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  #61  
Old 15-05-2016, 08:30 AM
glend (Glen)
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Thanks for that post Ray. Which dark did you use? I understand the new ZWO driver update posted by Sam to beta testers helped to reduce the amp glow in the 300" Dark they posted as an example. I think thing will continue to evolve as more people get the production versions and updated drivers are released.
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  #62  
Old 15-05-2016, 08:39 AM
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Thanks for that post Ray. Which dark did you use? I understand the new ZWO driver update posted by Sam to beta testers helped to reduce the amp glow in the 300" Dark they posted as an example. I think thing will continue to evolve as more people get the production versions and updated drivers are released.
the one in the 1600 section on the ZWO website Glen. I thought that dark looked quite nicely uniform anyway -not a lot of "glow" visible and very few bad pixels.

Yes, it is early days yet I guess and these things will only improve, but it is already exciting.

Last edited by Shiraz; 15-05-2016 at 10:04 AM.
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  #63  
Old 15-05-2016, 10:07 AM
glend (Glen)
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I hope to get mine by the end of this week, and will ring Bintel tomorrow to check on the arrival. The QHY 36mm filter wheel ships tomorrow out of Hong Kong via Fedex, i hope to be testing soon.
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  #64  
Old 16-05-2016, 02:11 AM
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Thanks Brett.
Thanks Ray.

You're welcome, Ray. I'm glad you took the time to review and edit your original post because I was quite surprised by some of the sweeping statements that you made. Would I be correct in saying that you no longer hold the view that Well Depth is simply a marketing gimmick?

If so, I'd be interested to know what changed your view overnight.

If not, I encourage you to do a quick search on the Cornell University archives (arXiv), where you will find an abundance of peer-reviewed papers which make heavy use of this important metric. Many of these originate from NASA/JPL. Given their experience in this field, I remain unconvinced that they would fall victim to mere marketing hogwash.

If I'm not mistaken, Ray -- and please by all means tell me if I am -- you made similar comments in the past with regards to pixel size, without having so much as an iota of data to back up your claims.

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I measured the RMS variability of the ZWO dark and it is ~12 electrons due mainly to the dark current of about 0.5e/s/p (I had to make of few assumptions here - ZWO has not published a dark current number). That is almost exactly equivalent to a 5 minute dark from your QHY12, which also has an RMS variability of 12 electrons due to read noise. Your darks will not have the pedestal of the ZWO dark, but, when that is subtracted, the total noise will be ~identical for the two cameras. For anything shorter than 5 minutes, the ZWO will be better, but the QHY will always have 12 electrons read noise. At a sub length of 5 seconds (say), the ZWO could have under 2 electrons RMS total noise - this is very close to zero noise and I know of no other affordable camera that even gets close.
Yesterday, you made mention of the ZWO dark and how it somehow compared to an SX ICX649-based camera (which is an excellent instrument) running at -10C. I'm not sure what you were trying to achieve there (given the difference in setpoint). Today, you say you've measured the ZWO dark variability and you're comparing it against... what?

Now I realize that comparing the QHY12 to the 1600MM is not an apples-to-apples comparison (forgive me, I don't have a 16Mpx sensor on hand), but a side-by-side visual inspection of 5 minute darks at -25C in no way suggests that the Panasonic sensor has less noise than the former -- much to the contrary. Look closely at the ZWO-supplied darks -- you'll find what many would consider a serious row defect consisting of almost 10 contiguous pixels. In my relatively limited experience, I've never seen a defect of that magnitude on any sensor, even at room temperature.

If you received a camera from nearly any other vendor with that sort of defect, you'd not only get a heartfelt apology, you'd more than likely be promptly provided with a replacement camera (especially if it were a company like SX, whose sensor you made mention of in your previous post).

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ZWO is going to have a problem though, because people are still thinking in CCD terms, where you must have long subs to get over the top of the read noise and that means that you must have deep wells to get around saturation on bright stars. The new CMOS chips will work best with short subs (where the older CCDs are hopeless) and that brings all sorts of advantages including drastically reduced mount requirements, no need for guiding, better resolution and almost unlimited well depth. However, it requires a complete rethink of how one uses a sensor - there will be people who will try to soak the new chips with 20 minute subs and f10 telescopes (like they used to do) and they will not get good results - expect a barrage of "this thing has bad dark current and saturates easily" as people drastically misuse the new cameras.
So you're suggesting that, in an age where we are apparently moving away from CCD, folks can look forward to taking images of DSO's with the help of hundreds of 5 second exposures, just to circumvent the so-called well-depth limitation/marketing ploy and read noise?

