Cygnis Wall - C11Edge vs TOA 130

[Rodd]

I have wanted to make this comparison ever since I shot the Cygnus Wall with the TOA.  I must say, the results are not what I was expecting (or desiring). The TOA data was registered to the C11Edge data, so the scales are identical.  The FOV is a bit different, but the critical part of the image is in both images, and this can be fixed with a bit of planning.  Conditions were comparable as far as I can remember - decent seeing for me.  The images were processed teh same.  If I get better seeing it is very infrequently.  Therefore, based on the results of this comparison, I see no compelling reason to continue to use the C11Edge if all  I need do is crop the TOA image to the same FOV.  I am thinking galaxies, which are small even in the C11 FOV.  On the other hand there are compelling reasons to use the TOA instead of the C11 Edge.  It provides a much larger FOV that can be cropped down for smaller galaxies, , while being able to be used at full size for larger targets, making it more cersatile.  Also, Binning the TOA data results in a pixel scale of 1.59", which is much more appropriate under typical conditions for me than 0.8", which is the C11edge with.7x reducer bin2.  I could bin 3 or even 4, but what is the point of shooting a galaxy like M100, say, with the resulting image being a postage stamp.  Might as well use a wider field scope in that case and crop the image to the desired size.

Maybe I am looking at this wrong, which is the reason for the post.  Granted, the C11 image is only 35 300 sec subs while the TOA image is 93 300 sec subs.  In all cases the C11 builds signal faster, but only in the best seeing does trhe C11Edge yield appreciably more detail.  If this was the extrent of it, it wouldn't matter.  But tghe truth of the matter is a much lower percentage of data from the C11Edge can be used in poor conditions than data collected with teh TOA.  Guiding is more difficult, the system is more prone to wind gusts and poor seeing.  The bottom line is at my location most of the time, the C11Edge does not outperfrom the TOA.  

Note--since the TOA image was cropped after registration in order to remove black sections that represented areas where the two images did not overlap, the image looks larger pre-post.  I am not sure what the will look like after I post.  I may have to do a bit of resizing to get the scales just right..  Well soon find oiut.

EDIT: The full resolution sizes are the same, and that is how the images should be compared.

C11Edge with .7x reducer and ASI 1600 Bin 2; 35 300 sec subs

TOA 130 native with ASI 1600 bin 1

Edited May 30, 2023 by Rodd

[vlaiv]

17 minutes ago, Rodd said:

Guiding is more difficult, the system is more prone to wind gusts and poor seeing.  The bottom line is at my location most of the time, the C11Edge does not outperfrom the TOA.  

But it is obvious that it outperforms the TOA.

If you look at the images - C11 image is sharper and more contrasty. It goes a bit deeper and I think it was easier to process by looking at both results. All of that in ~1/3 of time?

By most discussed metric by amateur astronomer images - which is "speed of the scope" and how to get a good image (which is equal to high SNR first and foremost) - C11 wins hands down.

If that metric is not as important to you - well, that is another matter. As you've put it - it is much easier for you to image with TOA and based on that - only you can say if difference is worth it to you or not.

[Rodd]

7 minutes ago, vlaiv said:

But it is obvious that it outperforms the TOA.

If you look at the images - C11 image is sharper and more contrasty. It goes a bit deeper and I think it was easier to process by looking at both results. All of that in ~1/3 of time?

By most discussed metric by amateur astronomer images - which is "speed of the scope" and how to get a good image (which is equal to high SNR first and foremost) - C11 wins hands down.

If that metric is not as important to you - well, that is another matter. As you've put it - it is much easier for you to image with TOA and based on that - only you can say if difference is worth it to you or not.

Of course it is.  But you are forgetting the non data time.  Yes, in 1/3 the data, the C11 Edge outperforms the TOA under the same conditions.   While I am not as convinced as you seem to be that the C11 image is superior, I will grant that it is a bit better.  I said that the images were processed the same--that is approximate.  Not precise.  Any perceived difference could, in part at least, be attributed to processing.  But I will grant that the C11Edge image wins (by a smidgeon).  If this was true most of the time, I would feel differently about it.  But the fact of the matter is, on many nights the conditions are far worse.  Many are the nights that I would have to bin the C11 data bin4 or bin5, while the TOA data holds up at Bin2.  Without a FOV, Bin4 or Bin5 is just not something I am interested in.  Also, there are tube currents to deal with and dewing is a much greater threat.  Much of the "in 1/3 the time" sentiment is eroded away by time spent collecting data that can't be used.  Not all, but enough.  

My point was that even if the C11Edge image is better--it is not THAT much better (maybe even less than that if I take greater care processing the TOA image)  The question is...is it worth spending the extra time and effort and subjecting myself to much more frustration to occasionally get an image that is a bit better.  Now, if I imaged from a dark site that frequently had good transparency and seeing, I am sure I would feel as you do.

[ONIKKINEN]

Im with Vlaiv on this one, the C11 is the winner and with only a third of the time investment of the refractor it should be obvious as to how much better it really is.

[Rodd]

1 minute ago, ONIKKINEN said:

only a third of the time investment

No--1/3 the data, but a greater time investment as more data must be tossed, and simetimes the night is a bust due to wind and poor seeing

[ONIKKINEN]

1 minute ago, Rodd said:

No--1/3 the data, but a greater time investment as more data must be tossed, and simetimes the night is a bust due to wind and poor seeing

If the end goal is 1.5" per pixel, surely there is no great need to have seeing or guiding to be as great as if you were planning on having 0.8" sampling?

[Rodd]

21 minutes ago, ONIKKINEN said:

If the end goal is 1.5" per pixel, surely there is no great need to have seeing or guiding to be as great as if you were planning on having 0.8" sampling?

No, but I am not partial to binning bin4.  When imaging with a small FOV, bin 4 results in a very small image.  The reason I like the C11Edge (or any longer focal length system) is to achieve an up-close view.  I want my image to fill the display area on a forum at full resolution viewing.  At bin 3, there is no difference between screen viewing (the first click) and full resolution (the second click).  Also, something I have not included, is the data is much cleaner with the TOA.  The C11Edge data always has brighter areas near the edges--well the side edges, not the top edges (even when the image is portrait--its the sides). 

With a larger FOV, a higher bin may cause the target, say a galaxy, to be just as small as the C11 scale-provided the pixel scale is the same-but there will be background image that will fill the viewing space.  I really do not like clicking on an image to view and the image actually gets smaller.  If I was fortunate enough to have more than one mount and camera, on those occasions I would much prefer shooting wider field, which the TOA provides, especially with the .7x reducer.

At its best, the C11 wins.  The problem is at my location, as you rightly pointed out on another thread, there are better options (4-5" refractor) for the conditions I normally get.  

Its like having a car that can go 200 mph but living in an area where only 1 road can support fast driving.  I think so much depends on conditions.  The best results are when the scope/camera system is matched to the sky conditions.  Seeing as I only have the ability to use one system at a time, what I am saying is the C11Edge is not the best system for me to choose if I want to produce images not only from data collected during the best seeing I get--say 10% of the time.

Edited May 30, 2023 by Rodd