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Old 17-05-2016, 03:43 PM
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Who said the 1600 refuses to capture photons if set to low gain for 10 minutes?
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  #82  
Old 17-05-2016, 04:15 PM
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Who said the 1600 refuses to capture photons if set to low gain for 10 minutes?
Exactly. The sample narrowband images of a bunch of short Ha images versus 1 15 minute image showed the 15 minute image as being nicer overall to my eye.

The camera can do both which is the edge over CCDs.

This sensor is really somewhat old in the sense that the current cutting edge Sony sensors have copper wiring (instead of the usual aluminium and what this means is 4X faster read time and probably less noise, plus a thinner stack meaning it can take light at greater acute angles) and backside illuminated with the circuitry on the back gaining an extra 40% imaging area for the pixels.

Backside illuminated sensors are what most new Sony sensors are using.
This is CCDs increases QE up to the 90-95% band. I am not sure what it does for Sony's. I don't think it is that much though. My Sony A7r2 has all this technology in its 42.4mp sensor and its a pretty amazing sensor. Not ideal in its current state for astro though as it has some colour noise in the shadows at high ISO long exposure (long exposure noise reduction gets rid of it but still).

In addition there are lots of subtle tricks like 3 stage ADC where the as the ISO rises at a certain point this kicks in and drops the noise further.

Some Sony sensors have a built in memory buffer chip on the back of the sensor to improve how many images they can hold.

Sony is also working on some exciting new types of CMOS sensors. One is able to control individual exposures per pixel, they have a curved full frame sensor already. They are supposed to be working on a similar sensor to the Foveon sensor with RGB pixels at different depths on the same pixel site.

Global shutters are not far away either.

Greg.
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  #83  
Old 17-05-2016, 04:33 PM
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Who said the 1600 refuses to capture photons if set to low gain for 10 minutes?
I thought the idea was to capture lots of really short subs, otherwise I cannot see where is the revolution......maybe except for a lower price for an astro-camera!
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Old 17-05-2016, 05:04 PM
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It can operate in either mode. And yes it is a price leader for what your getting. It is pretty clear that it is an upgrade path for many DSLR users, that cannot make the leap (financially) to the higher end CCD cameras. Let's wait and see what the new owners produce in either mode before making value judgements.
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Old 17-05-2016, 05:39 PM
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Although ithe download time is probably about 40ms for full res, so, even at 1sec, not many hotons will come along while the chip is doing something else.
t 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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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.
the full frame download time should be around 40ms (it runs at up to 23 fps full res), so the chance of photons being missed while the chip is doing something else is quite small, even at 1 second subs.

The big thing though is the low read noise, which allows you to get to sky-limited performance with short subs. One second is a bit extreme (but possible) - maybe 30 seconds would be more mainstream and still provide some significant advantages. You don't have to use short subs, but why not if there is no SNR penalty and you get improved dynamic range and all the mount advantages?

Note that short exposures are not unprecedented in the professional arena. For example, PanSTARRS has a low read noise detector (for larger pixels at 5 electrons) and is sky limited after 15 seconds - typical exposures are 30 seconds. Once you get to sky-limited, longer subs do not help you extract signal in the final image - longer subs will look better individually, but the final stack from a lot of short subs will be the same as that from a few long subs if they are all sky-limited. Longer total exposure improves things, but not longer subs.

Last edited by Shiraz; 17-05-2016 at 06:14 PM.
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Old 17-05-2016, 06:02 PM
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Thank you for explaining that Ray.

I thought that 1-second subs would be on the extreme end of the spectrum and even low read noise would most likely drown weaker signals from a DSO.
30 or so seconds sounds much more reasonable for faint fuzzies. So accurate guiding is still required meaning expensive mount for top quality data. I was quietly hoping I was wrong and could spend "dream mount" money on a boat...
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Old 17-05-2016, 06:21 PM
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I thought the idea was to capture lots of really short subs, otherwise I cannot see where is the revolution......maybe except for a lower price for an astro-camera!
Cooled mono sensor ~22mm diameter for under $2k? Revolution, pah
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Old 17-05-2016, 06:35 PM
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Of course, it takes significantly longer to get sky limited with narrowband, so it might still be a while before you have your magic bullet, Suavi.

I'm sure that low read noise, high QE sensors are the future and this might be another step on the road there... It will be good to see results from production hardware. I'd also like to see a 16803 sized sensor rather than these tiny toys

Cheers,
Rick.
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Old 17-05-2016, 08:44 PM
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Cooled mono sensor ~22mm diameter for under $2k? Revolution, pah
As long as desiccant tablets won't come loose!

But more seriously, maybe with significantly lower cost one beautiful day we will all be able to enjoy using cameras with sensors as big as 16803
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Old 17-05-2016, 10:02 PM
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But more seriously, maybe with significantly lower cost one beautiful day we will all be able to enjoy using cameras with sensors as big as 16803
Now that would be a manufacturing revolution I'd be happy to partake in......
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Old 18-05-2016, 10:16 AM
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QHY has a few already in planning. Look at the QHY42. That is similarly sized to the KAF16803 but with larger pixels which would suit long focal length (9 microns is a bit small for 3 metres).

Greg.
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Old 18-05-2016, 12:18 PM
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As long as desiccant tablets won't come loose!

