Major differences between lunar and planetary? [Solar System] Acquisition techniques · Jaymz Bondurant · ... · 16 · 462 · 4

I'll preface this by saying that I'm not at all seasoned when it comes to SSO photography. I feel like I'm very well versed in the basics and have a full understanding of the concepts. That knowledge has led me to acquire images of Jupiter and Saturn that I'm extremely proud of. They're not APOD worthy. But they're nothing to turn your nose up at either. 
I'm only telling you this to offer some contrast to my massive failures with lunar photography. I know what I'm doing for the most part. And I have the results to prove it. So, I'm baffled as to how I always seem to struggle so immensely with lunar shots. To my limited knowledge, the concepts of lunar and planetary photography are identical. So, how can I be so good at one and so terribly bad at the other?
A few nights ago, I pointed my scope at Saturn. I was merely working on my collimation and noticed it was up when I was done. I was so impressed with what I saw, I decided to switch over to SharpCap and start a capture. The resulting image was hands down the best image of Saturn I've ever produced. And that's why I don't understand why, when I point the exact same setup at the moon, I get wildly different results. Like Saturn, the live view of the moon looked better than it ever had since my recent successes with collimation. So, I was excited to try to the two shots I'd been wanting for 2 or 3 years now. One is the Apollo 11 landing site. The other is a shot that I call the "Moon Flyover". It's a closeup shot of the edge of the lunar disc that, to me, looks like you're hovering about 30 feet over the surface. Despite both shots looking good on screen, both stacks were unusable. It seems to me that with the moon being so much brighter and allowing for shorter exposure times, I should end up with not only higher quality frames due to being able to better freeze the seeing, but I should have more of them due to the higher frame rate. Win/win. Yet, for as long as I've owned a telescope, I've never been able to acquire a decent moon shot aside from a full disc shot about 3 years ago. What gives?

I'm not sure it matters because the setup is identical for both shots, but here's the relevant gear:
Meade SN8
ASI224MC
Celestron X-Cel XL 3x barlow (I know the problems a 3x can introduce. But, again, it's the same 3x giving me great photos of the planets).
SharpCap for acquisition 
PIPP, AutoStakkert, and RegiStax for processing (Side note: I still don't have a grasp on wavelets. In the past, I was able to salvage inferior photos and turn them into something decent. With the recent Saturn photo, I can't do anything better in RegiStax than the already sharpened image spit out by AutoStakkert automatically).

For good measure, I'll share my train of thought on why I might be having problems with one and not the other. 1) The astrophotography gods have deemed me unworthy of lunar shots. 2) There is something different about acquisition that I have either somehow overlooked or have forgotten. 3) There is some setting in pre-processing that I've either overlooked or have forgetten. I know PIPP and AS both have options to choose between lunar and planetary. To my knowledge, they each have one box to check. All other settings I leave the same. So, what am I missing???

Sean Mc:
Going to go out on a limb here… did you switch to lunar tracking?

Yes, everything’s identical to the planetary shots. The only thing that changes is the direction the scope is pointed. Everything looks good on screen. I mean, it’s a bit blurry. But so are the planets. That’s the point in lucky imaging. So, I don’t see why I’m getting drastically different results.

I think its easier to focus the image on a planet, especially Saturn with its rings that snap to focus relatively easily. With Jupiter there are the Galilean moons that only appear in the live feed at or close to the critical focus point. With the Moon however, it looks good on a screen even nowhere near the critical focus point because there are craters and surface features left right and center oozing out of every pixel. I think this may be one problem you are having. Try looking at a surface detail at a high zoom in the live view, something like 150-200%, and only start the recording when you are absolutely certain you are unable to focus the image any better.

Another part is processing, which you hinted at was an issue with not making sense of wavelets. It is a bit of a voodoo science of trial and error, ill give you that.I would advice against using PIPP before AS!4, simply because AS!4 has a special debayering method that is able to recover detail lost to the bayer matrix, which is something PIPP pre-processing would not do (if you chose to debayer the file as well).

For post processing give Imppg a try: https://greatattractor.github.io/imppg/


It is easier to make sense of than Registax wavelets with only a couple of sliders to work with. I think you'll be pleasantly surprised of how it deals with lunar images.

Jaymz Bondurant:

Oskari Nikkinen:
I think its easier to focus the image on a planet, especially Saturn with its rings that snap to focus relatively easily. With Jupiter there are the Galilean moons that only appear in the live feed at or close to the critical focus point. With the Moon however, it looks good on a screen even nowhere near the critical focus point because there are craters and surface features left right and center oozing out of every pixel. I think this may be one problem you are having. Try looking at a surface detail at a high zoom in the live view, something like 150-200%, and only start the recording when you are absolutely certain you are unable to focus the image any better.

