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ZWO ASI294MC upgrade path?

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#1 Ianp

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Posted 06 July 2020 - 05:03 PM

For EAA, does the ASI2400MC from ZWO seem like worthy candidate for an upgrade?   Based on my limited understanding of the specs, I can see how it would be for astrophotography.  But not clear how they apply - if it all - to near real time viewing with Sharpcap livestacking.

 

Still if I ever do have a spare 3.7k for the hobby, I'm sure that would spur me on to greater understanding of sensor sizes, QE, full well etc

 

Ian



#2 Noah4x4

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Posted 07 July 2020 - 09:52 AM

I presume you mean upgrade from ASI294mc to ASI2400mc?

 

If you advised us what telescope and mount you are using then folk might be better able to assist with your question. However, a $3,500 camera deserves a $3,500 mount.



#3 Ianp

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Posted 07 July 2020 - 04:34 PM

Hi Noah

 

I have a Meade LX600 16inch f/8 on a wedge, and an Orion 120mm f/5 piggybacked on top of the meade.  Both telescopes have an ASI294MC.  

 

My typical exposure time is 3 to 15 seconds and I almost always use Sharpcap's Livestacking feature.  Very enjoyable.

 

ZWO advised the ASI2400MC would be very good for EAA due to high sensitivity.  The full frame sensor is obviously the latest technology.  Is it the sensor you think that makes the price so high?

 

Ian



#4 Noah4x4

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Posted 07 July 2020 - 07:06 PM

Ian said....

 

....Is it the sensor you think that makes the price so high?

 

 

....Nope, it's the mugs willing to pay $3,800 for the latest sensor that makes the price so high.

 

Give it 18 months and I suspect there will be a new sensor with double the resolution at the same $3,800 price and an ASI2400mc will probably be entry level. In computing, this relationship between technology advance and time  is referred to as Moore's Law. I think I just invented Noah's Law for astro camera sensors. It's barely two years ago that 3 megapixel offered us wow status. 

 

But what can you do with extreme large sensor extreme megapixel cameras that can't be done with lesser but still double digit megapixel cameras when affordable computing and display monitors remain limited to 4K UHD? 


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#5 Clouzot

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Posted 08 July 2020 - 05:05 AM


 

But what can you do with extreme large sensor extreme megapixel cameras that can't be done with lesser but still double digit megapixel cameras when affordable computing and display monitors remain limited to 4K UHD? 

The main reason imho: being able to zoom into a large field of view, and not getting pixelated details when doing so.

 

I know you prefer displaying the image as a whole thanks to your carefully chosen 4K setup, but some (including me) will rather display with what they have - probably some HD or Retina display, no more - and will happily zoom into the image to inspect details.



#6 Noah4x4

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Posted 08 July 2020 - 08:37 AM

The main reason imho: being able to zoom into a large field of view, and not getting pixelated details when doing so.

 

I know you prefer displaying the image as a whole thanks to your carefully chosen 4K setup, but some (including me) will rather display with what they have - probably some HD or Retina display, no more - and will happily zoom into the image to inspect details.

Let's preface my comments and questions in the context that this is an Electronically Assisted Astronomy Forum. Also, that I am personally curious to know the answers as this has troubled me for a while...

 

I can see how having a larger sensor and higher resolution camera might benefit Astrophotography where, during post-processing, on (say) a 3860 x 2160 (UHD) display monitor, much of your huge image is typically hidden beyond visible screen dimensions.  You might then focus on a Region of Interest (ROI) within view and crop a portion of your massive 6062 x 4042 pixel original  image to the available 3860 x 2160 and/or Zoom to fill a 4k UHD display. Super stuff! All makes sense for AP.

 

But is having a large sensor and higher resolution camera of tangible practical benefit to those that pursue EAA in the context of near live observing where viewing is limited by a lesser display/monitor? I wonder....?

 

I deliberately pair a 16 megapixel resolution camera with a 4K UHD graphics card and 4K UHD display because I don't see the merit of so much resolution being output to a limited, far more common, 1080p HD laptop screen. Because of interlacing to fit the screen limits, many of the lhe lovely higher pixel count would simply be lost on the lower resolution screen. So if you use a 24 megapixel camera won't the benefit of a higher number of pixels similarly be liimited unless you upgrade to a matching graphics card and 8K display?

 

The counter argument will, of course, be to use Region of Interest (ROI). But how much of an advantage is that for EAA, and does ROI and Zoom in (say) Sharpcap work in the same manner as in a photo-processing application?  I am not convinced that it does....