But more seriously, maybe with significantly lower cost one beautiful day we will all be able to enjoy using cameras with sensors as big as 16803
yeah we'll have to keep dreaming for a while longer I reckon
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Old 18-05-2016, 04:57 PM
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Jon Rista over on CN has been doing some work on master darks, bias frames, and gain settings for this camera , which it seems he just received yesterday. It is worth checking out the files he has posted, on page 23.
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Old 18-05-2016, 05:57 PM
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Thanks Glen for the heads up.

Bias and Dark frames look good, except for a substantial amp glow even in a 120s dark. So darks at this stage would be essential in calibrating subs; not a big deal really. I must admit I am spoiled with my camera, as I only need to use a SuperBias and Flats
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Old 18-05-2016, 06:40 PM
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Jon Rista over on CN has been doing some work on master darks, bias frames, and gain settings for this camera , which it seems he just received yesterday. It is worth checking out the files he has posted, on page 23.
thanks Glen - gosh that looks like a very tidy DSO camera .

edit: no it isn't, it's brilliant.
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Old 18-05-2016, 06:52 PM
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Thanks Glen for the heads up.

Bias and Dark frames look good, except for a substantial amp glow even in a 120s dark. So darks at this stage would be essential in calibrating subs; not a big deal really. I must admit I am spoiled with my camera, as I only need to use a SuperBias and Flats
+1 ... however, with the lower read noise, smaller pixels (for me, if not you) and bigger FOV it's still very tempting. I reckon I can get more detail yet with a bit more resolution, and it's sometimes nicer (mostly for nebulae) to have a wider FOV... my camera's 674 chip is very small in terms of FOV.

For me to go forward with that acquisition I'd have to be certain that amp glow would calibrate out, and I'd very much like to know the absolute QE.
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Old 18-05-2016, 07:05 PM
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I am tempted myself, I am just being very picky

It certainly will be a very popular camera. Based on the results from CN, read noise at low gain is only 3.35e, full well circa 20,000e and dynamic range about 6000 steps - outstanding results IMO!

I will wait though for the 2nd generation of this camera...

EDIT: Not trying to detour the thread, but I was curious how my camera compares "on paper", so I have just run the same PI script and the results are attached. ICX 814 has half the well depth and significantly lower dynamic range of about 4300 steps, but read noise in ICX814 is still lower - only 2.4e according to this script. Nonetheless, the specs of the new CMOS sensor look very promising, especially at this price.
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Last edited by Slawomir; 18-05-2016 at 07:48 PM.
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Old 18-05-2016, 07:05 PM
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I'd have to be certain that amp glow would calibrate out
Even if it does it will leave noise behind. I'd let someone else be the early adopter. May be a great camera but it will probably get better after the initial teething problems are resolved...

Cheers,
Rick.
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Old 19-05-2016, 01:16 PM
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Some bad news for those of us waiting here in Australia for the ASI1600 camera. I just had an email from Sam at ZWO in reply to my question to him in the ASI1600 Q&As on their website, concerning emerging supply chain issues and information provided by Bintel to me regarding the pre-order shipment. Here is Sam's email in total:

"We arranged the Bintel's shippment on Tuesday, we planned to send it on Thursday, but we didn't send all of the new cameras they ordered, because we don't have enough stock, we are lack of PCB board ,whcih needs long time to produce,and that's also why shippment delayed. It's just supply problem.
We olny sent a few 1600 cameras to our customers who ordered directly from us.
More new cameras will be available at the end of this month or the start of next month."

So it appears that Bintel will be not be getting all their expected pre-ordered ASI1600s in this next pending shipment. And that direct orders are also having to wait. Lack of PCBs is a fairly serious impediment to supply at this launch point, and it's obvious that ZWO may have under estimated the demand they would have to fill.

Hopefully Bintel communicates with the pre-order list and lets them know who is getting cameras this month. I have sent Sam's email on to Bintel.
I expect that pre-order pricing must be honoured by all concerned until all have been supplied.
Obviously I am disappointed at having to wait, assuming I won't get one in this next shipment, but it provides more time for the CN beta testers to tease us.
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Old 19-05-2016, 02:22 PM
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Some bad news for those of us waiting here in Australia for the ASI1600 camera. I just had an email from Sam at ZWO in reply to my question to him in the ASI1600 Q&As on their website, concerning emerging supply chain issues and information provided by Bintel to me regarding the pre-order shipment. Here is Sam's email in total:

"We arranged the Bintel's shippment on Tuesday, we planned to send it on Thursday, but we didn't send all of the new cameras they ordered, because we don't have enough stock, we are lack of PCB board ,whcih needs long time to produce,and that's also why shippment delayed. It's just supply problem.
We olny sent a few 1600 cameras to our customers who ordered directly from us.
More new cameras will be available at the end of this month or the start of next month."

So it appears that Bintel will be not be getting all their expected pre-ordered ASI1600s in this next pending shipment. And that direct orders are also having to wait. Lack of PCBs is a fairly serious impediment to supply at this launch point, and it's obvious that ZWO may have under estimated the demand they would have to fill.

Hopefully Bintel communicates with the pre-order list and lets them know who is getting cameras this month. I have sent Sam's email on to Bintel.
I expect that pre-order pricing must be honoured by all concerned until all have been supplied.
Obviously I am disappointed at having to wait, assuming I won't get one in this next shipment, but it provides more time for the CN beta testers to tease us.
ok to be very clear with this from past experience BINTEL will only honour the special price if you have paid in full - as i said just my previous experience
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