#41  
Old 13-05-2016, 05:26 PM
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Shiraz (Ray)
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Pretty sure it is set point cooling.

the rolling shutter issue probably only applies to something that is moving rapidly. Hopefully most of the our targets will stay still.

The example dark frame shows no amp glow that I can see
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Old 13-05-2016, 05:52 PM
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The beta testers on CN report that it has set point cooling, however, remember it requires a 12v power supply with adequate amperage to get there. The power supply i believe is not supplied with the camera. This is not an issue as i have a couple of very good 6amp supplies that i use with my cooled DSLRs. Of course the TEC will only draw what it can handle so i know the supplies i have are adequate. In a dark site situation, on battery power, you probably need at least a 40AH battery for a nights imaging run, that ensures not discharging to low.

Now what exactly is their definition of set point cooling; is it set point against ambient or set point on the slider bar. My cooled dslrs are set point against ambient to a delta t of -30. I suspect the ASI1600s are setpoint against the slider bar position because i don't think the camera measures ambient. The result is a bit of mental gymnastics to work out the slider bar set point relationship with ambient results. I suspect that i will put in some form of ambient measurement near the camera to track ambient and i may use my dslr setpoint pwm switch to throttle the power to the TEC to get it to my externally measured ambient baselined setpoint. This is pretty easy to set up, well because i have the gear already, but some people may assume they are running at -25C when in effect the sensor is actually at 0C on a 25C night. Not necessarily a bad thing as long as you can cool to the sensors 'sweet spot', where bias frames equal long darks, which in the Canon 450D is 0C. Going deep below that is not necessary, so having temperature info is important.

Last edited by glend; 13-05-2016 at 06:15 PM.
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  #43  
Old 13-05-2016, 07:15 PM
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12v is standard for cooled CCD cameras so that's not an issue. I've already got a three big batteries in my micro obs for running my gear, hooked up to a portable solar panel that I rotate over the batteries.

I wouldn't expect the ASI1600 to measure ambient: it should measure the sensor temperature and if it's regulated, keep it at that specified temperature, so long as it's capable of doing so. If it can't do that, I'm not sure I'm interested. I've never tried dark scaling, maybe it's fine, but it does make wary.
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  #44  
Old 13-05-2016, 07:34 PM
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Originally Posted by codemonkey View Post
12v is standard for cooled CCD cameras so that's not an issue. I've already got a three big batteries in my micro obs for running my gear, hooked up to a portable solar panel that I rotate over the batteries.

I wouldn't expect the ASI1600 to measure ambient: it should measure the sensor temperature and if it's regulated, keep it at that specified temperature, so long as it's capable of doing so. If it can't do that, I'm not sure I'm interested. I've never tried dark scaling, maybe it's fine, but it does make wary.
All their specs are stated at absolute temperatures and they claim regulated cooling (which I take to mean that it is set to a fixed temperature). Cannot think of any reason why they would want to do it differently from everyone else and assume that they put a temperature sensor on the chip and a feedback loop.
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Old 14-05-2016, 01:21 AM
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This question was asked of Sam on a Cloudy Nights thread whether its ambient or a setpoint. He answered ambient.

Greg.
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  #46  
Old 14-05-2016, 02:56 AM
glend (Glen)
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Yes Greg i now agree. I asked the question on CN about set point temperature and have had several answers confirming it is adjusting temperature on the driver slider. Apparently Sam has confirmed it there somewhere as well. That is good news.
It appears that individual deliveries are now happening in the US for those that ordered direct from ZWO.
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  #47  
Old 14-05-2016, 09:14 AM
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Not many sleeps to go now Glen!

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Old 14-05-2016, 09:22 AM
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Awesome. I'll definitely be keeping an eye on this one.
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Old 14-05-2016, 09:53 AM
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the rolling shutter issue probably only applies to something that is moving rapidly. Hopefully most of the our targets will stay still.

As you say rolling shutter is only a problem for video of fast moving objects.
Perhaps it may impact planetary imagers and that was why it was brought up on Cloudy Nights? Don't planets sometimes flick around with the seeing?

Greg.
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Old 14-05-2016, 10:11 AM
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Quote:
Originally Posted by gregbradley View Post
the rolling shutter issue probably only applies to something that is moving rapidly. Hopefully most of the our targets will stay still.

As you say rolling shutter is only a problem for video of fast moving objects.
Perhaps it may impact planetary imagers and that was why it was brought up on Cloudy Nights? Don't planets sometimes flick around with the seeing?

Greg.
Back in the days when CMOS was about to take over from CCDs in planetary, there used to be a lot of waffle about rolling shutters being bad for planetary imaging. Then the ASI120 and QHY5L2 cameras came on the market - it turned out to be a total non-issue. Just another red herring from the CCD purveyors (and I guess we will hear a bit from them in the coming months as the CMOS chips show what alternatives might be possible in DSO imaging).

Last edited by Shiraz; 14-05-2016 at 10:26 AM.
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Old 14-05-2016, 10:28 AM
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There was a question about fast moving objects like comets, i think it was on the ZWO Q&A page.
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Old 14-05-2016, 01:26 PM
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There was a question about fast moving objects like comets, i think it was on the ZWO Q&A page.
Well I would be stunned if you got the jello wobbly effect of rolling shutter from something as slow as a comet. Examples of jello wobble usually are of an object like a tripod and then rapidly shaking the camera back and forth to create the bendy effect where the straight lines bend in video not stills.

