Thinking of C14 Edge vs RC16 ? Choices Choices!!

[ollypenrice]

This thread has sent me back to my TEC140 data on M51. My offically 'best' M51 combines this 12 hour run from the TEC 140 with a longer run using Yves Van den Broek's 14 inch ODK. So with a bit of tweaking, shoving and thuggery, what can I squeeze out of the TEC140 data? This is, remember, only 12 hours in HaLRGB. I'm chucking it in here at full size and cropped despite the fact that this will throw up JPEG losses for all to see. I don't claim a big reflector can't beat it. I just wonder by how much and with what degree of hassle?

Olly

 

[tony210]

Hi-I have a 12inch RCT but with skies in the South of England I am not sure I would go bigger. I am not convinced from my imaging in the last 2 years that I have realised the true resolution of my scope with my seeing.I have seen images with 8 inch scopes at high altitudes and great skies that blow my 12 inch away.If I went bigger the focal length gets even trickier and the FOV  is small which is itself limiting and technically challenging. Guiding with a focal length of 2.4 m is difficult if the skies don't cooperate Just my perspective- of course exposure lengths of your subs or number of subs can reduce for the same result  but if the guiding is suboptimal there is no real gain -bw Tony.

Edited April 18, 2020 by tony210

[Timebandit]

14 minutes ago, ollypenrice said:

This thread has sent me back to my TEC140 data on M51. My offically 'best' M51 combines this 12 hour run from the TEC 140 with a longer run using Yves Van den Broek's 14 inch ODK. So with a bit of tweaking, shoving and thuggery, what can I squeeze out of the TEC140 data? This is, remember, only 12 hours in HaLRGB. I'm chucking it in here at full size and cropped despite the fact that this will throw up JPEG losses for all to see. I don't claim a big reflector can't beat it. I just wonder by how much and with what degree of hassle?

Olly

 

 

 

 

Woow Olly , I am not an imager , but I can appreciate a stunning photo 👍

 

 

 

 

[Star101]

I can see my aspirations for the RC16 dwindling away and maybe a TEC140 or similar racing to the front.

Yes Olly, a great image of M51

 

Dave

[vlaiv]

3 hours ago, Star101 said:

Am I correct in thinking the 16"RC needs a camera with something like a 9um pixel size, KAF-16803 chip? 

RC16 and ASI6200 is match made for deep heavens

 

[oymd]

3 hours ago, ollypenrice said:

This thread has sent me back to my TEC140 data on M51. My offically 'best' M51 combines this 12 hour run from the TEC 140 with a longer run using Yves Van den Broek's 14 inch ODK. So with a bit of tweaking, shoving and thuggery, what can I squeeze out of the TEC140 data? This is, remember, only 12 hours in HaLRGB. I'm chucking it in here at full size and cropped despite the fact that this will throw up JPEG losses for all to see. I don't claim a big reflector can't beat it. I just wonder by how much and with what degree of hassle?

Olly

 

wow....gorgeous...

Can you please stop posting photos like that....?? You are leading some of us to desperation...!!

 

[Whirlwind]

22 hours ago, ollypenrice said:

These are cogent arguments but are predictated upon using CCD technology. For better or worse CCD chips will probably go out of production to be replaced by CMOS. What are the binning advantages of CMOS compared with CCD?

Olly

There's no fundamental difference between binning between CMOS and CCDs.  CMOS reads out each pixel individually whereas CCDs readout by line or column.  Generally then you hardware bin for CCDs as the readout occurs not at the pixel level and can be easily done in the readout column/row.  As CMOS is read out at the pixel level you readout each individually and then combine the data (so it is more 'software' binning).  They both do the same thing though which is combine the data from multiple pixels into one 'super pixel'.  They each have their own individual read noise characteristics but is still overall beneficial compared to trying to image at too high a resolution.

[Whirlwind]

11 hours ago, oymd said:

wow....gorgeous...

Can you please stop posting photos like that....?? You are leading some of us to desperation...!!

 

Lots of dark skies and low light pollution, good seeing and high transparency with many hours not affected by weather will always get pictures that can overachieve what you can do in the UK with even the largest of telescopes.  There are few places in the UK that can achieve even one of these.  It's why people consider remote imaging.

Edited April 19, 2020 by Whirlwind

[johnturley]

18 hours ago, kirkster501 said:

Quality refractors on a Mesu mount.  I'm not sure there is anything to beat that combination. 

I have observed The Moon through my TEC140 many times. Sure it may "only" be a 5.25 inch aperture.  But it is spectacular.  The Starfire will be even better.  It will be fabulous on imaging as well.