Another part is processing, which you hinted at was an issue with not making sense of wavelets. It is a bit of a voodoo science of trial and error, ill give you that.I would advice against using PIPP before AS!4, simply because AS!4 has a special debayering method that is able to recover detail lost to the bayer matrix, which is something PIPP pre-processing would not do (if you chose to debayer the file as well).

For post processing give Imppg a try: https://greatattractor.github.io/imppg/


It is easier to make sense of than Registax wavelets with only a couple of sliders to work with. I think you'll be pleasantly surprised of how it deals with lunar images.

Some really good info here. I’ll quickly walk you through some of my ideas on focusing and what I’ve tried to do about it. Maybe that will lead to more insight.
I wondered for a long time of focus was the issue. It does seem like the most logical thing to look for. I found it frustrating because, at high magnification, even perfect focus looks blurry due to the seeing. So, I’ve worked pretty hard at making sure it was right. All for naught. I’ve even gone as far as to take video of what I thought was perfect focus and then move the focuser in/out of either side of that slightly and take two more videos just in case I was off a bit. Still nothing. 
Then, as mentioned earlier, I would get a great shot of a planet. Using that as “proof” that my rig was good to go, I’d immediately turn it to the moon only to find that it is NOT good to go. 
Ok, maybe it’s mirror flop? Usually an issue with bigger scopes but doesn’t hurt to eliminate. So, I’d collimate and focus on one star and then flip it 180 degrees to another star. It holds collimation and focus. 
To further eliminate any potential mirror flop, I’ve tried starting near the moon. I’ll move slightly away from the moon itself, raise the exposure time and/or gain, and then run an autofocus routine on the stars right next to the moon. After what the program deems perfect focus, I nudge it ever so slightly back over to the moon just to have the same problem. At this point, I feel like I’ve covered all the possible focus issues. Yet, something is still wrong. 

As for the processing side, I’ll definitely take a look into that. But I can definitively say that my lack of skill with Registax is not the issue because none of my lunar shots have been good enough to make into Registax. They’re noticeably ruined before that point. For me, it’s hard to say exactly when an image is “ruined”. Saturn and Jupiter are blurry in the live view. They’re blurry in the recording. And they’re blurry after PIPP. It isn’t until AS!4 that I get anything useful. With planetary in AS!4, I get one blurry image and one sharpened image. To the untrained eye, the pre-sharpened version is ALMOST good enough to be considered the final version without any further adjustments. With lunar shots however, I just get two blurry versions (with one being slightly less blurry). So, whatever I’m doing wrong isn’t being done in Registax. I’m leaning toward there being a different setting in one of the other Terri programs that I need to change maybe. 

That finally leads me to your other suggestion. As soon as I’m done here, I’m going to read up on it. But I was under the impression that the purpose of PIPP was to align the frames for AS!4. So, bypassing PIPP doesn’t seem optional. Likewise, if I’ve already stacked the frames in AS!4, I don’t see the need for PIPP anymore. I’m sure it comes down to my lack of understanding about those processes. So, that’s why I’m off to read more about it!

Autofocus on stars is not nearly accurate enough for lucky imaging, that is one thing you may have taken a wrong turn if you relied on autofocus and/or star focus for Lunar. At typical focus exposures of a few seconds the acceptable critical focus area is significantly larger than with typical lunar exposure times of a few milliseconds, so star focus may have been good but Lunar focus is completely out. Seeing is the biggest hurdle here, and is what makes focusing difficult. You really just have to look at the feed and pick the least worst section of focus. Under good seeing it can be obvious when the scope has snapped to perfect focus, but usually not at all easy and it takes some time to get right.

Autostakkert can work with recordings that have modest shift and will align the frames for you. PIPP comes in to play when you have too much drift, such as an untracked mount or if you neglected to keep the framing (you need to manually "guide" the mount while recording is active to keep the same-ish framing). PIPP is also useful for combining separate recordings to one, also mostly useful for when you dont have the option to keep framing with an untracked mount. You can also circumvent the debayer issue by simply selecting to not debayer the recording at the PIPP stage, but if tracking was good then PIPP is kind of an extra step and can be left out.

But to go back to focus, it cannot be overstated how important this is. Why your planetary captures had better luck i am not sure, but could have been just luck at play. What i do is look at some small surface detail on the Moon at high zoom and rack my focuser in and out with the 10:1 reduction gear. Doing this for a while gives me an idea on where exactly in that focuser travel that critical point is, so i can stop racking at that point. Kind of like what autofocusers do, but manually.

Jaymz Bondurant:
I posted this earlier but didn't realize until you failed to respond to it that I posted it on the wrong thread. I wanted to add the 3 images in question. Maybe you can verify that focus seems to be the only issue or gain some other insight from it. All 3 are the sharpened versions from AS!4 and completely untouched.