Not this camera -- it simply doesn't have the sensitivity for the pipe-dream that you're describing. The saturation is real, Ray -- which is why well depth matters.

Let's look at the maths. The download time for a 16Mpx image, the storage required (admittedly of lesser concern in 2016) and the eventual processing power and thus the time involved is significant. Going by your 5 second suggestion, that's 120 images per minute and 7200 images per hour? Running that through PixInsight or Maxim? For a typical 3-4 hour session of imaging time (28,000 or so images?), you're looking at the better part of a day to fully integrate and stack all of the resulting data, even on an 8 or 12 thread system. No thanks It sounds to me as though you're trying to weasel your way out of the fact that this is a noisy CMOS sensor with highly limited wells.

This works on something like an ICX825 -- which many folks here (including myself) have. It might be a smaller sensor than the one in the 1600MM but it is far and away much more sensitive and for most astronomical targets, the ideal sensor for the imaging technique to which you are inferring. That's why it ships with software that does it.

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CCDs still have a place - the old methods still work well. The CMOS cameras also will likely not do quite as well at narrow band imaging, where the higher read noise will be more of a problem. They will also possibly do best with relatively fast scopes (haven't done that analysis yet). However, the new chips offer some very exciting possibilities for anyone willing to experiment with radically new ways of doing things (which will not be appealing to everyone). This really is shaping up to be a revolutionary development, as Emil's extraordinary image shows (see post #18)
Sorry to bring this up, Ray, but you in your previous post you asserted that the Panasonic sensor used in the 1600MM is a "dedicated astronomy sensor". This is untrue. I'm not sure where you sourced this information from (Cloudy Nights perhaps?) but few CCD manufacturers have developed a sensor specifically for astronomy usage and Panasonic is certainly not one of them, nor have they made any such claims about the intended market for this sensor.

What happened to your claims that the available QE data was useless/unhelpful/unreliable due to the fact that it is expressed in relative terms as opposed to the absolute? Has your stance changed on this point? Most of us here are using Sony sensors and are used to comparing such sensors using the relative data available on their whitepapers. Would you mind explaining how much difference there would be in having the absolute sensitivity characteristics available, when it's quite a simple matter to compare sensors using the available relative data, pixel size, read noise, well depth and other characteristics?

I'm not attempting to discredit cameras based on this sensor, just to be clear. I have one on backorder, but I intend to use it for guiding.
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  #65  
Old 16-05-2016, 03:42 AM
glend (Glen)
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Ah Eden you really like to stir the pot don't you? And nothing better to do in the middle of the night? I don't think i have heard such a long essay of sledges in some time. Disguised sledges are a real art form. And claiming you are going to relegate the ASI1600 to a guide camera role is a real hoot. Congratulations on your master piece. Now since you have no interest in this camera can you move on to lurking somewhere else.

Last edited by glend; 16-05-2016 at 03:59 AM.
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  #66  
Old 16-05-2016, 10:15 AM
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rmuhlack (Richard)
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The more I look into it, the more i think that CMOS lucky deep sky imaging is where the future innovation will lie. The ability to capture high resolution images with no guiding and far less demanding mount requirements will be a real game changer. All this is possible (as Ray has already explained) because of ultra low read noise. Furthermore, if the absolute QE is also high then there isn't even a compromise in sensitivity (see Ray's thread on sensitivity here for more detail). Data storage requirements are a magnitude larger as mentioned here already but fortunately storage is cheap (~$50 per TB), especially compared with a mount upgrade.

One thing I have been wondering about though is automation. Currently I'm using SGPro for automation and image acquisition with my SBIG ST8 and ST10, but this wont work directly for video capture. Does this mean that we will be (at least in the short term) sacrificing some automation convenience in favour of increased resolution...?

A compromise I have thought of is that one could use a more traditional capture camera on a guide scope (or maybe an ONAG). A sequence could be queued up in SGPro with the "guide" scope, giving the convenience of automated pointing and plate solving, meridian flips etc. In parallel, a capture sequence is setup in Firecapture to collect the higher frame rate video. Ideally we will see new software that will be able to combine these activities (eg plate solving and auto meridian flips in Firecapture...), but in the short term this might suffice...?
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  #67  
Old 16-05-2016, 10:38 AM
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The proof of all this will be in the images presented no matter what approach was taken. Then the better images will show the best way to achieve them. If that is traditional LRGB 5-15 minute subs 1x1 binned and 2x2 binned colour at 5-15 minute subs or very short stacked.