Why would you assume that the Starfire 130 would be superior to the TEC 140

John 

[Laurin Dave]

 A very interesting thread..  I too frequently ponder the advantages of a larger scope than my Esprit150... for speed of capture rather than an increase in resolution which I think will be hard to come by in the UK .   but then I look at this and wonder why..  another M51 this time from Bortle 4/5 Berkshire 12.5 hrs lum 5 hrs a channel RGB and 15 hrs Ha on piggybacked Esprit100.  not as good as the Haute Alpes but getting close..  

Dave

 

Edited April 19, 2020 by Laurin Dave

[Rocket Stars]

9 minutes ago, Laurin Dave said:

 A very interesting thread..  I too frequently ponder the advantages of a larger scope than my Esprit150... for speed of capture rather than an increase in resolution which I think will be hard to come by in the UK .   but then I look at this and wonder why..  another M51 this time from Bortle 4/5 Berkshire 12.5 hrs lum 5 hrs a channel RGB and 15 hrs Ha on piggybacked Esprit100.  not as good as the Haute Alpes but getting close..  

Dave

 

I think the question maby should be what timesaving it should a 16" give? A saw a ppl of galaxy images that killed most of other images I have seen. Though.. it was a 2 METER..RC.. (Well.. Its out of pretty much anyones reach) But it still had Just having 9 minutes uf integration.. Was just wow!! 

I have no way near the experience of all of you in this thread. But I argue that aperture saves integration time. (if same obj. and quality is compared) I might be wrong As there is so many factors involved. But we should compare as same observation data/time/place ect. 

 

[ollypenrice]

12 minutes ago, johnturley said:

Why would you assume that the Starfire 130 would be superior to the TEC 140

John 

I wouldn't put money on it either. The TEC was corrected primarily for visual and I did get some slight blue bloat occasionally, until I added the TEC flattener for use with my full frame camera. While TEC strenuously deny that it has any colour correction effects, I and plenty of other users insist from experience that it does. When I compare Alnitak shot in the TEC140 with the same shot in the Tak FSQ106N, the TEC blows the 106 out of the water. A set of 10 minute L subs from the TEC, given a basic log stretch, leave the star cleanly split as a double. In the Tak it's a blob and needs short subs and layer masking to save it. To be fair reflectors also split the star cleanly, though the diff spikes are prodigious.

Olly

[vlaiv]

3 minutes ago, Rocket Stars said:

I think the question maby should be what timesaving it should a 16" give? A saw a ppl of galaxy images that killed most of other images I have seen. Though.. it was a 2 METER..RC.. (Well.. Its out of pretty much anyones reach) But it still had Just having 9 minutes uf integration.. Was just wow!! 

I have no way near the experience of all of you in this thread. But I argue that aperture saves integration time. (if same obj. and quality is compared) I might be wrong As there is so many factors involved. But we should compare as same observation data/time/place ect. 

It is both integration time, but also something else - not often mentioned аnd spoken of even less often. Sharpness, or rather potential sharpness / resolution.

If you look at these images made with 140-150mm aperture, including this excellent example just posted:

you'll notice that none of them really goes lower than 1"/px. On the other hand, scopes are capable of much more and as planetary imagers know - if you have good SNR you can get sharper results than can be seen with naked eye in best of the seeing conditions. How come? There are tools that we can use to reverse impact of seeing and aperture (up to a limit) - and it depends on SNR just how much "frequency restoration" (fancy name for special kind of sharpening - that is reversing of impact of aperture and seeing) we can do.

Also - larger scope have less of aperture impact - which compounds with atmospheric influence (in very convoluted ways).

Large scope will provide needed SNR in same imaging time as smaller scope - it will give you potential for sharper image both due to aperture and also due to sharpening (if properly done).

[ollypenrice]

5 minutes ago, Rocket Stars said:

I think the question maby should be what timesaving it should a 16" give? A saw a ppl of galaxy images that killed most of other images I have seen. Though.. it was a 2 METER..RC.. (Well.. Its out of pretty much anyones reach) But it still had Just having 9 minutes uf integration.. Was just wow!! 

I have no way near the experience of all of you in this thread. But I argue that aperture saves integration time. (if same obj. and quality is compared) I might be wrong As there is so many factors involved. But we should compare as same observation data/time/place ect. 

 

Provided you don't kill the aperture advantage by over-sampling, you're perfectly right. Our adventures with a 14 inch ODK were hampered by oversampling because the SXVH36 we were using wouldn't bin properly. Not all CCD cameras do, be it said. We have two Atik 11000s here, one of which bins perfectly while the other just throws up artifacts.

Remember, though, that with a very long focal length you can bin in search of a good pixel scale but your chip doesn't get any bigger so your FOV risks being limited. For all that, there are plenty of small targets.