The first lunar image is difficult to take anything out of, since its the face-on bright part where details are not going to be obvious anyway. But i do see some weird lines and artifacts, hinting about some possible alignment issues. Either alignment points were not the right size, or the alignment itself went wrong. Hard to tell, no definite clues here.

The second shot looks similar to my 8'' newtonian images if seeing was bad, or the Moon was low in the sky, or focus was not perfect (or a mixture of the 3, which makes it difficult to say what to blame). It also looks maybe slightly aberrated in some other way i cant quite put my finger on. Its actually not terrible, it could probably be sharpened to a decent looking image (from the unsharpened AS!4 file, the auto sharpened version is just for a quick peek and troubleshooting).

Below is an example with my scope when i knew i had severe tilt in the imaging train, resulting in effective loss of collimation (some hodge-podge adapter contraption i had was at fault).
My example looks much worse than yours, with clear "something else" other than blurring due to seeing and focus going on, which would have been coma due to the tilt. Maybe something like this could be at play in your scope as well in a much smaller effect, although i am not well versed in what makes schmidt-newtonians tick and how they deal with coma and if the same rules apply as with normal newtonians. Collimating on a star with the barlow and imaging train as it would be in imaging configuration is really the only reliable way to figure out if the imaging train is to blame, so unfortunately takes some work and clear skies.

The Saturn looks ok, a bit small but it is what it is with 8 inch scopes. Rings are edge on so the easiest way to gauge sharpness with the gaps is not available at the moment, or the next few years so hard to say anything concrete. Not terrible i should say at least.

Before tearing your setup apart i would wait for the next opportunity to image again, and see how it goes with extra careful focusing. It could have just been a slight focus issue and bad seeing, so best not to be hasty but some food for thought with the above text.

Jaymz Bondurant:

Oskari Nikkinen:
Below is an example with my scope when i knew i had severe tilt in the imaging train, resulting in effective loss of collimation (some hodge-podge adapter contraption i had was at fault).

TILT!!!!! I didn't think of that! Do you think that could be my problem as well? I always collimate with my cooled cam. It's obviously heavier, but it also reaches focus much closer to the base of the focuser. My planetary camera, however, not only has a fairly heavy barlow on it, but it requires a rather long extender to reach focus. It's got a good bit of length on it. I'm just spitballing here because I'm no expert, but if I understand it correctly, the coma-like effects from tilt are more pronounced the further from the center you get. With the planets being centered, the effects would be minimal (I think). Similarly, I would think the size of the target would make a difference as well. With the planets taking up a limited number of pixels, the negative effects have less of a chance to present themselves across the sensor. I could be misunderstanding the actual effects of tilt. But it makes sense in my head so far.
Either way, it seems likely the extender on my focuser with the heavy barlow could be having a negative impact. It seems likely enough that I'm rather excited that you may have solved my problem (or at worst, led me to make significant improvements to my SSO imaging). Unfortunately, it doesn't look like I'm going to know for sure any time this week. Curse these clouds!!!

You hit the nail on the head with that thinking here, planets are a couple hundred pixels at best whereas the Moon fills the entire chip so ill effects from any optical problems are more likely to be seen especially in the corners. My setup with that disaster image i showed as an example was with a very long adapter combo on the barlow, because i did not have focus otherwise so tilt was extreme.

With normal newtonians we can calculate the coma free* field diameter as, i think it was, 0.022mm times focalratio^3. Barlow lenses multiply the field diameter by the barlow factor instead of changing the actual focal ratio. As an example with my roughly f/4.4 focal ratio mirror and a 2.7x barlow it would be 0.022 x 4.4^3 times 2.7  = 5.05mm field. If there was significant tilt or miscollimation, say 2mm worth, then i would realistically only have 3mm of coma free image which would be noticeable in a large panel with my 8mm diameter camera sensor (678MC).

*Coma free as in not actually truly free of coma, there will be coma any distance from the perfect center but at this distance it will not be noticeable.

However i dont think this formula works for Schmidt-newtonians, since there is the corrector plate and thus less coma than a normal open newtonian. But safe to say tilt will have an effect, just cant calculate how much. Star test in the next clear night with the planetary imaging train will reveal that, if it is a problem.

Good question, the same techniques apply in both cases. In theory, the moon should be easier to image to the same resolution that you are getting on the planets, for all the reasons you've pointed out. Just to make sure it's not a processing issue you might try AstroSurface for stacking. If find it gives slighly better results than AutoStakkert and much better than RegiStax. I have always had the opposite issues. My moon work is great but I am crap on the planets!

Were you able to verify that the collimation didn't change?

Great!