulting in that bright mottled pattern. The noise in the larger stacks has had the same sharpening applied (as you say you did the same to all 3 images) but as there are more frames in the stack, the noise is smoother and therefore doesn’t result in that mottled effect. You are right that the background of the 100 and 1000 stacks are much superior so what we need to achieve is the same background as the 100/1000 stacks but with the improved detail (to my eye at least) of the smaller stack. The way to do this is to sharpen the 10 stack (or something like 50 if it wasn’t an experiment) in imppg but use the “adaptive” settings. This allows you to sharpen brighter and darker parts of the image to different degrees. In fact you can actually apply smoothing rather than sharpening to darker parts of the image with the right settings. This way you keep the detail in the bright bits and don’t sharpen the noise in the dark areas. Hope that helps.

I wouldn’t worry about a new trial. Now that you have confirmed you used imppg to sharpen as I suspected, I am pretty certain I know what the problem is and how to solve it. However, dinner must come first so will be back in 30 mins!!!

You say these have minimal processing. It looks to me that includes sharpening. There is however clearly far more detail in the proms in the 10 stack than in the 100 stack. As I suggested, the additional frames have blurred the detail. As we are interested in the proms and not the background, then the 10 stack is the one to stick with but sort the background and the way to do that is through processing not by just stacking more frames and losing detail in the thing you are interested in. Let us know if the processing has included sharpening and if so, I can give you some pointers. Knowing what you use to sharpen (hopefully imppg) would be useful.

Managed to pick up a few spicules which was ok for the conditions. I usually keep my images mono as I think the colour can mask fine detail but as there isn’t much fine detail I thought I would give some false colour a go.

Some interesting comments there by “Merlin66” and obviously everyone has to find the settings that works with their particular setup. My thoughts and experiences however are that with a gain of 189 the benefits of max image depth are imperceptible but boy can you see the extra noise in the frames. The extra noise meaning you are going to have to stack more frames to control it, including poorer quality ones that will blur the final result. Also, when you are just concentrating on the proms as you are, setting the histo to 85-90% is going to be too low as to expose the proms correctly you will have to blow out the surface and hence the histo is going to be 100%. As said though, everyone has valid thoughts and it is best to think about which ideas may work for you, try out a number and see what works best for your particular setup.