New sensors from On Semi

[Shiraz (Ray)]

even better if the 12 bits are focused at the bottom of the dynamic range and the ADCs just saturate at a fraction of full well. Then, the main advantage of the deep wells is that they will handle brighter stars without lateral blooming, since I suspect that ABG will be difficult to implement in a back illuminated chip. At 48fps and nearly no read noise, this chip would be usable with very short subs, so lots could be used to get much more than 12 bits of dynamic range.

but we are dreaming - there is no such camera yet . Though it is refreshing to see something that does not appear at first glance to be based on a pixel design from the last century.

[Slawomir (Suavi)]

Originally Posted by RickS

I can't find a data sheet for the ICX695 but I found another camera vendor who says it is 12.5x10.0mm. That's the same as the result I get when I do the arithmetic. Did you get the info from the QHY site, Greg? Perhaps it is not accurate...

Cheers,
Rick.

After a bit of Internet searching I found that all other manufacturers state that ICX695 is the same size as ICX694. The only difference between ICX694 and ICX695 that I managed to identify is that the 695 has half the maximum frame rate supported by the chip that of 694. The same was for ICX814 and ICX815, 814 being the faster of the two (twice as fast). Not sure what impact that would have on astrophotography, maybe download speed would be slower and thus focusing would be affected?

Curiously, Sony does not have data sheets for ICX695 nor for ICX815.

EDIT: the website below has data sheets for these sensors, and numbers indicate that ICX695 has twice the dark signal of ICX694, and chip sizes are the same.

http://www.matrix-vision.com/manuals...58_section_1_1

[gregbradley]

QHY must have posted the wrong measurements.

Oh well the KAF16200 sounds the more interesting of the 2 new sensors.

The KAI8670 at 7.4 microns would be good for medium focal length RCs like an RC10.

Greg.

[RickS (Rick)]

Another sighting of the 16200 sensor: http://www.flicamera.com/16.html

[Slawomir (Suavi)]

Thank you Rick for the link.

Looks like a smaller and cheaper alternative to ML16803, at least when it comes to resolution. Hopefully FLI will bring read noise down though with the final product.

[RickS (Rick)]

The two FLI PL16803 cameras that I analysed for use at SRO both had read noise substantially below the sensor and camera specs so I think the chances of a better result in the final product are good, Suavi!

[gregbradley]

NIce find Slawomir.

I have mny eye on this sensor as it on paper would be an excellent match for the Honders at 6 microns and 40K well depth.

Hopefully the read noise comes down and it may with the slower download speed.

The other company talking about this sensor is Atik but I always considered them rightly or wrongly as a low end manufacturer. Perhaps they have come up to a high level. The Atik one is promoted as probably US$3999.

I imagine the FLI version is more like US$6995 then.

It may fill an imaging gap.

Not sure what the gain is over a KAI11002 apart from a better pixel size match for many setups.

Greg.

[RickS (Rick)]

Originally Posted by gregbradley

Not sure what the gain is over a KAI11002 apart from a better pixel size match for many setups.

Looks like the QE might be significantly better than a KAI-11K, Greg, though not as good as the Sony sensors.

Cheers,
Rick.

[Slawomir (Suavi)]

Originally Posted by gregbradley

The other company talking about this sensor is Atik but I always considered them rightly or wrongly as a low end manufacturer. Perhaps they have come up to a high level. The Atik one is promoted as probably US$3999.

Hi Greg, did you mean QHY?

If Atik was making a camera with this sensor, I would be very tempted. But need to save for a more refined mount first...

[gregbradley]

Originally Posted by RickS

Looks like the QE might be significantly better than a KAI-11K, Greg, though not as good as the Sony sensors.

Cheers,
Rick.

Perhaps not significantly 51% to around 58% at peak but perhaps the curve is better on the 16200. The main gain seems to be the lower read noise. Nowhere near the Sony's though but then the Sony's all have tiny well depths. Nothing's perfect eh? The 16803 though is a pretty good all rounder.

Originally Posted by Slawomir

Hi Greg, did you mean QHY?

If Atik was making a camera with this sensor, I would be very tempted. But need to save for a more refined mount first...

Oh yes sorry that's right. Its QHY. Are they up to making a high quality CCD?

Greg.

[Slawomir (Suavi)]

Originally Posted by gregbradley

Oh yes sorry that's right. Its QHY. Are they up to making a high quality CCD?

That's a good question Greg.

[RickS (Rick)]

Originally Posted by gregbradley

Perhaps not significantly 51% to around 58% at peak but perhaps the curve is better on the 16200.

Looks like the KAI-11002 has QE just over 30% at Ha: http://blog.astrofotky.cz/pavelpech/..._PBernhard.jpg
Let's say it's 32%. Unfortunately, it's difficult to read clearly from the graph.

The new mystery sensor is more like 46%: http://www.flicamera.com/16.html

A QE of 46% is a lot better than 32%... it's a 44% improvement (no matter what a certain SBIG reseller says ) And Ha is a pretty important wavelength to us all!

Cheers,
Rick.