 

My Atik Horizon has a 4/3" sensor and 4644 x 3506 pixels, but  pixel size of 3.8 um x 3.8 um. 

 

The ASI2400 has a much larger sensor, 6062 x 4042, but somewhat surprisingly, has a larger pixel size of 5.94 um x 5.94 um. This begs some interesting questions for EAA...

 

Surely if squeezing a larger FOV into a common screen dimension then DSO objects will appear smaller? Surely a larger FOV demands more Zoom than a smaller FOV? That is certainly my experience with Hyperstar.

 

However, note that the ASI2400mc  pixels are almost double the size of those of my Atik Horizon. How does that benefit Zoom? Surely the camera having the smaller pixels will offer the greater Zoom potential as for each degree of sky more pixels will have been captured? So might  a larger sensor and larger pixels offer no advantage for near live viewing unless you increment graphics and display capabilities to mirror the camera?

 

Sharpcap typically fills my screen at my normal resolution. But when I use ROI in Sharpcap, it simply crops to produce a smaller area than my original. It doesn't work like (say) Corel Photo-paint where an original image might have its perimeters outside visible screen display. Instead it fits to available screen When I apply Zoom, all remains constrained by original pixel size. As my camera might use a thousand pixels to capture an objects diameter and the ASI2400 might use merely 600 pixels of larger size, how can the latter be superior when applying Zoom? Surely, the ASI2400 camera's apparent higher resolution advantage is simply a product of the larger sensor. It is not a greater physical advantage and the larger FOV might even be a disadvantage if your software/monitor is designed to fit your original image to available screen. Or am I missing something?

 

As I said, I can see the benefit of having a full frame 24 megapixel resolution camera for Astrophotography where post processing is applied in a photo-processing Application. But is there any advantage for EAA within regular EAA software unless you have an 8K monitor? I really don't know, hence thought I should ask these thought provoking questions so that those more expert in camera technology might explain.


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#7 Ianp

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Posted 08 July 2020 - 09:29 AM

Hi Clouzot

 

Yes thanks I think you clarified the basic difference right?  Wow Noah's set up is very cool also I am studying it, as am also considering putting a computer by the scope due to USB3 length issues, and it makes me wonder if a new higher resolution monitor is in order.  Cheap upgrade there.

 

Ok so sensitivity and QE and whatever is better but just for short exposure livestacking, is that practically making a world (ie $3.7k's worth) of difference.  Unless money no object probably not.

 

The ASI12400mc has the"full frame" sensor with 41 degree diagonal compared to the approx 22m diagonal of the ASI294.   Resolution 6072 x 4042.   I don't quite know what to make of such a big size.  Wowser, I started off my EAA journey with Mallincam Extreme 640 x 480!

 

I do enjoy zooming in at the moment with the ASI294.  Its resolution is 4144 x 2822.  On my 22in 1920 x 1080 monitor, after binning 2 the image is around 70% on Auto preview so I can get quite meaningful zooms without pixelation.  I find it quite amazing how close up you can get to a small object doing this, even up to 200% just for the fun of it.  On objects like the Ring Nebula.

 

I am trying to visualize what the FOV would be like, but especially what the zoom would be like on the ASI2400mc say for the same object Ring Nebula.  After binning 2 I still have a resolution of 3036 x 2021, but with a bigger FOV on screen.  If I still have the same HD monitor, I guess I would be at around 50% on Auto.  So that is some pretty significant zooming capacity right there.  How does that Ring Nebula look at 100% zoom I wonder.

 

No Amazon reviews available, therefore one must muse.



#8 Clouzot

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Posted 08 July 2020 - 05:40 PM

@Noah of course you have a point: the larger the pixels, the more light they gather and the closer we get to the long awaited no-latency, real-time EAA. In color, of course. That is hopefully what the 2400MC will deliver to those who can afford it.

 

But that's also because you have the means of displaying the image without losing any definition thanks to your full 4K hardware chain. Whereas on my laptop (1920x1200), if I set Sharpcap's zoom to Auto to display the full FoV of the camera, I'm losing quite a lot of definition. Hence the need to zoom in until I reach a 1:1 relationship between the camera's and the screen's pixels. That's the main benefit of a camera that is "oversampled" in comparison to what the display can achieve from a resolution standpoint: large field of view, and ability to zoom in when needed. The drawback is it needs more subexposures, so that's where one needs a careful balancing of time VS resolution in order to stay within EAA limits (whatever they are!).