No way is it going to be a problem. For one thing we do DSO imaging tracked.

Greg.
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Old 14-05-2016, 05:32 PM
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The IMX224 has a rolling shutter but you don't hear many complaints from owners of cameras equipped with that sensor
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Old 14-05-2016, 09:02 PM
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Cameras based on this sensor are going to create a new market segment, particularly because of the sensor size and the projected pricing.

Pros:

Large sensor size
Relatively low cost compared to other cameras with similar sensor size
Smaller form factor and lighter weight than other cameras with similar specs

Cons:

Noisy sensor
Shallow wells
Low sensitivity beyond the visible part of the electromagnetic spectrum

The disadvantages easily explain the low cost at which vendors are able to deliver this product. However, these can be partially overcome with careful integration and studious processing. Moreover, this sensor will make deep-sky work more affordable for the budget-conscious and beginner market.

This sensor has caught the attention of ONAG owners, since it allows on-axis guiding at almost full aperture (depending on the OTA) and without the need to adjust the X/Y staging to find a guide star. This benefit is in some ways offset by the lower sensitivity at this end of the spectrum (compared to the ICX825 it is > 50% less sensitive).
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Old 14-05-2016, 10:13 PM
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Noisy sensor
Shallow wells
Low sensitivity beyond the visible part of the electromagnetic spectrum
these sensors have almost zero noise Brett - they are way less noisy than anything else out there, including all the super expensive hero cameras.

well depth is totally immaterial if you have a thousand frames to integrate - the effective well depth is then 1000x that of a single sub. 20,000,000 electrons should be enough well depth for the average user.

the quantum efficiency has not yet been specified, but this is a modern chip design from a state of the art digital camera - it has to be pretty good to be competitive in that arena.

you cannot really go past the image in Richard's link (#18) - this is definitely not el-cheapo technology.

Last edited by Shiraz; 14-05-2016 at 11:10 PM.
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  #56  
Old 14-05-2016, 10:34 PM
glend (Glen)
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Ha ha, Ray I was not going to take the bait, but you have my support. I don't know where he is getting his information from (maybe QHY). I don't discount the possibility that vendors have agents on these forums (paranoia yeah). He obviously has not followed the long beta test thread on CN for this camera.
http://www.cloudynights.com/topic/53...mmc-beta-test/

BTW Quantum Efficiency of the mono version is stated at 60% and likely a little higher (see the CN thread). The QE of the colour version of this Panasonic chip as used in the OM camera is shown by Senorgen to be 48%.
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Old 14-05-2016, 10:51 PM
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Yeah I was going to say something too. QE on this sensor is likely to be high.
Probably higher than CCDs which are quite dinosaur in their level of sophistication compared to Sony Exmor and other modern sensors that are packed with bright ideas.

Well depth I am not sure about but I thought I read somewhere that it was higher than KAF8300.

Low noise though is what this sensor is mostly about. Low noise, high QE like the Sony ICX CCDs. I expect it will be quite a hot camera for the price.

Olympus have many diehard fans out there who own the OMD series cameras.

Greg.
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Old 14-05-2016, 11:04 PM
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Hi Ray,

Quote:
Originally Posted by Shiraz View Post
these sensors have almost zero noise Brett - they are way less noisy than anything else out there, including all the super expensive hero cameras.
Almost zero noise? Are you sure about that, Ray? Looking at the ZWO-supplied 5 minute dark frame, I would hardly call this sensor "almost zero noise". The QHY12 I am using here might not necessarily be of precisely the same specification, nor is it the hero camera you describe, but it most assuredly produces less noisy 5 minute darks than those shown here:

http://astronomy-imaging-camera.com/...SI1600300s.zip

Quote:
Originally Posted by Shiraz View Post
well depth is totally immaterial if you have a thousand frames to integrate - the effective well depth is then 1000x that of a single sub.
If this is the case Ray, then why do sensor manufacturers bother with varying well depths at all? More importantly, why do discerning astrophotographers prefer sensors with deeper wells? If what you say is true, everyone may as well abandon all other sensors and immediately switch to the new Panasonic sensor.

Quote:
Originally Posted by Shiraz View Post
the quantum efficiency has not yet been specified, but this is a modern chip design from a state of the art digital camera - it has to be pretty good to be competitive in that arena.
There are numerous graphs which have been published which show the QE, both on ASI's site and also over at Point Grey.

Quote:
Originally Posted by Shiraz View Post
you cannot really go past the image in Richard's link (#18) - this is definitely not el-cheapo technology.
I never went as far as calling it "el cheapo", but let's face it Ray, if you look at the numbers this is not intended as a professional/scientific sensor.
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Old 15-05-2016, 09:02 AM
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Thanks Brett.

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.

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.

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)

Last edited by Shiraz; 15-05-2016 at 06:34 PM.
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Old 15-05-2016, 09:10 AM
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Good post Ray. You are good at summing things up in a concise way.

Greg.
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