Datalord

3 minutes ago, andrew s said:

@Datalord do you think one is significantly better than the other and if so how?

Regards Andrew 

1 hour ago, Datalord said:

There are differences in the end results. Even with being careful to reproduce my steps. The lower resolution does lose information that is used in the intermediate steps, and that loss adds up over the many processing steps. The noise is particularly troublesome in the dark areas for some reason, but that could probably be further processed away. The bright areas are very similar and I'm curious enough to want to try an imaging session with bin4 on the camera. Trouble being that I don't have bias and dark frames for it and I can't just take them.

Pretty much this.

8 minutes ago, vlaiv said:

Then just process that. That way we can be certain that any stretching and denoising and sharpening will be applied exactly the same to both images.

Well, that's not what I would do on a real image, so I don't think it is a path forward. To make this experiment work, for me at least, I want the processing to happen before upsampling, just as I would in real life. It makes no sense to me to do it the other way around.

To answer the question, the left one was the original bin1 process, the right is the bin4 process.

What I will try to do when I get the chance, is to collect bin4 images off my rig and process them. First with the regular processing, then with a drizzle. Then I can compare bin4+upsample to bin4+drizzle.

11 minutes ago, vlaiv said:

I'm having trouble distinguishing which one is which?

Which one is binned then up sampled and which one is original?

That's intentional. Which one do you think? 

Ok, I went back to my M106 project. Took a look at my lum files, which were originally bin1. I took all files from after staralignment and resampled them to bin4 with average setting. Then I processed the image with as close to possible parameters as possible (they are different because of scale). Finally, I resampled the binned image back up to full scale again.

Here are the results.

These have both been through Topaz DeNoise.

There are differences in the end results. Even with being careful to reproduce my steps. The lower resolution does lose information that is used in the intermediate steps, and that loss adds up over the many processing steps. The noise is particularly troublesome in the dark areas for some reason, but that could probably be further processed away. The bright areas are very similar and I'm curious enough to want to try an imaging session with bin4 on the camera. Trouble being that I don't have bias and dark frames for it and I can't just take them.

Anyone want to be a judge here?

I need to see a real life comparison, back to back, from start to end with a comparison between data gathered in bin1 and bin4 (or 3) to be convinced about this. It's counter intuitive and goes against what I have found when I process subs in just bin1 vs bin2. I find it massively better to have bin1 data for the final result.

Do you know of any a real life comparison somewhere?

8 minutes ago, vlaiv said:

Yes - that star on the right was actually binned x4 and it now looks the same after we enlarged it and then added some noise that was removed when we binned it by x4 (x4 SNR improvement).

It's an interesting exercise, but from a processing point of view, those images are simply not comparable from a processing PoV imho. The one binned, enlarged and put through noise is simply more noisy. It is a harder image to process. For that individual star, yes, I can see how that makes sense, but when you start processing nebula or galaxy dust, that noise will be a nightmare to process. It is simply not the same. Ok, we can create a starfield from a 100x100 image, sprinke a few pixels, enlarge, noise, great. That is not detail.

Have you actually done this on an image? Do you have some real data from such upsampling that results in a final image of reasonable resolution?

30 minutes ago, vlaiv said:

I would bin x4 and leave as is

This makes no sense to me. Don't get me wrong, if I could get the same result by using 16x less time, I'm going to be all over it. But I can't. And it's pretty easy to see why.

That's a closeup of the brightest star in the Ha image. If I were to bin4 on that, I would have a star with these 9 pixels:

You're saying I wouldn't lose information in my images by doing this?

Btw, I sent my entire set of images through CCDInspector to let it go through my FWHM. These are the results it gave:

Finally, this is the actual image I made with these frames. I really want to see the process with which I can achieve this result, in this same "empty resolution" by doing 16 times less imaging. Mind you, I used 19 hours of imaging time, so if I can achieve this result in 1½ hours, I'm SO game!

So, what you're saying is that I would have same quality image if I shoot at bin4 and up sample? 

9 hours ago, fireballxl5 said:

may not work in @Datalord's case

I really, really prefer not to have to do different exposure sets. That would mean a massive increase in imaging time for what is usually not the primary target in the images.

Pfft, who needs mounts when you can have a whole automated station?

3 hours ago, vlaiv said:

Could you post crop of both frames - just a piece so it'll be small upload size - but with enough stars without clipping? I want to measure both with AstroImageJ.