Olly

[Star101]

14 hours ago, vlaiv said:

RC16 and ASI6200 is match made for deep heavens

 

That is one gorgeous piece of imaging hardware. I will need a bigger hard drive too   

[Xplode]

It's very rare to find good images with cheap slow reflectors (sub 7$k)...and many don't seem to get an advantage  in resolution/sharpness with their larger aperture...
Most good images with reflectors in that price class is taken by f5 or faster newtonians.

You can compare this image i took with a TOA150 with another one taken with a Edge 11"
Camera is the same for both images.

 

TOA150, it's sharper and goes deeper with less imaging time and no luminance, there's of course a little noise

https://www.astrobin.com/full/oan4j1/B/

 

Edge 11", light pollution might contribute to this not going deeper.

https://www.astrobin.com/full/0ouned/0/


When Spain lifts the lockdown i will test the 14,5" f/5 reflector at my coowned remote observatory with ASI6200, will be interesting to see if i can beat the TOA150's sharpness.

[ollypenrice]

7 minutes ago, Xplode said:

It's very rare to find good images with cheap slow reflectors (sub 7$k)...and many don't seem to get an advantage  in resolution/sharpness with their larger aperture...
Most good images with reflectors in that price class is taken by f5 or faster newtonians.

You can compare this image i took with a TOA150 with another one taken with a Edge 11"
Camera is the same for both images.

 

TOA150, it's sharper and goes deeper with less imaging time and no luminance, there's of course a little noise

https://www.astrobin.com/full/oan4j1/B/

 

Edge 11", light pollution might contribute to this not going deeper.

https://www.astrobin.com/full/0ouned/0/


When Spain lifts the lockdown i will test the 14,5" f/5 reflector at my coowned remote observatory with ASI6200, will be interesting to see if i can beat the TOA150's sharpness.

It also looks as if you might have had less of a fight with the stars from the TOA 150? I'm looking at the green noise around the bright star to the right of the galaxy in the C11 image. They're both good images but I'd choose the Tak one, personally.

Olly

[Rocket Stars]

Very intresting inputs from you all! 

This forum and its contributors. It is just great! My learning curve is steep, and much hows it to this forum. 

As a former glider pilot and technician. Id hate to say it. But clouds is just now a menace!

Im going to start looking for a 2 week holiday trip with my wife. Think I need to go somewhere its super nights. And nice in the days. Checked my maps. In the skerries, where I sails during summer. Is about Bortle 2. Friends summerhouse is Bortle 2 also. Bummer that summer nights, here in the Northern part of the world. Is very short. And for a period, pretty much no pure black nights att all.. 

 

[Star101]

9 minutes ago, ollypenrice said:

It also looks as if you might have had less of a fight with the stars from the TOA 150? I'm looking at the green noise around the bright star to the right of the galaxy in the C11 image. They're both good images but I'd choose the Tak one, personally.

Olly

I have to agree with you both on this one. To me the TOA looks sharper.  The Edge image looks softer. Not sure if that is the processing or the scope. ...For this case I think I have to accept its the scope.

And I know Olly, your processing skills are on par with the best. If you say there is a green tinge, I take it as gospel. 

[Xplode]

7 minutes ago, ollypenrice said:

It also looks as if you might have had less of a fight with the stars from the TOA 150? I'm looking at the green noise around the bright star to the right of the galaxy in the C11 image. They're both good images but I'd choose the Tak one, personally.

Olly

It's most likely an artifact from the camera, the IMX455 sensor does unfortunately suffer a little from reflections

If you look around the image you can find some brightish stars with a smaller star close by, the TOA150 splits them nicely, but the Edge 11 makes them look like artifacts.
The refractor clearly show 2 stars and a fainter one, the Edge 11 barely shows the medium sized one as an artifact.
 

 

 

There's of course other things to consider when comparing here too, there's a large difference in the mount for example, comparing an EQ6-R to a GM2000 is of course not fair, but it makes me wonder why people buy such long FL scopes with a mount that can't handle the resolution of the setup.
Both images were taken around the same time when the jet stream was down south over Spain so seeing should have been pretty good over Germany too.

My advice for @Star101 would be to look at the images taken with the scopes considered and count the really good ones, my guess is there's far between them compared to the good ones taken with refractors.
 

[Star101]

18 minutes ago, Rocket Stars said:

Im going to start looking for a 2 week holiday trip with my wife. Think I need to go somewhere its super nights. And nice in the days. Checked my maps. In the skerries, where I sails during summer. Is about Bortle 2. Friends summerhouse is Bortle 2 also. Bummer that summer nights, here in the Northern part of the world. Is very short. And for a period, pretty much no pure black nights att all.. 

 

A holiday? I have heard that Sweden is not in Lock Down, unlike the UK.  They have even closed the parks.