[Peter Ward]

Originally Posted by RickS

A QE of 46% is a lot better than 32%... it's a 44% improvement (no matter what a certain SBIG reseller says ) And Ha is a pretty important wavelength to us all!

Cheers,
Rick.

Detecting one in three photons... versus just under one in two.
Fair enough

[RickS (Rick)]

Originally Posted by Peter Ward

Detecting one in three photons... versus just under one in two.
Fair enough

Or needing 10 hours of data to capture the same number of photons as 7 hours with the higher QE sensor. Sounds significant to me.

[Peter Ward]

Originally Posted by RickS

Or needing 10 hours of data to capture the same number of photons as 7 hours with the higher QE sensor. Sounds significant to me.

Having taken some very deep h-alpha images, I have to say I'm pushed to tell *any* difference between 7, then 10 hours of H-alpha data from the same 'scope.

I'd settle for 4 hours of data with superb seeing, over a slightly higher QE during any imaging session.

There are a vast number of award winning astroimages that have been taken with the KAF11002 hence I find this sort of QE difference to be a bit moot

[Shiraz (Ray)]

'Fraid the physics is against you Peter - imaging time is inversely related to QE and "award winning" is not a convincing technical measure that suggests otherwise.

there are 2 efficiency terms in the sensitivity equation that are very important - QE and optics efficiency. To illustrate, compare a Ha imaging system with a 30% QE chip (eg 11002) to one with a 60% QE chip (eg 694). Also assume that the system with the 11002 has 87% reflective mirrors (2 off) whereas the 694 system has 98% mirrors. If the 11002 system requires 10 hours to get to a given signal-to-noise ratio, the 694 system will only require around 4 hours*
- (10hrs*(30*.87*.87/60*.98*.98)). That is a huge difference and the 694 system will be able to image more than twice as many targets in the short periods between clouds.

this doesn't mean that 11002 sensors cannot produce fine images - they certainly can, but they will take a lot longer to do it (in both total exposure and sub length). QE is of fundamental importance and there is no way round that.

On this topic, I am surprised that (Kodak... Truesense....OnSemi...) cannot improve the QE of some of their ABG chips, when Sony and (Aptina... Onsemi..) have for years routinely produced chips with >70% QE, even ones with very small pixels.

*For equal aperture, sampling and obstruction,

[Peter Ward]

Originally Posted by Shiraz

On this topic, I am surprised that (Kodak... Truesense....OnSemi...) cannot improve the QE of some of their ABG chips, when Sony and (Aptina... Onsemi..) have for years routinely produced chips with >70% QE, even ones with very small pixels.

*For equal aperture, sampling and obstruction,

I'm not arguing the Physics, it's pretty cut and dry, but you can't ignore the seeing component of any imaging session either (I suspect this is difficult to quantify).

While they are not ABG, the KAF3200 has had one of the highest QE's bar some pretty expensive back-illuminated chips, for around a decade now...maybe more ..... yet, assuming imaging is the goal, there do not seem to be many world beating KAF3200 based images on the web.

Begging the question: does the theory matter that much given the practical applications of many astro-imagers?

[RickS (Rick)]

Originally Posted by Peter Ward

Begging the question: does the theory matter that much given the practical applications of many astro-imagers?

If you think that theory is irrelevant, why did you bother to buy a 16" scope, Peter? Or do you think that some of the basic parameters matter and others don't?

[Peter Ward]

Originally Posted by RickS

If you think that theory is irrelevant, why did you bother to buy a 16" scope, Peter? Or do you think that some of the basic parameters matter and others don't?

I had a back illuminated +95% QE Apogee camera for a while...frankly I found it to be nearly useless for imaging (instant blooming, , unstable bias, a fixed pattern noise that shifted with wavelength)....sure it was a sensitive sucker, but such a PITA to get clean data from....hence my scepticism about QE being a holy grail....there are so many other factors that need to also be working well.

I've had far more success upgrading mounts and the quality of my guiding (plus optical systems) over the years. The 16" was purchased for its native focal length more than anything else.... Sure the extra aperture is nice, but certainly not the prime reason for the upgrade.

[Shiraz (Ray)]

Originally Posted by Peter Ward

I'm not arguing the Physics, it's pretty cut and dry, but you can't ignore the seeing component of any imaging session either (I suspect this is difficult to quantify).

While they are not ABG, the KAF3200 has had one of the highest QE's bar some pretty expensive back-illuminated chips, for around a decade now...maybe more ..... yet, assuming imaging is the goal, there do not seem to be many world beating KAF3200 based images on the web.

Begging the question: does the theory matter that much given the practical applications of many astro-imagers?

none of this has the slightest bit to do with CCD QE Peter.

- Seeing will remain the same regardless of which chip you have and the high QE chips will still be twice as fast in good seeing as in bad
- the 3200 is a great science chip, but it has 3mpixels and it blooms - it is not a pretty pictures chip
- the theory is very well developed in professional circles and underpins all that we do, whether we know it or not. You might not like the implications, but the theory is a very accurate and complete representation of reality. It would be foolhardy to ignore it.