In my experience even reliable 60 second unguided image is difficult even with high end mounts. Star elongation sets in fast at anything above 500mm focal length.

But autoguided 60 second images are relatively "easy" ( I don't know that anything is "easy" in tracking!).

The Sony ICX CCD cameras required a different approach to the usual for optimal results. Dark subtraction often visibly added noise.

Time will tell meanwhile its fun to speculate on what might be. So no need for heated discussions on mere speculations and predictions.

The images will speak for themselves.

Greg.
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  #68  
Old 16-05-2016, 10:54 AM
glend (Glen)
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Richard, i saw a post on CNs saying Sam at ZWO was working with SGP on integration of the ASI1600, whatever that involves.
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  #69  
Old 16-05-2016, 11:57 AM
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So no need for heated discussions on mere speculations and predictions.

The images will speak for themselves.

Greg.
eg, some early examples Greg - apologies if these have already been linked to or if you have already seen.

(Richard's link to Emil's image) 2000x1second!!!! subs http://www.astrokraai.nl/dump/201605..._Kraaikamp.jpg

15 minute total narrowband comparison 45x20 seconds or 1x 900 seconds http://www.cloudynights.com/index.ph...tach_id=690427

~ 1 hour total colour - 54x30 seconds bin 2 for each of RGB http://www.cloudynights.com/index.ph...tach_id=690357

It has already gone past mere speculations and predictions Greg - and it looks like cMOS is poised to make some fundamental changes to our hobby. Unfortunately that is going to be a pretty scary time for some.

Last edited by Shiraz; 16-05-2016 at 12:55 PM.
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  #70  
Old 16-05-2016, 12:58 PM
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Let's look at the maths. The download time for a 16Mpx image, the storage required (admittedly of lesser concern in 2016) and the eventual processing power and thus the time involved is significant. Going by your 5 second suggestion, that's 120 images per minute and 7200 images per hour? Running that through PixInsight or Maxim? For a typical 3-4 hour session of imaging time (28,000 or so images?), you're looking at the better part of a day to fully integrate and stack all of the resulting data, even on an 8 or 12 thread system.
for anyone considering this camera, the above analysis is wrong by a factor of 10x. The processing will be onerous, but not this bad.

Last edited by Shiraz; 16-05-2016 at 01:37 PM.
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  #71  
Old 16-05-2016, 01:06 PM
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multiweb (Marc)
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(Richard's link to Emil's image) 2000x1second!!!! subs http://www.astrokraai.nl/dump/201605..._Kraaikamp.jpg
Expensive EQ mounts manufacturers will probably start to get worried. Big dobs might take over as imaging platforms.
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  #72  
Old 16-05-2016, 01:15 PM
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eg, some early examples Greg - apologies if these have already been linked to or if you have already seen.

(Richard's link to Emil's image) 2000x1second!!!! subs http://www.astrokraai.nl/dump/201605..._Kraaikamp.jpg

15 minute total narrowband comparison 45x20 seconds or 1x 900 seconds http://www.cloudynights.com/index.ph...tach_id=690427

~ 1 hour total colour - 54x30 seconds bin 2 for each of RGB http://www.cloudynights.com/index.ph...tach_id=690357

It has already gone past mere speculations and predictions Greg - and it looks like cMOS is poised to make some fundamental changes to our hobby. Unfortunately that is going to be a pretty scary time for some.

The M101 image is particularly impressive. 27 minutes total each for rgb = 81 minutes. How is it so deep with such little total time? I take it M101 is not super bright and equivalent to say Omega Cent or even less bright. If you just showed me that image I would assume it was 12 hours total expoure or more.

The 900 second Ha of the Crescent seems a bit nicer than the shorter stacked image but that is also impressive. The 2000 image M51 is OK but the core is totally overexposed and blown. Perhaps merely a processing error.

I wonder also about how to process 2000 x 1 sec x 32mb files. They are the same size as my Proline 16803 and CCDstack starts to chuck a wobbly if I open more than about 12 of those! Sam mentioned some free software perhaps it handles large files better than CCDstack which is rather poor at that.