 

ROI is not really an option for me, as both my cameras (183, 294) are quite noisy and need darks substraction to achieve a good performance. And using a ROI means different master darks and different flats. Which, I must admit, I'm too lazy to capture each time.



#9 Ianp

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Posted 08 July 2020 - 07:10 PM

It is interesting to note that the ASI2400MC -when binned via Sharpcap on 2 which is what I've found works best for me -  basically matches with a 4K monitor and may be a good match with a 2K WQHD monitor giving nice detail on Auto along with some ability to zoom in.

 

 


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#10 Noah4x4

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Posted 09 July 2020 - 01:34 AM

There is no doubt that; larger pixels will capture more photons and the ASI2400's 100ke full well is one big light bucket. That is a massive advantage for Astrophotography. But this Forum is about EAA.

 

Its  larger pixels must surely be counter productive to Zoom/Pixelation? As you apply Zoom, the fact they start larger, must surely mean they become visible (e.g. pixelate/go blocky) sooner? The higher resolution is simply the product of the increase in sensor size that increases FOV, which surely then makes objects smaller? 

 

The Atik Horizon full well is much smaller, but interestingly it has (marginally) lower read noise than the ASI2400. This is because Atik cleverly amplify Gain (see the video on its website). It's evident the ASI2400 will be superb for Astrophotography. But my original post challenged; does the ASI2400 add anything to EAA for the typical participant? I suspect that unless you upgrade computer and display/monitor, the answer might be no.

 

Clouzots observation about how his 1080p HD screen is a limiting factor suggests the same might apply here unless an 8k display is employed. But for Astrophotography involving post processing it will be an advantage on ANY screen. The reason being that a photo-processing application during post processing permits the image to exceed screen dimensions and hence its perimeter is out of screen vision, so you can scroll and crop to a ROI. But EAA applications like SharpCap don't work that same way as you start will the entire image constrained within screen dimensions. So the visual experience typically differs for EAA and why an 8K display will be desirable. It's why I pair my (circa) 4K camera with 4k display for EAA.


Edited by Noah4x4, 09 July 2020 - 01:50 AM.


#11 Ianp

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Posted 09 July 2020 - 02:36 AM

Noah do you use binning?  It sounds of course like you would always keep your binning on 1.   I"d be interested in some of your settings info to compare notes.

 

A 4K screen sounds interesting.   I never really considered it until reading your comments and equipment choices.  $200 to $350 on Amazon.

 

Unless ZWO specifically mention a new model for EAA, it sounds like we need to proceed with caution before putting this kind of money into a new camera.  The sensor may be marginally better in terms of sensitivity, but at end of day its really just bigger, so bigger FOV.  I get your point.

 

Perhaps someone with a the 2400 or even the 6200 will give feedback sometime about EAA application and show us their results.



#12 Noah4x4

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Posted 09 July 2020 - 04:20 AM

No, I don't use Binning, but I probably should in some circumstances. 

 

Combining pixels (or larger pixels) will increase sensitivity, but correspondingly, I suspect the bigger combined pixels may limit Zoom capabilities (as earlier discussed).  My theory (which might be wrong!) is with a high enough resolution display (perhaps 4k UHD) you only need binning if your camera lacks sensitivity or your photon gathering is too slow (say at f/6.3 or f/10), and you might as well benefit from the available optimum high resolution.

 

I use Hyperstar which gives me a fast f/2 scope which gathers light 25x faster than at f/10. This offers  many benefits, such as my typical exposures are as low as 2 to 10 seconds, hence no polar alignment. no wedge, no GEM, no guiding etc required. Given that my Atik Horizon has a full well of 20,000e and low read noise of~1e at x30 dB (=300 in ZWO speak) it's a fantastic combination on Hyperstar where I have noticed no benefit from using binning at f/2. A 4K + camera on a 4K display is inevitably a better combination than if on 1080p HD display for observing.

 

However, I can't use my Atik Horizon camera at f/6.3 or f/10 as it's too long to offer rear end clearance to the zenith on my Alt-Az.  Hence, I use a shorter ASI294mc at f/10 or f/6.3. There, I probably should embrace binning to help compensate for the slower photon gathering. Note that the ASI294 is also great on Hyperstar, but requires a different adapter as back focus differs from the Atik. But I use the Atik as it is cooled. 

