M16

[Rodd]

This should give some pause when attempting to choose between a small scope and a large scope.  One image is taken with C11Edge with .7x reducer, the other with FSQ 106 with .6x reducer.  I linear fit the FSQ image to the C11image after registration, so we are looking at precisely the same thing.  There is some difference between the outer regions , but those are mostly due to processing.  The focus of the comparison is tghe detail in the pillares of creation, which sem pretty close to me.  It doesnt make my life any easiere!

C11Edge

FSQ 106

[Graham Darke]

Not much in it is there. Were the number of subs in each image similar? 

[Elp]

If you took them at the same time and the processing is exactly the same the FSQ shows more detail in the dark nebulosity at the top

[david_taurus83]

The C11 definitely has the edge over the Tak. Picks out just a bit more detail if you pixel peep.

C11

 

Tak

[Rodd]

20 minutes ago, Elp said:

If you took them at the same time and the processing is exactly the same the FSQ shows more detail in the dark nebulosity at the top

Well. It breaks down pretty quickly because processing can’t really be the same unless you use precise settings in the tools. But it’s not linear, so a particular curve for one maynot have the same effect. In short, the processing  was close, but not really the same.  The sky probably is the dictator in the room. 

[Rodd]

38 minutes ago, Graham Darke said:

Not much in it is there. Were the number of subs in each image similar? 

They have about the same integration time; about 5 hours or so. 

[Graham Darke]

Interesting. 
 

[Rodd]

1 hour ago, Graham Darke said:

Interesting. 
 

I do these comparisons to try and decide upon what scope I want to use.  I change scopes maybe once per year.  Setting up is not one of my strong points

[jjohnson3803]

Great pic!  LRGB shots are gorgeous, but I still like B&W.  Might be nostalgia for when I did astrophotography with 103aO/E emulsions on glass plates.  😁

[Rodd]

4 minutes ago, jjohnson3803 said:

Great pic!  LRGB shots are gorgeous, but I still like B&W.  Might be nostalgia for when I did astrophotography with 103aO/E emulsions on glass plates.  😁

Wow--virtually a lost art.  Film AP is amazing.  How to know one is pointing at the target?  Film development takes time--focusing on stars is understandable, but framing?  A very different skill set.

I like black and white images as well (Ha).  I suppose one can look at LRGB images in black and white too.  There is something about black and white images.

[Nik271]

I think the limit of resolution for both scopes is not their aperture but the atmospheric seeing conditions. In most locations the seeing introduces 2 arcsecond blur over a long exposure, whereas the resolution limit of   100mm scope dictated by aperture is just 1.3 arcseconds. In principle C11 should produce a less noisy image but again after noise reduction any advantage of this  will be trumped by the seeing.

[Rodd]

1 hour ago, Nik271 said:

I think the limit of resolution for both scopes is not their aperture but the atmospheric seeing conditions. In most locations the seeing introduces 2 arcsecond blur over a long exposure, whereas the resolution limit of   100mm scope dictated by aperture is just 1.3 arcseconds. In principle C11 should produce a less noisy image but again after noise reduction any advantage of this  will be trumped by the seeing.

Yeah.  I didnt realize that 1.3 was the lilit for 4".  That is better seeing than I get 99% of the time.  1.3 is pretty good resolution. Maybe the FSQ is the scope I should use and forget about long focal length work--at least in my back yard.  

[Elp]

Unless if you've controlled the image acquisition parameters as well as the processing I don't think you can reach a balanced conclusion from the results above. Just blinking the two you can clearly see they have been processed slightly different which will skew any judgement. Both images are however excellent. From my experience the refractor will always been sharper on edges, even if it's aperture is smaller than the SCT, but for intricate wispy details the aperture of the SCT normally wins out with the edges being softer.

Edited October 30, 2023 by Elp

[Rodd]

1 hour ago, Elp said:

Unless if you've controlled the image acquisition parameters as well as the processing I don't think you can reach a balanced conclusion from the results above. Just blinking the two you can clearly see they have been processed slightly different which will skew any judgement. Both images are however excellent. From my experience the refractor will always been sharper on edges, even if it's aperture is smaller than the SCT, but for intricate wispy details the aperture of the SCT normally wins out with the edges being softer.

I agree.  Theye are too close to tell.  I guess in my sky, on most nights, there is little advantage to using the C11.  It will build signal faster, but any such benefit is tempered by a significantly resuced FOV.  When Nebula season comes around, I struggle to find suitable framings with the C11.

[Elp]

It's difficult I know. I tend to use my C6 95pc in HS config. I'd like to use it F6.3 reduced but it's painfully slow in comparison even though the detail on the smaller targets is better.

[Rodd]

7 hours ago, Elp said:

It's difficult I know. I tend to use my C6 95pc in HS config. I'd like to use it F6.3 reduced but it's painfully slow in comparison even though the detail on the smaller targets is better.

You like HS?

[Elp]

It certainly has its benefits, I can only imagine how much better the data acquisition will be with a larger aperture. If you like to have pin point stars across the field might not be the best option but I simply set the lens at its zero closed position and it looks okay for me, if I want proper stars I'll use my APO and blend the two stacks, target acquisition is the important factor for using it, especially with this weather. And the OTA becomes multi purpose which you can't match with any other OTA, visual native and imaging use, planetary, small DSOs at F6.3 and widefield HS F2 all imaging possible.

Edited October 31, 2023 by Elp