As I said at the beginning of this thread, its my Birthday in August. We looked at going to Japan for the Olympics as I used to practice/teach Karate and this year Karate was going to be entered as a new item. But, as we all know, its all on hold until further notice. I have kept my holiday request for a month off work....Looks like it will be in the garden. At least I can turn my phone off

[gorann]

I started imaging with a 14" Meade LX200R (ACF) on an EQ8 about a year ago and I have been very positively surprised by its performance. On nights with good seeing it certainly delivers more detail on distant galaxies than my Esprit 150 on a Mesu mount in my second obsy. But it needs guiding to be around 0.4 "/pixel for good performance. Yes, the big scope forced me to build a second obsy next to the old one since I realized that there is no way I could get myself to lift the 14" beast (weighs 40 kg) on and off the mount unless absolutely necessary (so far I have not lifted it off). So, with 14" or bigger scopes you don't really have the option of chosing what scope to put onto the pier on an particular night (unless you are a weight lifter). I do have the advantage of a very dark sky (SQM 21.4 - 21.6, so Bortle 2) and I doubt the 14" SCT would be so rewarding to use under light-polluted skies. As pointed out by others here you need a big pixel camera for such a long FL (3550 mm in my case) so I bought a used Sony A7s - a full frame 12 Mbit mirrorless DSLR with 8.3 µm pixels. It is not cooled but I have the advantage of cold nights (sub zero most of the imaging season) helping to suppress noise, and it is then not much more noisy than my cooled ASI cameras. Here is a recent image (7.7 hours at f/10) with the 14" SCT (more to be found on my Astrobin).

Cheers

Göran

Edited April 19, 2020 by gorann

[Rocket Stars]

2 minutes ago, Star101 said:

A holiday? I have heard that Sweden is not in Lock Down, unlike the UK.  They have even closed the parks.

As I said at the beginning of this thread, its my Birthday in August. We looked at going to Japan for the Olympics as I used to practice/teach Karate and this year Karate was going to be entered as a new item. But, as we all know, its all on hold until further notice. I have kept my holiday request for a month off work....Looks like it will be in the garden. At least I can turn my phone off

Yes, we are not in lockdown. But advised to stay at home as much as possible ect. No gathering of ppl is allowed, Over 10 ppl. (lots of ppl still docent seems to get the message...) Keep safe distance ect. I run my business from pretty much home. Fortunately I own my own my building where I have the production. 20meters walk from the house.. Well, its both pros and cons with that..  

Holiday is going to be when things has come down to a more normal level. But we can dream, cant we!   Ofcoarse, it depends how the economy looks after all this utter mess!!! I think we have hard times ahead of us, even when things starts to move on.. One of my buissines legs is production of display materials for fairs ect.. Let agree on that it moving at zero phase at the moment. Im very fortunate to have other projects going. But at a increasingly slower rate... 

But, we have to stay positive, and don't scream "wolf" at any problem. Take the time to appreciate family, hobbies ect!!! 

[Rocket Stars]

8 minutes ago, gorann said:

I started imaging with a 14" Meade LX200R (ACF) on an EQ8 about a year ago and I have been very positively surprised by its performance. On nights with good seeing it certainly delivers more detail on distant galaxies than my Esprit 150 on a Mesu mount in my second obsy. But it needs guiding to be around 0.4 "/pixel for good performance. Yes, the big scope forced me to build a second obsy next to the old one since I realized that there is no way I could get myself to lift the 14" beast (weighs 40 kg) on and off the mount unless absolutely necessary (so far I have not lifted it off). So, with 14" or bigger scopes you don't really have the option of chosing what scope to put onto the pier on an particular night (unless you are a weight lifter). I do have the advantage of a very dark sky (SQM 21.4 - 21.6, so Bortle 2) and I doubt the 14" SCT would be so rewarding to use under light-polluted skies. As pointed out by others here you need a big pixel camera for such a long FL (3550 mm in my case) so I bought a used Sony A7s - a full frame 12 Mbit mirrorless DSLR with 8.3 µm pixels. It is not cooled but I have the advantage of cold nights (sub zero most of the imaging season) helping to suppress noise, and it is then not much more noisy than my cooled ASI cameras. Here is a recent image (7.7 hours at f/10) with the 14" SCT (more to be found on my Astrobin).

Cheers

Göran

I have seen you're images Göran! They are great!  

[Star101]

https://www.rothervalleyoptics.co.uk/celestron-edgehd-1100-optical-tube-assembly.html

https://www.rothervalleyoptics.co.uk/takahashi-toa-150b-f73-triplet-ortho-apochromat-refractor-ota-package.html

I did agree with the images but then, on checking the scopes, the prices don't compare.

I am looking at something of value between the two.