 

It seems that there are relatively few of us using 4K UHD display.  A problem is that the cheapest 4k UHD Laptop is around £2,000, which I find inexplicable. However, most Intel NUCs do offer 4K graphics output and adding a 4K UHD monitor means you can halve the price of enjoying 4K experience. Region of Interest then becomes much more interesting. Similarly, I suspect one possibly needs an 8k display to get the best from an ASI2400 for live observing, but that's not necessary for AP as generally post processing applications will permit an image to be displayed with its perimeter extending beyond visual screen dimensions, whereas live stacking software tends to "fit to screen" when live observing. Now if only I had an 8ft wide 8K screen....

 

EDIT

Before buying a 4K UHD monitor, do ensure your computer graphics card can handle the output! 


Edited by Noah4x4, 09 July 2020 - 04:22 AM.


#13 Rickster

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Posted 10 July 2020 - 01:03 PM

It is interesting to note that the ASI2400MC -when binned via Sharpcap on 2 which is what I've found works best for me -  basically matches with a 4K monitor and may be a good match with a 2K WQHD monitor giving nice detail on Auto along with some ability to zoom in.

Bingo.  The reason for getting a large sensor is quite simple.  A 16in SCT is in an entirely different class than an 8in SCT.  A 16in SCT has a very long focal length.  It needs a correspondingly large sensor to get a reasonable field of view.  And the large pixel count is irrelevant.  Binning is the answer. At that long focal length, unbinned pixels are much smaller than the resolution that can be achieved when looking through the atmosphere.  Binning gives essentially the same benefits as adding a focal reducer without the downside of adding glass to your system.  So yes, getting a large sensor makes perfect sense for that scope.  And given the cost of a 16in SCT, the cost of a large sensor camera is not out of line.



#14 Ianp

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Posted 10 July 2020 - 03:36 PM

Hi Rick

 

Thanks for the post.   I understand what you mean by the focal reducer - My ASI294MC gives me a similar or slightly larger FOV with the 16inch Meade as did my old Malincam exterminator with a focal reducer.  So I was pleased to not have to use the FR.

 

This morning I was also looking at the ASI2600MC pro as a worthy upgrade.  Half the price, small pixel size, 28m diagonal sensor.  The sensor seems very similar to the one in the ASI2400, still plenty big but just smaller.  So same principles you mention would still apply.

 

What is your opinion about an potential upgrade for my widefield scope the Orion 120mm f/5, is there one at this time?  I know the Orion is not high-end or anything but still it works for me as a secondary.   My FOV with the ASI294 on that scope is fine for my needs, it gets objects in view like the Pleidies and large Nebula just fine.

 

Ian



#15 Rickster

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Posted 10 July 2020 - 05:32 PM

I think a full frame camera makes the most sense for your SCT.  I imagine that your budget will be the determining factor that decides which full frame camera.

 

I think that for starters I would put the 294 on the 120mm f5 and see how that works.  Well, actually, you have already tried that.  Yet, it seems to me that from a dollars and cents point of view it is hard to justify putting a $700 camera on a $250 scope.  An alternative would be to get a mono cam with sufficient sensor size that it could also be used with your 16in SCT.  The dual use angle makes it easier to justify the cost.  At least that is what I told myself when I bought my mono cam.  (I also keep a smaller scope piggy backed on my 16in).  And it turned out that I got hooked on using the mono cam on the 16in for going deep, especially during galaxy season.  So 90% of the time the mono is on the big scope and the color is on the small scope.  That makes sense because the small scope is best suited to the big showy colorful targets.  Whereas the big scope is best suited to small distant objects that have very little color. 


Edited by Rickster, 10 July 2020 - 05:35 PM.


#16 Ianp

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Posted 10 July 2020 - 08:11 PM

Thanks Rick.  

 

I am mulling over upgrading the Orion 120mm telescope this year, similar size and f ratio.   Something like a sharpstar f/5.6 refractor.  



#17 Avocette

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Posted 13 July 2020 - 03:05 PM

Noah4x4 wrote: “It seems that there are relatively few of us using 4K UHD display.  A problem is that the cheapest 4k UHD Laptop is around £2,000, which I find inexplicable. However, most Intel NUCs do offer 4K graphics output and adding a 4K UHD monitor means you can halve the price of enjoying 4K experience. Region of Interest then becomes much more interesting. Similarly, I suspect one possibly needs an 8k display to get the best from an ASI2400 for live observing, but that's not necessary for AP as generally post processing applications will permit an image to be displayed with its perimeter extending beyond visual screen dimensions, whereas live stacking software tends to "fit to screen" when live observing. Now if only I had an 8ft wide 8K screen....”