I've done similar comparison with actual data and I'd be happy to do it again for you if you wish. Point is in the numbers rather than text - difference between two subs if we know that resolution has been limited by blur of certain FWHM.

I tried to match the crops of those particular images to the same area. They were raw subs without alignment.

L_Ha_2020-01-06_23-40-59_Bin1x1_1200s__-40C_IC410-crop.fit L_OII_2020-01-12_20-27-54_Bin2x2_600s__-40C_IC 410-crop.fit

I'm losing sight of what the point is. The difference in my rig between bin 1 and 2 is 0.52" and 1.04". The seeing is the limiting factor, because obvious. This is measurable.

Going into what we can "see" is subjective, as we are essentially artists pixel peeping at thousands of images. I find this equally important, regardless of the measures, because we become experts at our own rigs and outputs. As such, I find the comparisons Vlaiv made in text to be borderline nonsense, because our brains observe text in a massively different way than it does images and especially closeup of starfields that we all know so well.

Anyway, I tried to measure something on existing images. Same target, IC410, in Ha and OIII. It is still not a fair comparison, because the Ha is 3nm, while the O3 is 8nm and exposure time is different. They are also on different nights, because that's how I roll. But, all other things being equal, that shouldn't affect FWHM too much.

Bin1: 0.52" per pixel      Bin2: 1.04" per pixel

So, the Ha is not clipped (much) and if I'm mathing correctly, the 1.576px*0.52"/px=0.81952" seeing? With that, I should be able to see a visible difference in an image where I sample above and below. Agree?

I'm not sure what to conclude about the O3. It is clipped in some stars, so that probably skews the measurement?

24 minutes ago, vlaiv said:

 

I would also like to see the difference - do you mind showing me the difference?

Same as Olly, I do different filters in bin1 and 2, as well as different exposure lengths. But I guess I could do a few shots to compare. 

38 minutes ago, ollypenrice said:

The question is, 'What are the active ingredients in high resolution amateur imaging?'

Focal length? Pixel size? Aperture? Seeing? Guiding?

We have to put seeing at the top because even quite modest amateur high res setups can offer, on paper, the other four ingredients in a measure which the seeing will always limit. The only way to beat your home seeing is to set up a remote rig in a dedicated location.

So what will your seeing support? 0.8 arsecs or 0.9, or whatever? It really isn't likely to be any less. In this case there will be a remarkable number of ways in which to get to that resolution by juxtaposing assorted focal lengths and pixel sizes. The combination I've chosen, small aperture and small pixels, can get very close indeed to what I used to get from a much bigger reflector and bigger pixels, so close that I'm not, personally, chasing more. However, a little more resolution is possible for those who want it.  What would really tempt me in a big reflector would be the opportunity to work in bin 2 or even bin 3 while retaining a pixel scale of just under an arcsec per effective pixel.  It would be fast. Unfortunately our time with a big reflector was affected by the fact that the camera we had would not bin satisfactorily so we were obliged to over-sample. It was never possible to present an image at full size because it just revealed 'empty resolution.' The price you pay is a drastically reduced FOV in exchange for a very small increase in final resolution. Yer pays yer money... etc.

Olly

I think we agree violently.

For reference, I use bin2 for everything colour related, so only lum and Ha is bin1. I'm going to argue, by having looked enough at subs, that there is a definite difference in the subs between bin1 and bin2, so having the rig at E-Eye, with that mount, enables me to benefit from 0.54" per pixel. But colour, yes, 1.04".

Shot over two nights with just 33*600s bin2 in RGB on my RC12. Pardon the heavy processing, but this is a shy galaxy to tease out.

The Draco Dwarf was not discovered until 1954 from photographic plates, despite being very close to us at 260,000 light years. It is an ancient, small galaxy, virtually dust-less and with primarily red stars formed over 10 billion light years ago. As you can see, there is nothing discernible structure or way to make it out if you don't know it is there. The Andromeda galaxy is estimated to be 100,000 times more luminous.

All of these properties has made it a target for lots of studies, because it seems to be the heaviest known object in the universe in terms of dark matter. And it's on our doorstep.

Interesting thing. The universe never fails to surprise.

I know this could be considered necro'ing a thread, but I think I have to update this particular topic to round off the ASA DDM85 in case someone considers buying one used (not produced anymore).