A great start.

I agree, this type of imaging will push for large aperture over tracking ability and high quality mounts. So a large dob with some basic tracker that can do 20 seconds would be good enough. Like Alex did with his 25 inch dob a few years back and a modded Sony NEX 5n.

Greg.
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  #73  
Old 16-05-2016, 01:28 PM
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I wonder also about how to process 2000 x 1 sec x 32mb files.
The M51 image with 2000x1s subs was processed with Autostakkert. Emil (who captured the M51 image) is the author of the Autostakkert software.

Note that in the Cloudy Nights thread he says that he captured that image with maximum gain, and because the saturation is so low at that gain level he captured using 8bit images only ("as that is enough to represent all the signal") see here
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  #74  
Old 16-05-2016, 01:33 PM
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Expensive EQ mounts manufacturers will probably start to get worried. Big dobs might take over as imaging platforms.
I would hate to be in their position. I guess that there will always be a market for strong accurate mounts, but I really hope they have some strategy for dealing with what seems to be coming in the entry/intermediate market. Same goes for the makers of CCD cameras I guess.

i guess that this is what is called a disruptive technology.
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  #75  
Old 16-05-2016, 01:34 PM
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Thanks Richard.

So he went 8bit to speed up the processing of the files at the expense of dynamic range. He can't say 8 bit was enough when the core is way overblown - it wasn't enough. It seems strange though as 1 second exposures surely can't blow out the core. But I suppose if he is shooting at the equivalent of ISO6400 or something you could. 8 bit would be sacrificing some dynamic range surely or the if not then the gain was too high.

Its an impressive image for 1 second exposures and 2000 of them (it must be some sort of record!). But basically its still a fail as far as a high quality astro image goes.

Greg.
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  #76  
Old 16-05-2016, 02:39 PM
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Getting ready, I have just installed Autostakkert (the new beta version 2.6.6) and had a look at it. A new world for sure but it seems logically laid out & includes ZWO Firecapture.

Prepping the laptop for the new camera, and I will be cleaning out alot of old image files that have piled up on the hard drive. Mostly individual RAW images off the old cameras, I will keep many of the final images and archive them off to my external USB3 drive.

Waiting to hear from Bintel.
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  #77  
Old 17-05-2016, 10:16 AM
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Just spoke to John at Bintel re shipping and was advise that ZWO has held up the shipment and it will not leave China until Thursday (19th) of this week. The reason for the delay is to resolve something with the cameras, don't know what. I do know that some Beta Testers had some AMP Glow concerns on long Darks and Sam (ZWO) had a fix for that, and one tester reported a problem with dessicant pills coming loose in transit, but no other concerns I am aware of right now. So given transit times, customs, etc I would not expect Bintel to get them until the end of next week (say 26th or so). So for those of us waiting, it looks like delivery in the first week of June.
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  #78  
Old 17-05-2016, 01:55 PM
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Its better ZWO holds up the shipment to enhance the camera rather than rush it out and people have trouble updating the firmware at home and possibly bricking the camera.

Greg.
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  #79  
Old 17-05-2016, 01:55 PM
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Slawomir (Suavi)
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I would hate to be in their position. I guess that there will always be a market for strong accurate mounts, but I really hope they have some strategy for dealing with what seems to be coming in the entry/intermediate market. Same goes for the makers of CCD cameras I guess.

i guess that this is what is called a disruptive technology.
Although it all sounds really promising and there is definitely a sense of fresh breeze in terms of new technologies being made available to astroimagers, but at the same time I remain sceptical, possibly due to my ignorance...

It seems to me that the laws of physics cannot be broken - there are only so many photons hitting a sensor from a DSO in a given time. So if there is one photon per say 2 seconds from a DSO per unit of area/pixel, chances are we will miss a significant percentage of them with 1s exposures. Just speculating here though...and to clarify, with ideally zero read noise, would longer exposures help to extract DSO's signal from noise coming from the skyglow, or is that corrected with number of subs alone

Either way, those brilliantly fast and sensitive sensors certainly open doors to new ways of imaging.
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  #80  
Old 17-05-2016, 02:22 PM
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Suavi, you have just hit the nail on the head as to why professionals are not going to go down the path of short subs (depending on situation obviously), faint stuff! Difficult to detect at the best of times, short subs can at times leave you with more noise detection than real stuff leading to faint bits being rejected.
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