 

This is an interesting issue and raises some others about visual acuity and screen sizes, not just screen resolution. Full-HD resolution (1920x1080) was designed for viewing at 3H meaning 3 picture heights. This was the conclusion resulting from the significant research programme of ‘subjective testing’ undertaken by the NHK TV laboratories in Japan and written up in the highly regarded Monograph from Dr Fujio. Personally, I find that my laptop with its Full-HD resolution and 15.6” screen diagonal is an entirely adequate resolution at my typical viewing distance (mostly limited by the need at my age for reading glasses). I also have a 24” Full-HD monitor which is for me just at the tipping point of being of sufficient resolution at a comfortable viewing distance for a desktop PC ( I also have access to a 27” Full-HD monitor which I find to be marginally too large and therefore lacking a little in resolution at these typical PC viewing distances). My other screens are a 42” Neo-plasma of Full-HD resolution usually viewed from 3 or 4m and a 66” 4K OLED viewed from a similar distance. I have used this latter as a 4K PC display, but find that I have to sit very close to it to gain the benefit of the fine detail (and read tiny text!) probably at around 1.5H which is a little over a metre.

My EAA camera is an ASI533MC with 3008x3008 resolution. I have conjured occasionally, when reading some of @Noah4x4 ‘s earlier postings whether I should attempt to link its images to the 4K screen, but have not done so yet.



#18 Noah4x4

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Posted 14 July 2020 - 03:44 AM

It's true that with a 4K UHD screen regular size Icons and fonts are smaller, but in Windows, you can switch to "large Icons" via settings to restore their original size. Similar "large fonts" etc. 

 

But your next step needs some thought. Will you benefit from a 4K UHD screen? It depends...

 

If you are strictly an Astrophotographer, hence capturing image data for later post processing, then a 4K UHD screen data output is probably a costly and unnecessary luxury at your scope. Hence a cheap mini-computer (or laptop) is all you need for data capture, and a 1080p HD screen.

 

Similarly, what you do later during post processing is a personal choice. However, most photo-processing applications when displaying in a limited 1920 x 1080p (HD) mode will display your larger captured 4K+ image with its extra pixel perimeters hidden beyond visible screen dimensions and you might use <scroll>. Using <crop> or <fit on-screen> is then an easy solution. You probably won't notice any difference when using a 4K display especially as the specific object you are targeting probably only embraces merely 10% of your screen and you will crop/enlarge in any instance.

 

However,  if you are an EAA observer, hence focussed on (near) real time viewing, then simultaneous capture and live-stacking applications generally don't work that way. They instead squeeze your amazingly rich fuller image into whatever limited screen dimensions are available.  Having the extra depth of larger screen full Ultra High Definiton is beneficial. But you do need camera, computer, graphics card, and display to all be of like capability. 

 

I would liken this to graphic designers creating larger posters. If they work at 1080p and on an 'A4' size screen and later Zoom their poster up to larger A3 or A2,  A1 sizes , it will lose definition and pixelate. So they will work in a resolution and pixel density to suit their final display/print, even if their working screen dimensions are limited. 

 

Whilst not so material to Astrophotography (as explained above), for EAA, you ideally want small pixel, high density of pixel and a screen display to comfortably mirror that. Correspondingly,  with an 8" or 9.25" OTA I think (say) an ASI294, ASI533 or ASI1600 camera having a 4k+ resolution and 4/3" sensor is ideal if paired with a 4K UHD graphics and display. My ASI294 and Atik Horizon work great with a 4K UHD display for me, but as an observer. 

 

However,  I suspect that I would not see the full benefits of an ASI2400 or other full size sensor camera unless I had a much larger OTA and greater display capabilities. But if I was post-processing (not live observing) , then benefits will arise. Hence the conclusion reached earlier in this thread that the OP having a 16" OTA will benefit from its giant sensor is correct. But for the majority of EAA observers with a lesser OTA, then it's larger pixels will increase sensitivity, but I suspect that is probably at the expense of true resolution and Zoom.  The apparent extra resolution of the ASI2400 is simply a product of larger sensor size. An Atik Horizon or ASI1600 has pixels almost half its size, so even Zoom x 300% will still produce a tiny (not visible) pixel point. But like all things "visual", whether eyepiece or camera, the major barrier is seeing conditions, and that I found is more material than pixelation at higher resolutions on a high resolution screen. If a cloud gets in your way, the result is identical. 




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