After a year of using it with guiding because my brain couldn't figure out the philosophy of the software that comes with the mount. During this year, the guiding with the mount has been spectacular. This thing is amazing. But...

One single line in an email from the vendor made it click in my head. I no longer guide. I set up the routine and it magically does its thing, finding an autofocus star every 30 min, then tracks a path to compensate for the next 30 minute of unguided run and then ticks away until the next round of autofocus and compensation. 

The results are, understated, quite ok. This is a 10 minute sub without guiding.

It is sad that they decided not to continue in the amateur market. It's such an amazing thing. 

So, I have a problem. Not entirely sure I want to fix it, but I would like some input.

So, I have had a problem with clipped stars. But it is isolated to the big ones. I snipped an area chart from Maxim:

This is a 600s bin2 red on the 16200 from the RC12.

Now, The obvious choice would be to reduce my exposure time, but I find my SNR (obviously) suffers more than I'm willing to accept. Or I was willing to accept. I'm also quite worried about losing detail on fainter targets, especially the galaxies in my cluster images and nebulae.

What is the consensus amongst the congregated stargazers here?

On 24/04/2020 at 10:37, ollypenrice said:

Being plug and play they save time while reflectors are arguing with their owners!

Fighting words! I have a few reflector images to compare. And the RC is very maintenance light.

First M106 with my RASA at 620mm. This is with a QHY247, so small pixels to Vlaivs point.

Here's M106 at 2361mm with my 12" RC.

So, when we talk about the "larger" galaxies, I don't think you win much by going up in aperture and FL. Like Olly says, you can crop your way to a lot. But my interest is very much in galaxies, especially the clusters farther away. I think this is where the longer FL has benefits.

Abell 779.

The long FL is what I love, but omg, making it work cost sweat and a small luxury car in financial outlay.

Damn, that is well done! 

I'm so torn about this thing. I have my e-Eye setup, for which I did everything myself and I'm very proud of my images for that reason.

But on the other hand, there is a lot to be said for being able to shoot whenever you want from all over the globe. Telescope as a Service will become bigger. 

3 minutes ago, DaveS said:

The Crux Harmonic Drive mounts certainly look interesting. You could always drop Rupert a line see if he has any suggestions.

ATM my ASA software is behaving itself and doing everything it should, including autofocus. Haven't added full automation yet though.

Autofocus is missing bit for me. I never got it to be better than me looking at the image and detecting a tiny eccentricity in either direction. Usually I have to move the focuser about 50 steps to fix it, which is less than an autofocus session will do for me.

14 minutes ago, Rocket Stars said:

I can get between 60-120 ish. Unguided with my hyperstar/AVX set up. (not screaming with happiness of that.) 

Was going to upgrade to another mount. But got "fever". Due to nights is vanishing here. So I got a Solarscope to play with. During the summer months.  

Ive got the impression CGX is a fairly good mount. Ofcoarse not up to premium ones. But had that one, as a possible upgrade. 

 

don't buy a CGX. If you insist, I have a used one you can buy for a reasonable price. 😆

3 minutes ago, Rocket Stars said:

Mmmm. 10 Micron, or ASA. Have that as one of my dream mounts. Just a tad expensive. I think if one gets that kind of quality mounts. Its hard to use anything less. 

Oh, did you try the CPWI software for Celestron mounts? My avx upped its performance with this! 

Oh, I can make a even trade with my avx! LOL

 

yeah, the CPWI software is really, really good. I love it, actually. Just as much as I dislike the ASA software. But it means nothing when the guide error makes even 180s at 620mm fl shots unusable. Meanwhile, 1200s is working perfectly at 2400mm fl on the ASA. You get what you pay for.

I have to add myself the Crux 200HD mount is looking extremely interesting to me. At £8k it is very top end for me, but what I have read of reviews, it is impressive.

28 minutes ago, cotak said:

I don't know if you need encoders for an RASA thought. It's not going to be a small image scale system is it?

No, you're right about that, but since getting my ASA mount on the RC12, my patience for guide error has drastically diminished to the point where I refuse to compromise. I love the hobby for the results, not for the anger at things that don't work as well as they are supposed to.

The other thing is that I might, some day, want to have a 6" refractor. And I could easily see myself pairing it with a QHY367C...

54 minutes ago, wornish said:

Apparently iOptron are about to release a CEM70. see post on here

I think I'm going to shy away from iOptron for now. Not in the mood for beta testing.