Next step in processing?

[bigfish]

Hello,
I think I finally understand enough to get some images stacked. This is my very first attempt at Jupiter and Saturn! I know they aren't very good but I learned a lot the night I took these. I now have a much better plan for next time the sky is clear.
Once I have an image how do I bring out detail and color?
I had the camera set to maximum resolution. Should I not do that? The planets are so small.
Also, If I'm using AutoStakkert! what is the best format to save to, TIFF or PGN?
I don't have Photoshop at the moment so a free alternative would be great. I have Gimp installed already but haven't used it much. Any other freeware?
Thanks for your help!

[Larry 1969]

Sorry bigfish but I don't do lunar or planetary photography.
However, I do use GIMP in place of PS for just a few finishing touches. It's fine freeware.
Good luck!

Larry

[KathyNS]

Unless your camera does binning, its resolution is fixed. You might be referring to ROI (region of interest). You should make this fairly small. It will have no effect on resolution (arcseconds per pixel), but it will reduce the field of view. You will have less black sky around the planets. Not that black sky per se is a problem: you can always crop it out. But reducing the ROI will allow the frame rate to increase. I try to aim for a frame rate of 50 - 60 frames per second. That allows me to accumulate several thousand frames in a short time. The more frames you start with, the more are keepers. And the more frames you stack, the clearer the image.

I have used GIMP for images, both DSO and planetary. In the more recent versions, it is quite a good tool. (Beware of older versions: they were limited to 8-bit processing, which is not adequate for astro images. If your version is more than a couple of years old, upgrade it.) GIMP has limited sharpening tools, but good colour tools.

You might want to run the stacked image through Registax, for access to its Wavelets function. I wouldn't recommend Registax over Autostakkert for stacking, as its user interface is messy. But it has a good wavelet function for sharpening.

[bigfish]

Unless your camera does binning, its resolution is fixed. You might be referring to ROI (region of interest).

Thank you for your reply. Yes, ROI is what I meant.
So, in ASICap where it says resolution it should say ROI? or I'm I missing something?

[Greenman]

Unless your camera does binning, its resolution is fixed. You might be referring to ROI (region of interest).

Thank you for your reply. Yes, ROI is what I meant.
So, in ASICap where it says resolution it should say ROI? or I'm I missing something?

Interesting, as I have the same question

[KathyNS]

The software is wrong. They mean ROI.

[Greenman]

The software is wrong. They mean ROI.

Thanks, I think my ability to get labels right in Chinese would be limited too. Thinking about it you can’t change the resolution unless you bin... I think you can do a 2x bin on the ASI 224MC.

[JayTee]

They are not technically wrong. That is the right word when you use 640 x 480, that is the resolution. The ROI (region of interest) is where you decide to put that 640 by 480 region in the larger resolution of your entire sensor. Sometimes nomenclature is not very clear.

Cheers,
JT

[KathyNS]

They are not technically wrong. That is the right word when you use 640 x 480, that is resolution.

Yeah, I guess "resolution" is one of those vague terms, like "magnification" that loses its meaning when you get right down to what it means. It could be talking about pixel scale or it could be talking about field of view.

To the OP:
When I read that you had selected the maximum resolution, I assumed that you thought you were selecting the most possible detail on the planet. The amount of detail available (what I would mean if I used the term resolution) is determined by the pixel scale and doesn't change.

The relevant terms in imaging, that replace vague terms like resolution or magnification are "pixel scale" and "field of view".

Pixel scale is measured in arcseconds per pixel. It is determined by focal length and the pixel density of the sensor. It determines how many pixels an object will occupy in the image. With my planetary setup, a C-11 with a 2x barlow, operating at 5600 mm focal length, and an ASI120MC camera, the pixel scale is 0.14 arcseconds per pixel. Jupiter was about 47.6" in diameter at this year's opposition, so it will occupy 340 pixels (= 47.6 / 0.14) on my camera's sensor.

A 640x480 ROI will make Jupiter occupy more than half (= 340 / 480) of the short dimension of the field of view. A 1280x960 ROI will make Jupiter occupy about a third (= 340 / 960) of the short dimension, but it will still be 340 pixels wide. According to the ASIcap terminonlgy, you would have changed the "resolution", but in terms of how much detail you can see (what I consider "resolution"), it is still the same. You have just increased the field of view.

I hope I haven't muddied the water too much.

[Greenman]

They are not technically wrong. That is the right word when you use 640 x 480, that is resolution.

Yeah, I guess "resolution" is one of those vague terms, like "magnification" that loses its meaning when you get right down to what it means. It could be talking about pixel scale or it could be talking about field of view.

A 640x480 ROI will make Jupiter occupy more than half (= 340 / 480) of the short dimension of the field of view. A 1280x960 ROI will make Jupiter occupy about a third (= 340 / 960) of the short dimension, but it will still be 340 pixels wide. According to the ASIcap terminonlgy, you would have changed the "resolution", but in terms of how much detail you can see (what I consider "resolution"), it is still the same. You have just increased the field of view.

I hope I haven't muddied the water too much.

That makes sense to me.

In absolutist terms, the resolution of the sensor is the final arbiter of the maximum resolution. Now I'm ignoring the optics entirely. The number of pixels is constant, and there is space between them to prevent ’blooming’ from pixel to pixel (an issue when they fill or saturate). Unless I bin the pixels I cannot change that resolution. It is dependent on the number of pixels per nm.

Now you complicate the meanings as optical systems have resolutions of their own, dependent on the F# and other parameters.

So are we actually saying that a region 640 x 480 is now projected on to to the whole of the sensor or only a selected area of that size is being positioned in the frame of the sensor? I think the second is true, so as I see it the size of the image is larger, but the resolution is the same in the sensor.

Does that make sense?

[JayTee]

only a selected area of that size is being positioned in the frame of the sensor? I think the second is true, so as I see it the size of the image is larger, but the resolution is the same in the sensor.

Correct and correct.

JT

[Greenman]

only a selected area of that size is being positioned in the frame of the sensor? I think the second is true, so as I see it the size of the image is larger, but the resolution is the same in the sensor.

Correct and correct.

JT

Cheers JT!